UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries (Revised July 2021)

James J Stapleton

These guidelines represent the best information currently available to the authors and are intended to help you in making the best choices for an IPM program. Not all registered materials are mentioned. Always check the label and with local authorities for the most up-to-date information regarding registration and restrictions on pesticide use.

https://www2.ipm.ucanr.edu/agriculture/floriculture-andornamental-nurseries/

Floriculture and Ornamental Nurseries March 2021 PEST MANAGEMENT GUIDELINES FOR AGRICULTURE Contents (Dates in parenthesis indicate when each topic was updated) General Management in an IPM Program ................................................................................................................................... 1 Integrated Pest Management (3/21) .......................................................................................................................................... 1 Diagnosing Plant Problems (3/21) ............................................................................................................................................ 2 Diagnosing the Causes(s) of Unhealthy Plants (3/21) .......................................................................................................... 3 Reflective Mulches (3/21) ........................................................................................................................................................... 6 Managing Pesticide Resistance (3/09) ...................................................................................................................................... 7 Diseases (Section reviewed 11/20) ................................................................................................................................................. 9 General Information......................................................................................................................................................................... 9 Management of Soilborne Pathogens (11/20) ......................................................................................................................... 9 General Properties of Fungicides 11/20)................................................................................................................................ 13 Key Diseases .................................................................................................................................................................................... 15 Armillaria Root Rot (Oak Root Fungus) (11/20) .................................................................................................................. 15 Aster Yellows (11/20) ................................................................................................................................................................. 17 Bacterial Leaf Spots, Blights, Cankers, and Rots (11/20) .................................................................................................... 18 Black Root Rot (11/20) ............................................................................................................................................................... 20 Cottony Rot (11/20) .................................................................................................................................................................... 22 Crown Gall (11/20) ..................................................................................................................................................................... 24 Damping-Off (11/20) ................................................................................................................................................................. 26 Downy Mildew (11/20) ............................................................................................................................................................. 29 Fungal Leaf Spots, Blights, and Cankers (11/20) ................................................................................................................. 31 Fusarium Wilt (11/20) ................................................................................................................................................................ 32 Gray Mold (11/20) ...................................................................................................................................................................... 35 Phytophthora Root and Crown Rots (11/20) ......................................................................................................................... 38 Powdery Mildew (11/20) ........................................................................................................................................................... 40 Pythium Root Rot (11/20) ......................................................................................................................................................... 44 Rust (11/20) .................................................................................................................................................................................. 46 Southern Blight (11/20) ............................................................................................................................................................. 49 Sudden Oak Death and Ramorum Blight (11/20) ................................................................................................................ 51 Verticilium Wilt (11/20) ............................................................................................................................................................ 55 Viruses and Viroid Diseases (11/20) ...................................................................................................................................... 57 Disease Control Outlines .............................................................................................................................................................. 59 Aster, China (Callistephus chinensis) (11/20)................................................................................................................................ 59 Azalea (Rhododendron spp.) (11/20).............................................................................................................................................. 60 Begonia (Begonia spp.) (11/20) .................................................................................................................................................. 61 Calla (Zantedeschia spp.) (11/20) ............................................................................................................................................... 62 Camellia (Camellia spp.) (11/20) ............................................................................................................................................... 63 Carnation (Dianthus caryophyllus) (11/20) ............................................................................................................................... 64 Cattleya (Cattleya spp.) (11/20) ................................................................................................................................................. 66 Chrysanthemum (Chrysanthemum grandiflora) (11/20) .......................................................................................................... 68 Cyclamen (Cyclamen spp.) (11/20) ............................................................................................................................................ 71 Cymbidium orchid (Cymbidium spp.) (11/20) ........................................................................................................................ 72 Dahlia (Dahlia spp.) (11/20) ....................................................................................................................................................... 73 Delphinium (Delphinium spp. and hybrids) (11/20).............................................................................................................. 75 Easter Lily (Lilium longiflorum) (11/20) .................................................................................................................................... 76 Fuchsia (Fuchsia spp.) (11/20).................................................................................................................................................... 77 Geranium (Pelargonium spp.) (11/20)....................................................................................................................................... 78 Gladiolus (Gladiolus spp.) (11/20) ............................................................................................................................................ 80 Gypsophila (Gypsophila paniculata) (11/20) ............................................................................................................................. 82 Heather (Calluna vulgaris, Erica spp.) (11/20) .......................................................................................................................... 83 Iris (Bulbous) (11/20) ................................................................................................................................................................. 84 Iris (Rhizomatous) (11/20) ........................................................................................................................................................ 86 Marguerite Daisy (Chrysanthemum (=Argyranthemum) frutescens) (11/20) ......................................................................... 87 Narcissus (Narcissus spp.) (11/20) ............................................................................................................................................ 88 Peony (Paeonia spp.) (11/20) ...................................................................................................................................................... 90 Poinsettia (Poinsettia spp.) (11/20) ............................................................................................................................................ 91 Pot Marigold (Calendula officinalis) (11/20) ............................................................................................................................. 93 Rose (Rosa spp.) (11/20) ............................................................................................................................................................. 94 Shasta Daisy (Chrysanthemum maximum) (11/20)................................................................................................................... 96 Snapdragon (Antirrhinum majus) (11/20) ................................................................................................................................ 97 Statice (Limonium spp.) (11/20) ................................................................................................................................................. 98 Stock (Matthiola spp.) (11/20) .................................................................................................................................................... 99 Strawflower (Helichrysum bracteatum) (11/20) ...................................................................................................................... 101 Sweet Pea (Lathyrus odoratus) (11/20)..................................................................................................................................... 102 Sweet William (Dianthus barbatus) (11/20) ........................................................................................................................... 103 Host-Pathogen Index (11/20) ...................................................................................................................................................... 104 Insects, Mites, and Other Invertebrates (Section reviewed 3/09) ........................................................................................ 109 General Information..................................................................................................................................................................... 109 Common Signs and Symptoms on Plants Damaged by Pest Insects, Mites, Slugs, and Snails (Arthropods) and the Probable Causes (3/21) ..................................................................................................................................................... 109 Monitoring With Sticky Traps (3/21) ................................................................................................................................... 111 Establishing Action Thresholds (3/21)................................................................................................................................. 113 Biological Control (3/21) ......................................................................................................................................................... 115 Insect, Mite, and Other Invertebrate Management ................................................................................................................ 117 Aphids (05/10) ........................................................................................................................................................................... 117 Armored Scales (5/10).............................................................................................................................................................. 121 Armyworms and Cutworms (5/10) ....................................................................................................................................... 123 Bulb Mites (3/09) ...................................................................................................................................................................... 126 Cabbage Looper (5/10) ............................................................................................................................................................ 127 Diamondback Moth (5/10) ..................................................................................................................................................... 129 Foliar-Feeding Mealybugs (5/10) .......................................................................................................................................... 131 Fungus Gnats (3/09) ................................................................................................................................................................. 134 Leafhoppers and Sharpshooters (5/10) ................................................................................................................................ 137 Leafminers (5/10) ...................................................................................................................................................................... 141 Leafrollers (5/10)....................................................................................................................................................................... 143 Root Mealybugs (5/10) ............................................................................................................................................................ 146 Shore Fly (5/10) ......................................................................................................................................................................... 148 Snails and Slugs (3/21) ............................................................................................................................................................ 150 Soft Scales (5/10) ...................................................................................................................................................................... 154 Thread-footed (Tarsonemid) Mites (5/10) ........................................................................................................................... 156 Thrips (5/10) .............................................................................................................................................................................. 158 Twospotted Spider Mites (5/10) ............................................................................................................................................ 161 Whiteflies (5/10) ....................................................................................................................................................................... 164 Nematodes (Section reviewed3/21) ........................................................................................................................................... 168 Weeds (Section reviewed 7/20) ................................................................................................................................................... 174 Common And Scientific Names Of Weeds In Floriculture And Nurseries (7/20) ...................................................... 174 General Methods Of Weed Management (7/20) ................................................................................................................ 176 Susceptibility Of Weeds To Herbicide Control (7/20)...................................................................................................... 180 Container Nurseries ..................................................................................................................................................................... 183 Integrated Weed Management For Container Nurseries (7/20) ...................................................................................... 183 Special Weed Problems For Container Nurseries (7/20) .................................................................................................. 186 Herbicide Treatment Table For Containers And Field-Grown Trees And Shrubs (7/20) ......................................... 188 Field-Grown Trees and Shrubs .................................................................................................................................................. 193 Integrated Weed Management For Field-Grown Trees And Shrubs (7/20) ................................................................. 193 Special Weed Problems For Field-Grown Trees And Shrubs (7/20).............................................................................. 194 Herbicide Treatment Table For Containers And Field-Grown Trees And Shrubs (7/20) ......................................... 195 Field-Grown Flowers ................................................................................................................................................................... 196 Integrated Weed Management For Field-Grown Flowers (7/20) .................................................................................... 196 Herbicide Treatment Table For Field-Grown Flowers (7/20) .......................................................................................... 198 Greenhouse-Grown Crops .......................................................................................................................................................... 201 Integrated Weed Management Inside Greenhouses (7/20) ............................................................................................. 201 Special Weed Problems Inside Greenhouses (7/20) .......................................................................................................... 202 Herbicide Treatment Table For Inside Greenhouses (7/20) ............................................................................................ 203 Integrated Weed Management Outside Greenhouses (7/20) .......................................................................................... 204 Herbicide Treatment Table For Outside Greenhouses (7/20) ......................................................................................... 205 Precautions For Using Pesticides ............................................................................................................................................... 207 ii UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Authors and Credits Suggested Citation Wilen CA, Koike ST, Ploeg A, Tjosvold SA., Bethke JA, Mathews DM, Stapleton JJ. Revised continuously. UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries. UC ANR Publication 3392. Oakland, CA. Crop Team: C.A. Wilen (emeritus), UC IPM Program, UCCE San Diego Co. (Crop Team Leader and UC IPM Facilitator); S.T. Koike (emeritus), TriCal Diagnostics, Hollister; A.T. Ploeg, Nematology, UC Riverside; S.A. Tjosvold (emeritus), UCCE Santa Cruz Co. Diseases: S.T. Koike, (emeritus), TriCal Diagnostics, Hollister; S.A. Tjosvold (emeritus), UCCE Santa Cruz Co., D.M. Mathews, Plant Pathology, UC Riverside Insects, Mites, and Other Invertebrates: J.A. Bethke (emeritus), UCCE San Diego; C. A. Wilen (emeritus), UC IPM Program, UCCE San Diego Co. (Snails and Slugs) Acknowledgment for contributions to Insects and Mites: K.L. Robb, UCCE Mariposa Co.; H.S. Costa, Entomology, UC Riverside; R.S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT; M.P. Parrella (emeritus), Entomology, UC Davis Nematodes: J.J. Stapleton, UC IPM Program, Kearny Agricultural Center; A.T. Ploeg, Nematology, UC Riverside Acknowledgment for contribution to Nematodes: J. Ole Becker, UC Riverside; Becky B. Westerdahl, UC Davis; M.V. McKenry (emeritus), Kearney Agricultural Center, Parlier Weeds: C.A. Wilen (emeritus), UC IPM Program, UCCE San Diego Co. Acknowledgment for contributions to Weeds: L.R. Oki, UC Davis; T.M. Bean, UC Riverside; C.L. Elmore (emeritus), Vegetable Crops/Weed Science, UC Davis About this publication Produced and edited by: UC Statewide IPM Program University of California, Agriculture and Natural Resources Coordinator P. Kosina, UC IPM S.H. Dreistadt, UC IPM Production F.G. Rosa This material is partially based on work supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Crop Protection and Pest Management Competitive Grants Program. These guidelines represent the best information currently available to the authors and are intended to help you make the best choices for an IPM program. Not all formulations or registered pesticides are mentioned. Always read the label and check with local authorities for the most up-to-date information regarding registration and restrictions on pesticide use. Check with your agricultural commissioner for latest restricted entry intervals. To be used with UC ANR Publication 3402, Integrated Pest Management for Floriculture and Nurseries This publication has been anonymously peer reviewed for technical accuracy by University of California scientists and other qualified professionals. This review process was managed by the ANR Associate Editor for Agricultural Pest Management. The UC IPM Pest Management Guidelines are available from: • Online: http://ipm.ucanr.edu • UC Cooperative Extension County Offices March 2021 iii UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES General Management in an IPM Program INTEGRATED PEST MANAGEMENT (3/21) Integrated pest management (lPM) is an ecosystem-based strategy that focuses on long-term suppression of pest abundance and prevention of pest damage through a combination of control strategies. Management actions are taken according to established guidelines or action thresholds after monitoring indicates that control action is warranted. IPM requires knowledge of pest life cycles and pertinent biology and an understanding of crop production. Pesticides when warranted are selected and applied in ways that minimize risks to workers and other persons, beneficial and nontarget organisms, and the environment (e.g., air and water quality). The goal is to suppress the abundance of, or exclude or remove, only the target organism(s) while maintaining the economic viability of the cropping system. Collectively all measures taken under an IPM strategy should attempt to minimize economic crop losses and environmental impact while simultaneously minimizing control efforts such that overall profitability is maximized. Key components of an IPM program in general order of implementation are: • Take preventive control measures, the start-clean and grow-clean strategy. • Monitor crops regularly. • Accurately identifying pests and their natural enemies and correctly diagnose the cause(s) of plant problems. • Develop thresholds or guidelines for when and how to take control actions. • Take appropriate and effective actions, generally both non-chemical and chemical controls in combination. For more information see What is Integrated Pest Management (IPM), For Retail Nurseries & Garden Centers, and University of California (UC) Agriculture and Natural Resources (ANR) printed publications that include Container Nursery Production and Business Management Manual, Integrated Pest Management for Floriculture and Nurseries, and Water, Root Media, and Nutrient Management for Greenhouse Crops. General Management in an IPM Program Integrated Pest Management (3/21) 1 Illustrated version at https://www2.ipm.ucanr.edu/agriculture/floriculture-and-ornamental-nurseries/ UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DIAGNOSING PLANT PROBLEMS (3/21) Diagnosis is the art and science of identifying the cause of the plant problem under investigation. Problem causes can be • abiotic (cultural and environmental) including chemical injury, inappropriate temperatures or soil moisture, mechanical injury, nutrient deficiency or excess, and salt damage • biotic (living organisms, pests) including insects, nematodes, mites, mollusks, plant pathogens, and weeds • combinations of causes including both abiotic and biotic (e.g., drought stress and spider mite damage) or a pest insect and plant pathogen it vectors (glassy-winged sharpshooter and Xylella fastidiosa) To diagnose the cause(s) of unhealthy plants • Ask and answer appropriate questions to define the problem and obtain information relevant to the situation under investigation. See DIAGNOSING THE CAUSE(S) OF UNHEALTHY PLANTS for a detailed example of this. • Thoroughly examine the plants, production areas, and plant care practices. • Use appropriate field diagnostic (quick-test) kits and properly collected samples for laboratory analyses of specific, suspected causes of abiotic and biotic maladies. • Compile the information and consult additional references and resources including local University of California Cooperative Extension (UCCE) Advisors and their publications. • Make an informed diagnosis. For example, to diagnose whether an insect is the cause of damage, it is important to • Learn the pest's life cycle. • Be able to identify each of development stages of the pest. • Know how that pest feeds on the crop or otherwise damages plants. • Learn which pest life stages are susceptible to the available management methods. Note that the most apparent life stage (e.g., flying adults captured in sticky traps, or adult female pests) can differ from the stage(s) that feed on and damage plants and are susceptible to control actions (commonly the immatures, larvae or nymphs). To help you diagnose pest problems, consult COMMON SIGNS AND SYMPTOMS ON PLANTS DAMAGED BY PEST INSECTS, MITES, SLUGS, AND SNAILS (ARTHROPODS) AND THE PROBABLE CAUSES. See DIAGNOSING THE CAUSE(S) OF UNHEALTHY PLANTS for a detailed example. General Management in an IPM Program Diagnosing Plant Problems (3/21) 2 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DIAGNOSING THE CAUSES(S) OF UNHEALTHY PLANTS (3/21) Diagnosing the cause(s) of plant problems can be done by asking a series of pertinent questions and investigating the answers: Questions About the Plant • • • • • • • What are the genus, species, and cultivar of the plant in question? Is this particular plant suited to the production area? Is the cultivar resistant or especially susceptible to diseases or other problems? Is the plant sensitive to certain environmental factors (e.g., salinity, excess or deficient soil moisture)? How does the plant normally appear when grown under various conditions (full sun, shadehouse, greenhouse, coastal versus inland production locations, winter versus summer) or at different stages of growth and development? What is the normal growth rate? What are the characteristics, appearance, and growth habits of a healthy plant, and could these features be confused with an unhealthy plant? Questions About the Symptoms • • • • • • • • • What are the symptoms of the affected plant? What plant parts are affected? Are symptoms restricted to external plant surfaces or are there also internal symptoms (vascular streaking, discolored crown tissue)? Are symptoms present only on exposed plant surfaces or also on protected covered tissues such as unexpanded inner leaves or unopened flowers? What is the distribution of the symptoms on any one particular plant (do symptoms occur on one side of the plant, only on older or newer leaves, on secondary roots but not on primary roots, etc.)? How did the symptoms first start? How do early symptoms differ from more advanced symptoms? How long have the symptoms been present? What is the extent (distribution and severity) of symptoms in the population of plants of a given species or cultivar? Growth Stage • • • • What is the growth stage of the affected plant (seedling, cutting, newly transplanted, mature flowering or fruiting plant, senescent plant)? Is a particular growth stage associated with the problem? What was the condition of the plant when first placed in the production area? How does the growth rate of the affected plant compare to that of a healthy plant? Symptoms on Other Plants • • • • • • Are symptoms restricted to one species or one cultivar of plant? Do the same symptoms occur on one type of plant that is located in different growing areas? Alternatively are there different plantings of the same plant type that are symptomless? What other plant species and cultivars appear affected? Do adjacent plantings, weeds, or nearby landscape plants exhibit similar symptoms? If other plants are affected, do they belong to a common group or family of plants? Patterns • • • How are the symptoms distributed within the specific production area(s) of concern? Are there patterns (repeating numbers of plants or plant rows) to the symptoms or do symptoms occur randomly throughout the planting? Are symptomatic plants found in clustered groups? General Management in an IPM Program Diagnosing the Cause(s) of Unhealthy Plants (3/21) 3 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES • • • • • • • Do the symptoms occur in lines, streaks, or circles? Are symptomatic plants found mostly along the edges of the planting? Are affected plants next to buildings, ditches, roads, weedy areas, or other crops or production areas? Are symptoms associated with subsets of plants within the planting, indicating an association with plants from certain transplant trays, different sources of plant material, or other production factors? Are symptoms associated with physical features at the nursery, such as low or high spots of the field, places where water does not drain well, presence or absence of underlying gravel, or particular soil types? Do such areas become flooded after rains or receive irrigation runoff? Are affected areas under sprinklers or watered by drip irrigation? Timing • • • • • What temporal factors are important? When did the symptoms first occur? Are there various stages of symptoms indicating new infections versus older ones? Have the features or severity of the symptoms changed over time? Do symptoms appear to have developed gradually over a period of time or rapidly and all at once? Biotic or Abiotic • • • Do symptoms resemble those caused by biotic agents, such as pathogens, nematodes, arthropods, or vertebrate pests? Alternatively, are symptoms more suggestive of physiological or abiotic factors, such as nutritional problems, physiological disorders, genetic mutations (chimeras), chemical damage, or environmental extremes? Do the symptoms provide evidence that more than one factor or pathogen is involved? Signs • • • • • • A sign is the visible presence of a causal agent or factor. Are such signs present? Examples of signs are bacterial ooze, chemical residue, fungal growth (e.g., mycelia or spores), and insect bodies or excrement (frass). Are there multiple signs indicating that more than one factor may be involved? What is the distribution of signs on the affected plant (present on all or only on certain plant parts)? Are signs present on all symptomatic plants and do they appear to be associated with the symptoms? Are signs present on adjacent plantings or nonsymptomatic plants? Timing and Context • • • • • • • What time of year did the problem occur? If the problem occurred before, did it take place during the same time of year? What are the current and past weather conditions? Have there been any unusual weather patterns or developments recently or in the past few weeks or months? Have there been any conditions that would hinder plant growth or favor arthropod or pathogen development? Is there evidence of abiotic stress factors (e.g., mineral deficiencies and toxicities, pollution, temperature extremes, salt buildup, water stress or excess, wind or other mechanical damage, etc.)? What is the general location of the nursery (coastal versus inland, next to other crops or nurseries, next to roads, etc.)? Biotic Factors • Which arthropod pests, nematodes, pathogens, snails and slugs, and vertebrate pests are known to occur on the host or cause feeding damage or other injury to the host? General Management in an IPM Program Diagnosing the Cause(s) of Unhealthy Plants (3/21) 4 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES • • Which biotic agents occur in the geographic area of concern? Compile a list of common pests that occur in the area and may be the cause(s) of the current problems. For sources of this information see COMMON SIGNS AND SYMPTOMS ON PLANTS DAMAGED BY PEST INSECTS, MITES, SLUGS, AND SNAILS (ARTHROPODS) AND THE PROBABLE CAUSES, the "Crop Tables" at the back of Integrated Pest Management for Floriculture and Nurseries and the similar information online: Flowers; Fruit Trees, Nuts, Berries, and Grapevines; Trees and Shrubs; and Vegetables and Melons. Source: Container Nursery Production and Business Management Manual. See this publication for more detailed help with problem diagnosis, such as example answers and problem-solving steps for the questions above. General Management in an IPM Program Diagnosing the Cause(s) of Unhealthy Plants (3/21) 5 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES REFLECTIVE MULCHES (3/21) Reflective mulch delays or prevents certain flying insects from infesting plants because reflected ultraviolet light confuses insects’ ability to locate their hosts. Reflective mulches have been effectively used to greatly reduce colonization of young crops by winged aphids, leafhoppers, thrips, and whiteflies. Although few floral crops have been studied, reflective mulches have been shown to be effective in various vegetable row crops against melon aphid, silverleaf whitefly, and western flower thrips. In field-grown crops especially sensitive to viruses or other insect-vectored pathogens, the added cost of reflective mulch may be justified because the mulch can be significantly more effective than insecticides in preventing pathogen infection. Insects that migrate onto a crop often have time to feed long enough to transmit viruses before being killed by pesticide residue on treated crops; reflective mulches can prevent such pests from alighting on the crop. Reflective mulches also conserve soil moisture and can improve crop growth beyond that provided by pest control, possibly due to warmer night soil temperatures, additional available soil moisture, more even soil moisture, and increased (reflected) light levels. Reflective mulch is most effective during early growth when plants are small. As plants grow larger, reflective mulch becomes less effective and other management methods may be warranted. Reflective mulches cease to repel insects when the plant canopy covers more than about 60% of the soil surface. Note that working around reflective mulches can be annoying to workers and require protective eyewear. Transplant through holes in the mulch or apply the mulch before seeded plants emerge from the soil by leaving a thin mulch-free strip of soil along the planting row. Reflective mesh is also available for application over the top of a crop; light-weight material is lifted as plants grow. Various materials, such as plastic (polyethylene or nylon) film, can be used. Silver or gray are the most effective colors for reflective mulch or mesh. White also works, but may not sufficiently suppress weed growth beneath it. Commercially available products include aluminum-metalized or silver embossed polyethylene. Aluminum foil is also effective, but it is expensive, delicate to handle, and not economically feasible on a large scale. Reflective material can also be sprayed onto planting beds. General Management in an IPM Program Reflective Mulches (3/21) 6 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MANAGING PESTICIDE RESISTANCE (3/09) Pesticide resistance can become a problem when the same chemicals are used over and over to control a particular pest. After a period, the pest may develop resistance to a chemical so that the chemical no longer effectively controls the pest at the same rate, and higher rates and more frequent applications become necessary until eventually the chemical provides little or no control. The best way to manage pesticide resistance is to focus on three strategies: avoid, delay, and reversal. Avoid the development of pesticide resistance problems with the use of Integrated Pest Management (IPM) programs, which reduce reliance on chemical control. Delay resistance by using pesticides only when needed, as indicated by monitoring, and when pests are at a susceptible stage. Delay can also be achieved by using pesticides from different chemical classes (e.g., organophosphates, carbamates, pyrethroids, biologicals, etc.) and rotating their use. Reversal of some resistance can occur by allowing time between applications of a class of pesticide to permit resistant populations to become diluted by pesticide-susceptible individuals. Key elements of resistance management include minimizing pesticide use, avoiding tank mixes, avoiding persistent chemicals, and using long-term rotations of pesticide from different chemical classes. Minimize Pesticide Use. Minimizing pesticide use is fundamental to pesticide resistance management. IPM programs incorporating pest monitoring in California, New York, Maryland, Canada, and elsewhere have demonstrated 25 to 50% reduction in pesticide use with an increase in crop quality. Ask your farm advisor for information on setting up and maintaining an IPM monitoring program. Such a program will help determine the best application timing for pesticides (when they will do the most good), thus helping to reduce the number of applications. The use of nonchemical strategies, such as pest exclusion (e.g., screening), host-free periods, crop rotation, biological control, and weed control may reduce the need to use chemicals and consequently slow the development of pesticide resistance. Avoid Tank Mixes. Avoid combinations (mixes) of two insecticides or miticides in a single application. Especially avoid mixing two insecticides with the same mode of action, such as the organophosphates acephate and malathion; this increases selection for resistant pests. Such a 'super dose' often increases the chances of selection for resistant individuals. In some cases, mixing pesticides from two different classes provides superior control. However, long-term use of these two-class pesticide mixes can also give rise to pesticide resistance, if resistance mechanisms to both pesticides arise together in some individuals. Continued use of the mixture will select for these multiple-pesticide-resistant pests. In specific situations the simultaneous application of two different types of chemicals may be necessary, but even in these cases tank mixes should be avoided. For example, insect growth regulators (IGRs) only control the immature stages of insects. If the adult stage must also be controlled, it will be necessary to apply another insecticide. Rather than applying an adulticide in the same manner as the IGR, however, choose a formulation that requires a different type of application. For instance, if the IGR is applied as a spray, it would be preferable for the adulticide to be applied as an aerosol or smoke with rapid kill of the adults and little residual that might select for resistance buildup in surviving immatures. Avoid Persistent Chemicals. Insects with resistant genes will be selected over susceptible ones whenever insecticide concentrations kill only the susceptible pests. An ideal pesticide quickly disappears from the environment so that persistence of a 'selecting dose' does not occur. When persistent chemicals must be used, consider where they can be used in a rotation scheme to provide the control needed and with a minimum length of exposure. One example of a persistent material that must be carefully timed to avoid prolonged exposure is the use of imidacloprid for control of whiteflies on poinsettias. Application of this material early in the crop prolongs the exposure of the whitefly population to this material. It may be best to use natural enemies and/or insect growth regulators early in the crop followed by imidacloprid, if needed. Applications that are too late do not allow the plant to adsorb the material to provide effective control. The best time to apply this material is not later than 3 weeks before poinsettia color initiation. Use Long-term Rotations. Resistance management strategies for insects, weeds, and fungal pathogens all include rotating classes of pesticides (e.g., pesticides with the same mode of action such as pyrethroids, organophosphates, carbamates, etc.). Pesticides with the same modes of action have been assigned the same group number by their respective pesticide resistance action committees (IRAC [Insecticide Resistance Action Committee], FRAC [Fungicide Resistance Action Committee], and HRAC [Herbicide Resistance Action Committee]). These group numbers have been included in the treatment tables of this guideline to help clarify when rotating pesticides, which ones can be rotated. However, the strategies General Management in an IPM Program Managing Pesticide Resistance (3/09) 7 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES used in rotations differ. For example, with fungicides, it is suggested that classes be rotated every application. With insecticides, a single chemical class should be used for a single generation of the target pest followed by a rotation to a new class of insecticide that will affect the next generation and any survivors from the first generation. Longer use of a single chemical class will enhance the chance of resistance since the survivors of the first generation and the next will most likely be tolerant to that class. Rotating through many chemical classes in successive generations will help maintain efficacy. If there is only one chemical that is effective against a pest and other available products are only marginally effective, a good strategy to follow is to use the marginally effective materials at times when pest pressure is less severe and to reserve the effective material for those periods of time when control must be most effective. For more information watch the videos on Fungicide Resistance Management, Herbicide Resistance Management, and Insecticide Resistance Management. General Management in an IPM Program Managing Pesticide Resistance (3/09) 8 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Diseases (Section reviewed 11/20) General Information MANAGEMENT OF SOILBORNE PATHOGENS (11/20) Soil is a reservoir for many plant pathogens and plants are under regular attack by these soilborne organisms. If inoculum levels are high enough and environmental conditions become favorable for infection, susceptible plants will develop disease. Soilborne pathogens are readily spread if infested soil or contaminated water moves into other fields or planting areas. Levels of soilborne pathogens, including bacteria, fungi, nematodes, and some viruses can be reduced in the soil by appropriate treatments. Learn which pathogens attack the crop to be grown. Examine the crop regularly, at least weekly, for symptoms of disease or signs of pathogens. To monitor for root diseases in floriculture and ornamental nurseries • Select a few plants from different locations, remove plants from their containers, and gently scrape or wash away soil. • Examine roots and crowns for discoloration, softness, shriveling, or other early indications of disease. • Know what healthy roots look like so diseased roots can be detected early. Healthy root characteristics may change or be different depending on species, root age, or growing conditions. • Look for discolored or wilted plants and fungal growths aboveground, which may indicate more advanced stages of disease. • Use test kits in combination with other information to make good pest management decisions. Test kits are readily available for detecting Phytophthora pathogens infecting greenhouse and container-grown nursery plants. Agdia (Elkhart, IN) supplies simple immunological test kits that detect Phytophthora species in minutes. A positive detection can usually help with the diagnostic process and get you quickly on the path to managing the problem. Sometimes, however, a positive result might be deceiving because these tests are not entirely accurate and can occasionally react to certain Pythium or Phytopythium species. These latter two groups of species may or may not be the primary cause of root disease or even a problem at all. Some of these are soil microbes that only break down already dead material, and many we do not fully understand yet. A nonpositive reaction of the immunological test might be deceiving also. Sometimes the tested root tissue may not have been sampled from infected root pieces, and certain Phytophthora species do not react with the tests. • Send a sample of diseased plants and their roots to an appropriate laboratory to test for the presence and identification of pathogens. Proper diagnosis is vital to making the correct management decisions. Understand the conditions and practices that promote disease and regularly examine for and remedy disease-promoting conditions and practices. Poor sanitation, inadequate drainage, and improper irrigation are the primary conditions that promote diseases of roots. Remove crop residue and old or low-quality plants that will not be marketed. Soil Solarization In warmer climatic areas, solarization has been effective for disinfesting containerized soil or growing medium, soil in cold frames, and soil in open fields. For soil in containers • Use either in bags or flats covered with transparent plastic or in layers 3- to 9-inches wide sandwiched between two sheets of plastic to solarize planting media. A double layer of plastic can increase soil temperature by up to 50°F. Diseases: General Information Management of Soilborne Pathogens (11/20) 9 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES • • Monitor the temperature of the growing medium closely by placing a temperature-measuring probe into the center of the mass of the soil mix to ensure the temperature is high enough to control pests. In warmer areas of California, soil inside black plastic sleeves can reach 158°F (70°C) during solarization, equivalent to target temperatures for soil disinfestation by aerated steam. At this temperature, soil is effectively solarized within 30 minutes. At 140°F (60°C), soil is solarized in 1 hour. In open fields, soil is more easily covered with a single layer of transparent plastic. Soil temperatures will be highest at the soil surface (first 12 inches). The plastic needs to be left in place for 4 to 6 weeks. For maximum effectiveness and treatment predictability, solarize open fields only in warmer climatic areas, unless previous testing has given consistently desirable results. The effectiveness of solarization, especially in cooler climatic areas, can be improved by adding various botanical products containing glucosinolates, such as mustard seed meal, broccoli, and cabbage. Solarization is acceptable where a non-chemical approach is desired. Heat Heating the soil is very effective and the soil can be used immediately after cooling, unlike chemically treated soil. Many plant pathogens are killed by short exposures to high temperatures. Most plant pathogens can be killed by temperatures of 140°F (60°C) for 30 minutes. However, some viruses such as Tobacco mosaic virus (TMV) may survive this treatment. Where weed seeds are a problem, a higher treatment temperature is required, and even then, some weed seeds may still survive. Although pure steam at sea level is at 212°F (100°C), the temperature of the steam used to treat soil is usually about 180°F because of air that is present in the steam or soil being treated. If air is mixed with steam, the temperature of the steam-air mixture can be closely controlled, depending on the ratio of air to steam. It has been demonstrated that some diseases, such as Rhizoctonia damping-off, are much less severe in soil that has been treated at 140°F rather than at 180°F. Experience will tell the grower which temperature will best treat the soil, but as a starting point try 140°F (60°C) for 30 minutes. If a cement mixer is used to heat a bulk quantity of soil, generally it is not necessary to introduce air into the steam because a large amount of air is present in the mixer and the temperature can be controlled by simply regulating the flow of steam. Expensive air blowers are not required for this method. Steam heating of containers filled with soil in vaults likewise may not require the introduction of air into the steam to control the temperature. However, circulation within the vault is important to ensure even distribution of heat. Circulating fans can be located within, or external to, the vault and the steam can be introduced into the recirculating air. Leave space between the vaults and check temperatures throughout the vault to ensure that there is good circulation of steam air. Soil Fumigants Only three fumigants with very limited suitability for soil fumigation remain allowed in California. Registered fumigants are chloropicrin, 1,3-dichloropropene (1,3-D), and methyl isothiocyanate (MITC) generators such as metam sodium, metam potassium, and Basamid. However, these products have many statewide regulatory restrictions and are also subject to local regulations. In the absence of methyl bromide, the most promising registered fumigants are chloropicrin alone or chloropicrin mixed with 1,3-dichloropropene applied sequentially in combination with metam sodium or metam potassium. These fumigants can be applied to the raised beds through drip irrigation systems. In drip fumigation, it is critical to distribute the water evenly throughout the field and throughout the target soil treatment zone. Chloropicrin and 1,3-dichloropropene should not be applied simultaneously with metam sodium to avoid their rapid degradation in the irrigation water. Only certified applicators can apply fumigants. Metam-sodium (Vapam), and dazomet (Basamid) alone are not very effective for controlling many soilborne pathogens, including Verticillium and Fusarium oxysporum. See the Activity of Soil Fumigants table for how effective each fumigant is against various types of pests. Chloropicrin (trichloronitromethane) is the best fumigant for controlling Verticillium dahliae. In the past it was combined with methyl bromide in various mixtures depending upon the organisms in the soil. If used alone, a water seal may be used to confine the gas; however, the gas is very objectionable and irritating (it is commonly known as tear gas) and, if not effectively confined, it may drift to inhabited areas. Diseases: General Information Management of Soilborne Pathogens (11/20) 10 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES This is a restricted use material and requires a permit from the county Agricultural Commissioner to be purchased or applied. Activity of soil fumigants. Common name chloropicrin Activity against Nematodes Fungi fair excellent fair excellent fair excellent excellent very good excellent excellent excellent excellent excellent excellent good good good good good good good good good good Trade name TriClor TriClor EC Telone II Telone C35 InLine Pic-Clor60 Pic-Clor60EC Vapam HL Sectagon 42 K-Pam HL Sectagon-K54 Basamid 1,3-dichloropropene 1,3 dichloropropene plus chloropicrin chloropicrin plus 1,3 dichloropropene metam sodium metam potassium dazomet Weeds poor fair* fair fair good* good* good* good good good good good * Using high rates or retentive plastic mulch (especially totally impermeable film) improves weed control. Soil Fungicides Some fungicides work best if incorporated before planting. Others may be incorporated or applied after sowing or planting. Some soil fungicides control a narrow range of organisms while others control a wide range of organisms. Some of the narrow range chemicals are the most effective in controlling a specific organism. Combinations are used to increase the number of organisms controlled. The Examples of Conventional and Biological Fungicides table is not a complete list of available and active fungicides against soilborne pathogens. It provides examples of conventional and biological fungicides. Salts or esters of phosphorous acid (Aliette) Gliocladium virens (SoilGard) Iprodione (Chipco 26019) Mefenoxam (Subdue Maxx) PCNB - pentachloronitrobenzene or quintozene (Terraclor) Streptomyces griseoviridis (Mycostop) Thiabendazole (Mertect) Thiophanate-methyl (Talaris) C C Diseases: General Information C C2 C C C N Seed rot Sclerotium rolfsii Sclerotinia Root & stem rot P C C Rhizoctonia Pythium Phytophthora Penicillium blue mold Fusarium sp. Foliar downy mildew Damping-off Cylindrocladium spp. Cottony rot Black root rot Common name (Example trade name) Alternaria and Phomopsis wilt Examples of conventional and biological fungicides. C C C C C C N N C P1 P1 P1 N N C C C C C2 N Management of Soilborne Pathogens (11/20) 11 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Trichoderma spp. (RootShield) C C C Triflumizole C (TerraGuard) C = control; P = partial control/suppression; N = no control 1 In the greenhouse it may suppress root rots of Pythium, Phytophthora, and Rhizoctonia. 2 Used for bulb or corm dips to control Fusarium basal rot and Penicillium blue mold Seed Treatments Streptomyces griseoviridis (Mycostop) is used as a seed treatment for damping-off and early root rots for ornamentals planted in fields or greenhouse. Captan is also a seed treatment, but offers only a limited protection. Treatment of Containers and Equipment Debris, soil, and plant material cling to containers and equipment; thoroughly wash equipment to remove all soil or planting mix particles. Heat treatment is effective in killing the plant pathogens that adhere to containers or that are in the debris. Where steam is not available, hot water or solarization can be very effective. Most plastic can be treated with hot water at temperatures that cause minimal softening. The minimum water temperature should be 140°F (60°C) whenever possible. Treatment time can be as short as 1 minute. Longer treatment times are more reliable, and the container or equipment must reach at least 140°F (60°C). For solarization, containers should be moistened, stacked, and placed beneath a double-layer tent. Incubate for 30 minutes at or above 158°F (70°C), or 1 hour at or above 140°F (60°C). Sodium hypochlorite (the active ingredient in bleach) is effective in killing most types of fungal spores and bacteria. However, it penetrates clinging soil and plant material very poorly. It is effective only as a surface disinfectant, so containers, tools, etc. must be free of soil and plant material and clean before treatment. Sodium hypochlorite is generally used as a surface disinfectant at 0.5%. To achieve this concentration of sodium hypochlorite, household bleach can be diluted 1 part bleach to 9 parts water. For known contaminated materials, a stronger solution diluted 1 part bleach to 4 parts water (1% sodium hypochlorite), may be more effective in killing pathogens. Allow the solution to be in contact with nonporous materials for a minimum of 5 to 10 minutes, then rinse well with clean water to remove bleach and avoid phytotoxicity. Bleach dilutions must be made fresh each day because once diluted, the effectiveness of the solution diminishes over time (50% loss occurs every 2 hours). Debris, potting mix, and other residues left over in bleach washes will also greatly reduce bleach concentration and effectiveness. Quaternary ammonia compounds are excellent bactericides and viricides and are effective in killing some kinds of fungal spores. They penetrate plant material and soil poorly, so containers, tools, etc. must be clean before treatment. Diseases: General Information Management of Soilborne Pathogens (11/20) 12 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GENERAL PROPERTIES OF FUNGICIDES 11/20) Common name (trade name) ametoctradin/dimethomorph (Orvego) azoxystrobin (Heritage) boscalid/pyraclostrobin (Pageant) Chemical class QoSI/carboxylic acid amides Activity systemic (local) single-site multi-site Qol2 carboximide/QoI2 Resistance potential low 11 7/11 high medium M 04 low M 05 21 low — Captan (Captan) phthalimides chlorothalonil (Daconil) cyazofamid (Segway) chloronitrile cyanoimidazole cyprodinil/fludioxonil (Palladium) dicloran (Botran) dimethomorph (Stature) etridiazole (Terrazole CA) fenamidone (Fenstop) anilinopyrimide/phenylpyrrole contact 9/12 aromatic hydrocarbon systemic (local) 14 carboxylic acid amines — 40 heteroaromatic — 14 QoI2-imidazolinones contact 11 low to medium medium low-medium low-medium high fenhexamid (Decree) fixed copper (Kocide) fludioxonil (Medallion) fluopicolide (Adorn) hydroxyanilide inorganic phenylpyrroles pyridinylmethyl-benzamides — multi-site — systemic (locally) 17 M 01 12 43 low-medium low low-medium low fluoxastrobin (Disarm) QoI2–dihydro-dioxazines systemic 11 high flutolanil (Prostar) succinate-dehydrogenase inhibitor biological dicarboximide inorganic — 7 medium — multi-site multi-site NC 2 M 02 low medium-high low Gliocladium virens (SoilGard) iprodione (Chipco 26019 N/G) lime sulfur multi-site (contact) multi-site contact Mode of action1 45/40 mancozeb (Dithane) dithio-carbamate (EBDC)4 mandipropamid (Micora) mandelic acid amides mefenoxam (Subdue Maxx) acylalanine myclobutanil (Rally) DMI3-triazole neem oil (Triact) oil PCNB (Terraclor) aromatic hydrocarbon piperalin (Pipron) amines potassium bicarbonate (Kaligreen) inorganic propiconazole (Banner Maxx) DMI3-triazole Reynoutria sachalinensis - knotweed, biological plant extract (Regalia) Salts or esters of phosphorous acid phosphonate (Aliette) Streptomyces griseoviridis (Mycostop)biological stylet oil (JMS) oil tebuconazole (Torque) DMI3–triazole thiabendazole (Mertect) benzimidazole Diseases: General Information multi-site — single-site single-site — single-site — — single-site — M 03 40 4 3 NC 14 5 NC 3 NC low low to medium high medium none low-medium low-medium none medium low multi-site P 07 low — — single–site BM 02 NC 3 low none medium single-site 1 high Comments resistance to FRAC 7 has been documented resistance risk unknown, but assumed to be medium to high cross-resistance to fungicides of QoI group documented cross-resistance to fungicides of QoI group documented incompatible with most other pesticides Resistance is known in several fungal species, cross-resistance is present in DMI–group General Properties of Fungicides (11/20) 13 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES thiophanate-methyl (Talaris) triadimefon (Bayleton) Trichoderma spp. (RootShield) trifloxystrobin (Compass O) triflumizole (TerraGuard) wettable sulfur — NC 1 2 3 4 thiophanate DMI3-triazole biological Qol2 DMI3-imidazole inorganic single-site single-site — single-site single-site multi-site 1 3 BM 02 11 3 M 02 high medium low high medium low = no information = not classified Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Qol = quinone outside inhibitor DMI = demethylation (sterol) inhibitor EBD = ethylene bisdithiocarbamate C Diseases: General Information General Properties of Fungicides (11/20) 14 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Key Diseases ARMILLARIA ROOT ROT (OAK ROOT FUNGUS) (11/20) Armillaria mellea and other species SYMPTOMS AND SIGNS Infected field-grown plants can be stunted, show poor growth, have smaller than normal leaves, and can have other symptoms associated with diseased roots and crowns. Eventually, foliage will wilt, turn brown, and die. The disease usually results in the complete collapse and death of the plant. Diseased crowns and main roots will have white to cream-colored fan-shaped mycelial mats, growing underneath the outer tissues. Dark brown to black stringy mycelial structures (rhizomorphs) are rarely seen on the root surface. COMMENTS ON THE DISEASES Armillaria mellea is a soilborne pathogen that is only found in field soil. The fungus survives on dead roots left in the ground. Woody crops, planted in areas that were formerly oak woodland, can become infected many years after infested oaks were removed. The fungus can spread from one plant to another through the contact of diseased roots with healthy roots. Wet soil conditions resulting from heavy rainfall or excessive irrigations can exacerbate the disease. Under suitable conditions, the mushroom stage of the fungus can emerge from buried diseased roots. The mushroom is large (cap diameter up to 6 inches wide), has a cap with variable coloration (yellow, tan, honey-colored, brown), and bears typical radiating gills with white spores. MANAGEMENT For field grown ornamental crops the only treatment is fumigation. Before chemical treatment, remove all infected plants and as many large roots as possible. Complete eradication is rarely achieved, and retreatment may be necessary in localized areas. If the soil is wet or if it has extensive clay layers to the depths reached by the roots, fumigant treatment may not be successful. Other management options include rotating crops and planting ornamentals that are not hosts to this pathogen. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. SOIL FUMIGATION A. Label rates See label CHLOROPICRIN*§ COMMENTS: Inject into soil and cover immediately with plastic tarps. Fumigants are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone. B. Sequential application of: (Note: Fumigants such as 1,3-dichloropropene and metam products are a source of volatile organic compounds (VOCs) but minimally reactive with other air contaminants that form ozone. CHLOROPICRIN*§/1,3 DICHLOROPROPENE*§ (Pic-Clor60) 300–332 lb (shank) See label (Pic-Clor60 EC) 200–300 lb See label COMMENTS: Very effective for control of soilborne fungal pathogens and insects. Drip irrigation requires an emulsifier. For shank fumigation, using higher rates or plastic mulch, especially virtually impermeable film (VIF), improves weed control. For drip fumigation the use of VIF will improve both nematode and weed control. According to state permit conditions, the maximum application rate of 1,3-dichloropropene is 332 pounds active ingredient per acre. Pic-Clor60: One gallon of weighs 12.1 lb; Pic-Clor60 EC: One gallon of weighs 11.8 lb. Key Diseases Armillaria Root Rot (Oak Root Fungus) (11/20) 15 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Following 5–7 days after fumigation: METAM SODIUM*§ (Vapam HL, Sectagon 42) 37.5–75 gal See label COMMENTS: Water-soluble liquid that decomposes to a gaseous fumigant (methyl isothiocyanate). Efficacy affected by soil texture, moisture, temperature, and percent organic matter. One gallon of product contains 4.26 lb of metam sodium. . . . or . . . METAM POTASSIUM*§ (K-Pam HL, Sectagon–K54) 30–45 gal See label COMMENTS: Water-soluble liquid that decomposes to a gaseous fumigant (methyl isothiocyanate). Efficacy affected by soil texture, moisture, temperature, and percent organic matter. One gallon of product contains 5.8 lb of metam potassium. . . . or . . . DAZOMET*§ (Basamid) 200 lb See label COMMENTS: Powder incorporated into the soil, followed by irrigation or tarping. It decomposes to a gaseous fumigant (methyl isothiocyanate). * 1 § ‡ Permit required from county agricultural commissioner for purchase or use. Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Do not exceed the maximum rates allowed under the California Code of Regulations Restricted Materials Use Requirements, which may be lower than maximum label rates. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Armillaria Root Rot (Oak Root Fungus) (11/20) 16 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ASTER YELLOWS (11/20) Aster yellows phytoplasma SYMPTOMS AND SIGNS Symptoms of aster yellows includes yellowing, dwarfed or distorted foliage, and the abnormal production of shoots. Flowers may not develop normally and are often replaced by green leafy structures. Aster yellows symptoms may closely resemble those caused by viruses. COMMENTS ON THE DISEASE Aster yellows is caused by a microscopic organism called a phytoplasma. Phytoplasmas are closely related to bacteria but are somewhat smaller in size and do not have a rigid cell wall. Initially, the aster yellows phytoplasma was thought to be a virus. Phytoplasmas are vectored by leafhoppers, plant hoppers, and psyllids and invade the phloem of infected plants. The aster yellows phytoplasma is vectored by leafhoppers, in which it can multiply. It has a very wide host range, which includes many ornamentals, food crops, and weeds. MANAGEMENT Aster yellows is difficult to control, in part, because of the extensive host range of the pathogen. Over 300 species of food, forage, ornamental, and weed plants are susceptible. While weed management should be practiced, this will have little effect on aster yellows. Plant pathogen-free plants and use good sanitation. Remove and destroy infected plants. There are no chemical controls for the aster yellows phytoplasma. Control of the leafhopper vector could reduce transmission of the phytoplasma. EXAMPLES OF HOSTS OF ASTER YELLOWS PHYTOPLASMA Ornamental hosts alyssum, calceolaria, calendula, China aster, chrysanthemum, cineraria, daisies, delphinium, gladiolus, gloxinia, gypsophila, larkspur, petunia, statice, sweet william, tagetes, veronica, zinnia, and many others Key Diseases Crop plant hosts Weeds and native plant hosts buckwheat, carrots, celery, lettuce, onion, California poppy, dandelion, plantain, parsley, parsnip, potato, safflower, spin- and many others ach, tomato, and many others Aster Yellows (11/20) 17 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BACTERIAL LEAF SPOTS, BLIGHTS, CANKERS, AND ROTS (11/20) Bacterial blight of chrysanthemum: Dickeya (=Erwinia) chrysanthemi Bacterial blight of geranium: Xanthomonas axonopodis pv. pelargonii (formerly X. campestris pv. pelargonii) Bacterial leaf spot of begonia: Xanthomonas axonopodis pv. begoniae (formerly X. campestris pv. begoniae) Bacterial leaf spot of poinsettia: Curtobacterium flaccumfaciens pv. poinsettiae Bacterial wilt of carnation: Burkholderia (=Pseudomonas) caryophylli Black leaf spot of delphinium: Pseudomonas syringae pv. delphinii SYMPTOMS AND SIGNS Foliar diseases caused by plant pathogenic bacteria result in a wide range of symptoms that vary greatly depending on the particular pathogen and the host plant. Leaf spots (also called leaf lesions) are discrete diseased sections of leaves that initially appear water-soaked, but later turn yellow, brown, or black. Leaf spots are usually angular in shape and bordered by the veins in the leaf. Leaf petioles can also develop such spots. Merging of numerous leaf spots results in the infection of large portions of the foliage; such symptoms are called blights. Rots occur when the bacteria infect fleshy stems, crown, bulbs, corms, and other parts of plants and cause a soft, watery decay. Infections on twigs and branches can cause cankers, which are sunken, discolored, and cracked areas in the woody tissue. In some cases, bacteria inside the diseased tissue will ooze to the surface of the plant and are visible as cream to yellow colored exudates, collecting outside the plant. COMMENTS ON THE DISEASES There are many different kinds of bacterial diseases of flower and nursery crops. In many cases these bacteria are host specific and will only infect one plant species. In other cases, for example with soft rot bacteria, the pathogen is able to infect a larger number of plant hosts. All bacteria in this section can be spread through infected cuttings and other propagative material, and some of these bacteria may be carried in seed and irrigation water. Bacteria are dependent on splashing water for their dispersal and for creating a suitable environment for infection and disease development. MANAGEMENT Use pathogen- and disease-free seed, cuttings, transplants, and other propagative materials. • Implement sanitation measures when dealing with containers, flats, benches, pruning tools, and other items that come in contact with plants. • Avoid using overhead sprinkler irrigation. • Rogue out (remove) diseased cuttings, transplants, and plants. • Sanitize hands or use disposable gloves when handling diseased plants. • Prevent injuring bulbs, corms, and other fleshy parts of plants to avoid soft rot problems. Copper-based fungicides may provide some control but can be phytotoxic to some ornamentals. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. FIXED COPPER (Kocide 2000)# Label rates 48 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 01) COMMENTS: A protectant fungicide. Growth of some plants may be reduced by this material; follow label directions carefully to reduce the risk of phytotoxicity. Check label for registered use ornamental species list in California. Not all copper compounds are approved for use in organic production; be sure to check individual products. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions. Fungicides with a different group number are suitable to alternate in a resistance management program. In Key Diseases Bacterial Leaf Spots, Blights, Cankers, and Rots (11/20) 18 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ‡ # California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Acceptable for use on organically grown ornamentals. Check with your certifier. Key Diseases Bacterial Leaf Spots, Blights, Cankers, and Rots (11/20) 19 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BLACK ROOT ROT (11/20) Thielaviopsis basicola SYMPTOMS AND SIGNS Black root rot is also called Thielaviopsis root rot. Plants are stunted and grow poorly. Infected roots may initially have small dark brown to black bands where infection has taken place. As the disease progresses, roots can become badly rotted. Stems below ground may enlarge and develop black, rough, longitudinal cracks. Characteristic dark brown to black, thick-walled, barrel-shaped chlamydospores form in infected tissues and may be visible under magnification. COMMENTS ON THE DISEASE The fungus has a wide host range: 120 species in 15 families are known to be susceptible. Strains of the fungus are known that differ in pathogenicity and virulence. Important ornamental hosts include begonia, cyclamen, geranium, gerbera, kalanchoe, pansy, petunia, poinsettia, primula, snapdragon, sweet pea, verbena, and viola. The disease is favored by wet, cool soil and any condition that weakens plants; it is most severe from 55° to 61°F, while only a trace of disease develops at 86°F. Alkaline soil favors the disease, which can be prevented at pH 4.8 and greatly reduced at pH 5.5 or below. However, many plants do not grow well under such acidic conditions. The fungus is soilborne and capable of prolonged survival in the absence of susceptible plants. Two kinds of spores are formed: • barrel-shaped chlamydospores (resting spores) in short chains of three to seven and • rectangular-shaped endoconidia. The fungus can be spread in water, soil, by infected plants or vectored by fungus gnats and shore flies. Some sources of peat are known to harbor Thielaviopsis spores. MANAGEMENT Use appropriate sanitation measures to prevent spread of the pathogen via diseased plant material, contaminated soil mixes and containers, and contaminated water runoff. The use of pathogen-free plants, along with improved sanitation and cultural practices, has reduced the importance of this disease, which at one time was widespread, especially in poinsettias. The fungus can still be troublesome in field-grown flowers. The benzimidazole fungicides such as thiophanate-methyl are very active against the fungus and are used as soil treatments to control it. To treat container media, steam (at 140°F for 30 minutes), or solarize (double-tent at 160°F for 30 minutes or 140°F for 1 hour). For flower production in outdoor fields, solarization in warmer climates has been successful for control of Thielaviopsis in many crops. Solarization and steaming are acceptable for organic production. For more information, see MANAGEMENT OF SOILBORNE PATHOGENS. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. THIOPHANATE-METHYL (Talaris 4.5 F) 20 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: Apply as a drench or heavy spray. Generally applied after sowing. Absorbed by plant parts exposed to the chemical. Roots may absorb the fungicide (or its breakdown product carbendazim), which moves in the xylem to transpiring leaves. B. TRIFLUMIZOLE (TerraGuard SC) Key Diseases 2–8 fl oz/100 gal water 12 Black Root Rot (11/20) 20 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Apply as a cutting soak or soil drench at 3 to 4 week intervals as needed on potted plants. A protectant fungicide; use is restricted to enclosed commercial structures such as greenhouses and shade houses. C. 1 ‡ FLUDIOXONIL (Medallion WDG) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Phenylpyrroles (12) 12 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Black Root Rot (11/20) 21 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Cottony Rot (11/20) Sclerotinia sclerotiorum SYMPTOMS AND SIGNS Under high humidity the fungus produces a mass of white cottony mycelia on the soil or plant surface. Later, large (1/4 to 1 inch long), black sclerotia (hard, dark masses of hyphae) are formed on and inside infected plant parts. Frequently the sclerotia are found inside hollow stems. Plant tissues killed by the fungus often take on a bleached appearance. Gray mold (Botrytis cinerea) causes a similar bleaching and also has black sclerotia, but they are much smaller than those of Sclerotinia. Additionally, Botrytis produces gray mycelium and spores instead of the mass of white, cottony growth that Sclerotinia does. COMMENTS ON THE DISEASE Cottony rot, also called Sclerotinia rot or white mold, affects many kinds of plants. It is also a disease of vegetables, such as beans, carrots, celery, and lettuce. Moisture and high humidity are necessary for development of the disease and this is one reason the disease is found lower in the plant canopy. Infection can either be soilborne or airborne. Sclerotinia sclerotiorum does not produce asexual conidia. Sclerotia formed by the fungus undergo a dormant period that is broken by low temperatures (optimal is 56° to 59°F) and high soil moisture. In fall and spring, when temperatures are in the optimal range, sclerotia germinate and can infect the plant near the soil line either directly by producing vegetative strands (hyphae) or by forming apothecia (saucershaped, dime-sized structures on stalks) that produce ascospores (sexual spores). Ascospores are discharged forcibly into the air and are carried by air currents. They do not directly infect healthy tissue, but if they land on injured tissue in the presence of moisture, infection can occur on any aboveground part. Flower petals of many plants are susceptible. Foliage may become infected if there is an injury or if the tissue is senescent. If diseased tissue comes in contact with healthy tissue, the fungus can invade the healthy tissue. MANAGEMENT Protective fungicides, as well as steaming (at 140°F for 30 minutes), solarization (double-tent at 160°F for 30 minutes or 140°F for 1 hour), or fumigation of the growing medium can be helpful. For flower production in open fields, solarization in warmer climates has been successful for control of Sclerotinia diseases in many crops. Solarization and steaming are acceptable for organic production. In open fields airborne spores can blow in from outside the field, so soil treatment may be limited in its effectiveness. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. BOSCALID/PYRACLOSTROBIN (Pageant) 12–18 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Carboximide (7) and quinone outside inhibitor (11) B. CYPRODINIL/FLUDIOXONIL (Palladium) 2–4 oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Amino acids and protein synthesis (9) and signal transduction (12) C. IPRODIONE (Chipco 26019 N/G) 6.5 oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2) COMMENTS: Apply as a drench (1–2 pt/sq ft) at seeding or transplanting. Effective against Rhizoctonia damping-off and Sclerotinia. Some iprodione is absorbed by plant parts. Key Diseases Cottony Rot (11/20) 22 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES D. PCNB (Terraclor 400) Label rates 12 MODE OF ACTION GROUP NAME (NUMBER1): Aromatic hydrocarbon (14) COMMENTS: Inhibits germination of sclerotia when incorporated into top two inches of soil. Insoluble in water. Must be thoroughly mixed with soil to reach its desired depth of control. Works through vapor action and has good residual action. Germination of some seeds may be inhibited and small plants may be stunted by this fungicide. E. 1 ‡ THIOPHANATE-METHYL (Talaris 4.5 F) 20 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: Apply as a drench or heavy spray (1–2 pt/sq ft) after sowing. Absorbed by plant parts exposed to the chemical. Roots may absorb the fungicide (or its breakdown product carbendazim), which moves in the xylem to transpiring leaves. Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Cottony Rot (11/20) 23 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CROWN GALL (11/20) Agrobacterium tumefaciens SYMPTOMS AND SIGNS Crown gall is caused by a bacterium that produces galls at the base of the stem, root crown or on other plant parts. The bacterium infects only through fresh wounds. If infected at a young age, plants may be stunted and not grow properly. COMMENTS ON THE DISEASE A wide variety of both woody and herbaceous plants are susceptible. The disease is most damaging to trees because the galls are perennial and increase in size with growth of the tree. Galls may occur on roots, stems, and even leaves. Aerial galls are common on grapes and caneberries. Under moist conditions aerial galls are often seen on chrysanthemum. The disease may have further impact on growers, because regulations prohibit the sale of some plant materials infected with crown gall. Gall tissue is disorganized growth with an enlarged cambium layer and irregular vascular tissue. Movement of water and nutrients is severely impaired by galls. The early stages of gall formation can be difficult to distinguish from normal callus tissue. Isolation of the pathogenic bacterium is the most common method of confirming that the bacterium is present. Callus tissue, which is soft and easily wounded, can be a common site of infection. The bacterium Agrobacterium tumefaciens is common in many agricultural soils. When the plant is wounded, the bacterium attaches to an exposed plant cell and transfers a portion of its genetic material, DNA (deoxyribonucleic acid), into the cell where it is incorporated into the genetic material of the host cell. The host cell is induced to become a tumor cell and also to produce a unique substance (opine) that only the crown gall bacterium can readily utilize. Agrobacterium tumefaciens is then able to multiply between cells and in cracks of the gall with somewhat less competition from other microorganisms. MANAGEMENT The only useful method of treating soil for crown gall pathogen is with heat. The common soil fumigants reduce the amount of bacteria but do not result in satisfactory control of the disease. Steam (at 140°F for 30 minutes) or solarize (double-tent at 160°F for 30 minutes or 140°F for 1 hour) the soil. For flower production in open fields, solarization in warmer climates has been successful for control of crown gall. Steaming and solarization are acceptable for organic production. Sanitation is very important in a control program, especially where cuttings are produced. Rose propagative material and work areas are often soaked or cleaned with hypochlorite solution to kill any bacteria that may be present on the surface. Grape propagative material, and perhaps some others, have also been treated in this manner. In some plants, such as grape, the bacterium may occasionally enter the xylem. Cuttings taken from such plants may develop crown galls. Tools and surfaces that contact the propagative material should be cleaned and periodically treated with a disinfectant. Monitoring and Treatment Decisions The K-84 strain of Agrobacterium tumefaciens (formerly A. radiobacter), which is available for use in preventing infection by the crown gall pathogen, is an excellent biological control agent. Galls on many woody plants can be treated with a mixture of chemicals that are toxic to and kill crown gall tissue but are safe on uninfected woody tissue. The mixture, which is currently marketed under the name Gallex, was previously sold as Bacticin. It has been used with success on rose crown galls. Common name (Example trade name) Key Diseases Amount to use REI‡ (hours) Crown Gall (11/20) 24 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. AGROBACTERIUM TUMEFACIENS K-84 (Galltrol)# Label rates 4 . . . or . . . AGROBACTERIUM TUMEFACIENS K-1026 (Nogall) Label rates 4 COMMENTS: Products may list bioagent under former name A. radiobacter. Prevents infection by the crown gall pathogen if it is applied to fresh wounds. It must be applied as soon as possible after wounding; i.e., within 24 hours. It has been used with success on Prunus spp. and Rosa spp. B. # ‡ 2,4-XYLENOL/META-CRESOL (Gallex) Label rates COMMENTS: For killing of existing galls; apply directly to galls winter through spring. 24 Acceptable for use on organically grown ornamentals. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Crown Gall (11/20) 25 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DAMPING-OFF (11/20) Damping-off: Pythium spp., Rhizoctonia solani, and others SYMPTOMS AND SIGNS Emerging seedlings rot at or below the soil line and are killed. Some seedlings may be infected before emergence and therefore not appear above ground. If the problem is caused by Pythium, it usually begins at the root tips. Damping-off pathogens can also infect planted seeds and cause death of the seed before it germinates. COMMENTS ON THE DISEASE Damping-off is the name given to seedling diseases most often caused by fungi and oomycetes (funguslike organisms). As the name implies, the disease is associated with damp conditions. Some Pythium species are favored by cool, wet conditions, but Rhizoctonia and other Pythium species can cause disease under drier and warmer conditions. MANAGEMENT Vigorous seedlings grown from the best seed under ideal light and temperature conditions may survive in the presence of these fungi, while seedlings low in vigor will succumb under unfavorable conditions. Damping-off can be minimized by providing good drainage (raised beds, properly graded fields), careful irrigation, planting when soil and air temperatures are favorable for rapid seedling emergence, proper depth and spacing of planting, seed treatments, and drenches of soil fungicides. For more information, see MANAGEMENT OF SOILBORNE PATHOGENS. For container media, steam (at 140°F for 30 minutes) or solarize (double-tent at 160°F for 30 minutes or 140°F at 1 hour). For flower production in open fields, solarization in warmer climates has been successful for control of damping-off in many crops. Reports of inadequate control of some high temperature species (e.g., P. aphanidermatum) have been made. Solarization and steaming are acceptable for organic production. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. SEED TREATMENT A. STREPTOMYCES GRISEOVIRIDIS (Mycostop)# 0.08 oz/lb of seed 4 MODE OF ACTION GROUP NAME (NUMBER1): Microbial (BM 02) COMMENTS: For control of seed rots, root and stem rots, and wilt diseases of ornamental crops caused by Alternaria, Fusarium, and Phomopsis. Suppresses also Botrytis, Pythium, and Phytophthora. May be used for both field-grown and greenhouse ornamentals. SOIL FUNGICIDE – Pythium spp. A. CYAZOFAMID (Segway) 1.5–3.0 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Quinone inside inhibitor (21) COMMENTS: Toxic to aquatic organisms. B. C. FENAMIDONE (Fenstop) 7–14 fl oz/50–100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Toxic to aquatic organisms. FLUOPICOLIDE (Adorn) 1–4 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Benzamides (43) Key Diseases 12 12 12 Damping-off (11/20) 26 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES COMMENTS: Toxic to aquatic organisms. D. MEFENOXAM (Subdue Maxx) Label rates 48 MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (4) COMMENTS: Applied at planting as a drench and periodically thereafter as needed. Available also in a granular formulation to use before planting. It is water-soluble and readily leached from soil. It is absorbed primarily through roots and is translocated in the plant through the xylem. Use of this material over a period of time may lead to resistance. SOIL FUNGICIDE – Rhizoctonia solani A. FLUDIOXONIL (Medallion WDG) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Phenylpyrroles (12) B. C. 12 IPRODIONE (Chipco 26019 N/G) 6.5 oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2) COMMENTS: Apply as a drench at seeding at the rate of 1–2 pt/sq ft 12 FLUTOLANIL (Prostar 70 WG) 3–6 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Succinate-dehydrogenase inhibitor (7) D. PCNB (Terraclor 400) Label rates 12 MODE OF ACTION GROUP NAME (NUMBER1): Aromatic hydrocarbon (14) COMMENTS: Insoluble in water. Must be thoroughly mixed into the top 2 inches of soil to reach its desired depth of control. It works through vapor action and has good residual action. Germination of some seeds may be inhibited, and small plants may be stunted by this fungicide. E. THIOPHANATE-METHYL (Talaris 4.5 F) 20 fl oz/100 gal for 800 sq ft bench area 12 MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: Generally applied after sowing, as a drench or heavy spray. Thiophanate-methyl is absorbed by plant parts exposed to the chemical. Roots may absorb the fungicide (or its breakdown product carbendazim), which moves in the xylem to transpiring leaves. F. TRIFLUMIZOLE (TerraGuard SC) 4–8 fl oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: For use in enclosed commercial structures only; less effective against Rhizoctonia than other materials. Apply as a soil drench at 3 to 4 week intervals as needed. SOIL FUNGICIDE – Pythium spp. and Rhizoctonia solani A. BOSCALID/PYRACLOSTROBIN (Pageant) 12–18 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Carboximide (7) and quinone outside inhibitor (11) B. TRICHODERMA spp. (RootShield)# Label rates NA MODE OF ACTION GROUP NAME (NUMBER1): microbial (BM 02) COMMENTS: Formulated as a seed protectant, a soil drench, and as granules. This biological fungicide may provide some protection against both Pythium and Rhizoctonia. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Acceptable for use on organically grown ornamentals. # ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Damping-off (11/20) 27 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES N A Not applicable. Key Diseases Damping-off (11/20) 28 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DOWNY MILDEW (11/20) Downy Mildew: Bremia sp., Peronospora spp., Plasmopara spp. SYMPTOMS AND SIGNS The name downy mildew is somewhat descriptive of the fluffy appearance of the white, lavender, or purple sporulation that occurs usually on the undersides of diseased leaves. Downy mildew leaf lesions are often angular in shape and delimited by veins. Paleyellow, purple, or necrotic areas often are visible from the upper side of the leaf. Extensive disease can result in the death of large portions of the leaves. In some plants, when young shoots are infected, the fungus may become systemic and the resultant growth is stunted, malformed, and discolored. COMMENTS ON THE DISEASE In contrast to powdery mildews, the downy mildews require very wet or humid conditions to flourish. Water is required for infection, and humidity above 90% is needed for sporulation. Growth of the pathogens is favored by cool temperatures. Downy mildew spores are usually short-lived, although they may survive several days under cool, moist conditions. They are airborne, and when they land on a susceptible plant with free water present, germination and infection generally occur within 8 to 12 hours. Some downy mildews also produce a sexual spore (oospore) that can survive dry conditions. This enables the pathogen to survive in the absence of a host. Downy mildews are favored by moist and cool conditions (40° to 60°F). MANAGEMENT Use varieties resistant to downy mildew. Avoid sprinkler irrigation and reduce relative humidity in greenhouses. Fungicide treatment of susceptible varieties is needed when the disease occurs on transplants or early in crop development in the field; repeated applications may be required to protect new growth. Treatment during early flowering is required on some seed crops. Organically Acceptable Methods Resistant varieties and some copper sprays are suitable for organically grown crops. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. AMETOCTRADIN/DIMETHOMORPH (Orvego) 11–14 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Mitochondrial respiration inhibitor (45) and cell wall synthesis inhibitor (40) B. BOSCALID/PYRACLOSTROBIN (Pageant) 12–18 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Carboximide (7) and quinone outside inhibitor (11) C. FIXED COPPER (Kocide 2000)# Label rates 48 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 01) COMMENTS: A protectant fungicide. Growth of some plants may be reduced by this material; follow label directions carefully to reduce the risk of phytotoxicity. Not all copper compounds are approved for use in organic production; be sure to check individual products. D. CYAZOFAMID (Segway) 2.1–3.5 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Ubiquinone reductase, Qi site (21) COMMENTS: Toxic to aquatic organisms. Key Diseases 12 Downy Mildew (11/20) 29 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES E. F. FENAMIDONE (Fenstop) 7–14 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Toxic to aquatic organisms. FLUOPICOLIDE (Adorn) 1–4 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Benzamides (43) COMMENTS: Toxic to aquatic organisms. 12 12 G. SALTS OR ESTERS OF PHOSPHOROUS ACID (Aliette WDG) 2.5–5 lb/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (P 07) COMMENTS: For control of downy mildew on roses. Spray to wet using no more than 400 gal/acre. H. MANCOZEB (Dithane 75DF) 1–1.5 lb/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 03) COMMENTS: A protectant fungicide. Thorough coverage is important for control. I. J. K. 1 # ‡ MANDIPROPAMID (Micora) 4–8 fl oz/100 gal MODE OF ACTION GROUP NAME (NUMBER1): Carboxylic acid amides (40) MEFENOXAM (Subdue Maxx) 0.5–1.0 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (4) COMMENTS: Tank-mix with a non-Group 4 fungicide labeled for downy mildew. REYNOUTRIA SACHALINENSIS# (Regalia CG) Label rates MODE OF ACTION GROUP NAME (NUMBER1): anthraquinone elicitor (P 05) 24 4 48 4 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Acceptable for use on organically grown ornamentals. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Downy Mildew (11/20) 30 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FUNGAL LEAF SPOTS, BLIGHTS, AND CANKERS (11/20) Leaf spot of aster: Stemphylium callistephi Ovulinia petal blight of azalea: Ovulinia azaleae Alternaria blight of carnation: Alternaria saponariae (formerly A. dianthi) Leaf blotch of peony: Cladosporium paeoniae Black spot of rose: Diplocarpon rosae Cercospora leaf spot of statice: Cercospora insulana SYMPTOMS AND SIGNS Foliar diseases caused by plant pathogenic fungi result in a wide range of symptoms that vary greatly depending on the particular pathogen and the host plant. Leaf spots (also called leaf lesions) are discrete, diseased sections of leaves that initially may be dull green or yellow in color, but later turn brown, black, or display another abnormal color. Leaf spot shapes also vary greatly, but usually are oval, oblong, or round. Leaf petioles can also develop such spots. The occurrence and merging of numerous leaf spots results in the infection of large portions of the foliage; such symptoms are called blights. Infections on twigs and branches can cause cankers, which are sunken, discolored, and cracked areas in the woody tissue. In many cases, the mycelium and fruiting structures of the pathogenic fungi will grow on top of the diseased leaf spot, blight, and canker areas. COMMENTS ON THE DISEASE There are many different kinds of foliar fungal diseases of flower and nursery crops. In many cases these fungi are host specific and will only infect one plant species. Most of these organisms produce spores that are spread by wind currents and splashing water from rain or sprinklers. Moist, humid conditions are needed for infection and disease development. Some of these fungi are carried in the seed; all can be carried in infected cuttings and other propagative material. MANAGEMENT Use pathogen- and disease-free seed, cuttings, transplants, and other propagative materials. Implement sanitation measures when dealing with containers, flats, benches, pruning tools, and other items that come in contact with plants. Avoid using overhead sprinkler irrigation. Rogue out diseased cuttings, transplants, and plants. Sanitize hands or gloves after handling diseased plants. Fungicides provide some control. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. Strobilurins such as AZOXYSTROBIN, PYRACLOSTROBIN, TRIFLOXYSTROBIN and FLUOXASTROBIN (Heritage, Compass O 50WDG) Label rates See label MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) 1 ‡ Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Fungal Leaf Spots, Blights, and Cankers (11/20) 31 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FUSARIUM WILT (11/20) Fusarium oxysporum SYMPTOMS AND SIGNS Symptoms include yellowing, stunting, and death of seedlings and yellowing and stunting of older plants. Infected plants wilt readily, lower leaves yellow and dry, the xylem tissues turn brown, and the plant may die. In the early stages of disease, the roots are not rotted. In many plants such as carnation and gladiolus, the symptoms may be one-sided at first. COMMENTS ON THE DISEASE The fungi that cause Fusarium wilt diseases are composed of a group of host-specific forms (forma specialis) abbreviated f. sp. For example, the fungus that causes wilt of carnations is Fusarium oxysporum f. sp. dianthi and infects only carnations and closely related plants. Generally, the f. sp. relates to the host; e.g., callistephi (China aster), pisi (pea), cyclaminis (cyclamen), etc. Within the specialized forms are races of the fungus that are characterized by specialization on different cultivars of a host species. Cultivar A may be susceptible to race 1 and resistant to race 2, while cultivar B may be susceptible to both race 1 and race 2. This complicates the grower’s task of selecting which cultivars to grow, as well as making it more difficult to select a breeding strategy for developing resistant cultivars. There are many saprophytic forms of F. oxysporum, and recovery of this fungus from diseased plant material does not mean that the isolate is a wilt pathogen. For example, it is quite common to recover a saprophytic F. oxysporum from the roots of chrysanthemum plants killed by Pythium spp. or other pathogens. There are also strains of F. oxysporum that cause root rots but are not wilt pathogens. The fungus can produce several different kinds of spores. Chlamydospores have thick walls and are resistant to drying and adverse conditions, enabling the fungus to survive for extended periods (years) in the soil. Conidia are thin–walled spores that can be either long and multi-celled (macroconidia) or short and only one- or two-celled (microconidia). Conidia are produced in a sporodochium, which is a mass of conidiophores (conidia-bearing stalks) growing tightly together. However, sporodochia are rarely seen in Fusarium wilt diseases. Conidia are spread in contaminated soil, by splashing water, and on contaminated tools and hands. Conidia are generally not airborne, but the fungus can become airborne on bits of infected plant debris or in dust. In the presence of roots, chlamydospores or conidia germinate and penetrate susceptible plants. The fungus enters the xylem and grows upward, plugging the tissue and reducing the movement of water. Toxins are produced that cause the foliage to turn yellow. Fusarium wilts are favored by high air and soil temperatures (75° to 86°F). Disease may not occur at low soil temperatures (below 68°F), or an infected plant may remain symptomless at lower temperatures. The fungus can be spread with infected cuttings or other forms of vegetative propagation taken from healthy appearing but infected plants. MANAGEMENT If seed is taken from infected plants, the seed itself is usually healthy, but the seed coat often becomes contaminated by microscopic pieces of infected tissue and by spores. Many important Fusarium wilt diseases are spread in this manner. • Treat seed with a fungicide or heat to destroy the fungus on the seed and to protect the emerging seedlings from infection. • Dip bulbs and corms in fungicide or hot water (or both) to reduce Fusarium. Presence of pathogenic Fusarium in the soil can be reduced by heat treatments and chemical fumigation. These treatments are more effective in controlling the fungus in annual plantings than in perennial plantings. In general, however, Fusarium wilt diseases are best controlled by using resistant or tolerant cultivars, not by using soil applied fungicides. Liming soils and using nitrate nitrogen fertilizer have been effective for management of F. oxysporum on chrysanthemum, aster, gladiolus, cucumber, tomato, and Key Diseases Fusarium Wilt (11/20) 32 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES watermelon. In greenhouse production use steam from boilers and apply to raised field beds or raised benches to control soil borne diseases such as Fusarium wilt. In field production use long rotations or try to follow a fumigated crop like strawberry. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. SOIL FUMIGATION A. CHLOROPICRIN* Label rates See label COMMENTS: Inject into soil and cover immediately with plastic tarps. Fumigants are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. B. Sequential application of: (Note: Fumigants such as 1,3-dichloropropene and metam products are a source of volatile organic compounds (VOCs) but minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.) CHLOROPICRIN*/1,3 DICHLOROPROPENE* (Pic-Clor60) 300–332 lb (shank) See label (Pic-Clor60 EC) 200–300 lb See label COMMENTS: Very effective for control of soilborne fungal pathogens and insects. Drip irrigation requires an emulsifier. For shank fumigation, using higher rates or plastic mulch, especially virtually impermeable film (VIF), improves weed control. For drip fumigation the use of VIF will improve both nematode and weed control. According to state permit conditions, the maximum application rate of 1,3-dichloropropene is 332 pounds active ingredient per acre. Pic-Clor60: One gallon of weighs 12.1 lb; Pic-Clor60 EC: One gallon of weighs 11.8 lb. Following 5 to 7 days after fumigation: METAM SODIUM* (Vapam HL, Sectagon 42) 37.5–75 gal See label COMMENTS: Water-soluble liquid that decomposes to a gaseous fumigant (methyl isothiocyanate). Efficacy affected by soil texture, moisture, temperature, and percent organic matter. One gallon of product contains 4.26 lb of metam sodium. . . . or . . . METAM POTASSIUM* (K-Pam HL, Sectagon–K54) 30–45 gal See label COMMENTS: Water-soluble liquid that decomposes to a gaseous fumigant (methyl isothiocyanate). Efficacy affected by soil texture, moisture, temperature, and percent organic matter. One gallon of product contains 5.8 lb of metam potassium. . . . or . . . DAZOMET* (Basamid) 200 lb See label COMMENTS: Powder incorporated into the soil, followed by irrigation or tarping. It decomposes to a gaseous fumigant (methyl isothiocyanate). * # § Permit required from county agricultural commissioner for purchase or use. Acceptable for use on organically grown ornamentals. Do not exceed the maximum rates allowed under the California Code of Regulations Restricted Materials Use Requirements, which may be lower than maximum label rates. Key Diseases Fusarium Wilt (11/20) 33 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Fusarium Wilt (11/20) 34 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GRAY MOLD (11/20) Botrytis cinerea SYMPTOMS AND SIGNS Gray mold is one of the most destructive plant pathogens and attacks a wide variety of plants. Flower petals and ripening fruits and vegetables are particularly susceptible to infection, but leaves and stem tissues may also get infected. Young seedlings of several crops can be killed if infected with gray mold. In high relative humidity, the fungus may sporulate on infected tissues and produce masses of characteristic gray or brownish spores that become airborne, which is primarily how the fungus is disseminated. Spores must have moisture to germinate and infect. COMMENTS ON THE DISEASE Botrytis does not invade healthy green tissue such as leaves and stems unless (a) an injured or dead area is present, or (b) it grows directly from a food base such as a fallen petal or leaf. The fungus will first colonize the food base and then attack healthy green tissues. However, flower petal tissue differs significantly from leaf and stem tissue, and Botrytis can directly invade petals of African violet, aster, begonia, carnation, chrysanthemum, cyclamen, cymbidium, gerbera, geranium, gladiolus, hydrangea, marigold, orchid, petunia, poinsettia, primrose, ranunculus, rose, snapdragon, zinnia, and others. Although the fungus is capable of growth within a wide range of temperatures from about 28° to 90°F, growth is very slow at the extremes. Optimum temperature range for growth is 70° to 77°F. The fungus, which is more active below 70° than it is above 77°F, is particularly troublesome under conditions of moderate temperature and high humidity. MANAGEMENT Refrigeration at temperatures near 32°F will retard but not completely stop the development of gray mold; when infected tissue is warmed, decay can proceed rapidly. Moisture often is more of a limiting factor than temperature. Free moisture is necessary for germination of Botrytis spores. Moisture is also necessary for growth within plant tissues, and low humidity may result in arrested growth of the fungus. However, growth can resume when moisture again becomes available. Gray mold is most severe during times of the year when the humidity is high. In California, this is usually in the late fall and winter months, when rainfall is common. The worst time for disease development is from September to December, because there is an abundant amount of herbaceous vegetative material (crop refuse and dying summer plants) available for fungal colonization and, as a consequence, many spores are present in the air and on plant parts. Cultural Control Botrytis cinerea produces innumerable asexual spores (conidia) that are moved by air currents. Because spores may readily develop in decaying vegetation and old flowers, elimination or reduction of sources of the spores is an important part of any control program. • Remove old flowers before they become infected and function as spore sources. The fungus can develop and sporulate at low temperatures, so do not overlook old flowers and foliage in refrigerators. • Avoid condensation of water on susceptible plant parts, as free moisture is necessary for germination and infection • Avoid overhead watering during blooming. If this is the only method of irrigation available, irrigate early in the day so that the foliage can dry as rapidly as possible. • Maximize the period between irrigations to further enhance drying of foliage and flowers. • Increase plant spacing to increase ventilation and minimize leaf wetness. This can help reduce both disease incidence and severity. Key Diseases Gray Mold (11/20) 35 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Chemical Control Numerous fungicides are effective against B. cinerea but not all of them can be used on all crops. Some products can damage plants. To avoid damage and the development of fungal strains that are resistant to fungicides, growers should alternate different fungicides. The fungicides are preventives and must be applied before infection. In some crops, such as chrysanthemum, the lower foliage of crowded plants becomes infected and acts as a source of spores that then infect the flowers. In these crops, it is important to apply fungicides at an early stage when the lower foliage can be adequately covered by the chemical. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. AZOXYSTROBIN 4–8 oz/100 gal water 4 (Heritage) MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Apply as a broadcast or banded spray targeted at the foliage or crown of the plant. A locally systemic fungicide. B. BOSCALID/PYRACLOSTROBIN 12–18 oz/100 gal 12 (Pageant) 1 MODE OF ACTION GROUP NAME (NUMBER ): Carboximide (7) and quinone outside inhibitor (11) C. CHLOROTHALONIL 1.375 pt/100 gal water 12 (Daconil WeatherStik) 1 MODE OF ACTION GROUP NAME (NUMBER ): Multi-site contact (M 05) COMMENTS: Do not apply to either green or variegated Pittosporum or to Schefflera. Effective for the control of Botrytis spp., Alternaria spp., Rhizoctonia spp., as well as other leaf-spotting fungi on many ornamentals. D. CYPRODINIL/FLUDIOXONIL 12 (Palladium) 4–6 oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Amino acids and protein synthesis (9) and signal transduction (12) E. F. FENHEXAMID 0.75-1.5 lb/100 gal water (Decree 50 WDG) MODE OF ACTION GROUP NAME (NUMBER1): Hydroxyanilide (17) COMMENTS: Apply as a spray; very effective and can be applied after infection. FLUDIOXONIL Label rates (Medallion WDG) MODE OF ACTION GROUP NAME (NUMBER1): Phenylpyrroles (12) G. FLUOXASTROBIN 4–8 fl oz/100 gal (Disarm 480 SC) 1 MODE OF ACTION GROUP NAME (NUMBER ): Quinone outside inhibitor (11) COMMENTS: Preventative application. H. IPRODIONE 6.5 oz/100 gal water (Chipco 26019 N/G) MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2) Key Diseases 12 12 12 12 Gray Mold (11/20) 36 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES COMMENTS: Apply as a drench (1–2 pt/sq ft) at seeding or transplanting. Some resistance has been reported with this material. Effective against Rhizoctonia damping-off, Sclerotinia, and gray mold. Some iprodione is absorbed by plant parts. I. MANCOZEB 1–1.5 lb/100 gal water 24 (Dithane 75DF) MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 03) COMMENTS: Protects against leaf spots, Botrytis, rusts, and blight. Not systemic so thorough coverage is important for control. J. THIOPHANATE-METHYL 20 fl oz/100 gal water 12 (Talaris 4.5 F) 1 MODE OF ACTION GROUP NAME (NUMBER ): Methyl benzimidazole (1) COMMENTS: Apply as a drench or heavy spray (1–2 pt/sq ft) after sowing. Some resistance has been reported with this material. Thiophanate-methyl is absorbed by plant parts exposed to the chemical. Roots may absorb the fungicide (or its breakdown product carbendazim), which moves in the xylem to transpiring leaves. K. DICLORAN (Botran 75-W) Label rates MODE OF ACTION GROUP NAME (NUMBER1): AH-fungicides (14) 1 ‡ 12 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Gray Mold (11/20) 37 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PHYTOPHTHORA ROOT AND CROWN ROTS (11/20) Phytophthora spp. SYMPTOMS AND SIGNS Many, if not most, Phytophthora species can infect roots in the same manner as Pythium species. In addition, Phytophthora species infect crowns, stems, and larger roots, particularly in woody plants. Infection of the roots, crowns, and lower stems result in dark, discolored tissues. Tissues of diseased roots become soft and mushy and outer layers of the root may slough off. Plants with infected roots and crowns become stunted, are low in vigor, wilt, and appear as if they were water stressed. Foliage turns yellow, leaves fall off, and the plant may wilt and die. Aerial plant parts, including branches and shoots, can also be infected by some species of Phytophthora under wet conditions if infested soil, water, or airborne spores contact these aboveground parts. COMMENTS ON THE DISEASE The pathogens that cause Phytophthora root and crown rots are related to Pythium species. Pythium and Phytophthora are sometimes collectively referred to as the water molds and are grouped in the family Pythiaceae. Root and crown rots are most common under wet or over-irrigated soil conditions. Ideal soil conditions for the growth of Phytophthora are wet soils with temperatures in the range of 59° to 74°F. Like Pythium spp., these fungi can be spread by fungus gnats and shore flies. Phytophthora species have the same type of reproductive structures as Pythium species (i.e., oospores, sporangia, chlamydospores, and zoospores). Sporangia of some Phytophthora species (e.g., P. infestans and P. nicotiana) are airborne and aerial plant parts are the principal infection sites. ELISA test kits are available for detecting Phytophthora. MANAGEMENT Emphasis in control of Phytophthora diseases is placed on providing good drainage and water management. In addition, because aerial parts often are infected, propagative material can be a source of infection. Deep planting where soil covers the base of the stem encourages infection by Phytophthora. The same fungicides active against Pythium species also have activity against Phytophthora species. Copper-containing fungicides are also useful in protecting aerial parts of plants from infection by Phytophthora spp. Both Pythium and Phytophthora species can be introduced to planting areas via contaminated surface water and soil. Aerial infections by Phytophthora species of a number of plants have been observed where overhead irrigation with water from streams is practiced or where untreated, recirculated water is used. For more information, see MANAGEMENT OF SOILBORNE PATHOGENS. Steam (at 140°F for 30 minutes), solarize (double-tent at 160°F for 30 minutes or 140°F for 1 hour), or chemically treat growing medium. Sanitation is important because Phytophthora spp. can survive in dust, planting medium, or soil particles on greenhouse floors and in flats and pots. Remove and discard diseased plants. Use of properly composted pine bark as 20% of potting mix is reported to provide some control of Pythium and Phytophthora root rots. For flower production in open fields with warmer climates, solarization has successfully controlled most Phytophthora species in many crops. Care must be taken not to re-infest treated soil via contaminated plants, soil, media, or water. Solarization, steaming, and composting are acceptable for organic production. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. AMETOCTRADIN/DIMETHOMORPH (Orvego) Key Diseases 11–14 fl oz/50–100 gal water 12 Phytophthora Root and Crown Rots (11/20) 38 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MODE OF ACTION GROUP NAME (NUMBER1): Mitochondrial respiration inhibitor (45) and cell wall synthesis inhibitor (40) B. C. CYAZOFAMID (Segway) 3.0–6.0 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Ubiquinone reductase, Qi site (21) COMMENTS: Toxic to aquatic organisms. FENAMIDONE (Fenstop) 7–14 fl oz/50–100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Toxic to aquatic organisms. D. FLUOPICOLIDE (Adorn) 1–4 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Benzamides (43) COMMENTS: Toxic to aquatic organisms. E. F. FLUOXASTROBIN (Disarm 480 SC) 0.15–0.60 fl oz/100 gal MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) 12 12 12 12 SALTS OR ESTERS OF PHOSPHOROUS ACID (Aliette WDG) 2.5–5 lb/100 gal water for foliar application 12 MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (P 07) COMMENTS: Foliar spray is more effective than the soil drench. When applied as a foliar spray it is absorbed by foliage and moves into roots. G. MANDIPROPAMID (Micora) 4–8 fl oz/100 gal MODE OF ACTION GROUP NAME (NUMBER1): Carboxylic acid amides (40) 4 H. MEFENOXAM (Subdue Maxx) 0.5–1.0 fl oz/100 gal water 48 MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (4) COMMENTS: Applied at planting as a drench and periodically thereafter as needed. Available also in a granular formulation to use before planting. It is water-soluble and readily leached from soil. It is absorbed primarily through roots and is translocated in the plant through the xylem. Use of this material over a period of time may lead to resistance. I. 1 # ‡ REYNOUTRIA SACHALINENSIS (Regalia CG)# Label rates MODE OF ACTION GROUP NAME (NUMBER1): anthraquinone elicitor (P 05) 4 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Acceptable for use on organically grown ornamentals. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Phytophthora Root and Crown Rots (11/20) 39 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES POWDERY MILDEW (11/20) Powdery mildew: Erysiphe spp., Golovinomyces spp., Leveillula (=Oidiopsis) taurica, Oidium sp., Podosphaera spp. SYMPTOMS AND SIGNS Powdery mildew is the name given to diseases resulting from infection by fungi that produce a white to gray, powdery growth on the surfaces of leaves and sometimes other plant parts. Leaves may yellow, then brown and die. Infected tissues may be distorted and misshapen. COMMENTS ON THE DISEASE There are many kinds of powdery mildew fungi, and most are highly specialized. For example, the powdery mildew that infects squash plants will infect some other plants in the cucurbit family but will not infect roses, and the powdery mildew from roses will not attack zinnias (and vice versa), although the fungus that infects zinnias also infects many other members of the composite family. Powdery mildew fungi are obligate parasites; that is, they can grow only on living plant tissue. When the mildew-infected plant part dies, so does the mildew unless chasmothecia (spherical, resting stages of the fungus) are formed. Most powdery mildew fungi grow over the surface of the leaf, sending short food-absorbing projections (haustoria) into the epidermal cells. The fungi produce masses of spores (conidia), which become airborne and spread to other plants. Powdery mildew spores require no external moisture for germination, while most other fungi require free water in the form of dew, guttation, rain, or water from overhead irrigation for germination and infection. Conidia of powdery mildew (except those that infect grasses) die in water. Spores may be dispersed, however, by splashing water. The fungus survives in the absence of susceptible host tissues by forming a sexual stage (chasmothecia) resistant to drying and other adverse environmental conditions. With many perennial plants, such as rose, the fungus survives as mycelium in dormant buds or actively on plant tissues. Powdery mildews are particularly severe in semiarid regions, such as most of California, and are less troublesome in high rainfall areas. Powdery mildews are favored by warm days and cool nights and moderate temperatures (68° to 86°F). At leaf temperatures above 90°F, some mildew spores and colonies are killed. Shade or low light intensities as well as high relative humidity (greater than 95%) favor powdery mildew fungi. Greenhouse conditions are often ideal for development of the disease. MANAGEMENT The best control is through the use of resistant cultivars. However, little attention has been paid to the development of resistant cultivars in flower and nursery crops. Increased air movement around the plants in the greenhouse tends to reduce infection potential of mildews. Plants that have been treated with antitranspirants are less likely to develop powdery mildew infections Monitoring and Treatment Decisions In general, there are two types of fungicidal control: eradication of existing infections and protection of healthy tissues. In practice, some products provide both protection and eradication, especially when good wetting of the plant is achieved. To achieve good wetting, some of these products may require the addition of surfactants. The fungus has developed resistance to some of these fungicides. Rotate the different fungicides to help slow down the development of fungicide resistance within fungal strains. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing Key Diseases Powdery Mildew (11/20) 40 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. PROTECTANTS (Must be applied to healthy tissues before infection takes place) A. TEBUCONAZOLE (Torque) 4–10 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A systemic fungicide applied as a foliar spray; both a protectant and eradicant. B. CYPRODINIL/FLUDIOXONIL (Palladium) 4–6 oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Amino acids and protein synthesis (9) and signal transduction (12) C. BOSCALID/PYRACLOSTROBIN (Pageant) 6–12 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Carboximide (7) and quinone outside inhibitor (11) D. FLUOXASTROBIN (Disarm 480 SC) 1–4 fl oz/100 gal MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) 12 E. WETTABLE SULFUR# 3 lb/100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 02) COMMENTS: Use a wetting agent. Effectiveness of sulfur increases with increasing temperature, but the likelihood of plant injury increases also. Plant damage may result if sulfur is applied at temperatures exceeding 90°F. Some plants, such as melons, are sensitive to sulfur. Sulfur can be applied as a dust or as a spray. Repeated applications are generally necessary to protect new growth and also to renew deposits removed by rain or irrigation. F. MYCLOBUTANIL (Rally 40WSP) 3 oz/50 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A systemic fungicide applied as a foliar spray; both a protectant and eradicant of rusts or powdery mildew on carnations, crape myrtle, gerbera, roses, and snapdragons. G. AZOXYSTROBIN (Heritage) 1–4 oz/100 gal water 4 MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Acts as a protectant but has some eradicant properties. A locally systemic fungicide that is an eradicant and protectant against some powdery mildews. H. TRIADIMEFON (Bayleton Flo) Label rates 12 MODE OF ACTION GROUP NAME (NUMBER1): DMI (Group 3)1 triazole fungicide COMMENTS: A long-lasting systemic fungicide that provides for general control of some powdery mildews, some rusts, and leaf blight and spots in greenhouses and commercial nurseries. I. THIOPHANATE-METHYL (Talaris 4.5 F) 10–20 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) Key Diseases 12 Powdery Mildew (11/20) 41 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES COMMENTS: Not as effective against powdery mildew as other materials. Thiophanate-methyl is absorbed by plant parts exposed to the chemical. Roots may absorb the fungicide (or its breakdown product carbendazim), which moves in the xylem to transpiring leaves. J. K. L. PROPICONAZOLE (Banner Maxx II) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A preventive fungicide. REYNOUTRIA SACHALINENSIS# (Regalia CG) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Anthraquinone elicitor (P 05) 12 4 POTASSIUM BICARBONATE (Kaligreen)# 1–3 lb/100 gal water/acre 4 MODE OF ACTION GROUP NAME (NUMBER1): Inorganic salt (NC) COMMENTS: Primarily a protectant but it eradicates some existing infections with thorough coverage. Apply at first signs of infection. Thorough coverage is essential for good protection. Labeled for use on roses, field ornamentals, and greenhouse ornamentals. ERADICANTS A. LIME SULFUR 28% (Rex lime sulfur solution)# 0.5 gal/100 gal water 48 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 02)1 COMMENTS: Primarily an eradicant but has some protectant properties. Plant damage may result if applied when temperatures exceed 80°F. Not as effective against powdery mildew as other materials. Not for use in greenhouses. B. NEEM OIL (Triact 70)# Label rates 4 MODE OF ACTION GROUP NAME (NUMBER1): (NC) COMMENTS: A broad-spectrum botanical pesticide derived from the neem tree that is effective against various fungal diseases including black spot on roses, powdery mildew, downy mildew, anthracnose, and leaf spot. Registered for landscape and nursery ornamentals; oils work best as eradicants but also have some protectant activity. When using as a protectant, apply on a 14-day schedule; as an eradicant, apply on a 7-day schedule. Do not repeat oil applications frequently as multiple applications may burn leaves and flowers. Never apply any oil within 2 weeks of a sulfur spray or plants may be injured. C. PIPERALIN (Pipron) 4–8 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Amine (morpholine) (5)1 COMMENTS: Requires thorough coverage. For use in greenhouses only. A foliar spray that eradicates powdery mildew on rose, lilac, dahlia, phlox, zinnia, chrysanthemum, and catalpa. D. STYLET OIL (Organic JMS Stylet Oil)# 1 oz/gal water 4 MODE OF ACTION GROUP NAME (NUMBER1): (NC) COMMENTS: A good eradicant for mild to moderate powdery mildew infections; oils work best as eradicants but also have some protectant activity. Registered for use on chrysanthemum, dieffenbachia, philodendron, poinsettia, and roses. May be phytotoxic, especially on greenhouse roses. Do not repeat oil applications frequently as multiple applications may burn leaves and flowers. Do not apply to plants suffering from heat or moisture stress. Never apply any oil within 2 weeks of a sulfur spray or plants may be injured. Key Diseases Powdery Mildew (11/20) 42 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES E. TEBUCONAZOLE (Torque) 4–10 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A systemic fungicide applied as a foliar spray; both a protectant and eradicant. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. # Acceptable for use on organically grown ornamentals. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Powdery Mildew (11/20) 43 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PYTHIUM ROOT ROT (11/20) Pythium spp. SYMPTOMS AND SIGNS Pythium attacks juvenile tissues such as the root tip and newly germinated seedlings. After gaining entrance to the root the fungus may cause a rapid, brown to black rot of the entire primary root and may even move up into the stem tissue. As the soil dries, new roots may be produced and the plant may recover or never show symptoms of disease. Under wet conditions brought about by poor soil drainage or excess irrigation, more and more roots are killed and the plant may wilt, stop growing, or even collapse and die. Bulbs of susceptible plants turn brown to black, gradually desiccate, and form a hard mummy. COMMENTS ON THE DISEASE The pathogens that are responsible for Pythium root rot, also known as water molds, are present in practically all cultivated soils and attack plant roots under wet conditions. These fungi can be spread by fungus gnats and shore flies and end up contaminating potting mixes in containers. There are many species of Pythium; a few of these species are beneficial in that they compete with or parasitize the pathogenic species. Of the many pathogenic species, some have limited host ranges while others, such as Pythium ultimum, have very wide host ranges. Some Pythium species, such as P. aphanidermatum, are pathogens only at high temperatures (above 77°F), and some are active only at low soil temperatures. Soil moisture conditions of 70% or higher of available water capacity are conducive to infection by Pythium. It is likely that soil from a field contains several pathogenic Pythium species. Pythium species form several types of spores, but not all species form all types. Zoospores, which are produced in sporangia, are motile in water. Oospores, which result from a sexual process, usually undergo a period of dormancy and can withstand long periods of drying. Some species also form chlamydospores, which are asexual and have thick cell walls. These structures can serve as survival or overwintering structures. Sporangia and zoospores in general do not survive in air or dry soil for long periods of time. MANAGEMENT In the control of Pythium diseases, emphasis is placed on providing good drainage and water management. • Steam (at 140°F for 30 minutes), solarize (double-tent at 160°F for 30 minutes or 140°F at 1 hour), or chemically treat the growing medium. • Sanitize well because Pythium spp. can survive in dust, planting medium, or soil particles on greenhouse floors and in flats and pots. • Remove and discard diseased plants. • Use of properly composted pine bark as 20% of a potting mixture is reported to provide some control of Pythium and Phytophthora root rots. Additionally, the mycoparasite Gliocladium virens is used as a Pythium biocontrol agent. For flower production in outside fields, solarization has been successful for control of damping–off in many crops that are grown in warmer climates. There are reports of inadequate control of some high temperature species (e.g. P. aphanidermatum). Solarization and steaming are acceptable for organic production. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. FLUOPICOLIDE (Adorn) Key Diseases 1–4 fl oz/100 gal water 12 Pythium Root Rot (11/20) 44 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MODE OF ACTION GROUP NAME (NUMBER1): Benzamides (43) COMMENTS: Toxic to aquatic organisms. B. C. CYAZOFAMID (Segway) 1.5–3.0 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Ubiquinone reductase, Qi site (21) COMMENTS: Toxic to aquatic organisms. FENAMIDONE (Fenstop) 7–14 fl oz/50–100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Toxic to aquatic organisms. 12 12 D. BOSCALID/PYRACLOSTROBIN (Pageant) 12–18 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Carboximide (7) and quinone outside inhibitor (11) E. F. REYNOUTRIA SACHALINENSIS# (Regalia CG) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Anthraquinone elicitor (P 05) 4 MEFENOXAM 0.5–1.0 fl oz/100 gal water (Subdue Maxx) 48 MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (4) COMMENTS: Applied at planting as a drench and periodically thereafter as needed. Available also in a granular formulation to use before planting. It is water-soluble and readily leached from soil. It is absorbed primarily through roots and may be translocated in the plant through the xylem. Use of this material over a period of time may lead to resistance. G. SALTS OR ESTERS OF PHOSPHOROUS ACID (Aliette WDG) 2.5–5 lb/100 gal water for foliar application 12 MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (P 07) COMMENTS: When applied as a foliar spray, it is absorbed by foliage and moves into roots. Soil drench is less effective than a foliar application. H. ETRIDIAZOLE (Terrazole CA) 4–6 oz/100 gal 1 MODE OF ACTION GROUP NAME (NUMBER ): Heteroaromatics (14) I. GLIOCLADIUM VIRENS# (SoilGard) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Microbial (BM 02) 12 4 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. # Acceptable for use on organically grown ornamentals. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Pythium Root Rot (11/20) 45 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES RUST (11/20) Rust: Phragmidium spp., Puccinia spp., and others SYMPTOMS AND SIGNS Rust pustules appear as powdery masses of yellow, orange, purple, black, or brown spores on leaves and sometimes on stems. Depending on the particular plant host, pustules can be found on either side of leaves. Severe rust can result in dried, dead foliage. The most significant impact of rust disease is the reduction of quality and marketability of the commodity. COMMENTS ON THE DISEASE The rust fungi are obligate parasites in the order Uredinales. Some have complicated life cycles that include up to five different spore stages and two distinctly different hosts. Other rusts produce less than five or sometimes only one type of spore and infect only one kind of plant. Stem rust (Puccinia graminis) of wheat alternates between barberry (Berberis spp.) and wheat (Triticum vulgare) and all five spore stages are produced. Rose rust produces four spore stages but only roses (Rosa spp.) are infected. Urediniospores ("repeating" spores) are produced in pustules that appear yellow, orange, or brown as a result of masses of spores. These spores can re-infect the same host that produces them, making them the damaging phase of most rust diseases. Urediniospores are windborne and infect the plant through stomata. Water is required for short periods (6–8 hours or less) for germination and infection. Heavy dew is often sufficient. Once infection has occurred, water is no longer needed for continued development, and the infection and spore production will continue for the life of the leaf. Some rusts, including rose (Phragmidium tuberculatum) may survive the winter on leaves that do not fall off the plant. Rose rust also survives as teliospores (dark, thick–walled, overwintering spores) that form in fall. These spores survive in a dormant stage on fallen leaves. MANAGEMENT Rust diseases are favored by moderate temperatures that favor the growth of the host. Rust spores can be killed by high temperatures. Some rust infections, such as geranium rust (Puccinia pelargonii-zonalis), can be eradicated by hot water treatment of cuttings, although some damage to the host can occur. Because water is necessary for infection, overhead irrigation should be avoided when rust is a problem. Eliminate alternate hosts. Chrysanthemum white rust, caused by Puccinia horiana, and Gladiolus rust, caused by Uromyces transversalis, are under an eradication program in California. Gladiolus rust also causes disease on other members of the iris family such as Crocosmia, Tritonia, and Watsonia. See specific guidelines under the DISEASE CONTROL OUTLINE FOR CHRYSANTHEMUM and DISEASE CONTROL OUTLINE FOR GLADIOLUS. There are several fungicides that can be used to protect plants from infection. Mancozeb as a protectant and myclobutanil as an eradicant are generally effective against all rusts while triadimefon is effective against only specific rusts. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. TEBUCONAZOLE (Torque) 4–10 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A systemic fungicide applied as a foliar spray; both a protectant and eradicant. Key Diseases Rust (11/20) 46 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES B. MANCOZEB (Dithane 75 DF) 1–1.5 lb/100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 03) COMMENTS: Provides protection only; must be applied before infection. Protects against leaf spots, Botrytis, rusts, and blight. Thorough coverage is important for control. C. MYCLOBUTANIL (Rally 40WSP) 3 oz/50 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A systemic fungicide applied as a foliar spray; both a protectant and eradicant of rusts or powdery mildew on carnations, crape myrtle, gerbera, roses, and snapdragons. D. BOSCALID/PYRACLOSTROBIN (Pageant) Label rates 12 MODE OF ACTION GROUP NAME (NUMBER1): Carboximide (7) and quinone outside inhibitor (11) E. F. FLUOXASTROBIN (Disarm 480 SC) 1–4 fl oz/100 gal MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) 12 TRIADIMEFON (Bayleton Flo) Label rates 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A long-lasting systemic fungicide that provides for general control of some powdery mildews, some rusts, and leaf blight and spots in greenhouses and commercial nurseries. Because this material is closely related to growth retardant materials, it can have a toxic effect on certain plants, such as greenhouse roses. G. AZOXYSTROBIN (Heritage) 1–4 oz/100 gal water 4 MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Apply as a broadcast or banded spray targeted at the foliage or crown of the plant. A locally systemic fungicide that is effective against rusts. H. REYNOUTRIA SACHALINENSIS# (Regalia CG) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Anthraquinone elicitor (P 05) 4 I. WETTABLE SULFUR# 1–3 lb/100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 02) COMMENTS: Use a wetting agent. Not as effective as other materials. Apply this material with caution when temperatures exceed 85°F. J. CHLOROTHALONIL (Chlorothalonil 720 SFT) 1.375 pt/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M 05) COMMENTS: Provides protection only; must be applied before infection. 12 K. PROPICONAZOLE (Banner Maxx II) 2–16 fl oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Controls white rust of chrysanthemums but may cause phytotoxic symptoms on some cultivars. L. NEEM OIL (Triact 70)# Label rates MODE OF ACTION GROUP NAME (NUMBER1): (NC) Key Diseases 4 Rust (11/20) 47 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES COMMENTS: Registered for landscape and nursery ornamentals, neem has some protectant properties against rust, but is not effective for rust on rose. Apply on a 14-day schedule. * 1 Permit required from county agricultural commissioner for purchase or use. Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. # Acceptable for use on organically grown ornamentals. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Rust (11/20) 48 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SOUTHERN BLIGHT (11/20) Sclerotium rolfsii SYMPTOMS AND SIGNS Southern blight, also called southern wilt, southern stem rot, southern root rot and other names, results from infection by the soilborne fungus Sclerotium rolfsii. The fungus survives in the soil as small (0.04–0.08 inch), tan to brown, round sclerotia. The sclerotia resemble mustard seeds in size and color and the fungus is sometimes referred to as the "mustard seed fungus." Plants are attacked at the soil line or below ground. The fungus produces abundant white hyphae or mycelia around infected parts and in and on the soil. Sclerotia are formed by the mycelia on infected plant parts and in the soil; their presence is the main diagnostic feature of the disease. The initial symptoms are similar to those caused by other basal stem rots (cottony rot, Rhizoctonia stem rot, etc.): discolored crown/stem lesion at the soil line, discoloration of lower leaves, wilting, plant collapse, and death. COMMENTS ON THE DISEASE The disease is favored by warm moist soil, hence it occurs in the summer months. The fungus has a wide host range and includes many field, vegetable, and ornamental crops. This pathogen is a regulated pest in California nurseries and must be eradicated. Contact your County Agricultural Commissioner for details. MANAGEMENT Steam (at 140°F for 30 minutes), solarize (double-tent at 160°F for 30 minutes or 140°F for 1 hour), or chemically treat growing medium for container-grown plants. For outdoor field production, soil fumigation or soil solarization (in warmer climatic areas) is effective in killing soilborne sclerotia. Bulbs and other planting stock may carry the fungus. The fungus is killed by exposure to 122°F for 30 minutes and some plant materials such as caladium tubers, iris rhizomes, and gladiolus corms can be treated successfully with hot water. Use of heat treatment (steam, solarization, and/or hot water) is acceptable for organic production. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. SOIL FUMIGATION A. CHLOROPICRIN* Label rates See label COMMENTS: Inject into soil and cover immediately with plastic tarps. Fumigants are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. SOIL FUNGICIDE A. TEBUCONAZOLE (Torque) 4–10 fl oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A systemic fungicide applied as a foliar spray; both a protectant and eradicant. B. CYPRODINIL/FLUDIOXONIL (Palladium) 2–4 oz/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Amino acids and protein synthesis (9) and signal transduction (12) C. FLUTOLANIL (Prostar 70 WG) 3–6 oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Succinate-dehydrogenase inhibitor (7) Key Diseases 12 Southern Blight (11/20) 49 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES D. PCNB (Terraclor 400) Label rates 12 MODE OF ACTION GROUP NAME (NUMBER1): Aromatic hydrocarbon (14) COMMENTS: Helpful in preventing infection when incorporated into top 2 inches of soil. Best available material for southern blight caused by Sclerotium rolfsii. Insoluble in water and must be thoroughly mixed with soil to reach its desired depth of control. Works through vapor action and has good residual action. Germination of some seeds may be inhibited and small plants may be stunted by this fungicide. * 1 § ‡ Permit required from county agricultural commissioner for purchase or use. Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Do not exceed the maximum rates allowed under the California Code of Regulations Restricted Materials Use Requirements, which may be lower than maximum label rates. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Southern Blight (11/20) 50 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SUDDEN OAK DEATH AND RAMORUM BLIGHT (11/20) Phytophthora ramorum SYMPTOMS AND SIGNS Although hosts of P. ramorum show a range of foliar symptoms, the disease is generally characterized by irregular, necrotic leaf lesions, instead of distinct leaf spots. Leaf infections can spread to the petiole and twigs, but diseased leaves often fall off before the lesion reaches the petiole. Sometimes infections occur initially on stems or develop into stems, where associated leaves eventually wilt, become necrotic, and die. On some hosts, a fairly distinct dark line can mark the advance of leaf infection, especially in cool and wet conditions. Symptoms are most often found on leaf tissue where free water remains for long periods: leaf tips, leaves hanging down or located deep within the canopy, leaves near or touching the soil, or leaves that overlap or are cupped. Root infections are possible on some hosts, but the roots often appear more or less healthy. Root rot symptoms, typical of infections by other Phytophthora species, are not seen. The importance of these cryptic root infections in the spread of P. ramorum in the nursery trade is not yet clear. While not commonly seen on nursery hosts, bark cankers on the trunks of woodland trees, such as oak and tanoak, are also associated with this disease. Cankers have red-brown to black discoloration, dark black to reddish colored sap, and often develop 3 to 6 feet above the ground, although they can be higher or lower. Symptoms caused by fertilizer burn, chemical injury, drought injury, freeze damage, sunburn, and root damage can sometimes look like P. ramorum foliar infection. However, these abiotic injuries are often found distributed over the entire plant, while lesions caused by P. ramorum are often only found initially on a few leaves or on one portion of the plant. There are many damaging species of Phytophthora other than ramorum, so diagnosis by a qualified lab is extremely important. COMMENTS ON THE DISEASE In the mid to late 1990s, portions of woodlands in Marin, Santa Cruz, and Monterey counties changed dramatically. Tree crowns turned brown within a few weeks, giving the impression of instantaneous mortality. Since then more than a million tanoaks, (Notholithocarpus [=Lithocarpus] densiflorus), California black oaks (Quercus kelloggii), coast live oaks (Quercus agrifolia), and other oak species have died as a result of P. ramorum infection in northern and central California. The pathogen also causes mortality in forested regions of southern Oregon. Additionally, it can be found in streams as well as the natural waterways of Washington. A distinct European lineage of P. ramorum is causing similar diseases on ornamentals in some nurseries, botanic gardens, and landscapes in Europe. It has been infecting Vaccinium spp. in the heathlands of Scotland and Wales. Oak, and especially Japanese larch plantations, have been heavily impacted in the United Kingdom. Camellias, rhododendrons, viburnums, Pieris spp., and other popular ornamental plants are susceptible to P. ramorum infection, and the pathogen can move long distances through shipments of infected nursery stock. Federal and state quarantines are in effect that require nursery inspections. If the pathogen is found, affected nursery stock must be destroyed. For a current host list and additional regulatory information, refer to the U.S. Department of Agriculture Animal and Plant Health Inspection Service’s website on P. ramorum. BIOLOGY Phytophthora ramorum, while having many features in common with fungal organisms, is not a true fungus. Phytophthora species are Oomycetes or "water molds" and require a moist environment to actively grow and reproduce. Phytophthora ramorum produces several reproductive structures important for pathogen spread and survival, including sporangia, zoospores, and chlamydospores. Sporangia give rise to the zoospores, which can swim in water. Chlamydospores are resting spores that help the pathogen survive extreme temperatures, dryness, and other harsh conditions. Phytophthora ramorum can grow within a temperature range of 36° to 80° F with an optimum temperature of 68° F. Key Diseases Sudden Oak Death (11/20) 51 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Spores can form on leaf surfaces of susceptible leaves and twigs following prolonged wetting. They are moved from plant to plant via windblown or splashed rain or by direct contact with infected leaves. Spores produced on infected plants can move to healthy plants in water runoff created by rain or sprinkler irrigation water. In California forests the pathogen sporulates prolifically on California bay laurel trees (Umbellularia californica), which serve as reservoirs for inoculum. Infected California bay laurel can also be an important source of inoculum when near the nursery stock. MANAGEMENT There are federal and state quarantines that require inspections for nursery stock in regulated California counties. If the pathogen is detected, the affected plants are destroyed and the pathogen is eradicated. Disease symptoms may take weeks to several months to develop and become apparent, so infected plants may appear healthy at first. Fungicides that have activity on Phytophthora might prevent new infections and therefore interfere with detection of this pathogen; it is best not to apply fungicides while evaluating the disease status. For most nurseries, the foremost objective of pest management programs is to prevent the introduction of the pathogen into the nursery via infected plant material. This can be partly accomplished by careful inspection of all incoming host propagative material and stock. • Monitor new outside source stock at least biweekly in summer and at least weekly during rainy periods when environmental conditions are highly conducive to pathogen infection and development. For nurseries surrounded by native host trees and shrubs and in the vicinity where P. ramorum is found, monitor areas surrounding the nursery, especially wet areas, near puddles, or rain runoff zones. It is very important to detect the pathogen early, while it is still at very low levels. • Periodically inspect nearby native hosts for disease symptoms. Infected California bay laurel trees near the perimeter of nurseries may produce inoculum that can spread and cause infection of nearby host plants, so removal of these trees may be warranted. • Consider building berms to prevent water and soil movement into production areas from hillsides surrounding the nursery that may contain infected hosts. • Irrigation water pumped from streams and ponds in areas of infected native hosts may be contaminated with P. ramorum. Consider having this water periodically tested to detect P. ramorum. If it is found to be present, use alternative irrigation sources, such as well water or water disinfection treatments. For more information on developing a detection and monitoring program, see Nursery Guide for Diseases Caused by Phytophthora ramorum on Ornamentals: Diagnosis and Management, UC ANR Publication 8156. Cultural Practices Cultural practices that can be useful to reduce disease risk: • Avoid irrigation practices that leave foliage wet for prolonged periods. If sprinklers are used, irrigate in the morning to allow for thorough and quick drying of foliage. • Monitor and maintain irrigation systems to insure the most uniform application of water to the crop. Correct low spots, areas of poor drainage, and clogged or leaking irrigation heads. • Monitor irrigation-water sources, other than well water, for P. ramorum. Use disinfection systems if using recycled water. • Wounded leaves (even tiny wounds or scratches) are much more susceptible to infection. Avoid handling host plants if they might be wounded when environmental conditions favor disease. • Avoid splashing water from soil to foliage, as well as from foliage to soil or container soil. Use raised benches, gravel, or other means to elevate susceptible plants above soil. Transplants, even on gravel beds, appear to be very susceptible to disease because of the close proximity of foliage to soil, runoff water, or rain splash. Raised benches may be warranted for transplants. • Remove plants or plant parts that are suffering from poor vigor, disorders, or other serious problems from production areas and destroy them. A small number of plants or plant parts could be Key Diseases Sudden Oak Death (11/20) 52 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES • • bagged and disposed. If a cull pile is needed temporarily, cover it with a clear polyethylene sheet until the culls can be destroyed or composted. Propagate cuttings only from disease-free hosts. Use only new or disinfested containers and soil. Place potting soil piles as far from infected native hosts or cull piles as possible and covered with clear polyethylene sheeting. Do not mix potting soil components on bare soil. Monitoring and Treatment Decisions Fungicides used to protect nursery stock from P. ramorum function as preventive treatments only. Currently, even the most active fungicides do not stop the development of P. ramorum once foliar lesions are present. The use of Phytophthora-specific fungicides may be warranted for high risk situations, such as where a nursery is exposed to local inoculum sources from surrounding infected native hosts or where P. ramorum has been detected previously in the nursery. Fungicides should only be used after other management strategies and preventive steps have been fully implemented. When applying fungicides, good coverage over the foliage is important; add a wetting agent to prevent significant run-off and loss of fungicides on the hard-to-wet leaves of certain plant species. Apply treatments before environmental conditions favor pathogen infection; for example, spraying before a period of rainy weather will allow water to linger on leaf surfaces for many hours. Some fungicides applied to the foliage move into leaves and are not washed off by rain or sprinkler irrigation, while others provide a protective layer of chemical on the leaf surface. Some can be applied to the soil, where they are absorbed and moved upward to the leaves, to protect them from infection. Some have residual activity that can last for several weeks after they are applied. Read fungicide labels and technical information provided by the fungicide manufacturer to learn how the fungicide can be used most effectively. See PHYTOPHTHORA ROOT AND CROWN ROTS and management in this section. Resistance management. To help reduce the potential for the development of resistance by P. ramorum to fungicides, alternate or tank mix fungicides with different mode-of-action group numbers. Fungicides active on P. ramorum may already be used in the nursery to control other foliar or soil-inhabiting Phytophthora species or related pathogens (such as downy mildews), and their use should be considered in planning the overall fungicide resistance management program. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. A. CYAZOFAMID (Segway) 3.0–6.0 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Ubiquinone reductase, Qi site (21) COMMENTS: Toxic to aquatic organisms. B. C. DIMETHOMORPH (Stature SC) 12.25 fl oz/100 gal MODE OF ACTION GROUP NAME (NUMBER1): Carboxylic acid amides (40) 12 12 MEFENOXAM (Quali-Pro Mefenoxam 2 AQ) Label rates 48 MODE OF ACTION GROUP NAME (NUMBER1): Phenyl amides (4) COMMENTS: The granular formulation may be applied preplant or the liquid formulation can be applied as a drench at planting. Mefenoxam is water-soluble and readily leached from soil. It is absorbed primarily through roots and may be translocated in the plant through the xylem. D. MANDIPROPAMID (Micora) Key Diseases 4–8 fl oz/100 gal 4 Sudden Oak Death (11/20) 53 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MODE OF ACTION GROUP NAME (NUMBER1): Carboxylic acid amides (40) E. F. FLUOPICOLIDE (Adorn) 1–4 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Benzamides (43) COMMENTS: Toxic to aquatic organisms. Drench application. 12 FENAMIDONE (Fenstop) 7–14 fl oz/50–100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) COMMENTS: Toxic to aquatic organisms. 12 G. BOSCALID/PYRACLOSTROBIN (Pageant) 12–18 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Carboximide (7) and quinone outside inhibitor (11) H. SALTS OR ESTERS OF PHOSPHOROUS ACID (Aliette WDG) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (P7) 1 ‡ 12 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action group number. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Sudden Oak Death (11/20) 54 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES VERTICILIUM WILT (11/20) Verticillium wilt: Verticillium albo-atrum, Verticillium dahliae SYMPTOMS AND SIGNS Symptoms vary somewhat with the kind of plant and the environment, but some symptoms are common to most situations. The leaves may wilt and turn yellow, first at the margins and between the veins, then they turn tan or brown and die starting from the base to the tip of the plant or branch. Dead leaves can either fall off or remain attached to the plant. Woody plants often are affected first on one side, and affected branches usually die. The water-conducting tissues (xylem) of infected plants are often discolored with dark brown to black streaks. In some plants, including olive, ash, and roses, there is little or no discoloration. COMMENTS ON THE DISEASE Verticillium wilt, one of the most widespread and destructive soilborne diseases of plants, affects a large number of herbaceous and woody species throughout the world. The causal fungus, Verticillium dahliae, infects susceptible plants through the roots and plugs the water conducting tissues. Susceptible flower crops include China aster, chrysanthemum, cineraria, dahlia, geranium, gerbera, heather, marigold, peony, pelargonium, rose, snapdragon, statice, stock, and strawflower. The V. dahliae fungus forms microscopic black resting structures (microsclerotia) capable of surviving in soil for many years in the absence of a susceptible plant. When a susceptible plant is planted in infested soil, the microsclerotia germinate and infect the plant. Long rotations with nonsusceptible plants are not effective in controlling the fungus. The fungus also produces conidia that can be transported in irrigation water; however, they are not longlived. The fungus can be disseminated by leaves dropping from infected plants and being blown around by the wind. MANAGEMENT Many horticultural crop plants have been selected or bred for resistance to the fungus. Use resistant cultivars and pathogen-free plants whenever possible. Steam (at 140°F for 30 minutes), solarize (double-tent at 160°F for 30 minutes or 140°F for 1 hour), or chemically treat growing medium. For outdoor cut flower or nursery production, avoid fields previously used for susceptible crops (e.g., tomato, cotton, potatoes, strawberries, as well as the ornamentals listed above) unless disinfected. Soil fumigation or soil solarization (in warmer climatic areas) can be useful. During the growing season, remove and destroy any plants that exhibit symptoms of Verticillium wilt. Common name (Example trade name) Amount to use REI‡ (hours) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first–the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide’s properties and application timing, honey bees, and environmental impact. Always read the label of the product being used. SOIL FUMIGATION A. CHLOROPICRIN* Label rates See label Allowable for use under a Critical Use Exemption only. Fumigants are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. B. Sequential application of: (Note: Fumigants such as 1,3-dichloropropene and metam products are a source of volatile organic compounds (VOCs) but minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.) CHLOROPICRIN*/1,3 DICHLOROPROPENE* (Pic-Clor60) (Pic-Clor60 EC) Key Diseases 300–332 lb (shank) 200–300 lb See label See label Verticillium Wilt (11/20) 55 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES COMMENTS: Very effective for control of soilborne fungal pathogens and insects. Drip irrigation requires an emulsifier. For shank fumigation, using higher rates or plastic mulch, especially virtually impermeable film (VIF), improves weed control. For drip fumigation the use of VIF will improve both nematode and weed control. According to state permit conditions, the maximum application rate of 1,3-dichloropropene is 332 pounds active ingredient per acre. Pic-Clor60: One gallon of weighs 12.1 lb; Pic-Clor60 EC: One gallon of weighs 11.8 lb. Following 5 to 7 days after fumigation: METAM SODIUM* (Vapam HL, Sectagon 42) 37.5–75 gal See label COMMENTS: Water-soluble liquid that decomposes to a gaseous fumigant (methyl isothiocyanate). Efficacy affected by soil texture, moisture, temperature, and percent organic matter. One gallon of product contains 4.26 lb of metam sodium. . . . or . . . METAM POTASSIUM* (K-Pam HL, Sectagon–K54) 30–45 gal See label COMMENTS: Water-soluble liquid that decomposes to a gaseous fumigant (methyl isothiocyanate). Efficacy affected by soil texture, moisture, temperature, and percent organic matter. One gallon of product contains 5.8 lb of metam potassium. C. DAZOMET* (Basamid) 200 lb See label COMMENTS: Powder incorporated into the soil, followed by irrigation or tarping. It decomposes to a gaseous fumigant (methyl isothiocyanate). SOIL FUNGICIDES A. REYNOUTRIA SACHALINENSIS (Regalia CG)# Label rates MODE OF ACTION GROUP NAME (NUMBER1): anthraquinone elicitor (P 05) * § ‡ 4 Permit required from county agricultural commissioner for purchase or use. Do not exceed the maximum rates allowed under the California Code of Regulations Restricted Materials Use Requirements, which may be lower than maximum label rates. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Key Diseases Verticillium Wilt (11/20) 56 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES VIRUSES AND VIROID DISEASES (11/20) SYMPTOMS AND SIGNS Virus diseases are recognized by several characteristic symptoms. Light and dark green mosaic patterns, mottles, ringspots, distortion of leaves and other plant parts, vein clearing, and vein enations are some of the symptoms seen in the leaves. Deformed, yellow, stunted growth, or overall stunting are other possible symptoms. COMMENTS ON THE DISEASE Viruses multiply only in living cells. They are too small to be seen with a light microscope and are therefore considered to be submicroscopic. Viruses are composed of a nucleic acid (most plant viruses contain ribonucleic acid [RNA]) and are enclosed in a protein coat. The nucleic acid of a few plant viruses (Carnation etched ring virus, Dahlia mosaic virus) is deoxyribonucleic acid (DNA). Viroids consist of low molecular weight RNA that lacks a protein coat. Chrysanthemum stunt viroid and Chrysanthemum chlorotic mottle viroid are examples of viroids. Positive identification of virus infection involves several procedures, including visualization of virus particles with the electron microscope, serological techniques such as ELISA (enzyme-linked immunosorbance assay), sap inoculations of indicator plants, budding and grafting to indicator plants, microscopic examination for inclusion bodies (aggregates of virus particles or virus-induced protein structures), RNA and DNA hybridization, polymerase chain reactions (PCR), and gel electrophoresis. Many viruses enter the host plant via the feeding activity of vectors that transmit the virus into plant cells. Insects, especially aphids, whiteflies, and leafhoppers, vector many viruses. Thrips vector Tomato spotted wilt virus and Impatiens necrotic spot virus. Mites, nematodes, and lower fungi also serve as vectors of a few viruses. See the Viruses With Wide Host Ranges table for a list of common plant viruses and their hosts, how they are spread, and links to photographs of their damage. Most viruses are transmitted by vegetative propagation of new plant material from infected mother plants. Many plant viruses and viroids are spread by physical contact or by tools. Some orchid viruses are spread when healthy plants come in contact with diseased ones. Some viruses are pollenborne (Cherry leaf roll virus, Prunus necrotic ringspot virus). A few viruses are seedborne (Squash mosaic virus in muskmelons, Tomato mosaic virus in tomato, and others). Several viruses, including Tobacco mosaic virus, can survive in water run-off from infected plants, which, when recycled and used as irrigation water, can result in new infections. MANAGEMENT Control of virus diseases is a matter of prevention–the use of virus-free planting stock and resistant varieties. Once a plant is infected by a virus it usually remains infected for the life of the plant as there are no available pesticide treatments. Plants vegetatively propagated from infected mother stock are usually infected. However, virus-free plants can be obtained from infected plants by a combination of heat treatment and shoot tip (meristem) culture, and sometimes with the aid of chemical inhibitors of virus multiplication. Some viruses are transmitted from plant to plant by means of the feeding activity of insects. Once an insect has acquired a virus, it may retain it in a persistent (up to lifetime) or non-persistent (usually means minutes to hours) manner. Controlling insect vectors may help in reducing the spread of persistently transmitted viruses; however, with non-persistently transmitted viruses, insects can often spread the virus before they are inactivated by insecticides. Remove weeds and other plants that may harbor the virus and/or the vector. Disinfection of pruning or propagation tools between cuts, or at least between different plant sets, varieties, or species, and the use of disposable gloves can help reduce the spread of virus diseases in a greenhouse operation. A solution of 1 part household bleach in 4 parts of water, applied for 5 minutes, acts as an effective disinfectant for virus-contaminated materials (tools, benches, etc.). Bleach solutions must be rinsed off with clean water to avoid toxicity to plants. (Note: Bleach treatments are corrosive to metal tools.) See MANAGEMENT OF SOILBORNE PATHOGENS section for more details. Cultural Control Key Diseases Viruses and Viroid Diseases (11/20) 57 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES In outdoor field crop production, silver reflective mulch has been shown to repel aphids and whiteflies, thus reducing their numbers in and around plant canopies. In addition, virus transmission by these insects was greatly reduced. For best results, apply mulches at the time of planting or transplanting the crop. Apart from reducing aphid and virus incidence, silver reflective mulch increased cut flower production and reduced the crop requirement for irrigation water and fertilizer. This method is acceptable for organic production. Viruses with wide host ranges. Ornamental hosts Crop plant hosts Weed and native plant hosts Virus Transmission Bean yellow mosaic (potyvirus group) aphids; mechanically gladiolus, sweet pea, violets legumes, bean, clovers, to an extent in gladiofava bean, pea, soybean, lus sweet clover legumes, Chenopodium, clovers, sweet clover Beet curly top (geminivirus group) leafhoppers cosmos, coreopsis, geranium, nasturtium, petunia, strawflower, stock, viola, zinnia bean, beets, borago, buckwheat, celery, clovers, cress, cucurbits, fava bean, fennel, flax, horseradish, pepper, potato, radish, rhubarb, tobacco, tomato, vetch Atriplex spp., Chenopodium spp., clovers, Polygonum spp., Rumex spp., Russian thistle, shepherd's-purse Cauliflower mosaic (caulimovirus group) aphids honesty (lunaria), stock crucifers, broccoli, cabbage, mustard, Raphanus spp., cauliflower, Chinese cabshepherd's-purse bage, mustard Cucumber mosaic (cucumovirus group) aphids; mechanically in many hosts begonia, buddleia, calenbuckwheat, carrot, celery, dula, China aster, columcucurbits, cowpea, pepper, bine, dahlia, daphne, delpotato, tobacco, tomato phinium, geranium, gerbera, gladiolus ligustrum, lily, lobelia, nasturtium, passionvine, primula, snapdragon, vinca, viola, zinnia commelina, lambsquarters, lupine, milkweed, nightshade, penstemon, pigweed, pokeweed, tree tobacco (Nicotiana glauca) Prunus necrotic ringspot (ilarvirus group) grafting; pollen Prunus spp., rose apple, hops, Prunus spp. Prunus spp. Tobacco mosaic (tobamovirus group) mechanical; seeds delphinium, petunia, phlox, may be externally wisteria, flowering tobacco contaminated, can be soilborne beans, tobacco, tomato, peppers Emilia, tree tobacco artichoke, basil, bean, celery, clover, cowpea, endive, fava bean, lettuce, papaya, pea, peanut, pepper, pineapple, spinach, tobacco, tomato, and others bindweed, chickweed, emilia, jimsonweed, knotweed, lupine, malva, Mesembryanthemum, miner's lettuce, physalis, pigweed, nightshade, shepherd's-purse, and others Impatiens necrotic thrips spot and tomato spotted wilt (tospovirus group) amaryllis, aster, ageratum, begonia, calendula, calla, chrysanthemum, coreopsis, cosmos, dahlia, forget-menot, gerbera, gladiolus, gloxinia, gypsophila, impatiens, kalanchoe, lily, nasturtium, nemesia, papaver, petunia, phlox, primula, ranunculus, salvia, stock, sweet pea, tagetes, verbena, zinnia, and others Turnip mosaic (potyvirus group) anemone, nasturtium, petu- Brussels sprouts, cabbage, cruciferous weeds nia, statice, stock, sweet wil- cauliflower, cress, horseradliam, wallflower, zinnia ish, lettuce, mustard, radish, rape, rhubarb, swede turnip Key Diseases aphids Viruses and Viroid Diseases (11/20) 58 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Disease Control Outlines ASTER, CHINA Callistephus chinensis (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Fusarium wilt* (Fusarium oxysporum f. sp. callistephi) Plants yellow and wilt, often on one side. Brown discoloration of vascular system develops. Disease also causes damping-off of young seedlings at soil temperatures of 75° to 80°F. Commonly seedborne. In soil for many years. Disease is most severe when soil and/or air temperatures are high. Use disease-free seed. Fumigate the seedbed with chloropicrin or a sequential application of chloropicrin/1,3 dichloropropene and metam sodium or solarize soil. Grow on clean land, or only once every 5 years on infested land. Treat seed with a fungicide. Gray mold* (Botrytis cinerea) Brown, water-soaked decay of flowers. Fuzzy gray fungus spores form on rotted tissues. Fungus also attacks base of plant. In plant debris. Favored by cool, wet conditions. Avoid overhead irrigation. Mist blooms with iprodione or fenhexamid. Leaf spots (Stemphylium callistephi) Circular, irregular, brown spots appear on lower leaves. Leaves may die. In plant debris. Airborne spores require long (48 hrs), damp periods for infection. Avoid low-lying areas where air movement is poor. Do not use overhead irrigation. Protect foliage with a fungicide such as mancozeb. Root rot (Pythium* and Phytophthora spp.*) Plants wilt or suddenly collapse. Roots decay. Blackish discoloration of leaves, stems, and roots occurs. Also causes damping-off of seedlings. In soil. Favored by heavy, waterlogged soils. Rust* (Coleosporium asterum) Orange pustules of powdery spores form on undersides of leaves. On living plants and possibly from spores from alternate host (three-needle pines). Favored by free moisture from rain, dew, or fog. Avoid overhead irrigation. Treat at the first signs of rust and continue until conditions are no longer favorable for the disease. Grow seedlings away from main crop. Cottony rot or Sclerotinia rot Infection girdles stems. Cottony, white fungal growth and large, black sclerotia develop on and inside stems. Stems take on a bleached-white color. Airborne spores produced by sclerotia in soil, but infection more common from growth of hyphae from sclerotia. Favored by wet weather. Avoid overhead irrigation. Treat planting area with PCNB. Spray plants with iprodione or thiophanate-methyl before rainy periods and at 2- to 4-week intervals during wet weather. Remove plant debris from field. Stem rot (Rhizoctonia solani, Botrytis cinerea) A brown decay develops at the soil line and affects the basal leaves and stem. Soilborne and in plant debris. Gray mold (B. cinerea) favored by cold, damp conditions. Disease development can be rapid under high temperature conditions. Before planting or transplanting, mix PCNB or Trichoderma spp. into top inch of soil. Spray bases of seedlings with thiophanate-methyl, iprodione, or Trichoderma spp. Verticillium wilt* (Verticillium dahliae) Symptoms are almost identical to Fusarium wilt. Not a common disease of asters in California. In soil for many years. Symptoms most severe during warm weather that follows a cool period. Avoid planting in fields where fungus has occurred or fumigate soil as described for Fusarium wilt. Virus or viruslike diseases Symptoms Host range and natural spread Comments on control Aster yellows* (Aster yellows phytoplasma) Infected plants produce an upright basal rosette of yellow shoots. Sometimes one-sided. Flowers are deformed and remain green. Sporadic disease of asters in California. Aster yellows phytoplasma has a wide host range. Vectored by leafhoppers. Locate seedbed away from weedy areas. Control weeds and leafhoppers in noncropped areas. (Sclerotinia sclerotiorum) Disease Control Outlines Aster, China (11/20) 59 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES AZALEA Rhododendron spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Cutting rot and graft decay (Rhizoctonia solani and Cylindrocladium scoparium) Basal rot of cuttings occurs. Under humid conditions, tops are rotted and covered with fungal strands (mycelium). In soil and plant debris. Favored by moist conditions and temperatures of 75° to 80°F. Steam or chemically treat propagating media, flats, etc. Grow stock plants in treated media and observe strict sanitation. Spray or drench cuttings in rooting media with thiophanate-methyl or iprodione. Cylindrocladium is difficult to control with fungicides; triflumizole can be used in enclosed commercial structures. Flower blight (Ovulinia azaleae) Small, round spots rapidly enlarge and cause entire flower to collapse. Rotted flower becomes soft and clings to leaves or stems. Black fungal structures (sclerotia) produced in diseased flowers and survive in soil. Favored by cool, rainy weather and by moisture on flowers. Spores are airborne. Avoid overhead irrigation. Remove and burn diseased blossoms. Mulch soil with 4-inch layer. Treat soil with PCNB several weeks before plants bloom. Protect blossoms with thiophanate-methyl or triadimefon. Leaf gall (Exobasidium vaccinii) All or part of leaf becomes greatly thickened, distorted, and crisp. Also affects flowers. Infected parts are covered with a white or pinkish bloom of fungal spores. On living plants. Airborne spores produced only during wet weather. Hand-pick galls where practical before they turn white. Avoid overhead irrigation. Protect foliage with a fungicide, such as mancozeb, during wet weather. Ramorum blight* (Phytophthora ramorum) Leaf lesions that vary in size from 0.2 inches to covering nearly half the leaf. Lesions primarily at leaf tip or edge; can be surrounded by diffuse margins or thick black zone line. Infected leaves drop prematurely and lower part of plant can defoliate. Symptoms may be confused with leaf scorch in areas of high heat/sun. Spore structures commonly form on leaf surfaces and twigs, following prolonged wetting. They are moved in contaminated soil, from plant to plant via windblown rain, or by direct contact with infected leaves. Monitor incoming stock and areas surrounding the nursery for symptoms, follow good cultural and sanitation practices, and use preventive treatments before environmental conditions favor development of the pathogen. Root rot (Pythium* and Phytophthora spp.*) Plants are low in vigor. Leaves wilt and turn dull green and fall prematurely, so only a few terminal leaves remain on the plant. Plants frequently die. Wood under bark at soil line is discolored. Roots become discolored and rotten (Pythium). Root and basal stem rot (Phytophthora). Water molds occur in soil. Favored by overwatering, poor drainage, and other factors that weaken plants. Treat growing media with chloropicrin or other recommended fumigants. Select cuttings from high on stock plants. Drench plants with oomycete (water mold) specific fungicide, or spray with fosetyl-Al. Septoria leaf spot or leaf scorch (Septoria azaleae) Dark, reddish brown, angular spots appear on leaves, which fall prematurely. Leaves yellow on some cultivars. On living and dead leaves. Favored by wet weather. Fungal spores spread in splashing water. Avoid overhead irrigation. Protect foliage with a fungicide such as mancozeb or thiophanate-methyl. Azaleas are also susceptible to crown gall* (Agrobacterium tumefaciens), gray mold* (Botrytis cinerea), powdery mildew* (Erysiphe sp.), and web blight (Rhizoctonia solani). * For additional information, see section on Key Diseases. Disease Control Outlines Azalea (11/20) 60 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BEGONIA Begonia spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial leaf spot (Xanthomonas campestris pv. begoniae) Circular, necrotic spots start as small, water-soaked, blisterlike spots. Premature abscission occurs when spots are numerous. Systemic as well as in dead begonia leaves. Favored by splashing water or overhead irrigation and high temperatures (80° to 90°F). Keep humidity low. Avoid wetting foliage. Do not crowd plants. Remove and destroy infected plants. Gray mold* (Botrytis cinerea) Soft, brown rot of leaves, stem, and flowers occurs. Fuzzy gray fungal spores form on decayed tissues. Fungus is common on weakened plants. Botrytis may also start in powdery mildew spots, sunburned tissues, tissues injured by other means, or in ligules. In plant debris; common on any dead plant material on soil if moist. Resting sclerotia favored by high moisture conditions and low temperatures. Control root rots and powdery mildew*. Pick up dead flowers and leaves. Keep humidity low. Protect plants with fungicide such as fenhexamide. Avoid overhead irrigation. Powdery mildew* (Erysiphe begoniicola, Golovinomyces orontii) White, powdery spots develop on upper and lower leaf surfaces and small, greasy spots occur on undersides of leaves. Also may appear on flowers of some fibrous begonias. On living begonia leaves; rarely as resistant fungal structures (chasmothecia). Spores are airborne as well as spread in water, but do not survive in free water. Favored by moderate temperatures and shade. Common on plants as they senesce in fall. Increase air movement; some resistant cultivars available. Spray at the first sign of mildew and at 2- to 3-week intervals thereafter. Use myclobutanil, or triadimefon. Triadimefon is very effective but expect stunting of some plants. Root and stem rot* (Pythium spp.) Plants are stunted, unthrifty, and may die. Root system is small and discolored. Also invades tubers of tuberous begonias. Stem rot phase: stems become water soaked and discolored, and collapse. Disease also causes damping-off of seedlings. Plants are predisposed to sunburning. In soil. Spores spread in water and when infested soil is moved to uninfested areas. Favored by excess water. Steam or chemically treat soil. Observe strict sanitary measures. Drench plants with oomycete (water mold) specific fungicide. Do not drench very young seedlings. Virus or viruslike diseases Symptoms Host range and natural spread Comments on control Spotted wilt (Tomato spotted wilt virus) Rings or zoned spots develop on leaves. Plants are stunted; flowers are of poor quality. Infects begonias, nasturtiums, callas, dahlias, and some weeds. Transmitted by thrips. Eliminate nearby weeds and susceptible ornamental plants. Control thrips. Begonias are also susceptible to Armillaria root rot (Armillaria mellea), anthracnose (Gloeosporium sp.), black root rot (Thielaviopsis basicola), cottony rot* (Sclerotinia sclerotiorum), crown gall* (Agrobacterium tumefaciens), foliar nematode** (Aphelenchoides olesistis), leaf spot (Phyllosticta sp.), Rhizoctonia stem rot (Rhizoctonia solani), root knot nematode** (Meloidogyne spp.), soft rot (Pectobacterium (=Erwinia) carotovorum), and Verticillium wilt* (Verticillium dahliae). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Begonia (11/20) 61 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CALLA Zantedeschia spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Crown rot (Rhizoctonia solani) Base of stems of callas are infected at or below the soil line, causing a general chlorosis of foliage. Favored by warm, moist conditions. Fungus is present in most field soils. Avoid deep planting and overwatering. Treat soil with PCNB before planting. Pythium rot* (Pythium ultimum) Roots may rot first. Pink and yellow corms develop irregular-shaped, shallow, water-soaked lesions that may coalesce. Infection spreads into interior tissues of root structures, producing irregular-shaped gray lesions that are sharply delimited. Pathogen enters root structures through wounds. It is present in many field soils and has a wide host range. Disease is favored by warm, moist conditions, heavy soils, and poor drainage. Avoid injuries to the rhizomes. Clean and dry root structures soon after digging. Store below 50°F. Some of the water mold fungicides would probably be effective in controlling the disease. Phytophthora root rot* Yellowing of leaf margins of outer leaves followed by general yellowing and wilting. Feeder rootlets are rotted. Pathogen is present in some field soils. Several other types of plants may be infected. Favored by wet soil conditions. Grow on raised beds and provide good drainage. Do not overirrigate. Treat with oomycete (water mold) specific fungicide. A soft rot of the rhizomes. Plants may rot off at the soil line. Bacterium is a common secondary invader of succulent plant parts and generally requires some sort of injury to cause disease. Has odor. Bacterium is present in some field soils. Favored by warm, moist conditions and plant parts attacked by other organisms. Avoid injuries to the rhizomes. Do not overwater. Yellow callas are more susceptible than others, but there are new yellow cultivars that are more resistant. (Phytophthora cryptogea) Soft rot (Pectobacterium (=Erwinia) carotovorum) Virus or viruslike diseases Symptoms Host range and natural spread Comments on control Dasheen mosaic (Dasheen mosaic virus) Mosaic patterns in leaves, which may be severely distorted. Infects plants low in vigor. Common because callas frequently propagated vegetatively, which spreads the virus. Virus is spread by aphids. Spread in a planting can be rapid. Can be transmitted by sap but not by seed. Obtain or develop virus-free plants by heat treatment and tissue culture. Control aphids. Remove infected plants. Spotted wilt (Tomato spotted wilt virus and Impatiens necrotic spot virus) Foliage, petioles, and flower stalks are streaked or spotted by whitish or yellowish areas, and sometimes by small, concentric rings. Necrotic areas that develop in leaves may be colonized by secondary fungi. Sometimes the necrotic areas are attributed to fungi, but usually they are secondary invaders. Common because callas frequently propagated vegetatively, which spreads the disease. Both viruses are also transmitted by several thrips species. Virus is acquired by nymphal stage and transmitted by adult throughout its life. The virus has a very wide host range including many weeds and ornamental plants. Control weeds and thrips. Destroy infected callas. Callas are also susceptible to leaf spots (Gloeosporium callae, Coniothecium richardiae, and Cercospora richardiae), powdery mildew* (Oidiopsis taurica), Armillaria root rot* (Armillaria mellea), gray mold* (Botrytis cinerea), Phytophthora spp., seedling rot (Rhizoctonia solani), southern blight* (Sclerotium rolfsii), and root knot nematode** (Meloidogyne spp.) * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Calla (11/20) 62 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CAMELLIA Camellia spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Dieback (Glomerella cingulata) Wilting and dying of branches. Leaves darken and often remain attached. Branch is girdled by fungus that enters through injuries, including leaf scars. Found in warmer areas of California. Favored by wet, warm conditions, weakened plants, and injuries. Fungus spores (conidia) are spread by splashing water. Fungus has a wide host range. Prune diseased tissues and protect wounds with a fungicide such as captan. Avoid overwatering. Flower blight (Ciborinia camelliae) Flowers have dry rot with accented veins. Only petal tissues are infected. First symptoms are small tan or brown necrotic spots in the center of the flower that enlarge and move rapidly to the base of flower. Rotted flowers are heavy and easily fall to ground. The fungus continues to develop, forming sclerotia in the calyxes of infected flowers. Sclerotia survive on or in soil and germinate for several years producing fruiting bodies (apothecia) that discharge spores (ascospores) forcibly into the air. Where practical, pick up all blossoms because fallen blossoms either may be infected or may become infected while on the ground. Prevent sclerotia from germinating by spraying ground with PCNB annually. Thiophanate-methyl will protect petals from infection but sprays must be applied frequently as new flowers open. Mulches 4 inches or more deep will help prevent apothecia from reaching the surface. Gray mold* (Botrytis cinerea) Necrotic, brown spots. Rot does not move to the base of the flower as rapidly as the flower blight fungus. Fuzzy gray fungus spores form on decayed blossoms under high humidity. Favored by cool wet weather. Spores are airborne. Fungus survives on and in old flowers. Avoid overhead irrigation. Clean up plant debris, especially floral tissues. Protect flowers with a fungicide effective against Botrytis such as fenhexamid. Phytophthora root rot* (Phytophthora spp.) Plants stunted and low in vigor. Foliage yellows, plant wilts and dies. Roots rotted. When plants collapse, the stem is girdled at or below the soil line. Phytophthora cinnamomi is often involved but other species also infect camellias. Phytophthora spp. survive in soil as resting spores. They are common in stream and ditch water. Infective spores (zoospores) swim very short distances in soil water. Disease is favored by poor drainage, long wet periods, and standing water. Heat or chemically treat propagation and growing media. Drench plants on a preventative basis with oomycete (water mold) specific fungicide. Ramorum blight1 Leaf lesions that vary in size from 0.2 inches to covering nearly half the leaf. Lesions primarily at leaf tip or edge; can be surrounded by diffuse margins or thick black zone line. Infected leaves drop prematurely and lower part of plant can defoliate. Symptoms may be confused with leaf scorch in areas of high heat/sun. Spore structures commonly form on leaf surfaces of susceptible leaves and twigs following prolonged wetting. They are moved in contaminated soil, from plant to plant via windblown rain, or by direct contact of infected leaves. Monitor incoming stock and areas surrounding the nursery for symptoms, follow good cultural and sanitation practices, and use preventive treatments before environmental conditions favor development of the pathogen. (Phytophthora ramorum) Camellias are also susceptible to several viruses and viroids such as color break virus and golden ring spot complex.* * For additional information, see section on Key Diseases. 1 Phytophthora ramorum was isolated from the following C. japonica cultivars on two or more occasions: Bob Hope, Mrs. Charles Cobb, Daikagura var. Debutante, Elegans Splendor, Glen 40, Kumasaka, Kramer's Supreme, Mathotiana Supreme, Nuccio's Gem, Nuccio's Pearl, Silver Waves, Shiro Chan, Tom Knudsen, P. ramorum was isolated from the following C. sasanqua cultivars on two or more occasions: Apple Blossom, Cleopatra, Hana Jiman, Jean May, Kanjiro, Setsugekka, Yuletide. P. ramorum was isolated from the following C. oleifera cultivar on two or more occasions: Winter's Fire. Disease Control Outlines Camellia (11/20) 63 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CARNATION Dianthus caryophyllus (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Alternaria leaf spot* and branch rot (Alternaria saponariae) Gray-brown leaf or petal spots with purple margins. Black spore masses form in spots. Branch rot starts at nodes and girdles stem. In infected plants and debris. Airborne spores. Moist conditions for 8 to 10 hours required for infection. Provide good air circulation and keep humidity low. Irrigate in early morning. Do not wet foliage with irrigation water. During periods of high humidity, protect plants with iprodione, mancozeb, or chlorothalonil. Bacterial wilt* (Pseudomonas caryophylli) Sudden wilting of tops or individual branches. Basal stem cracks. Roots may be rotted. Vascular discoloration in stems is yellowish to brown. The outer layer (epidermis) separates easily from stem, which is sticky to the touch. Infected plants and debris. Bacteria spread in water. Favored by high temperatures. Use disease-free cuttings and treat soil as above. Bacteria can spread quickly. Avoid use of cutting dips and avoid splashing water. Break cuttings from stock plants. Disinfect tools. Calyx rot (Stemphylium botryosum) Rot starts at tip of calyx and progresses towards base. In old leaves, stems, and debris. Favored by high humidity. Same as Greasy blotch. Harvest regularly. Fairy-ring leaf spot (Cladosporium echinulatum) Conspicuous tan spots with concentric rings. Margin of spot may be red. Dark spores form in spots. Infected plants and debris. Airborne spores. Favored by wet weather. Provide good air circulation and keep humidity low. Irrigate in early morning. Do not wet foliage with irrigation water. Protect foliage with mancozeb. Fusarium bud rot (Fusarium tricinctum) Outwardly normal buds are brown and decayed inside. Cottony white growth and plump white mites may be visible. Fungus carried by grass mite, Pediculopsis graminum. Destroy infected buds. Control mites. Do not bring field-grown carnations into greenhouse. Control weeds outside growing area. Fusarium stem rot (Fusarium avenaceum, F. culmorum, F. graminearum) Stem rotted at soil line and high up on plant. Roots and base of stem rotted. Tops wilt and die. Pink cushions of spores may form at base of plant on decayed tissues. Common as a cutting rot. In soil and plant debris. Spores spread in water. Also favored by warm, humid conditions. Also favored by high N fertilization and high N:K ratio. Use clean cuttings and rooting medium. Spray cuttings in rooting medium with thiophanate-methyl. Fusarium wilt* (Fusarium oxysporum f. sp. dianthi) Yellow, wilted branches frequently occur on one side at first. Vascular discoloration is dark brown. Root system usually remains intact. In late stages, stem develops a dry, shredded rot. Infected parts die. Soil and infected plants. Spores spread in water. Favored by soil temperatures 75°F and above. Restricted below 60°F. Plant resistant cultivars. Use disease-free cuttings planted in treated soil. Steam soil in raised beds at 140°F for at least 30 minutes. Solarize soil or fumigate with chloropicrin. Adjust soil pH to 6.5 to 7.0. Moderately resistant: Ace, Apache, Barsemi Yasmino, Big Red, Comanche, Corona, Exquisite Select, Felicia, Fiesta, Georgia Ann, Jolievette, Lucy Carrier, Maman, Mei-Sciang, Orchid Beauty, Pallas, Shiro, Silvery Pink, Sweetheart, White Elegance Highly resistant: Barbi, Candy Maj, Capello, Carbasio, Improved Lilac, Juanita, Lady Di, Light Pink Marble, Maiko, Maj Pink, Meiling, Melody, Moonlight, Picotee Orange, Scarlett Elegance, Siri #1, White Melody Gray mold* (Botrytis cinerea) Fuzzy gray fungal spores form on soft, brown, decayed blossoms and can move into plant parts wherever blossoms touch them. In plant debris. Airborne spores. Favored by high moisture conditions and low temperatures. Remove old flowers from growing area. Maintain horizontal air movement. Lower humidity where possible. Mist blooms with iprodione or fenhexamid. Continued on next page . . . Disease Control Outlines Carnation (11/20) 64 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Carnation, continued Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Greasy blotch (Zygophiala jamaicensis) Greasy-appearing spots on leaves with radiating weblike margins. Pimpling of infected areas. In infected plants and debris. Favored by high humidity. Not too common. Provide good air circulation and keep humidity low. Irrigate in early morning. Do not wet foliage with irrigation water. Phialophora wilt (Phialophora cinerescens) Gradual wilting of plants; leaves become straw colored. Not one-sided as Fusarium wilt may be. Brown discoloration of vascular system. Little or no tissue rotting in late stages. Uncommon. Soil and infected plants. Spores spread in water. Favored by cool soil temperatures. Use disease-free cuttings and treat soil as above. Phytophthora stem rot* (Phytophthora parasitica) Stem rotted at soil line. May be mistaken for Rhizoctonia stem rot. In soil and plant debris. Favored by warm, moist soil and poor drainage. Steam or fumigate soil. Drench at planting with oomycete (water mold) specific fungicide. Pythium root rot* (Pythium spp.) Plants are stunted, particularly in lower, poorly drained areas. Rootlets rotted. Soilborne. Common in most soils. Favored by poor drainage, low spots, excessive irrigation. Steam or fumigate soil (see Fusarium wilt). Drench plants with oomycete (water mold) specific fungicide periodically, depending on severity of disease. Make first application at planting. Rhizoctonia stem rot (Rhizoctonia solani) Stem rotted at soil line. Rot progresses from the outside. Entire plant wilts and dies. Dark fungal strands and sclerotia may be visible with a hand lens. Soilborne; plant debris. Favored by warm, moist conditions. Steam rooting medium and soil. Use PCNB before transplanting, or spray base of transplant with iprodione. Rust* (Uromyces dianthi) Small pustules of powdery brown spores. Spores are airborne. Carried over only on living plants. Favored by moist conditions. Use resistant cultivars or protect plants in problem areas with myclobutanil or mancozeb. Virus or viruslike diseases Symptoms Host range and natural spread Comments on control Mottle Faint leaf mottle or no symptoms. Common in virtually all carnation cultivars. Handling and cutting knife. Not transmitted by insects. May be spread in drainage water. Reduce spread of mottle by disinfecting tools between blocks of plants and several times a day. Obtain virus-free plants. Etched ring Rings usually oval or elongated; rarely concentric on older leaves and stems. Symptoms may be slight in young cuttings. No obvious effect on plant vigor. Aphids. Not spread by handling. Obtain virus-free plants. Control aphids. Necrotic fleck Reddish purple necrotic flecks, streaks, or spots appear in leaves. Symptoms are masked at low temperatures. Aphids. Obtain virus-free plants. Control aphids. Ring spot Small 0.5- to 1-inch rings; sometimes concentric. Chlorosis, mottling, and distortion of young leaves. Plants obviously stunted. Cutting knife and handling. Insect vectors unknown. Same as for mottle. Vein mottle (not common in California) Young leaves exhibit a vein clearing, which develops into chlorotic spots and patterns that mostly follow veins. Symptoms tend to disappear on old leaves. Aphids. Not spread by handling or cutting knife. Obtain virus-free plants. Control aphids. (Carnation mottle virus) * For additional information, see section on Key Diseases. Disease Control Outlines Carnation (11/20) 65 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CATTLEYA Cattleya spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial soft rot (Dickeya (=Erwinia) chrysanthemi) Soft, watery rot of leaves; often foul smelling. Starts as small water-soaked area. Infection is through wounds. Often kills cattleya plants. In soil and decaying plant debris. Bacteria spread in water. Favored by warm, moist conditions. Avoid overhead watering, wounding plants, and provide horizontal air movement and good aeration. Observe strict sanitation. Disinfect knives between cuts. Black rot and seedling damping-off (Pythium ultimum*, Phytophthora cactorum*) Starts as small, water-soaked leaf spots and root rot. Decay may progress rapidly. Affected tissues turn black and are sometimes soft. Soilborne fungi. Spores spread in water. Favored by warm moist conditions (above 65°F). Drench plants with oomycete (water mold) specific fungicide. Steam or chemically treat growing media and used pots. Remove badly infected plants. Botrytis flower brown speck or rot (Botrytis cinerea) Tiny, light-brown spots on blossoms may enlarge to rot entire flower. Fuzzy gray fungal spores develop on flowers if kept moist. On plant debris. Spores airborne. Favored by cool, moist conditions. Eliminate old flowers. Eliminate plant debris, both inside and outside growing area. Avoid getting flowers wet. Treat with fenhexamid. Gloeosporium leaf spot (Gloeosporium spp.) Prominent, sunken, reddish brown spots with definite margins. Spots may coalesce and kill entire leaf. Spots start as minute, dark areas, often at leaf tips. In infected plants. Spores spread in water. Favored by moist conditions and unfavorable growing conditions. Provide better growing conditions. Avoid wetting foliage. Remove infected tissues. Rust (Sphenospora kevorkianii, Uredo nigropuncta) Pustules of powdery, yellow or orange spores on undersides of leaves. In infected plants. Spores airborne. Moisture needed for only short period. Not too common. Avoid wetting leaves. Destroy infected leaves. Virus or viruslike disease Symptoms Natural spread and host range Comments on control Blossom necrotic streak (a strain of Cymbidium mosaic virus) Blossoms open without evidence of brown spots or streaks, which become visible after about 1 week or longer. Long, yellowish, irregular streaks may develop on leaves. Can be spread on cutting tools. Use clean cutting tools. Destroy infected plants. Leaf necrosis (Cymbidium mosaic virus) Irregular, elongated streaks of dead tissue on undersurface of older leaves. Some leaves may be killed or various patterns of sunken, black tissue may develop. Infected plants may show no symptoms. Spread by pruning tools. Cattleya and its hybrids, Cymbidium, Epidendrum, Zygopetalum, Angraceum, Laelia, Oncidium, Spathoglottis. Use clean and disinfected cutting tools. Mild flower break (Odontoglossum ringspot virus) Flowers less variegated than above and without distortion. Leaves show only mild, hard-to-detect mosaic symptoms. Spots and streaks of increased pigment intensity. Unknown, but can be transmitted by juice inoculations. Cattleya and its hybrids, Cymbidium, Odontoglossum, Phalaenopsis. Isolate or destroy infected plants. Disinfect tools between cuts with a quaternary ammonium disinfectant. Severe flower break Variegation of flower color. May also distort sepals and petals. Leaves mottled with streaks of light and dark green tissue. Dark green areas somewhat raised, producing ridges and bumps. Spread by green peach aphid. Cattleya and its hybrids, Cymbidium. Same control for all viruses. Virus or viruslike disease Symptoms Natural spread and host range Comments on control Symmetrical flower break A symmetrical variegation in which pigment occurs along sepal margins and over most of petals, except in middle Unknown, but can be transmitted by juice inoculations. Cattleya. Use clean and disinfected cutting tools. Disease Control Outlines Cattleya (11/20) 66 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES areas that have little or no pigment. Leaves may develop an inconspicuous mosaic mottle. * For additional information, see section on Key Diseases. Disease Control Outlines Cattleya (11/20) 67 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CHRYSANTHEMUM Chrysanthemum grandiflora (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial blight* (Dickeya chrysanthemi) Water-soaked lesions; pith becomes jellylike; tops turn black and exude drops of liquid. Stem may break or split. In plant debris. Favored by high temperatures (80° to 90°F), absence of free water, and high humidity. Use disease-free cuttings. Reduce humidity in growing areas. Dip cuttings in streptomycin. Cottony rot* (Sclerotinia sclerotiorum) Stems rotted; flower rot is similar to gray mold. Cottony, white fungal mass may occur on rotted tissues. Black sclerotia may form inside or outside stems. Sclerotia in soil. Spores produced from sclerotia are airborne but infect only through flowers and dead tissues. Favored by high humidity. Same as for gray mold. Also, treat soil with PCNB before planting and spray foliage with iprodione or thiophanate-methyl. Crown gall (Agrobacterium tumefaciens) Irregular or round galls on stems and sometimes leaves. Soil and galls. Infection favored by moist conditions. Destroy infected plants. Foliar nematode (Aphelenchoides ritzemabosi) Dark green, angular spots in leaves develop progressively upward from base of plant. Leaves turn yellow. These nematodes are rarely important in California. Adults can survive up to 3 years in dead leaves. Spread by splashing water. Leaves need to be wet for infection to take place. Use disease-free plants. Discard infected plants. Avoid overhead irrigation. Control weeds. Submerge infected plants in hot water (115°F) for 10 minutes.** Fusarium wilt* (Fusarium oxysporum f. sp. chrysanthemi and f. sp. tracheiphilum) Unilateral chlorosis of one or more leaves near the apex, followed by curvature of the stem towards the affected side. As the disease progresses, there is a general chlorosis and wilt and stunting of leaves. The vascular system becomes a reddish brown. Soilborne and carried in cuttings. Favored by high soil temperatures (80°F). Use disease-free cuttings in clean soil. Treat soil (see Verticillium wilt). Adjust pH of soil to 6.5 to 7.0 and use nitrate nitrogen. Avoid planting highly susceptible cultivars (Bravo, Cirbronze, Illini Trophy, Orange Bowl, Royal Trophy, Yellow Delaware) Gray mold* (Botrytis cinerea) Brown, water-soaked spots on petals. Fuzzy gray fungal spores form on decayed tissues. Rotting of lower leaves. Fungus may enter and girdle stem. In plant debris. Favored by high humidity, low temperatures (50° to 60°F), and water on plant. Keep humidity low; avoid overhead irrigation. Protect foliage with a fungicide, especially lower-dense foliage. Mist blooms with chlorothalonil, iprodione, or fenhexamid. Hollow stem (Pectobacterium (=Erwinia) carotovorum) Pith of rooting cuttings deteriorates and collapses. Affected tissues are brown. Surviving plants do not grow satisfactorily and pith collapse may extend upward involving several internodes. Red Torch, Tempo, and Tempter are very susceptible cultivars. Bacteria may be present in vascular bundles of symptomless chrysanthemums. Bacteria also present in undecomposed debris. Favored by high temperatures and high moisture. Use disease-free cuttings. Reduce humidity in growing areas. Streptomycin dips may be helpful. Powdery mildew* (Golovinomyces cichoracearum) White powdery growth on leaves and stems. Found mainly on older leaves. Airborne spores produced only on living plants. Favored by high humidity, crowding of plants, and cool weather. Spray with piperalin to eradicate existing infections. Protect foliage with myclobutanil or triadimefon. Pythium root rot and basal stem rot* (Pythium spp.) Girdling black lesions occur near soil line. Plants stunted because of reduced root system caused by root rot. Plants may die. Soilborne pathogen. Spores spread in water or in soil. Favored by excess soil moisture and poor drainage. Treat soil as for Verticillium wilt. Drench plants with oomycete (water mold) specific fungicide. Ray blight (Phoma chrysanthemi) Basal leaf and stem rot. Below ground stem infection may cause a one-sided distortion and necrosis of foliage. Blackish rot of petals (ray blight) may extend into flower stalk. In chrysanthemum refuse. Waterborne spores. Favored by rainy weather. Use disease-free cuttings. Avoid wetting foliage and keep humidity low. Protect foliage with chlorothalonil. Continued on next page . . . Disease Control Outlines Chrysanthemum (11/20) 68 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Chrysanthemum, continued Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Rhizoctonia stem rot (Rhizoctonia solani) Stem rotted at soil line. Plants stunted. Dark fungal strands may be visible with hand lens. May kill plants. Soilborne fungus. Favored by warm, moist conditions. Avoid deep planting. Spray base of transplants with thiophanate-methyl, chlorothalonil, or iprodione after planting, or treat soil with PCNB before planting. Rust* (Puccinia tanaceti) Small pustules of powdery, chocolate-brown spores on undersides of leaves and on stems. Airborne spores produced only on living plants. Free moisture necessary for infection. Principally a field disease. Use resistant cultivars. Protect foliage with triadimefon or mancozeb before rust starts to build up. Avoid wetting foliage. Keep humidity low. Septoria leafspot (Septoria obesa, S. chrysanthemi) Irregular or circular, brown or black dead spots develop progressively upward from base of plant. Tiny black fungal fruiting bodies in centers of spots. In plant debris and in soil debris for 2 years. Spores spread in splashing water. Favored by wet weather. Protect foliage with a fungicide at first sign of disease. Greenhouse: avoid wetting foliage. Keep humidity low. Verticillium wilt* (Verticillium dahliae) Yellowing and wilting of foliage, may be one-sided. Leaves die and dry upward from the base of the plant. Vascular tissue may be discolored. Soilborne for many years. Carried in cuttings and root divisions. Favored by cool weather followed by hot weather during flowering. Use resistant cultivars and pathogen-free plants. Fumigate with chloropicrin or other chloropicrin combinations. In sunny climates, soil solarization might be considered. White rust (Puccinia horiana) Whitish pustules on the lower leaf surface. On the upper surface the infection is evident as pale-green to yellow spots up to 4 mm in diameter. Raised, waxy, pink-colored pustules are formed on lower leaf surface and can coalesce into large areas covering the leaf, Pustules found on stems and sometimes flowers. As they mature and produce spores, they turn whitish in color. This microcyclic rust survives on living chrysanthemum foliage. Teliospores in the leaf pustules germinate in place producing basidiospores that are airborne and infect by direct penetration. Favored by the same conditions as ordinary rust (cool, damp weather), except that direct sunlight destroys airborne basidiospores. Principally a greenhouse disease. White rust is widespread throughout many areas of the world but is not confirmed as established in the United States. Any offshore introduction of this pathogen is a significant threat to the United States floriculture industry. It spreads rapidly in greenhouse and nursery environments, resulting in severe losses. As a quarantine pest, detection leads to federal and state regulatory action. See USDA Plant Pest Program for Chrysanthemum White Rust. Continued on next page . . . Disease Control Outlines Chrysanthemum (11/20) 69 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Chrysanthemum, continued Virus or viruslike disease Symptoms Host range and natural spread Comments on control Aspermy (Tomato aspermy virus) Flower distortion and reduction in flower size. Color break in florets of red, bronze, and pink cultivars. Foliar symptoms not apparent. Some cultivars are symptomless. Transmitted by handling, cutting tools, and vegetative propagation. Also transmitted by aphids. Use disease-free cuttings. Control aphids; remove infected plants. Chlorotic mottle (Chrysanthemum chlorotic mottle viroid) Mottling followed by complete chlorosis. May be confused with nutritional problems. Symptoms somewhat masked under low light and cool temperature conditions below 70°F. Spread by handling, cutting tools, and vegetative propagation. Use disease-free cuttings. Remove infected plants. Spotted wilt (Tomato spotted wilt virus, Impatiens necrotic spot virus) Frequently one-sided in plant. Ring patterns on leaves of some cultivars. Leaf distortion and necrosis. Dark necrotic streaks on stems. Flowers may be distorted and with some necrosis. Thrips-transmitted; not spread by cutting knife, but can be spread by vegetative propagation. Many weeds and perennial ornamental plants act as reservoirs of virus (dahlia, calla, nasturtium, mallow, knotweed, plantain, and others). Eliminate nearby susceptible ornamental plants and weeds. Control thrips inside and outside growing areas. Use virus-free cuttings. Stunt (Chrysanthemum stunt viroid) General stunting of plants. Foliage may be pale with upright, young leaves. Flowers are smaller than normal and some cultivars may flower 7 to 10 days early. Viroid is easily transmitted by handling, cutting knives, vegetative propagation, etc. Not spread by insects. Viroid has a wide host range. Symptomless in some plants. Obtain disease-free plants from a propagation specialist using an indexing program. Chrysanthemums are also susceptible to Ascochyta blight (Mycosphaerella ligulicola, Ascochyta chrysanthemi), aster yellows* (aster yellows phytoplasma), charcoal rot (Macrophomina phaseolina), and southern blight* (Sclerotium rolfsii). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Chrysanthemum (11/20) 70 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CYCLAMEN Cyclamen spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Anthracnose (Cryptocline [=Gloeosporium] cyclaminis) Distinctly zonate, pale green and circular spots. Orange to pink-colored spores on stems and leaves. Gray mold* (Botrytis cinerea) Spotting of flowers. Decay of emerging flower stems and leaf petioles under leaf canopy. Fuzzy gray fungal spores form on rotted tissues. In plant debris, especially flowers. Common saprophytic fungus. Favored by cool, wet weather. Water necessary for spore germination. Avoid overhead watering. Remove old flowers. Improve air circulation. Control humidity to avoid moisture condensation. Treat with iprodione or fenhexamid. Soft rot (Dickeya (=Erwinia) chrysanthemi) Plants collapse suddenly. Tuber is mushy. Infected plants and debris. Disease is favored by high temperatures (75°F and above). Bacteria are spread by splashing water and handling. Discard infected plants. Avoid excessive water splashing. Maintain sanitary conditions. Keep greenhouse cool. Root rot (Pythium* and Phytophthora spp.*) Plants are stunted. Roots are discolored and rotten, lower leaves wilt and may turn yellow. Pathogens are normal inhabitants of natural soil. Disease is favored by poor drainage and overwatering. Heat-treat growing medium at 140°F for 30 minutes or fumigate. Drench plants with oomycete (water mold) specific fungicide. Fusarium wilt* (Fusarium oxysporum f. sp. cyclaminis) A progressive yellowing and wilting of leaves starts with oldest. Brown discoloration of the vascular tissues in tubers. Tuber remains firm unless secondary bacteria are introduced. Survives as resting spores (chlamydospores) in soil. No other plants are infected. Disease is favored by temperatures above 70°F. May be seedborne. Discard infected plants and soil; don't save seed from infected plants. Good sanitation generally provides adequate control. Thiophanate-methyl drenches during early growth period should be helpful. Adjust soil pH to 6.5 to 7.0. Treat seed with a fungicide. Leaf spots* (Phyllosticta cyclaminis) Yellowish-to-brownish spots near leaf margins. On diseased plants and plant debris. Favored by wet conditions. Dissemination of spores is by splashing water. Control is same as for gray mold. Protect foliage with a fungicide. Septoria leaf spot (Septoria cyclaminis) Red concentric spots turn gray with red borders. Stunt (Ramularia cyclamanicola) Conspicuous stunt. Flower peduncles shortened so that flowers open below surrounding leaves. Reddish brown necrosis in tuber. Brown irregular leaf spots. Frosty appearance on underside of lower yellowed leaves. Infected plants and debris. Spores are airborne. Favored by warm, moist conditions. Dispose of infected plants, keep humidity low. Keep seedlings away from older plants. Protect plants with thiophanatemethyl. Cyclamen are also susceptible to black root rot (Thielaviopsis basicola) and Cylindrocladiella disease (Cylindrocladiella peruviana). * For additional information, see section on Key Diseases. Disease Control Outlines Cyclamen (11/20) 71 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CYMBIDIUM ORCHID Cymbidium spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Black rot* (Pythium ultimum) Rapid, black rot of pseudobulb and rotting of roots. Bulb, usually firm at first, gradually desiccates, forming a hard mummy. Soilborne pathogen. Spores spread in water. Favored by poor drainage and excess water. Provide better drainage. Avoid excess irrigation. Drench plants with oomycete (water mold) specific fungicide. Steam or chemically treat growing medium. Flower spotting (Botrytis cinerea) Small black, brown, or colorless spots often surrounded by water-soaked areas. In plant debris. Spores airborne. Favored by cool (45° to 60°F), moist conditions and condensed moisture on flowers. Avoid wetting flowers. Keep humidity as low as possible. Eliminate old flowers and plant debris both inside and outside growing area. Sclerotium or collar rot (Sclerotium rolfsii) Rapid rotting and collapse of the leaf bases and stem. White fungus growth and small resting structures (sclerotia) that resemble mustard seeds usually present on plant and planting medium. Sclerotia survive in soil for many years. No spores form. Favored by warm, moist soil. Fungus has a wide host range. Destroy infected plants. Heat-treat soil, fumigate with chloropicrin or another chloropicrin combination, or mix granular PCNB with planting medium before planting. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Bar mottle (Cattleya severe flower break virus) Yellow bar-shaped streaks and blotches on leaves. Green peach aphid. Cymbidium, Cattleya, and its hybrids. Same as for mosaic. Also, control insects. Diamond mottle (Odontoglossum ringspot virus) (Tobacco mosaic virus, orchid strain) Elongated chlorotic areas are sometimes diamondshaped. Older leaves sometimes develop brown-to-black flecks and streaks. Can be transmitted by juice inoculations. Cymbidium, Cattleya, Odontoglossum, Phalaenopsis. Same as for mosaic. Mosaic (Cymbidium mosaic virus) Symptoms vary in pattern and severity. Small, elongate pale areas in young leaves may later develop into dead, dark spots or streaks. Mottling of young leaves, sometimes becomes inconspicuous in old leaves. No flower variegation. Transmitted by pruning tools. Cymbidium, Cattleya, Epidendrum, Zygopetalum, Angraceum, Laelia, Oncidium, Spathoglottis. All virus diseases are propagated with plant. Once infected, plant remains so for life. Destroy infected plants. Disinfect tools between cuts or heat-sterilize in a flame. Ringspot virus (Cymbidium ringspot virus) Necrotic ringspot patterns on young and old leaves. Plants severely stunted. Can be lethal. Can be transmitted by juice inoculations. Cymbidium, Cattleya, Spathoglottis, Trichosoma. Same as for mosaic. * For additional information, see section on Key Diseases. Disease Control Outlines Cymbidium Orchid (11/20) 72 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DAHLIA Dahlia spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Crown gall* (Agrobacterium tumefaciens) Overgrowths or galls occur on stems and roots. In soil for as long as 3 years; bacteria enter through wounds and can survive on infected roots. Gall development favored by rapidly growing host. Avoid wounding plants. Do not grow plants in infested soil for 3 years, or fumigate soil. Discard infected roots. Rotate with non-woody crops, such as cereals and legumes. Fusarium wilt* (Fusarium oxysporum) Symptoms are almost identical to those of Verticillium wilt. Not common in California. Soilborne for many years. Disease most severe when soil temperatures are high. Destroy infected plants. Grow plants in new areas or fumigate soil; see below for control of Verticillium wilt. Gray mold* (Botrytis cinerea) Brown, water-soaked spots appear on petals. Fuzzy gray fungus spores form on soft, brown, decayed tissues; fungus may invade plant tissue that touches infected petals. Plant debris. Favored by cool, wet conditions and condensed moisture on plants. Remove withered or diseased flowers promptly. During cool, wet weather, spray with iprodione, mancozeb, or fenhexamid. Powdery mildew* (Golovinomyces cichoracearum) White, powdery fungus principally grows on older leaves and stems. Severely affected leaves dry up and may fall. On living dahlia leaves and as small, dark, resting structures (chasmothecia) on old leaves. Free water is not necessary for infection. Protect foliage with myclobutanil or sulfur. Root knot nematode** (Meloidogyne spp.) Knots or small swellings, caused by root knot nematodes, occur on feeder and fleshy roots. In soil and on the roots of many plants. Favored by warm, sandy soils. Use a nematicide to treat infested soil before planting or solarize soil. Destroy infected roots. Sclerotinia or cottony rot* (Sclerotinia sclerotiorum) Plants wilt and die suddenly. Water-soaked stem cankers appear near the soil line. Cottony, white fungal growth; later, large black sclerotia are found on insides and outsides of stems. In soil as sclerotia, which produce airborne spores that infect only inactive or weak tissues. Sclerotia also produce hyphae, which infect plant tissue. Favored by cool, moist conditions. Avoid soil where disease has occurred (common disease of many vegetable crops). Treat soil with PCNB before planting. Protect plants with iprodione or thiophanate-methyl. Smut (Entyloma dahliae) Yellowish, circular to irregular spots appear on leaves. Leaves later become brown and dry. Plant debris. Favored by wet weather. Do not use overhead irrigation. Mancozeb applied to control gray mold should help control smut. Storage rots (Botrytis cinerea, Pectobacterium (=Erwinia) carotovorum, Fusarium spp.) Roots rot in storage. Plant debris. Favored by high temperature and humidity. Avoid plant injuries. Maintain a storage temperature of 40°F and avoid high humidity. In mild climates, leave roots in soil. Verticillium wilt* (Verticillium dahliae) Basal leaves wilt and turn yellow. Frequently, only one branch is affected at first. Later, the entire plant dies. Dark discoloration of the vascular system occurs. In soil for many years. Symptoms most severe during warm weather after a cool period. Fungus has a wide host range. Destroy infected plants and roots. Fumigate soil with chloropicrin or a chloropicrin combination (tarped). Fumigation also controls most other fungi, bacteria, weeds, nematodes, and soil insects. Soil solarization might be considered in sunny climates. Continued on next page . . . Disease Control Outlines Dahlia (11/20) 73 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Dahlia, continued Virus or viruslike disease Symptoms Host range and natural spread Comments on control Dahlia mosaic (Dahlia mosaic virus) The normal green color of leaves develops irregularly. Bands adjacent to the veins remain pale green (vein-clearing). Leaves may be distorted. Shortening of internodes (stunt) occurs in some cultivars. Flower color is usually normal. Aphids. Spread vegetatively by cuttings and roots. In some cultivars, the virus is almost symptomless. Destroy infected plants. Control aphids. Mosaic (Cucumber mosaic virus) Mild leaf mottle accompanied by little or no leaf distortion. Some varieties are symptomless carriers of the virus. Not common in California. Aphids. Spread vegetatively by cuttings and roots. Many plants: cucurbits, tomato, pepper, legumes. Destroy infected plants. Control aphids and weeds. Ringspot (Tomato spotted wilt virus) A well-defined mosaic mottle or irregular concentric rings or wavy lines in leaves. No leaf distortion or stunting occurs. Symptoms seen on older leaves. Thrips. Spread vegetatively by cuttings and roots. Many plants. Eliminate reservoir hosts and weeds. Destroy infected plants. Control thrips. Eliminate virus by taking small, stem-tip cuttings from rapidly growing plants. Dahlias are also susceptible to southern blight* (Sclerotium rolfsii) and foliar nematodes (Aphelenchoides spp.).** * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Dahlia (11/20) 74 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DELPHINIUM Delphinium spp. and hybrids (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Black leaf spot* (Pseudomonas syringae pv. delphinii) Irregular, tarlike, black spots in leaves. Petioles and stems also infected. Spots viewed from lower leaf surface appear brown. Bacteria survive in plant debris from previous delphinium crop. Disease is favored by cool, wet weather. Bacteria are spread in splashing water. Rotate field to a different crop. In perennial plantings, remove old leaves and stems from field. Avoid overhead irrigation. Diplodina disease (Diplodina delphinii) Brown to black stem cankers often at stem bases of older plants. Basal canker may girdle the stem, causing the tops to die and break over. Tiny, black fungus fruiting structures (pycnidia) may be visible in necrotic tissues. Uncommon. Fungus survives on delphinium debris and in crowns of living plants. Spores are spread in splashing water. Avoid overhead irrigation. Plant on raised beds. Do not replant fields for 2 or more years. In perennial plantings remove old stems and plant debris. Protective fungicidal sprays would probably be effective. Downy mildew* (Peronospora spp., Plasmopara spp.) Purplish red to dark brown, irregular angular spots on leaves. Lower surface covered with sparse, downy fungal growth that may be hard to see. Leaves turn yellow and fall. Spores produced only on living plants. Resistant spores (oospores) carry fungus over unfavorable periods. Moist, humid conditions. Protect foliage with mancozeb, fosetyl-Al, dimethomorph, or mefenoxam. Powdery mildew* (Erysiphe aquilegiae and Podosphaera delphinii) White powdery patches on surface of leaves and stems. Basal leaves yellow, then brown and die. Flowers may be deformed. Larkspur is particularly susceptible. Fungus survives on living plants. Spores are airborne. Disease is favored by moderate temperatures, shade, crowding, and dry foliage. Avoid overcrowding. Protect foliage with a powdery mildew fungicide. Soft crown rot and black leg (Pectobacterium (=Erwinia) atrosepticum) Stem bases are blackened and rotted, causing stems to fall over. New shoots may develop disease free under drying conditions or entire crown may rot. Rotted tissues usually have an offensive odor. Disease often appears at time of flowering. Favored by warm, wet conditions. Bacteria survive in plant debris. Seeds may be contaminated by bacteria. Infection is through normal stem cracks and wounds. Bacteria are spread in water. Avoid overhead irrigation, especially after flower spikes begin to elongate. Plant on raised beds and avoid wetting crowns. Heat treat or fumigate soil used to produce seedlings. Water mold root rots (Pythium* and Phytophthora spp.*) Plants are stunted and yellow. Roots rotted. When Phytophthora spp. are involved, crown tissues may be rotted. Lower stems are sometimes infected. Pathogens are soilborne and present in most agricultural soils. Spores (zoospores) are spread in water. Favored by wet weather, poor drainage, and overwatering. Improve drainage. Grow on raised beds. Do not overirrigate. Fungicides used to control Pythium and Phytophthora should be useful. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Aster yellows* (Aster yellows phytoplasma) Flowers are converted to green leafy structures. Plants infected the preceding year produce many spindly, upright yellow shoots and no flowers. Phytoplasma that has a wide host range and is spread by leafhoppers. Not spread by seed, other insects, or handling. Do not plant seed beds downwind from delphinium, carrot, or celery fields. Control leafhoppers. Eliminate nearby weeds. Destroy infected plants. Delphiniums are also susceptible to gray mold* (Botrytis cinerea), southern blight* (Sclerotium rolfsii), cottony rot* (Sclerotinia sclerotiorum), root knot nematode** (Meloidogyne spp.), Verticillium wilt* (Verticillium dahliae), damping-off* (Rhizoctonia solani, Pythium spp.), curly top (Beet curly top virus), various virus diseases (Tobacco mosaic virus, Radish mosaic virus, Cucumber mosaic virus), leaf spots (Ascochyta aquilegiae, Cercospora delphinii, Ramularia delphinii), white smut (Entyloma winteri), rust* (Puccinia delphinii), and Fusarium wilt* (Fusarium oxysporum f. sp. delphinii). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Delphinium (11/20) 75 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES EASTER LILY Lilium longiflorum (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Botrytis blight (Botrytis elliptica, B. cinerea) Circular or oval orange or reddish brown spots usually appear on older leaves. Under damp conditions, fuzzy gray fungal spores form on spots. Brown spotting of blooms occurs. Botrytis elliptica infects healthy tissue whereas B. cinerea invades only dead or dying tissue. In plant debris. Spores are airborne. Favored by cool, wet conditions and condensed moisture on plant parts. Keep humidity below 85% by heating and ventilation. Do not use overhead irrigation. Mist blooms and foliage with iprodione, mancozeb, or fenhexamid. Bulb rots (Rhizopus spp., Penicillium spp.) Bulb rot may be soft and mushy (Rhizopus spp.) or dry and rotted (Penicillium spp.) In plant debris. Spores are airborne. Favored by warm storage temperatures. Do not injure bulbs. Store bulbs under cool and dry conditions. Thiabendazole bulb dips usually prevents Penicillium decay. Fusarium bulb rot (Fusarium oxysporum f. sp. lilii) Lower leaves become yellow or purple and die. Plants are stunted and of poor quality. Brown basal rot of bulb occurs, causing the scales to fall off. In diseased bulbs and soil. Favored by warm temperatures. Do not plant bulbs that show any signs of infection. Dip bulbs in thiabendazole. Plant deep in pot to force stem roots. Leaf scorch (nonparasitic) Semicircular brown areas develop along leaf margins. Leaf tips turn brown. Most severe in high-acid and low-fertility soils. Adjust soil pH to 6.5 or 7.0. Maintain adequate levels of nitrogen and calcium. Root rots* (Pythium spp., Rhizoctonia solani) Roots turn brown and rot. Plants are stunted with yellowing of lower leaves and leaf scorch. Buds are blasted, resulting in a reduced bud count. In soil and on bulbs. Favored by overwatering and poor drainage. Drench plants with mefenoxam in combination with thiophanate-methyl. Mefenoxam at high rates may cause yellowing of leaf margins of Easter lilies. Shoot rot (Phytophthora cactorum) Growing points of emerging plants are rotted. Stems of older plants are rotted, causing the plants to wilt and collapse. Roots are also frequently rotted. Soilborne. Spores are spread in water. Favored by poorly drained soil and overwatering. Steam or chemically treat soil. Oomycete (water mold) specific fungicide drenches also help control the fungus. (See root rot control, above.) Virus or viruslike disease Symptoms Host range and natural spread Comments on control Fleck (Cucumber mosaic virus and Lily symptomless virus) Small, brown, elongated spots appear parallel to leaf veins mostly on older leaves. Flowers are smaller and fewer than on healthy plant Many hosts; transmitted by aphids. Remove infected plants and control aphids. Mosaic (Tulip breaking virus) Foliage shows a slight, dark and light green mottling. Plants are usually salable. Spread by aphids. Obtain virus-free bulbs, if possible. Control aphids. Destroy infected plants. Root rot is more severe on virus-infected plants. Rosette (Lily rosette virus) Leaves curl downward and are flat. Internodes are shortened, giving plants a flat rosette or cylindrical appearance in contrast to pyramid shape of a healthy plant. Flowers fail to open correctly. Symptoms tend to be masked at high temperatures (above 75°F). Easter Lilies are also susceptible to foliar nematodes (Aphelenchoides olesistis)** that cause bunchy top and black scale rot (Colletotrichum lilii). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Easter Lily (11/20) 76 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FUCHSIA Fuchsia spp. (11/20) Disease (causal agent) Fuchsia rust* (Pucciniastrum epilobii) Symptoms Survival of pathogen and effect of environment Comments on control Initially, small brown areas appear on underside of leaves. Later, large circular areas of chlorosis occur and yellow-orange uredospores appear on the underside of leaves. Older leaves may have green tissue around infected areas. Eventually uredospores appear on both sides of leaf. Infected leaves usually drop. Overwinters as teliospores on fireweed or as basidiospores on fir. Uredospores on fuchsia can reinfect fuchsia. Remove fireweed and infected plants. Applications of mancozeb are effective. Avoid wetting leaves. Prune back to stems and remove cuttings. Fuchsias are also susceptible to crown gall* (Agrobacterium tumefaciens), Verticillium wilt (Verticillium dahliae), Armillaria root rot* (Armillaria mellea), damping-off* (Pythium rostratum, P. ultimum and Rhizoctonia sp.), Phytophthora root and crown rots* (Phytophthora spp.), various viruses* (Tomato spotted wilt virus), eriophyid mites, and root knot nematodes** (Meloidogyne hapla). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Fuchsia (11/20) 77 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GERANIUM Pelargonium spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Alternaria leaf spot* (Alternaria tenuis) Water-soaked areas occur on undersides of leaves. Spots enlarge to 0.25 to 0.5 inch and have a slightly sunken center surrounded by concentric rings of darker brown or red tissue. Common on Pelargonium domesticum. In plant debris and leaf spots. Favored by cool wet conditions. Protect foliage with mancozeb. Iprodione sprays applied for gray mold also may help. Bacterial blight* (Xanthomonas axonopodis pv. pelargonii) Round sunken leaf spots or angular dead areas appear and are followed by wilting and death of leaf. Systemic infection results in defoliation and frequently death of plant. Infected stems are blackened and shriveled. Black streaks may occur in nonrotted portions of stem. Older plants may not exhibit symptoms. In infected cuttings and plants and in plant debris in soil for 1 year. Disease develops rapidly at high temperatures. Bacteria are spread in water and can be vectored by greenhouse whitefly from diseased to healthy geranium plants. Use disease-free propagative material and observe strict sanitation. Steam or chemically treat rooting media. Disinfect cutting knives in a solution containing quaternary ammonia. Avoid overhead irrigation. Bacterial leaf spot (Pseudomonas cichorii) Dark brown to black, irregularly shaped spots (0.25 to 1 inch in diameter). Margins are water-soaked. Spots may develop tan centers and have a yellow halo. Infected plants. Many kinds of plants are susceptible. Favored by warm temperatures, rain, and overhead irrigation. Avoid overhead irrigation. Maintain sanitation. Blackleg and root rot* (Pythium spp.) Brown water-soaked bases of cuttings and young plants. Lesions enlarge rapidly, move up the stem, and turn black. Affected plants wilt and die. Soilborne. Favored by overwatering and poor drainage. Follow recommendations above. Drench plants with oomycete (water mold) specific fungicide. Remove and destroy infected plants. Edema (nonparasitic) Small, water-soaked, pimplelike spots appear on undersides of leaves and stems. Spots later become corky. Favored by cloudy, cool weather. Actual cause unknown. Do not overwater. Keep humidity low. Maintain higher temperatures. Gray mold* (Botrytis cinerea) Brown water-soaked decay of flowers occurs. Fuzzy gray fungal spores form on rotted tissues. When infected flower parts fall on leaves, they also rot. Disease may affect stems. In plant debris, especially flowers. Favored by cool wet conditions and water on plant. Protect plants with chlorothalonil, iprodione, or fenhexamid. Where practical, remove old blossoms and dead parts. Avoid overhead irrigation. Rust* (Puccinia pelargonii-zonalis) Pustules of orange-brown spores form on undersides of leaves. On living leaves. Favored by moist conditions and water on plants. Spores are airborne. Protect foliage with triadimefon and myclobutanil. Lower humidity to avoid condensation of water on leaves. Mancozeb also will help control rust. Verticillium wilt* (Verticillium dahliae) Lower and middle leaves wilt, yellow, die, and fall. Shoots die back. Plants are stunted. In later stages, water-conducting tissues (xylem) may be discolored. Remains in soil for many years. Also spread by infected cuttings and plants. Fungus has wide host range (tomato, strawberry, chrysanthemum, nightshade, and many others). Favored by moderate temperatures. Symptoms most severe in warm weather. Use pathogen-free cuttings. Steam treat or fumigate soil with chloropicrin or a chloropicrin combination. Avoid soil previously planted to tomatoes, strawberries, potatoes, chrysanthemums, or other susceptible crops. Continued on next page . . . Disease Control Outlines Geranium (11/20) 78 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Geranium, continued Virus or viruslike disease Flower break (Pelargonium flower break virus) Leaf curl (Pelargonium leaf curl virus) Symptoms Host range and natural spread Comments on control Symptoms vary depending on viruses present, cultivar, and growing conditions. Symptoms include light and dark green mottling of foliage, chlorotic spotting, ring spotting, leaf distortions, leaf breaking, vein clearing, and others. In infected geranium plants. Symptoms of some are masked during warm weather. Obtain virus-free cuttings. Do not propagate from plants that have shown symptoms of virus. Line pattern (Pelargonium line pattern virus) Mosaic (Cucumber mosaic virus) Ringspot (Tomato ringspot virus or Tobacco ringspot virus or both) Geraniums are also susceptible to Armillaria root rot* (Armillaria mellea), crown gall* (Agrobacterium tumefaciens), bacterial fasciation (Rhodococcus fascians), and cottony rot* (Sclerotinia sclerotiorum). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Geranium (11/20) 79 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GLADIOLUS Gladiolus spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Botrytis disease* (Botrytis blight, Neck rot, Corm disease) (Botrytis gladiolorum, B. cinerea) Tiny brown leaf spots develop; spots may expand or coalesce. Brown water-soaked spots appear on flower petals. Basal stem infections (neck rot) may penetrate corm; corm decay may continue in cold storage. Fuzzy gray fungus spores may form on decayed tissues. Black seedlike sclerotia may form on underground parts. In corms and on crop refuse. Spores are airborne. Favored by moist conditions and low temperatures (50° to 70°F). Complete control program essential in coastal areas: cure and treat corms as outlined at end of this section; protect foliage with chlorothalonil, iprodione, mancozeb, or thiophanate-methyl. After harvest and before packing, spray flower spikes with a fungicide. Fusarium yellows (Fusarium oxysporum f. sp. gladioli) Leaves tend to turn downward, yellow progressively, and die prematurely. Brown rot of corms begins in basal plate and core, and extends upward into the leaf bases via vascular strands. Corms may rot in ground or while in storage. Cultivars vary in symptoms and susceptibility. Infection without obvious symptoms is common. In diseased corms and in infested soil for many years. Favored by temperatures of 70°F or above. Plant disease-free corms in clean soil, or grow resistant cultivars. Hot water treatment of cormels eliminates the fungus from infected stocks. Cure and treat corms as outlined at end of this section. Fumigate infested soil with chloropicrin or a chloropicrin combination. Disease is less severe if soil pH is 6.6 to 7.0 and 80 to 90% of nitrogen is the nitrate form. Penicillium corm rot (Penicillium gladioli) A firm brown corm rot develops in storage; frequently in association with other corm rots. If conditions are moist, greenish blue spore masses appear over rotted areas. On corms and corm debris and as spores on storage-room equipment. Rot develops rapidly when humidity is high. Cure and treat corms as outlined at end of this section. Rhizoctonia neck rot (Rhizoctonia solani) Stem below ground and husks at harvest appear shredded. Brown fungus strands (mycelium) visible with a hand lens. Common soilborne fungus with wide host range. Favored by warm, wet conditions. Corm dips help control the fungus. Treat soil with PCNB before planting. Sprays of iprodione or thiophanate-methyl should reduce spread of the fungus down the row. Rust (Uromyces transversalis) First seen as small yellowish spots that later break out of leaves, stems, and sometimes flowers, forming pustules with yellow-orange spores. May also include yellowish-brown (uredinia) or blackish-brown (telia) pustules. Besides Gladiolus species, other hosts include other members of the Iris family: Crocosmia, Tritonia, and Watsonia. Spores can contaminate corms, rhizomes and bulbs. Spores can be blown long distances by wind. Only accept corms and plants from known clean sources. Prevent introduction into nursery by careful regular monitoring. Scab (Pseudomonas gladioli pv. gladioli) Mainly seen on corms as irregular or round sunken brown spots with a shiny, brittle, varnishlike material (bacterial exudate) on the surface. On corms and in soil refuse for 2 years. Favored by heavy, wet soils and warm weather. Encouraged by heavy nitrogen fertilization. Rotate every 3 years. Control measures for other diseases usually take care of scab. Control chewing insects in the soil. Stemphylium leaf spot (Stemphylium spp.) Small round or angular yellow spots with a red dot in the center appear on green parts of plants. Spots are larger on some cultivars. Cultivars differ in susceptibility. Carried over on gladiolus foliage and refuse. Favored by warm, wet weather, especially sprinkler irrigation and rain. Spray mancozeb at 10- to 14-day intervals. Plow under gladiolus crop residues. Stromatinia rot (Stromatinia gladioli) Leaves yellow and die. Leaf sheaths rot at soil level (neck rot). Rotted tissues appear shredded. Numerous, very small black fungus resting structures (sclerotia) are imbedded in dead tissue. Corm lesions are dark brown and sunken with raised margins. On diseased corms and in soil for 10 years or more. Favored by wet soil. Cure and treat corms as outlined at end of this section. Use uninfested or chemically treated land. Fumigate soil with chloropicrin or a chloropicrin combination. Disease Control Outlines Gladiolus (11/20) 80 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Virus or viruslike disease Symptoms Host range and natural spread Comments on control Grassy top (Aster yellows phytoplasma*) Current season infection results in early maturity, small corms, and arrested root development. Next year, the corms produce numerous thin, weak shoots—grassy top. Flowers produced by grassy top plants are green. Leafhoppers. Many kinds of plants, including some weeds. Destroy infected plants. Mild mosaic (Bean yellow mosaic virus) A faint leaf mottle and sometimes a pencil-stripe color break of blossoms. Disease is common in nearly all gladiolus cultivars but symptoms are more severe in some cultivars. Blossoms may fail to open all the way. Aphids. Mechanically transmitted by harvesting tools. Legumes (beans, peas, vetch). Propagate from selected disease-free plants grown in isolated areas. Ringspot (Tobacco ringspot virus, Yellow or white ring patterns and blotches on leaves. Nematodes. Mechanically transmitted by harvesting tools. Many kinds of plants, including weeds. Destroy infected plants. White streaking or flecking of leaves and a white blotch or color break in petals. Flowers sometimes fail to open completely or shrivel prematurely. Aphids. Corm-propagated. Sometimes transmitted by harvesting tools. Cucurbits (melons, cucumber, squash), peppers, tomatoes, nandina, and hundreds of other hosts. Propagate from selected disease-free plants grown in isolated areas. Rogue infected plants at flowering time or as soon as virus symptoms appears. Control aphids. Tomato ringspot virus) White break (Cucumber mosaic virus) Gladiolus are also susceptible to Septoria leafspot (Septoria gladioli) and leaf smut (Urocystis gladiolicola), which are rare diseases in California. Curvularia leafspot (Curvularia lunata) appears occasionally as a neck rot, particularly in cormel stocks. * For additional information, see section on Key Diseases. CARING FOR CORMS The major gladiolus pathogens can be carried on the surface of or inside corms. To control the pathogens, it is essential to correctly cure, store, and dip corms before planting. Curing: Immediately after digging, place corms in shallow trays in storage rooms maintained at 95°F (35°C) and 80% relative humidity. Use fans to circulate air through and around corms. When old corms break off easily, usually after 6 to 8 days, clean the new corms. Return corms to storage at 95°F and 80% relative humidity for 4 more days. Storage: Store cured corms at 40°F and 70 to 80% relative humidity. In mild climates, clean corms can be replanted if Fusarium yellows is not a problem. Preplant dip: Before planting, dip corms in iprodione or thiabendazole plus 4 to 6 fluid ounces of wetting agent/100 gal water. The water should be at a temperature of 80° to 90°F. Allow corms to dry before planting. Sanitation: Maintain sanitary storage facilities. Burn all gladiolus refuse. Steam treat or disinfect trays, tools, and the like. Hot water treatment of cormels: (1) Select sound, hard, fully dormant corms grown in warm soil and harvested before cold weather. Cure as outlined. (2) Presoak corms for 2 days in water when the air temperature is 60° to 80°F. Discard any corms that float. (3) Immerse 30 minutes in water heated to 131°F. (4) Cool immediately with clean, cold water. (5) Dry thoroughly and quickly in warm air or sunshine. (6) Dust with a fungicide and store at 40°F and 70 to 80% relative humidity. Disease Control Outlines Gladiolus (11/20) 81 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GYPSOPHILA Gypsophila paniculata (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial gall (Pantoea agglomerans (formerly Erwinia herbicola)) Soft, light brown galls up to 2 inches (5 cm) in diameter develop at or below soil line. Galled plants are often stunted and some die. Bacteria survive in galls and in aerial parts of the plant. Infection is favored by warm conditions. Use pathogen-free stock developed through tissue culture. Avoid wounding plants when establishing field plantings. Maintain strict sanitation in propagation. Flower blight (Alternaria sp.) Infected flowers turn black. Favored by moist conditions. Avoid overhead irrigation during flowering. Protective sprays of iprodione or chlorothalonil may be helpful in severe situations. Phytophthora crown rot* (Phytophthora parasitica) Leaves wilt and turn light green. Entire plant may collapse and die. Crown tissue is discolored and a soft, wet decay develops. Secondary bacteria cause the diseased tissue to putrefy. Pathogen is soilborne and may be present in many fields. Disease is favored by warm temperatures 90°F, moist conditions, and poor drainage. Improve drainage by planting on raised beds. Do not moisture-stress plants, but do not overwater. Soil drenches of oomycete (water mold) specific fungicide are helpful in preventing the disease. Root rot* (Pythium spp.) Soft wet decay of seedlings and plants in propagation. Leaves of infected plants turn grey-green. In the field, roots are rotted and plants are stunted. Several species of Pythium are involved. Pythium aphanidermatum is favored by warm or hot conditions while P. ultimum develops at lower temperatures. Both pathogens are present in many field soils. Disease is favored by overwatering and poor drainage. An oomycete (water mold) specific fungicide is helpful when used in preventative programs. Stem rot (Rhizoctonia solani) All stages of growth may be affected. Stems are infected at or just beneath the soil line. Sunken dark lesions are dry in the early stages but later the decay becomes soft and wet. Fungus occurs naturally in many soils. Favored by warm, wet conditions and deep planting. Treat soil or planting medium with granular PCNB before planting. Avoid deep planting. Spray base of plants before or after planting with iprodione or PCNB. Keep PCNB off foliage. Gypsophila is also susceptible to gray mold* (Botrytis cinerea), bacterial fasciation (Rhodococcus fascians), root knot nematode** (Meloidogyne spp.), cottony rot* (Sclerotinia sclerotiorum), southern blight* (Sclerotium rolfsii), crown gall* (Agrobacterium tumefaciens), and aster yellows* (Aster yellows phytoplasma). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Gypsophila (11/20) 82 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES HEATHER Calluna vulgaris, Erica spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Armillaria root rot* (Armillaria mellea) Symptoms are similar to crown rot but distribution in the field is different. Examination of affected plants reveals white fungus plaques beneath the bark at or below soil line on main stem. Erica canaliculata and E. hirtiflora have been infected. Fungus survives for long periods in infected roots buried in soil. Infection is favored by the same conditions that are favorable for plant growth. Avoid fields just cleared of oaks or other susceptible woody plants. This is not a common disease of heather. Chlorosis (Iron deficiency) Foliage turns yellow and some turns almost white, especially new growth. Terminal growth may die and plants are stunted. Occurs if soil pH is too high. Soils that are too basic as a result of too much calcium. Spray plants with ferrous sulfate using 6 to 8 pounds/100 gal water. Thoroughly wet the plants using 100 to 150 gal/acre. Apply once a month starting in early spring as growth commences. If stems turn black, reduce dosage and frequency of treatment. Acidify soil. Powdery mildew* (Erysiphe azaleae, Golovinomyces orontii) Shoot tips are reddened, then yellow and turn brown and fall off. A side bud develops into the new terminal and successive killing of the tips causes crooked, twisted growth. The white powdery mildew growth is often difficult to find. Affected plants are stunted and bushy. Erica persoluta is damaged. On living heather foliage. Fungus is favored by moderate temperatures, partial shade, and dry foliage. Several fungicides are available to protect foliage from infection. Start applications in spring and after each irrigation. During very hot periods, sulfur may damage foliage and flowers; avoid excessive rates of application. Root and crown rot (Pythium spp.*, Phytophthora cinnamomi*) Plants are stunted or may suddenly wilt and collapse. Roots are killed and the base of the stem (crown) is attacked, causing a complete or partial girdling. Erica hirtiflora (=E. regerminans) and E. hyemalis are very susceptible. Erica canaliculata (E. melanthera) is moderately resistant and E. persoluta is resistant. Soilborne pathogens with wide host range. These organisms also survive in infected plants. Favored by excessive soil moisture, poor drainage, and warm temperatures. Avoid introduction into new areas by growing or obtaining disease-free plants. Take cuttings from high on the plant and use heat-treated or fumigated propagative and growing medium. Prevent infection in the nursery by periodic treatments with an oomycete (water mold) specific fungicide. Careful water management will provide some relief in field plantings. Oomycete (water mold) specific fungicides applied as a drench also helps. Rust* (Uredo ericae) Small pustules of powdery orange spores occur on leaves. Infected leaves usually turn yellow and abscise. Erica hirtiflora and E. persoluta var. alba are infected. On foliage. Spores are airborne and may be carried by the wind for many miles. Pathogen is favored by moderately low temperature and dew or rain. Protect foliage with sulfur applied as a dust or spray. Start applications in late March and continue at 10- to 14-day intervals until rains stop. During very hot periods sulfur may cause damage to foliage and flowers; avoid excessive rates of application. Also avoid overhead watering. Verticillium wilt* (Verticillium dahliae) Wilting, yellowing, and defoliation occur frequently on only one side of the plant. Examination of crown and roots, which appear healthy, helps differentiate this disease from root and crown rot. Symptoms usually first appear in early summer. Erica australis and E. persoluta are affected. Fungus is soilborne and has a wide host range. Fungus invades plant in the cool spring plugging the water-conducting tissues. Symptoms occur when plant is stressed for water, particularly during warm periods. Avoid fields that have been in susceptible crops or weeds such as tomato, chrysanthemum, strawflowers, nightshade, and others. Propagate plants, using heat or chemically-treated medium. The fungus can be eliminated from field soil by fumigation with chloropicrin or a chloropicrin combination. * For additional information, see section on Key Diseases. Disease Control Outlines Heather (11/20) 83 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES IRIS (Bulbous) (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial blight* (Xanthomonas campestris pv. tardicrescens) Elongated, water-soaked spots or lesions that usually occur near the base of leaves. Under moist conditions, lesions rapidly enlarge causing leaf to turn yellow and collapse. Flower stems may be infected. Bacteria survive in infected bulb scales and tissues. Rhizomatous iris also is susceptible. Disease is favored by warm, moist conditions and by injuries and frost damage. Avoid excessive overhead irrigation. Space plants wide enough to promote air circulation and rapid drying of foliage. Discard infected plants. Use pathogen-free planting stock. More info* Basal rot (Fusarium oxysporum f. sp. gladioli) Stunted, yellowed plants. Basal plate and scales are affected by a firm brown rot. Blue mold may develop as a secondary rot. Fungus survives as chlamydospores in soil for several years. Spread by infected bulbs. Disease is favored by warm soils (above 57°F). Gladiolus, crocus, Ixia, Tigridia, Tritoma, and freesias are also attacked. Do not plant in infested soil for 3 to 4 years or fumigate soil with chloropicrin or a chloropicrin combination. Dip bulbs in thiabendazole. Fusarium oxysporum f. sp. gladioli has shown some resistance to thiabendazole and to benzimidazole fungicides. Black slime (Sclerotinia bulborum) Plants yellow, wilt, and die or fail to emerge. Diseased plants tend to occur in clumps. Below ground shoots and bulbs are covered with a mass of gray fungus. Infected parts contain pockets of gray or white mycelium and black sclerotia. Favored by cool weather. Fungus survives as sclerotia in soil for several years. Rotate out of iris for 3 to 4 years. Include PCNB in bulb dip. Blue mold (Penicillium spp.) Plants are stunted, off-color, lack flowers, and prematurely die. Blue-green mold on rotted bulbs. Also common on stored bulbs. Wounds caused by insects, harvesting, sunburn, etc. are necessary for infection. Late or early digging favors disease. Frequently starts on corms stored incorrectly. Avoid very early or very late digging. Avoid injuries. Cure bulbs rapidly and provide good ventilation during storage. Heat cure bulbs within 5 days of digging. Dip bulbs in thiabendazole. Some Penicillium spp. have shown resistance to thiabendazole and other benzimidazole fungicides. Fire (Leaf spot) (Mycosphaerella macrospora =Didymellina macrospora, conidial state Heterosporium gracile) Oval to elliptical leaf spots with pale yellow or reddish brown borders. As the spots become old, centers turn tan. Spots are often near tips of leaves. Flower buds, stems, and bulbs may be infected. Dark green spores may be seen in the spots. Disease is favored by mild temperatures (50° to 70°F) and wet conditions. Spores are airborne. Fungus also infects rhizomatous iris. Dig bulbs annually. Protect foliage with myclobutanil, chlorothalonil, or mancozeb. Destroy old leaf tissues. Ink spot (Drechslera iridis) Dark reddish brown elongated spots with chlorotic margins. Older leaves develop gray centers. Dark spore masses may be visible on lesions. Usually older leaves are infected. Irregular inky-black stains occur on Iris reticulata bulbs. Disease may be severe on plants left in the ground for 2 years. Disease is favored by mild (68° to 77°F), moist conditions. Fungus survives on infected bulbs and debris. Not common. Dig bulbs every year. Remove and destroy all debris; rotate on a 3-year basis. Protect foliage with mancozeb. Nematode** (Ditylenchus destructor) Plants are stunted. Black streaks occur along veins of the outer husks. Outer husks become shredded at the base and the basal plate becomes honeycombed and grayish. Nematodes survive in bulbs. Damage is worse in cool, moist climates. Other hosts include alfalfa, potato, sugarbeet, tulips, and some weeds and fungi. Harvest bulbs 7 to 10 days earlier than normal. Treat dormant bulbs in hot water (110°F) for 3 hours. Cool and dry promptly. Disinfect tools, trays, etc. by heat treatment such as steam or hot water at 185°F. Do not replant infested fields for 2 years. Continued on next page . . . Disease Control Outlines Iris (Bulbous) (11/20) 84 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Iris (Bulbous), continued Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Rust* (Puccinia iridis) Reddish brown powdery pustules on leaves. Cultivars differ in susceptibility. Fungus survives on living iris leaves. Spores are airborne. Favored by condensed moisture and overhead irrigation. Irrigate so that water does not remain on leaves longer than a few hours. Chlorothalonil, myclobutanil, and mancozeb used to control leaf spot will help control rust. Remove and destroy old infected leaves. Southern blight* (Sclerotium rolfsii) This disease is also called crown rot or southern wilt. Outer leaves turn yellow. Eventually all leaves are affected. Leaf bases and bulb are affected by a soft rot. White mycelium is present on bulbs and in soil. Small, tan to reddish brown sclerotia are found in and on bulbs and soil. Sclerotia survive in soil. Disease is favored by warm (77° to 95°F), moist soil. May be spread by infected bulbs and anything that moves infested soil. PCNB mixed with soil before planting helps. Bulbous irises are also susceptible to gray mold* (Botrytis cinerea), gray bulb rot (Rhizoctonia tuliparum), root rot* (Pythium irregulare), neck rot (Rhizoctonia solani), Iris mosaic virus, mosaics, and black storage molds (Rhizopus sp., Aspergillus sp.). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Iris (Bulbous) (11/20) 85 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES IRIS (Rhizomatous) (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial soft rot* (Pseudomonas spp.) Wilting and dying of fans accompanied by a soft, wet, foul-smelling rot of rhizome. Fans separate easily from rotted rhizome or topple over. In infected tissue. Favored by warm, wet weather, but rot may continue when conditions are dry. More serious when rhizomes are buried when planted. Bacteria enter through wounds, so prevent injuries to plant. Remove infected plants, cut away rotted tissues, and allow cut surfaces to thoroughly dry before replanting. Plant high or on ridges so that the top of the rhizome is not covered. Leaf spot* (Mycosphaerella macrospora, Didymellina macrospora, conidial state; Heterosporium gracile) Circular to elongated spots 0.125 to 0.25 inch in diameter and up to 1 inch in length. At first, yellowish flecks appear. Spots later turn light brown and have a distinct red border. If severely infected, leaves of some cultivars die back. Dark green spores may be found in spots. On living and dead leaves. Favored by wet weather. Fungus also infects bulbous iris and other iris species. Collect and burn or bury dead leaves. Where practical, cut off infected parts of leaves. Protect foliage during wet weather with chlorothalonil, myclobutanil, mancozeb, or copper fungicides. Addition of a wetting agent may be necessary. Rust* (Puccinia iridis) Reddish brown, powdery pustules on leaves. Infected areas frequently surrounded by yellow tissues. Cultivars differ greatly in susceptibility to rust. On living iris leaves. Spores are airborne. Favored by atmospheric moisture (rain, dew, overhead irrigation). Irrigate so that the water does not remain on leaves longer than a few hours. Chlorothalonil, myclobutanil, and mancozeb used to control leaf spot will also help control rust. Southern blight (Sclerotium rolfsii) Rhizomes and leaf bases become rotted. The fungus is visible as a white, cottony growth on the surface and in the soil, and as small, brown resting structures (sclerotia). In soil as sclerotia. Favored by high temperatures and wet soil. Attacks many other plants. Avoid planting in infested soils. Fumigate soil before planting. To prevent spread, drench infested areas with PCNB or mix granular form with planting medium before planting. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Mosaic (Iris virus 1) Light and dark green mottling and yellow stippling of foliage. Mottling and stippling are especially prominent on young leaves. Mosaic is most severe on bulbous iris and some rhizomatous species. Iris germanica and its hybrids are only slightly stunted and sometimes exhibit no symptoms. Iris family (Iridaceae). Transmitted by aphids. Oncocyclus iris and their hybrids can be severely damaged. Serious on Tigridia. Rogue infected plants. Control aphids. Rhizomatous irises are also susceptible to root knot nematode** (Meloidogyne hapla). Rhizome rot caused by Sclerotinia convoluta and bacterial leaf blight caused by Xanthomonas tardicrescens, do not occur or are rare in California. * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Iris (Rhizomatous) (11/20) 86 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MARGUERITE DAISY Chrysanthemum (=Argyranthemum) frutescens (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Cottony rot* (Sclerotinia sclerotiorum) Plants wilt and die. Basal stem rot. Cottony, white mycelium present in and on stems under moist conditions. Long, black sclerotia form in and on stems. Fungus survives in soil as sclerotia, which germinate after a cold-dormancy period to produce airborne spores. Direct infection from sclerotia may occur. Fungus has a wide host range. Favored by overhead irrigation and high humidity. Avoid planting in infested fields or fumigate soil. Treat soil with PCNB before planting. Carrots, celery, and lettuce are common hosts. Irrigate early in the day so plants dry quickly. Spray base of plants and lower foliage with thiophanate-methyl. Crown gall* (Agrobacterium tumefaciens) Spherical galls on stems most often at base of plant. Heavily infected plants are stunted. Soilborne bacterium with a wide host range. Survives in soil for several years. Plant disease-free plants. Propagate from clean plants. Dip or spray cuttings with Agrobacterium radiobacter 'K84' immediately if wounded. Avoid wounds, especially when plants are wet. Downy mildew* (Peronospora radii) Young tip leaves are dull green, severely stunted, and roll downward. Gray-purple fungus grows on undersides of leaves. Disease is common on seedling phase; large plants are less frequently attacked. Infected plants fail to produce flowers. Thick-walled resting spores (oospores) in dead plant parts. Airborne spores. Favored by cool (40° to 60°F), wet weather. In greenhouse, reduce humidity. Drench seedlings with an oomycete (water mold) specific fungicide. Do not replant in fields where disease has been severe. Steam treat to kill resting spores. Protect foliage with mancozeb. Pythium root rot* (Pythium spp.) Plants stunted as a result of reduced root system. Small roots rotted. Soilborne pathogen. Spores spread with soil and water. Favored by excess soil moisture and poor drainage. Avoid poorly drained soils. Plant on raised beds. Reduce amount of irrigation water. An oomycete (water mold) specific fungicide applied at transplanting will help get plants started. Root knot nematode** (Meloidogyne hapla) Plants are stunted; swellings or galls on roots. Galls have lateral roots. Nematodes survive in soil as eggs. Disease is usually most severe in sandy soils. Also prevalent in cooler climates: optimum temperature to invade roots is 59° to 68°F (15° to 20°C) and for growth and reproductions is 68° to 77°F (20° to 25°C). Preplant fumigate with chloropicrin or a chloropicrin combination or solarize soil. Root lesion nematode (Pratylenchus spp.) Plants are stunted. Necrotic lesions on roots that involve the cortex and deeper tissues. Nematodes survive in soil as adults, larvae, and eggs. Preplant fumigate with chloropicrin or a chloropicrin combination or solarize soil. Southern blight* (Sclerotium rolfsii) Plants wilt and collapse. Basal stem and roots are rotted. White cottony fungus growth may be present on infected parts and soil. Small (0.625 inch), tan or brown sclerotia form on rotted tissues and in soil. Sclerotia survive in soil. No airborne spores are formed. Sclerotia germinate and infect susceptible plants. Fungus has a wide host range. Avoid fields where the disease has occurred or fumigate with chloropicrin or a chloropicrin combination. PCNB applied to the base of plants or as a preplant treatment will help. Marguerite Daisy is also susceptible to powdery mildew* (Golovinomyces cichoracearum), Verticillium wilt* (Verticillium dahliae), leaf spot (Ramularia sp.), curly top (Beet curly top virus), and aster yellows (Aster yellows phytoplasma). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Pot Marigold (11/20) 87 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES NARCISSUS Narcissus spp. (11/20) Disease (causal agent) Basal rot (Fusarium oxysporum f. sp. narcissii) Symptoms Survival of pathogen and effect of environment Comments on control Infected plants are stunted with distorted and yellow leaves, and usually die. The basal plate is decayed and reddish brown in color. The white to pinkish fungus is sometimes seen at the base between the scales. Eventually the bulb rots. Fungus survives as chlamydospores in soil for long periods. Short rotations are not effective. Disease is favored by warm soils and is limited below 55°F; disease is favored by high levels of nitrogen fertilization. Potassium fertilizer may decrease disease sensitivity. Avoid excessive fertilization. Dig up bulbs in diseased areas as soon as possible. Store bulbs below 64°F. Dip bulbs in thiabendazole as soon as possible after digging. Hot water treatment (see stem and bulb nematode) is also effective in reducing the disease. Rotate out of narcissus for at least 3 years. Plant when soil is cool. Susceptibility of narcissus cultivars to basal rot: Susceptible: Carlton, Golden Harvest Moderately susceptible: Toorak Gold, Dutch Master, Hollywood Moderately resistant: Malvern City, Rijinveld's Early Sensation, White Lion, Soleil d'Or, Dulcimer Resistant: St. Keverne Crown rot or Southern blight (Sclerotium rolfsii) A bulb rot that is at first wet and later becomes dry and woody. A white fungus mat and small (0.03–0.125 inch), round, tan to brown sclerotia occur on decaying bulbs and in surrounding soil. Disease is favored by warm weather. Fungus survives in soil for long periods (10 years). Fungus has a wide host range. Can be spread by infected bulbs. Avoid infested fields for 4 years or longer. Deep plowing is sometimes practiced to bury sclerotia. Treat bulbs in hot water. (See stem and bulb nematode.) PCNB applied in the furrow at planting can be effective. Fire (Botryotinia polyblastis) Water-soaked areas on petals that become brown and wither. Flowers are attacked first, and later the foliage. Foliage spots are small, elliptical, tan and usually near the tips. Yellow streaking follows the leaf spots. Fungus survives as sclerotia in leaf debris. Sclerotia germinate in spring to produce fruiting bodies (apothecia), which produce airborne spores (ascospores). Conidia, which are also airborne, cause secondary spread. The disease is favored by mild, humid conditions. Remove flowers before fungus produces apothecia in March/April. Protect flowers and foliage with a fungicide. Scorch (Stagonospora curtsii) Yellow to brown lesions at leaf tips. Elongate reddish brown leaf spots. Small black pycnidia form in necrotic areas. The fungus survives in the neck and between scales. Disease is favored by mild, moist conditions. Spores are spread in splashing water. The fungus infects members of the Amaryllidaceae. Treat bulbs with hot water. Protect plants in the field with fungicides. Make first application as leaves emerge. Smoulder (Botrytis narcissicola) A dark brown lesion first appears on leaf tips. Infected leaves may curl when infection occurs on inner edge. Masses of fuzzy gray spores (conidia) and small black sclerotia form on diseased tissues, especially near soil. Fungus survives in infected bulbs and as sclerotia in soil. Conidia are airborne. Favored by cool, wet weather. Rotate with other crops. Dig bulbs early. Dip bulbs in suitable fungicide such as thiabendazole. If disease is severe in field, spray with iprodione, fenhexamid, or thiophanate-methyl. Continued on next page . . . Disease Control Outlines Narcissus (11/20) 88 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Narcissus, continued Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Stem and bulb nematode** (Ditylenchus dipsaci) Leaves are stunted and distorted, and often swollen and thickened near the base. Yellow or brown swellings occur in leaf centers and margins. Severely infected bulbs are unproductive and may rot. Nematodes survive in infected bulbs and in bulb debris in fields for about 3 years. Optimum temperature for infection and reproduction is 50° to 60°F. (Little activity occurs when soil temperatures are lower than 50°F and greater than 68°F.) Nematodes are spread by irrigation water and equipment. They also survive in weed hosts and can survive desiccation. Remove infected plants and surrounding plants from the field. Clean equipment after use in diseased fields. Treat bulbs in hot water. Store bulbs at 60° to 64°F before treatment to reduce heat injury. Presoak bulbs 2 to 3 hours or overnight in water plus a wetting agent at 75°F. Increase temperature in morning to 109°F. Once the temperature of the treatment solution reaches 109°F, maintain a constant temperature of 109° to 111°F for 3 to 4 hours. Cool and dry bulbs immediately. CAUTION: Hot water treatment may injure bulbs causing stunting and flower blast or deformation. Obtain expert advice before large-scale treatment. White mold (Ramularia vallisumbrosae) Small, sunken, grey or yellow spots on leaves and green parts. Spots enlarge and darken to a yellow- brown with yellow margins. Masses of white, powdery spores (conidia) occur on leaves under moist conditions. Small, dark sclerotia are produced in older infected tissues. Fungus survives as sclerotia in dead leaves and on bulbs. Sclerotia germinate to produce conidia as leaves emerge. Disease is favored by warm, moist conditions. Do not replant for 1 year in fields where the disease has occurred. Protect foliage with mancozeb. Copper fungicides are also helpful. Virus or viruslike disease Symptoms Host range and natural spread Comments on control White streak (Narcissus white streak virus) Narrow, dark green to purple streaks, which later become white to yellow-white, appear in leaves and flower stalk after flowering. Bulb size and yields are reduced by premature senescence. Narcissus is the only host of the virus, which is transmitted by aphids. Symptoms do not occur until air temperatures exceed 64°F. Eliminate infected plants. Control aphids. Yellow stripe (Narcissus yellow stripe virus) Conspicuous light green to yellow streaks and mottling of leaves and flower stalk, which occurs shortly after emergence. Sometimes leaves are distorted and a color-break of flowers occurs. Bulb yields are reduced. The virus infects only narcissus and is spread by aphids. Symptoms appear early in growing season. Eliminate infected plants. Control aphids. Equipment that has come into contact with diseased bulbs should be thoroughly cleaned by heat treatment. Narcissus may become infected by a number of other viruses; some produce inconspicuous symptoms. Narcissus is also susceptible to Stromatinia dry rot (Stromatinia narcissi), black slime (Sclerotinia bulborum), soft rot (Rhizopus stolonifer), bacterial streak (Pseudomonas sp.) and root lesion nematode** (Pratylenchus penetrans). ** For additional information, see section on Nematodes. Disease Control Outlines Narcissus (11/20) 89 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PEONY Paeonia spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Gray mold* (Botrytis cinerea or B. paeoniae) Leafy shoots wilt and fall over as a result of rotting at the base. Fuzzy gray fungus sporulation is usually visible on infected tissues. Flower buds darken and wither; leaves also may be attacked. Disease is favored by wet weather and injured tissue. Fungus survives on plant debris and as sclerotia in or on soil. Remove or burn old growth in fall. Cut stalks below the ground level. Planting on raised beds also is helpful. Treat with fenhexamid. Leaf blotch (Cladosporium paeoniae) Small (0.02 to 0.04 inch), oval leaf spots that reach a diameter of 0.08 to 0.12 inch before they penetrate through the thickness of leaf. As spots enlarge, they merge giving the leaf an irregular, blotchy appearance. The upper surface of spots become purple while the lower surface is a dull brown. Fungus survives on infected peony debris and probably on infected scales of crown buds. Disease is favored by rainy weather in spring. Burn or remove plant residues in fall. Protect foliage in spring with a fungicide starting as soon as green shoots appear. Phytophthora blight (Phytophthora cactorum) Young shoots turn black and die or cankers appear along stems and cause them to collapse. Crown infections produce a wet rot that often destroys the entire plant. Favored by cool, wet conditions such as very heavy rains, excessive irrigation, and poor drainage. Grow plants in raised beds. Do not overwater. Some of the fungicides effective against Phytophthora spp., such as mefenoxam, would probably be helpful. Verticillium wilt* (Verticillium dahliae) Plants wilt at flowering, but no basal rots are present. The water-conducting tissue (xylem) in stems is discolored. Infected plants may appear to recover, but symptoms will reoccur the following year. Fungus is systemic in plant. Disease is favored by cool, rainy weather and hot weather at flowering. Water stress exacerbates the disease. Fungus has a wide host range and survives for many years as microsclerotia in soil. Avoid fields where susceptible plants such as tomatoes, cotton, strawberries, chrysanthemum, and others have been grown. Fumigate soil with chloropicrin or a chloropicrin combination. Do not propagate from plants that exhibit any symptoms of the disease. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Le Moine Disease (cause unknown) Plants are dwarfed with many spindly shoots that fail to form flowers. Roots of affected plants are often irregularly swollen. The disease slowly spreads in plantings in a manner suggesting a soilborne vector. Plants are systemically affected and do not recover. Destroy infected plants. Ringspot (Peony ringspot virus) A marked yellow mottle that is in the form of chlorotic rings occasionally accompanied by small necrotic spots. Growth is probably reduced but not obviously. Virus is systemic in infected plants. The virus is mechanically transmitted but little else is known about natural transmission. Destroy infected plants. Peonies are also susceptible to Armillaria root rot* (Armillaria mellea), crown gall* (Agrobacterium tumefaciens), and black root rot* (Thielaviopsis basicola). * For additional information, see section on Key Diseases. Disease Control Outlines Peony (11/20) 90 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES POINSETTIA Poinsettia spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial canker* (Curtobacterium flaccumfaciens pv. poinsettiae) Longitudinal water-soaked lesions on stems and petioles. Spotting of leaves and defoliation. In advanced stages, stem lesions split open. Infected poinsettia plants and debris. Favored by warm, moist conditions. Bacteria spread in water. Bacteria may be present in symptomless plants and cuttings. Plant pathogen-free cuttings. Avoid overhead irrigation and syringing. Steam soil and disinfect benches with copper naphthenate; disinfect tools. Bacterial leaf spot* (Xanthomonas campestris subsp. poinsettiaecola) Spots start out on the undersides of leaves, expand, and become visible on the upper surfaces. Spots are grey to brown, becoming darker as they expand. Generally, they are surrounded by a water soaked area of lighter green or yellow. Infected poinsettia plants and cuttings can survive in dried leaf debris for one year. Favored by high humidity, warm temperatures, and close plant spacing. Prevention is the best management strategy, primarily by avoiding overhead watering that allows splashing of bacteria to adjacent plants. Once present, discard affected plants and disinfect benches. Control can be difficult, but sprays of copper compounds have shown some level of success. Bacterial stem rot (Dickeya (=Erwinia) chrysanthemi) Watery, soft rot of cuttings or stems, resulting in disintegration of infected tissues. Rot develops rapidly and plant collapses. In diseased plant tissues. Favored by high temperatures (73° to 86°F) and succulent plants. Avoid high temperatures and practices that produce succulent growth. Careful sanitation practices will minimize spread of bacteria. Disinfect tools with quaternary ammonium. Gray mold* (Botrytis cinerea) Blasting of flowers and browning or spotting of bracts. Fuzzy gray fungal growth forms on dead parts. Lesions on stems and leaves. In plant debris. Favored by cold, moist conditions and condensed moisture on bracts and flowers. Provide better growing conditions and air circulation. Clean up plant debris. Avoid wetting leaves and try to lower relative humidity. Protect plants with fenhexamid. Greasy canker (Pseudomonas viridiflava) Greasy-appearing cankers on stems. Necrotic lesions with chlorotic margins on leaves. Sometimes confused with bacterial canker. Infected plant debris. Bacterium has a wide host range. Disease favored by high humidity, high temperature, and condensed moisture on plants. Reduce humidity. Sanitize pruning tools. Avoid wetting foliage. Powdery mildew* (Oidium spp.) Yellow spots or whitish growth on upper leaf surfaces and bracts. On living plants. Favored by moderate temperatures and crowded, shaded foliage. Regularly inspect plants. Remove, bag, and dispose of infected plants at first sign of infection. Apply protectant fungicide when plants are young and more easily sprayed. Root and stem rot* (Thielaviopsis basicola, Rhizoctonia solani, Pythium spp.) Plants are stunted and wilt easily. Lower leaves become chlorotic and may fall. Roots are rotted and dark brown, water-soaked stem lesions develop. Large roots and lower stem may be enlarged and ridged. Young plants frequently are killed. Each fungus can cause disease independently, or fungi may interact to produce rapid decline. Symptoms vary with the pathogen. In soil. Favored by excess moisture and overcrowding of plants. Thielaviopsis and Pythium severe at high (86°F) or low (63°F) soil temperatures, whereas Rhizoctonia develops most rapidly between 63° to 79°F. Disease development most severe at rooting and just before maturing. Plant disease-free cuttings in heat-treated or chemically treated soil. Before planting, mix into soil mefenoxam plus thiophanate-methyl. If root rots occur after potting, drench with mefenoxam plus thiophanate-methyl. Rust* (Uromyces euphorbiae) Pustules of cinnamon-brown spores on both leaf surfaces. On living plants. Favored by moist conditions. Pick off and burn diseased leaves. Protective fungicide sprays help in control. Spot anthracnose or scab (Sphaceloma poinsettiae) Circular, buff-colored spots that develop into scablike lesions on leaves and stems. Infected plants and debris. Favored by wet conditions. Spores spread in water. Do not wet foliage. Protective fungicidal sprays should help in control. Avoid splashing water. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Mosaic Distortion of leaves and bracts. Some bracts may fail to May be symptomless in poinsettias. Mechanically Obtain virus-free plants. Grow at higher temperatures. Discard Disease Control Outlines Marguerite Daisy (11/20) 91 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES (Poinsettia mosaic virus) color normally. Mild mottling of leaves. Angular leaf spotting, apparent only under cool temperatures. Symptoms most severe on plants grown at 61° to 68°F. Plants grown at 75° to 82°F appear normal. transmitted. plants with symptoms. Poinsettias are also susceptible to Rhizopus soft rot (Rhizopus stolonifer). * For additional information, see section on Key Diseases. Disease Control Outlines Marguerite Daisy (11/20) 92 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES POT MARIGOLD Calendula officinalis (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Powdery mildew* (Podosphaera xanthii) White, powdery mildew fungus on surface of leaves and stems. More common on older leaves and older plants. Disease is favored by moderate temperatures and somewhat shaded conditions; however, powdery mildew may occur on lower leaves of plants in full sun. Spores (conidia) are windborne. Protect plants with a powdery mildew fungicide. Root rot* (Phytophthora spp.) Plants are stunted and somewhat chlorotic. Roots are rotted. Phytophthora spp. are present in many field soils. Favored by poor drainage, heavy soils, or overwatering. Plant on raised beds. Drench soil with an oomycete (water mold) specific fungicide. Smut (Entyloma calendulae) Circular to irregular (0.25 to 0.5 inch in diameter), greenish yellow to brownish spots, sometimes with a darker brown border. Spots are somewhat thickened and evident on both sides of the leaf. Spores are windborne or rainborne. Fungus survives on Calendula and Calendula refuse, and probably on other related hosts. Favored by rain and overhead irrigation. Avoid overhead irrigation. Protect foliage with mancozeb. Pot marigolds are also susceptible to Pythium root rot* (Pythium spp.), gray mold* (Botrytis cinerea), rust* (Puccinia melampodii), spotted wilt (Tomato spotted wilt virus), root knot nematode** (Meloidogyne spp.), aster yellows* (Aster yellows phytoplasma), mosaic (Cucumber mosaic virus), southern blight* (Sclerotium rolfsii), cottony rot* (Sclerotinia sclerotiorum), Alternaria leaf spot (Alternaria sp.), Charcoal root rot (Macrophomina phaseolina), stem rot* (Sclerotinia sclerotiorum), and Verticillium wilt* (Verticillium dahliae). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Poinsettia (11/20) 93 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ROSE Rosa spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Armillaria root rot* (Armillaria mellea) A general decline and eventual death. White plaques of fungal growth develop between bark and wood. In infected wood buried in soil. Could be introduced with leaf mold if there are woody branches or roots present or in incipient infection on plant. Fumigate infested soil with chloropicrin or a chloropicrin combination. Black spot* (Diplocarpon rosae) Black spots with fringed margins mainly on both sides of leaves and on succulent stems. Yellowed areas develop around spots. Causes defoliation. On living and dead leaves, and on infected stems. Waterborne spores are spread by splashing water. Avoid wetting foliage. Remove, incorporate, or burn infected fallen leaves when pruning. Protect foliage with chlorothalonil. Do not compost unless using rapid methods. Botrytis blight* (Botrytis cinerea) Spotting of flower petals and bud rot. Twig dieback and cane canker. Fuzzy gray fungal spores form on decayed tissues. Plant debris. Favored by high humidity, condensed moisture, and low temperatures. Spores are airborne. Clean up debris. Protect susceptible tissues with chlorothalonil, iprodione, mancozeb. Canker diseases (Coniothyrium fuckellii, Botryosphaeria dothidea, Cryptosporella umbrina) Brown cankers, sometimes with gray centers. Small, black, spore-producing fungal structures (pycnidia) develop in dead tissues. On dead plants and debris. Favored by wet weather. Spores are waterborne. Infection occurs mainly through wounds. Keep plants in vigorous condition. Prune diseased portions. When pruning, cut back to node. Crown gall* (Agrobacterium tumefaciens) Overgrowths or galls form on stem and roots. Infection occurs mainly through wounds. In soil. Bacteria spread in water. Gall development is favored by rapidly growing host. Avoid injuring base of plant and roots. Paint galls with Gallex to eradicate them. Use good sanitation in propagating areas. Downy mildew* (Peronospora sparsa) Purplish red to dark brown, irregular angular spots on leaves. Lower surface covered with sparse, downy fungal growth that may be hard to see. Leaves turn yellow and fall. Spores produced only on living plants. Resistant spores (oospores) carry fungus over unfavorable periods. Moist, humid conditions. Protect foliage with mancozeb, fosetyl-al, or mefenoxam. Powdery mildew* (Podosphaera pannosa var. rosae) White-to-gray powdery growth on leaves and other green parts, mainly on new growth. Leaves are distorted and discolored. On living plants and in infected buds. Favored by moderate temperatures (60° to 80°F) and high relative humidity at night (90 to 99%). Protect foliage with myclobutanil, neem oil, propiconazole, stylet oil, potassium bicarbonate, or sulfur. Eradicate infections with horticultural oils, neem oil, or jojoba oil. Rust* (Phragmidium disciflorum or P. speciosum, P. tuberculatum) Small orange pustules on undersides of leaves and other green parts. Leaves frequently are yellow. May cause defoliation. Cultivars differ widely in susceptibility. In fall, black teliospores form on leaves. On living leaves; rarely on stems. Favored by cool, moist weather, and condensed water on leaves. Spores are airborne. Avoid overhead irrigation. Protect foliage with myclobutanil, triadimefon, or mancozeb. Remove and destroy all leaves during winter months. Verticillium wilt* (Verticillium dahliae) Leaf fall is followed by dieback of one or more shoots. One-sided purpling of stems sometimes present. In soil for many years. May go undetected in budwood. Symptoms are most severe during warm weather following a cool period. Fumigate infested soil. Obtain disease-free plants. Manetti rootstock is resistant to most strains of the fungus. Continued on next page . . . Disease Control Outlines Rose (11/20) 94 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Rose, continued Virus or viruslike disease Symptoms Host range and natural spread Comments on control Mosaic (Prunus necrotic ringspot virus, Rose mosaic virus (=Apple mosaic virus), Arabis mosaic virus among others. Mixed infections common.) Symptoms vary with rose cultivar and virus. Symptoms range from general yellowing to conspicuous yellow blotches and intricate rings with line patterns. Plants may be somewhat stunted. Carried in living plants and spread by budding and grafting and by rooting cuttings from infected plants. No insect vectors known. Arabis mosaic virus can be transmitted by nematodes. Symptoms appear at moderate-to-low temperatures and are masked at high temperatures. Obtain virus-free plants. Heat treatment helps control the virus in rose stocks; 100°F temperatures for 4 weeks inactivates virus in 99% of cuttings taken from treated plants. Rose leaf curl (probably a virus) Downward curling of leaves and cane dieback. Leaves readily fall from new shoots, which are characteristically pointed with a broad base. Infected rose plants. Slow natural spread. Obtain healthy, symptomless plants. Destroy infected plants. Rose ring pattern (probably a virus) Symptomless or inconspicuous in some cultivars, especially floribunda types. Rosa multiflora 'Burr' is severely stunted with small, deformed leaflets that have a distinct mottling and wrinkling. Most hybrid teas show green mosaic and fine-line patterns in few or many leaves. Infected rose plants. No natural spread. Readily transmitted by grafting. Obtain virus-free plants. Virus is sensitive to thermal inactivation. (See Mosaic) Rose spring dwarf (probably a virus, RSDaV) Leaves that emerge in spring are balled or recurved on very short shoots and exhibit conspicuous vein clearing. Symptoms tend to disappear later in growing season. Infected rose plants. No natural spread. Obtain virus-free plants. Roses are also susceptible to crown canker (Cylindrocladium scoparium), gray mold* (Botrytis cinerea), hairy root (Agrobacterium rhizogenes), root lesion nematode** (Pratylenchus spp.), root knot nematode** (Meloidogyne spp.), and virus diseases: leaf curl (virus suspected), Rosette (virus suspected), and streak (virus suspected). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Rose (11/20) 95 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SHASTA DAISY Chrysanthemum maximum (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Plant disease-free plants. Fumigate soil with chloropicrin or a chloropicrin combination. Acremonium wilt (Acremonium strictum) Wilting, stunting, chlorosis and necrosis, often unilateral, of lower leaves. Vascular browning. Symptoms often develop with the onset of flowering. Soilborne fungus. Disease is intensified if plants are stressed by excessive soil moisture. Fungus has a wide host range, including many weeds. Cottony rot* (Sclerotinia sclerotiorum) Plants wilt and die. Basal stem rot. Cottony, white mycelium present in and on stems under moist conditions. Large black sclerotia form in and on stems. Fungus survives in soil as sclerotia that germinate after a Avoid planting in infested fields or fumigate soil. Carrots, celery, cold-dormancy period and produce airborne spores, which and lettuce are common hosts. Treat soil with PCNB before infect only dead or dying tissue. Direct infection from sclero- planting. Protect plants with thiophanate-methyl. tia may occur. Fungus has a wide host range. Optimum temperature for germination of fungus is 56° to 59°F and needs high soil moisture for at least 10 days. Fasciation (Rhodococcus fascians) Short, swollen clumps of distorted shoots that do not elongate at the base of plants. Vigor of plant is reduced. Secondary rotting of clumps may kill plant. Bacteria survive on infected plants and debris. Bacterium has a wide host range. Spreads in water. Plant disease-free plants. Avoid injuries to base of plant, especially when plant is wet. Control is difficult; plants may have to be discarded. Leaf spot* (Septoria leucanthemi) Brown, circular and irregular spots on leaves. Heavily infected leaves yellow and die. Minute black dots (pycnidia) are visible in the center of spots. Fungus survives on infected plants and debris. Spores are spread by splashing water. Pathogen needs condensed moisture to germinate and infect. Use disease-free plants. Rotate land for 2 years. Avoid overhead irrigation and cultural operations when foliage is wet. Protect plants in rainy weather with chlorothalonil or thiophanatemethyl. Pythium root rot* (Pythium spp.) Plants stunted as a result of reduced root system. Small roots rotted. Soilborne pathogen. Spores spread with soil and water. Favored by excess soil moisture and poor drainage. Avoid poorly drained soils. Plant on raised beds. Reduce amount of irrigation water. An oomycete (water mold) specific fungicide applied at transplanting will help get plants started. Root knot nematode** (Meloidogyne hapla) Plants are stunted. Swellings or galls on roots. Nematodes survive in soil as eggs. Disease is usually most severe in sandy soils and in warmer climates. Preplant fumigate soil with chloropicrin/chloropicrin combination or a nematicide or solarize soil. * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Shasta Daisy (11/20) 96 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SNAPDRAGON Antirrhinum majus (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Black root rot* (Thielaviopsis basicola) Roots are girdled by decay; tops slowly die. In less severe cases, elongated, black lesions occur on roots. Disease is particularly damaging to seedlings. Soilborne fungus; produces dark, resting spores. Spores are spread in water. Favored by cool, wet soils. In greenhouse, steam or chemically treat soil. Before planting, incorporate thiophanate-methyl into top 3 inches of soil. Cottony rot* (Sclerotinia sclerotiorum)* Infections girdle plant stems. Cottony fungal growth or large, black sclerotia develop inside stems. Dead stems take on a bleached, white color. As sclerotia in soil. Airborne spores produced by sclerotia, which infect dead or weak tissues. Sclerotia produce hyphae, which infect plant tissues. Favored by wet weather. In greenhouse, steam treat or fumigate soil. Treat soil with PCNB before planting. Protect plants with iprodione, or thiophanate-methyl. Mancozeb also helps control this fungus. Damping-off and stem rot* (Rhizoctonia spp., Pythium spp., Phytophthora spp.) Seedlings killed. Stems rot at soil line. If problem is caused by Pythium, it usually begins at root tips. Soilborne organisms. Favored by conditions unfavorable for plant growth. Steam treat or fumigate soil. Incorporate PCNB into top inch of soil before transplanting, or spray bases of plants with thiophanate-methyl or iprodione to control Rhizoctonia. Include an in preplant treatment or use later as a drench to protect against Pythium and Phytophthora spp. Downy mildew* (Peronospora antirrhini) Young tip leaves are dull green, severely stunted, and roll downward. Gray-purple fungus grows on undersides of leaves. Disease is common on seedling phase; large plants are less frequently attacked. Infected plants fail to produce flowers. Thick-walled resting spores (oospores) in dead plant parts. Airborne spores. Favored by cool (40° to 60°F), wet weather. In greenhouse, reduce humidity. Drench seedlings with mefenoxam or oomycete- or water mold- specific fungicide. Do not replant in fields where disease has been severe. Steam treat to kill resting spores. Protect foliage with mancozeb. Gray mold* (Botrytis cinerea) Brown, water-soaked decay of flowers, leaves, and stems. Fuzzy gray fungal spores form on rotted tissues. Frequently found on stems of cut flowers. In plant debris. Airborne spores. Favored by continued cool, moist conditions. Reduce humidity in greenhouse. Clean up all plant debris. Protect foliage with iprodione or fenhexamid. Mancozeb also helps control gray mold. Powdery mildew* (Golovinomyces orontii) White, powdery fungus grows on both leaf surfaces. Severely infected leaves may be killed. On living leaves. Airborne spores; not in soil or on seeds. Favored by moist, shaded conditions, and dry foliage. Protect foliage with triadimefon or sulfur. Rust* (Puccinia antirrhini) Pustules of dark brown to purple powdery spores develop on leaves and stems. Rapid water loss from severely rusted leaves causes them to dry up. On living snapdragon plants and spores on seed. Does not survive in soil, but does in plant refuse. Airborne spores. Favored by abundant dew, cool nights (50° to 55°F), and warm days (70° to 75°F). In greenhouse, avoid wetting foliage and prevent moisture condensation at night by balancing heat and ventilation. Protect foliage with myclobutanil or triadimefon. Mancozeb also helps protect foliage from infection. Remove and destroy infected plants. Verticillium wilt* (Verticillium dahliae) Plants wilt, frequently on one side. Wilting is more pronounced near time of bloom. Problem is most important in seed fields. In soil for many years. Favored by cool weather. Plants wilt during hot weather. Steam treat or fumigate soil with a chloropicrin or a chloropicrin combination or solarize soil. Water mold root rots (Pythium spp. and Phytophthora spp.*) Plants are stunted, wilt, or suddenly collapse. Roots decay. Plants fail to "push" after flowers are cut. Remaining stubs are more susceptible to gray mold. Soilborne pathogen. Favored by heavy, waterlogged soils. Avoid planting on poorly drained soils. Do not overirrigate. Steam treat or fumigate greenhouse soil. Drench plants with oomycete (water mold) specific fungicide. Snapdragons are also susceptible to collar rot (Rhizoctonia solani), crown gall* (Agrobacterium tumefaciens), leaf and stem spot (Phyllosticta antirrhini), mosaic* (Cucumber mosaic virus), root knot nematode** (Meloidogyne spp.), and stem rot (Phyllosticta antirrhini). Anthracnose (Colletotrichum antirrhini) is important elsewhere but is not found in California. * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Snapdragon (11/20) 97 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES STATICE Limonium spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Anthracnose (Colletotrichum gloeosporioides) Plants wilt and become mildly chlorotic. Crown tissues decay and plant may die. In initial stages, roots are not affected. The fungus also causes leaf, stem, and flower spots, but this phase of the disease is not common in California. Gold Coast cultivar is highly susceptible; blue and white cultivars are more tolerant. The fungus survives on infected plants and debris. The disease is favored by wet weather and overhead irrigation. Spores are spread by splashing water. Avoid overhead irrigation. Protect plants with chlorothalonil or copper. Chlorothalonil may cause blackening of flowers. Cercospora leaf spot (Cercospora insulana) Small, dull red lesions that enlarge up to 0.67 inch (15 mm) and become tan and membranous in the center with reddish borders. Spores are airborne. Disease is favored by warm, moist conditions and condensed water on foliage. Avoid overhead irrigation. Protect foliage with chlorothalonil. Downy mildew* (Peronospora statices) Bluish gray sporulation occurs on undersides of leaves. On upper surface of leaves, infections appear as light green areas that turn yellow, then coalesce, and eventually the leaf dies. In California it is currently found on cultivars in the "Misty" series; in Europe it occurs on many Limonium species. Unlike powdery mildew fungi, this fungus requires very wet conditions to flourish. Favored by cool temperature. High relative humidity (90% or greater) and free moisture required for spores to germinate and infect plants. Spores require a minimum of 8 hours of wetness before infection occurs. In greenhouse, provide good air circulation and keep relative humidity below 85%. Avoid wetting foliage, using drip instead of overhead irrigation if possible. Remove infected plants immediately. Protect foliage with fungicides if necessary. Gray mold* (Botrytis cinerea) Rot of leaves, stems, and flowers. Rot may enter crowns and kill plants. Fuzzy gray fungus sporulation develops on decayed tissues. Flower stubs remaining after flower harvest are particularly susceptible. The fungus also may kill seedlings. Fungus has a wide host range and develops on dead plant parts. Spores are airborne. The disease is prevalent in California in cool (below 77°F) rainy weather. Clean up plant debris. Incorporate crop residue into soil as soon after harvest as feasible. Avoid overhead irrigation especially when flowers are present. Protect plants with iprodione or fenhexamid. Verticillium wilt* (Verticillium dahliae) Plants are stunted. Lower leaves yellow, wilt, and dry. The fungus, which has a wide host range, survives in soil as microsclerotia. Fumigate soil with chloropicrin or a chloropicrin combination. Heat, fumigate, or solarize soil used in production of transplants. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Aster yellows* (Phytoplasma) Stunted growth, multiple production of short stalks, malformation and bunching of young leaves. Leaves on more mature plants are reddened in the basal rosette. Flowers are abnormal: reduced size, abnormal shape and color (frequently green), and may fail to open. Phytoplasma is transmitted by leafhoppers. Control insects. Destroy infected plants. Turnip mosaic* (Turnip mosaic virus) Plants are stunted and have a mosaic pattern of light and dark green in leaves. Plants infected when young often die. Leaves may be distorted. Virus is transmitted by several different aphids and is common in many weedy plants in the mustard family (Cruciferae). Control nearby cruciferous weeds. Control aphids. Statice is also susceptible to powdery mildew* (Erysiphe polygoni), rust* (Uromyces spp.), bacterial crown rot (Pseudomonas spp.), southern blight* (Sclerotium rolfsii), Broad bean wilt virus, Cucumber mosaic virus, Statice virus Y, Tobacco rattle virus, Tomato bushy stunt virus, and root knot nematode** (Meloidogyne spp.). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. Disease Control Outlines Statice (11/20) 98 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES STOCK Matthiola spp. (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial blight* (Xanthomonas campestris pv. incanae) Basal leaves turn yellow and drop. Leaf scar is blackened. Soft, water-soaked stem cankers later become dark and sunken. Plant stems may break and fall over because they are weakened by the cankers. Black discoloration of the vascular system occurs. Seedborne and in plant debris; also in soil for 2 years. Favored by cool, wet weather. Bacteria are spread by water. When buying seed, specify that it be grown from seed treated in hot water (122° to 131°F for 10 minutes). Follow a 3-year crop rotation. Avoid splashing water. Cottony rot* (Sclerotinia sclerotiorum) Girdling infections that cause stems to turn chalky white. Cottony, white masses of fungus or large, black sclerotia develop on and in stems. Black sclerotia may develop in seed pods in the shape of stock seed. As sclerotia in soil. Airborne spores produced by sclerotia only infect weak or dying tissue. Sclerotia also produce hyphae that infect plant. Favored by cool, moist conditions. Avoid fields where disease has occurred (common disease of many vegetable crops). Apply PCNB to soil before planting. Spray foliage with thiophanate-methyl combined with mancozeb. Foot rot or wire stem* (Rhizoctonia solani) Brown rot of stem occurs at the soil line; area later becomes a dry, sunken canker. Stems are girdled. Brown fungus strands are visible with a hand lens. Also causes damping-off of seedlings. Soilborne fungus. Favored by warm, moderately moist soil. Use PCNB on soil before planting. Spray iprodione or thiophanate-methyl over the row and bases of plants. Fusarium wilt* (Fusarium oxysporum f. sp. mathioli) (important in seed fields) Lower leaf veins turn yellow, then entire leaf becomes yellow, withers, and drops. Basal leaves are affected first. Plants are stunted. Seed pods turn a light-tan color. Brown vascular discoloration occurs. Soilborne for many years; also seedborne. A warm-weather disease; rarely a problem in the winter grown cut-flower crop. No control necessary for the cut-flower crop grown in cool, coastal areas. Fumigate soil with a chloropicrin or a chloropicrin combination (tarped). Gray mold* (Botrytis cinerea) A soft, brown decay that occurs on flowers or entire flower heads. Fuzzy gray fungus spores form on decayed tissues. Decay may also start on dead leaves and rot the growing points and flower buds. In plant debris. Favored by cool, moist conditions and condensed moisture on plants. Spores (conidia) are airborne. Protect flowers with thiophanate-methyl in combination with mancozeb or treat with iprodione. Avoid overhead irrigation. Leaf spot* (Alternaria raphani) Round to elongate, concentric, brown spots covered with black, powdery spores. Spots are small at first, then turn gray-green with water-soaked margins. On growing stock, cruciferous plants, and crop refuse. Favored by wet weather. Spores are airborne. Also found on other cruciferous crops. Destroy all plant refuse by plowing under plants as soon as flowers are harvested. Spray with a copper fungicide or mancozeb during wet weather. Avoid overhead irrigation. Verticillium wilt* (Verticillium dahliae) Foliage yellows and wilts. Leaves die and dry progressively upward from the base of the plant. Dark discoloration may occur in the vascular system. Soilborne as microsclerotia for many years. Symptoms most severe when weather turns warm after a cool period. Host range of this form of Verticillium is different from that of the common Verticillium. Avoid fields where disease has occurred or fumigate soil with a chloropicrin or chloropicrin combination (tarped). This combination also controls most weeds, nematodes, soil insects, and other fungi and bacteria. Water mold root rots Phytophthora spp.* and Pythium spp.*) Plants wilt easily or suddenly collapse. Roots and crown become decayed. Also causes damping-off of seedlings. Soilborne pathogens. Associated with poorly drained, waterlogged soils. Spores are spread in water. Provide drainage and avoid excessive irrigation. Plant on raised beds. Seed treatments help to control the damping-off phase. An oomycete (water mold) specific fungicide may also be effective. Continued on next page . . . Disease Control Outlines Stock (11/20) 99 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Stock, continued Virus or viruslike disease Symptoms Host range and natural spread Comments on control Mosaic (several viruses, including Impatiens necrotic spot virus and Turnip mosaic virus) Leaf mottling and flower breaking occur. Leaf symptoms vary with different viruses. White and yellow varieties do not show flower breaking. In cruciferous weeds (mustard, wild radish, shepherd'spurse, etc.). Spread by aphids. Not seedborne. Symptoms favored by cool weather. Destroy nearby weeds. Avoid fields near uncontrolled weedy areas. Plow under stock as soon as the crop is cut. Control aphids. Stock is also susceptible to downy mildew* (Peronospora parasitica). * For additional information, see section on Key Diseases. Disease Control Outlines Stock (11/20) 100 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES STRAWFLOWER Helichrysum bracteatum (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Downy mildew* (Plasmopara halstedii and Bremia lactucae) Two distinct downy mildews infect strawflower, though symptoms are similar for both diseases: yellow foliage with downy white sporulation on the undersurface. Leaves roll downward. Tissues sometimes are killed Disease is favored by cool (59°F), wet weather. Spores (sporangia) are airborne. Chilean tarweed (Madia sativa) and other members of the family Compositae are hosts of P. halstedii. Control tarweed for some distance away if possible. Protective fungicides should be effective but few if any are labeled for strawflower. Verticillium wilt* (Verticillium dahliae) Wilting and yellowing of lower leaves on one side of plant. Vascular discoloration. Favored by cool spring. Symptoms develop rapidly in hot weather at flowering. Fungus survives in soil for long periods as microsclerotia. Many plants are infected including weeds, crop plants, and ornamentals. Avoid fields that are known to be infested. Soil fumigation with chloropicrin or a chloropicrin combination is effective. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Aster yellows* (Aster yellows phytoplasma) Plants stunted and yellow. Frequently one-sided. Flowers may be green. Aster yellows phytoplasma is spread by leafhoppers. A wide variety of plants including weeds are susceptible. Control weeds in and around planting. Leafhopper control may help. * For additional information, see section on Key Diseases. Disease Control Outlines Strawflower (11/20) 101 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SWEET PEA Lathyrus odoratus (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Black root rot* (Thielaviopsis basicola) Poor top growth. Black lesions on roots and root rot. Seedlings may be killed. Fungus is soilborne. Favored by cool, wet soils and any condition that weakens the plant. Avoid fields previously planted in legumes. Avoid overirrigation and overfertilization. Plant on raised beds. Powdery mildew* (Erysiphe trifolii) White powdery growth on surface of leaves and stems. Older infected leaves yellow and wither. Growth of heavily infected plants is diminished. Favored by moderate temperatures. Spores (conidia) are produced in great abundance and they are airborne. Moisture is not necessary for germination and infection and is detrimental to the fungus. Several powdery mildew fungicides are effective if applied in a regular preventative program commencing with the first signs of the fungus. Check product label for registration. Ramularia leaf spot (Ramularia deusta) Large, irregular or circular tan spots without definite margins. Lower leaves are first affected. Infected leaves often drop. Fungus is specific to sweet pea and survives in sweet pea refuse. Favored by wet conditions. Rotate with other crops for 2 years. A fungicide may be necessary in some severe cases. Avoid overhead irrigation. Seed decay (Pythium spp. and other fungi) Seeds rot in soil. Seedlings do not emerge. Favored by wet soil and poor aeration. Provide better drainage. Grow on raised beds. Virus or viruslike disease Symptoms Host range and natural spread Comments on control Enation mosaic (Pea enation mosaic virus) Leaves contain scattered translucent areas ("windows"). Foliage may be crumbled and stunted. There may be "windows" in the flowers. Virus is spread by aphids. Host plants include many legumes. Control nearby weeds, especially legumes. Control aphids. Mosaic (Pea mosaic virus) Mottling and chlorosis of the foliage. Dark green areas interspersed with yellow-green portions of leaves. Flowers have "broken" colors. Virus is spread by aphids. Host plants include many legumes. Control nearby weeds, especially legumes. Control aphids. Spotted wilt (Tomato spotted wilt virus) Reddish brown streaks on stems. Leaves with circular spots that are yellow at first and later turn brown. Plant may die. Spread by thrips. Virus has a wide host range, including many weeds. Juvenile thrips (nymphs) acquire the virus and transmit it as adults. Control nearby weeds including grasses. Control thrips. Sweet peas are also susceptible to Ascochyta blight (Ascochyta lathyri), bacterial streak (Pantoea agglomerans, formerly Erwinia herbicola), fasciation (Rhodococcus fascians), Pythium root rot* (Pythium spp.), cottony rot* (Sclerotinia sclerotiorum), downy mildew* (Peronospora trifoliorum), and damping-off* (Rhizoctonia solani, Fusarium spp., and Pythium spp.) * For additional information, see section on Key Diseases. Disease Control Outlines Sweet Pea (11/20) 102 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SWEET WILLIAM Dianthus barbatus (11/20) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Fusarium wilt* (Fusarium oxysporum f. sp. dianthi) Yellowing of new growth. Plants stunted and leaves point downward instead of upward as in a healthy plant. Leaves gradually turn yellow and die. The vascular system of the lower stem and roots is brown. Fungus survives in soil for many years as chlamydospores. Disease is favored by warm soils and high temperatures. Fumigate soil with chloropicrin or a chloropicrin combination. Grow seedlings in heat-treated, solarized, or fumigated soil or growing medium. Leaf spot (Cladosporium echinulatum) Yellowish brown, withered spots surrounded by a purplish margin on leaves. As the disease progresses, entire leaves and stems become necrotic. Spores (conidia) are airborne. Fungus survives on sweet william debris. Favored by wet weather and overhead irrigation. Avoid overhead irrigation. Protect foliage with a fungicide. Sweet williams are also susceptible to rust* (Uromyces caryophyllinus and Puccinia arenariae), root rot* (Pythium ultimum), gray mold* (Botrytis cinerea), stem rot (Rhizoctonia solani), southern blight* (Sclerotium rolfsii), Septoria leafspot (Septoria dianthi), anther smut (Microbotryum violaceum, formerly Ustilago violacea), curly top (Beet curly top virus), and aster yellows* (aster yellows phytoplasma). * For additional information, see section on Key Diseases. Disease Control Outlines Sweet William (11/20) 103 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Host-Pathogen Index (11/20) The host-pathogen index is a list of ornamental hosts not covered in the Disease Control Outlines and some of the pathogens that attack these hosts. Diseases covered in Key Diseases are noted with an asterisk. African Violet (Saintpaulia ionantha) Bacterial blight Foliar nematode** Gray mold* Phytophthora crown rot* Powdery mildew* Pythium root rot* Rhizoctonia stem rot Ring spot Christmas cactus (Schlumbergera bridgesii) Crown rot* Fusarium rot* Gray mold* Root and stem rot Root rot* Stem rot Stem rot and leaf spot Virus Candytuft (Iberis amara) Alternaria leaf spot* Dickeya (=Erwinia) chrysanthemi Aphelenchoides ritzemabosi Botrytis cinerea Phytophthora parasitica Odium spp. Pythium spp. Rhizoctonia solani physiological (cold water and light) Phytophthora parasitica Pythium aphanidermatum Fusarium oxysporum Botrytis cinerea Rhizoctonia solani Pythium irregulare Phytophthora spp. Bipolaris cactivora Cactus virus X Alternaria brassicae Basal stem rot Phoma lingam Club root Plasmodiophora brassicae Downy mildew* Gray mold* Phytophthora root rot* Powdery mildew* Pythium root rot* Root knot nematode** White rust Peronospora parasitica Botrytis cinerea Phytophthora spp. Erysiphe cruciferarum Pythium spp. Meloidogyne sp. Albugo candida Cineraria (Senecio cruentus) Collar rot Downy mildew* Gray mold* Impatiens necrotic spot Leaf spot* Powdery mildew* Root and collar rot* Root rot* Spotted wilt Stem rot* * For additional information, see section on Key Diseases. * * For additional information, see section on Nematodes. Rhizoctonia solani Plasmopara halstedii Botrytis cinerea Impatiens necrotic spot virus Alternaria cinerariae Erysiphe cichoracearum Sphaerotheca fuliginea Phytophthora spp. Pythium ultimum Tomato spotted wilt virus Sclerotinia sclerotiorum Host Pathogen Index (11/20) 104 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Gardenia (Gardenia jasminioides) Bacterial leaf spot Chlorosis Petal blight (gray mold)* Phomopsis canker Root knot nematode** Gerbera (Gerbera jamesonii) Bacterial leaf spot* Black root rot* Crown and root rot Gray mold* Leaf spots Phytophthora crown rot* Powdery mildew* Pythium root rot* Sclerotinia crown rot Spotted wilt Verticillium wilt* White rust*** German violet (Exacum affine) Basal stem rot Gray mold* Root rot* Spotted wilt Gloxinia (Sinningia speciosa) Cottony rot and flower blight* Crown rot Crown rot and tuber rot Gray mold* Ring spot Root and crown rot* Root rot* Southern blight* Spotted wilt Hydrangea (Hydrangea macrophylla) Gray mold* Powdery mildew* Rhizoctonia stem rot Ringspot Root knot nematode** Root rot* Virescens * ** ** * Xanthomonas campestris pv. maculifoliigardeniae iron deficiency Botrytis cinerea Phomopsis gardeniae Meloidogyne spp. Pseudomonas cichorii Thielaviopsis basicola Rhizoctonia solani Botrytis cinerea Alternaria porri Cercospora gerberae Septoria spp. Ascochyta gerberae Phytophthora cryptogea and others Golovinomyces cichoracearum Pythium spp. Sclerotinia sclerotiorum Tomato spotted wilt virus Verticillium dahliae Albugo tragoponis Nectria hematocca Botrytis cinerea Pythium ultimum Tomato spotted wilt virus Sclerotinia sclerotiorum Myrothecium roridum Rhizoctonia solani Botrytis cinerea physiological (cold water and light) Phytophthora cryptogea P. nicotiana Pythium spp. Sclerotium rolfsii Tomato spotted wilt virus Botrytis cinerea Golovinomyces orontii Rhizoctonia solani Hydrangea ringspot virus Meloidogyne spp. Pythium spp. Phytoplasma For additional information, see section on Key Diseases. For additional information, see section on Nematodes. Not reported in U.S.A. Host Pathogen Index (11/20) 105 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Impatiens (Impatiens walleriana) Bacterial fasciation Bacterial leaf spot* Black root rot* Brown crown canker Crown rot* Downy Mildew* Gray mold* Impatiens necrotic spot Leaf spot Root rot* Southern blight* Spotted wilt Verticillium wilt* Rhodococcus fascians Pseudomonas syringae Thielaviopsis basicola Rhizoctonia solani Pythium ultimum Rhizoctonia solani Plasmopara obducens Botrytis cinerea Impatiens necrotic spot virus Phyllosticta sp. Pythium sp. Sclerotium rolfsii Tomato spotted wilt virus Verticillium dahliae Kalanchoe (Kalanchoe blossfeldiana) Aster yellows* Edema Fasciation Impatiens necrotic spot Kalanchoe mosaic Leaf and stem blight Leaf spots Powdery mildew* Root and crown rot* Spotted wilt Stem rot Aster yellows phytoplasma Physiological; cause unknown Cercospora sp. Impatiens necrotic spot virus Kalanchoe mosaic virus Botrytis cinerea* Stemphylium spp. Sphaerotheca fuliginea Phytophthora spp. Tomato spotted wilt virus Myrothecium roridum Lilac (Syringa vulgaris and S. persica) Armillaria root rot* Bacterial blight** Crown gall* Gray mold* Leaf blotch Phytophthora blight Phytophthora root rot** Powdery mildew* Shoot blight* Armillaria mellea Pseudomonas syringae pv. syringae Agrobacterium tumefaciens Botrytis cinerea Heterosporium syringae Phytophthora spp. Phytophthora spp. Microsphaera penicillata Sclerotinia sclerotiorum Lilies (Lilium spp.) Cottony rot and petal blight* Foliar nematode* Gray mold* Leaf spots* Root knot nematode Rust* Scale rots Lisianthus (Eustoma grandiflora) Foliar nematode** Gray mold* Leaf spot* Powdery mildew* Root knot nematode** Root and stem rot Sclerotinia sclerotiorum Aphelenchoides spp. Botrytis spp. Cercospora, Heterosporium, and Ramularia spp. Meloidogyne spp. Uromyces spp. Colletotrichum spp. Aphelenchoides spp. Botrytis cinerea Cercospora eustomae Leveillula taurica Meloidogyne spp. Fusarium avenaceum, Phytophthora, Pythium, and Rhizoctonia spp. Host Pathogen Index (11/20) 106 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Viruses Tomato spotted wilt virus, Impatiens necrotic spot virus Pouch Flower (Calceolaria x herbeohybrida) Cottony rot* Gray mold* Root and crown rot* Root rot* Spotted wilt Stem rot Verticillium wilt* Sclerotinia sclerotiorum Botrytis cinerea Phytophthora spp. Pythium spp. Tomato spotted wilt virus Myrothecium sp. Verticillium dahliae Primula (Primula x polyantha) Crown rot Fasciation Gray mold* Leaf spot Root rot* Spotted wilt Rhizoctonia solani Physiological; cause unknown Botrytis cinerea Ramularia primulae Pythium spp. Tomato spotted wilt virus Protea (Protea, Banksia, Leucospermum, and other spp.) Canker Botryosphaeria spp. Gray mold* Botrytis cinerea Leaf spots Colletotrichum spp., Mycosphaerella spp. Root and crown rot* Phytophthora spp., Rhizoctonia solani Root knot nematode* Meloidogyne spp. Verticillium wilt* Verticillium dahliae Queen Anne’s Lace (Daucus carota) Aster yellows Bacterial blight* Black root rot Early blight* Leaf blight* Powdery mildew* Root and stem rot Root, crown, and stem rots* Southern blight* Tuber rot Viruses Ranunculus (Ranunculus spp.) Aster yellows* Bacterial blight* Cottony rot* Downy mildew* Gray mold* Leaf spots* Powdery mildew* Root rots* Rust Smut Southern blight* Viruses Aster yellows phytoplasma Xanthomonas campestris pv. carotae Alternaria radicina Cercospora carotae Alternaria dauci Erysiphe heraclei Fusarium spp. Phytophthora, Pythium, and Rhizoctonia spp. Sclerotium rolfsii Rhizopus spp. Celery mosaic virus, Carrot motley dwarf virus Aster yellows phytoplasma Xanthomonas campestris pv. carotae Sclerotinia sclerotiorum Peronospora spp. Botrytis cinerea Ramularia spp. Erysiphe polygoni Pythium spp., Rhizoctonia solani Puccinia spp. Entyloma spp. Sclerotium rolfsii Tomato spotted wilt virus, Ranunculus mosaic virus Host Pathogen Index (11/20) 107 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Stephanotis (Stephanotis floribunda) Crown rot Gray mold* Powdery mildew* Stem dieback Virus Sunflower (Helianthus sp.) Aster yellows* Charcoal rot Cottony rot* Downy mildew* Gray mold* Head rot Leaf spots* Powdery mildew* Root and stem rot* Rust* Smut Southern wilt* Rhizoctonia solani Botrytis cinerea Oidium sp. Glomerella cingulata Impatiens necrotic spot virus, Tomato spotted wilt virus Aster yellows phytoplasma Macrophomina phaseolina Sclerotinia sclerotiorum Plasmopara halstedii Botrytis cinerea Rhizopus oryzae Alternaria, Cercospora, and Septoria spp. Golovinomyces cichoracearum Phytophthora sp. Coleosporium, Puccinia, and Uromyces spp. Entyloma calendulae Sclerotium rolfsii * For additional information see section on Key Diseases. Host Pathogen Index (11/20) 108 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Insects, Mites, and Other Invertebrates (Section reviewed 3/09) General Information COMMON SIGNS AND SYMPTOMS ON PLANTS DAMAGED BY PEST INSECTS, MITES, SLUGS, AND SNAILS (ARTHROPODS) AND THE PROBABLE CAUSES (3/21) Symptoms arthropod by-products bleached, bronzed, stippled, or yellowed foliage chewed or tattered blossoms or foliage Insects and Mites Causes • cast skins (translucent or whitish): aphids, leafhoppers, lace bugs, spider mites • dark fecal specks: lace bugs, leafminer adults, plant bugs, shore fly adults, thrips • flocculence (cottony, waxy material): adelgids, certain aphids, lerp psyllids, mealybugs, certain scale insects, whiteflies • large excrement (frass) particles: caterpillars, leaf beetles • pale foam or spittle: spittlebugs • pitch masses: larvae of certain moths e.g., Sequoia pitch moth • pitch tubes: certain bark beetles (Scolytinae) • shiny trails or slime: fungus gnat larvae, slugs, snails • silken mats, tents, or webs or rolled leaves: leafrollers, tent caterpillars, webworms • sticky honeydew and blackish sooty mold: aphids, mealybugs, psyllids, soft scales, whiteflies • eriophyid mites e.g., blister, bud, erineum, gall, or rust mites • lace bugs • leafhoppers • plant bugs • spider mites • thrips • adults and larvae of leaf-feeding beetles • crickets, grasshoppers, or katydids • larvae (caterpillars) of butterflies and moths (Lepidoptera) e.g., armyworms, cabbage looper, cutworms, diamondback moth, European pepper moth (Dufo moth) • larvae of sawflies (broad-waisted wasps) e.g., rose slugs Common Signs and Symptoms on Plants Damaged by Pest Insects, Mites, Slugs, and snails (Arthropods) and the Probable Causes (3/21) 109 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Symptoms dieback of plant parts distortion of plant parts foliage mines holes in stems, bark or twigs Causes • leafcutting bees, which are important pollinators and should not be killed. Where these bees have been collecting material for their nests covering those plants with cheesecloth or other screening prevents further damage. Place out these barriers when leaf cutting is first observed or the time of year (late winter or spring) when damage first occurred during previous seasons. Barriers can be removed about midsummer when the mother bees are no longer active. • snails or slugs e.g., brown garden snail • armored scales • gall wasps • katydids • larvae of boring beetles or moths • sharpshooters (large leafhoppers) • weevils • aphids • eriophyid or tarsonemid mites e.g., broad, cyclamen, blister, bud, erineum, gall, or rust mites • gall wasps • larvae of certain moths • lygus bugs or stink bugs • other true bugs (Heteroptera) • psyllids • thrips • larvae of certain flies, moths, or sawflies (broad-waisted wasps) • adult beetles e.g., bark beetles, flatheaded borers, longhorned beetles • larvae of boring beetles or caterpillars (e.g., clearwing moths) feeding hidden in plants Adapted from Container Nursery Production and Business Management Manual, UC ANR Publ. 3540 Insects and Mites Common Signs and Symptoms on Plants Damaged by Pest Insects, Mites, Slugs, and snails (Arthropods) and the Probable Causes (3/21) 110 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MONITORING WITH STICKY TRAPS (3/21) Trapping can be an efficient and informative monitoring tool. Traps can alert growers to pests early before crop damage occurs and before pests become abundant and more difficult to control. Yellow sticky traps Yellow cards (commonly 3 × 5 inches or larger) covered on both sides with sticky material attract and capture the adults of various flying insects. Yellow sticky traps can indicate localized spots of high pest abundance or periods of migration of adult pests into crops and the predominant direction from which they are arriving (e.g., from an adjacent field of drying weeds). Traps can also provide a relative measure of insect abundance; comparisons of the number of adults caught among sample dates can indicate whether pest density is decreasing, increasing, or remaining about the same over time. Pests captured by yellow sticky traps include adults of fungus gnats, thrips, and whiteflies, aphids, psyllids, and sharpshooters. Others presented side-by-side for comparison in Sticky Trap Monitoring of Insect Pests include leafminers, shore flies, and adults of certain parasites and predators. Blue sticky traps are sometimes used for thrips because this color is more attractive to thrips. However insects are more difficult to discern and count in blue traps. Yellow sticky traps attract a wider variety of pest insects and are recommended for most situations. Sticky traps may not be a good tool for deciding treatment need, whether any action thresholds are exceeded (see ESTABLISHING ACTION THRESHOLDS), and they are generally not effective for direct control. Immature stages feeding on crops commonly cause the most damage; sticky traps typically capture only airborne adults, which in many species do not feed on plants. Adult trapping sometimes is not a reliable indicator of pest presence or abundance on the crop. Many of the trapped adults may be migrating species that don't feed on the crops being grown. Adults often cannot readily be discriminated to species; for example, the adults can obviously be aphids but whether they are aphid species that infest the crops present may not be discernable from specimens stuck in sticky material. Always use traps in combination with visual inspection of plants for the presence of damage and pest feeding stages. Unless other guidelines are recommended use at least one sticky trap per 10,000 sq. ft. of growing area. When monitoring whiteflies, use about one trap per 1,000 sq. ft. of growing area with crops susceptible to infestation. Actual trap density will be dictated by the growing area and the time and effort devoted to trapping. But each pest management unit should have at least one, well-maintained, yellow sticky trap. In addition, put one trap inside growing areas by doors and vents to detect pests migrating in. Also put at least one trap in each crop that is very susceptible to damage by pests and do not locate the most pest-susceptible crops near doors. Use bright yellow traps, each 3 × 5 inches or larger and covered with sticky material. Orienting traps horizontally (facing the soil or upwards) is sometimes recommended when monitoring pests such as fungus gnats and shore flies that emerge from or rest upon growing media. However, to catch a wider range of targeted insects, orient the longest part of the trap vertically (up and down). Place each trap so that its bottom is even with the top of the plant canopy. For rapidly growing crops, locate trap bottoms a few inches above the canopy so that the plants do not soon overgrow the traps. As plants grow, move each trap up so that its bottom remains about even with the top of the canopy or somewhat higher. For example use one or two clothespins to attach each trap to a bamboo post or wooden dowel embedded in the growing media or a stand. Alternatively hang traps from rafters or wires strung between posts. Number each trap and map its location in your growing area. Inspect each trap at least once or twice weekly. It is easiest to replace traps each time you inspect them. Wrap traps in clear plastic film and take them to a more comfortable location for counting. Alternatively replace traps when they become too fouled to effectively capture insects or count them quickly. If traps are reused, note this because catches become cumulative; you must subtract the number of insects present the last time that particular trap was checked, or sum and average the counts from all traps in a specific growing area then subtract the previous average from that currently. Count and record the number of each type of pest caught. When abundant it is not necessary to count all insects on the entire trap; counting the insects in a vertical column 1 inch wide on both sides of the trap, Insects and Mites Monitoring with Sticky Traps (3/21) 111 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES then multiplying the results by the trap width in inches, gives results that are representative of the entire trap. Do not reduce traps to 1 inch vertical strips because smaller traps will be less attractive to insects. Waterless hand cleaner can be useful for removing the sticky material from hands. Because many insects in traps may be beneficial or harmless, carefully identify insects before taking management actions. High-quality color photographs and line drawings of commonly trapped insects are available in Sticky Trap Monitoring of Insect Pests. You can also wrap used traps in clear plastic and take those containing unknown insects to offices of the UC ANR Cooperative Extension or county agricultural commissioner for help in identification. Interpreting Information from Yellow Sticky Traps Regularly summarize trap data to facilitate comparison. For example, graph the average numbers of each pest in all traps from a particular growing area on each sample date. This allows visual recognition of trends in pest abundance and facilitates comparison to stages of crop growth and when particular management actions were taken. Interpreting trap information requires knowledge, skill, and practice. Traps catch both migrating insects as well as adults that emerged from the crop. Canopy density, plant foliage quality, and temperature influence adults' tendency to fly. Wind and ventilation fans can discourage flight, reducing trap catches. The number of adults trapped may temporarily drop after a pesticide application even if there has been relatively little change in immature abundance on plants. Conversely, adult numbers of some species may temporarily increase in traps after applying an adulticide, so the numbers caught for several days after an application might not be best when comparing adult densities among sample dates. Foliage disturbances, such as sprinkling with water (overhead irrigation) or shaking plants to promote pollination or monitor adults (e.g., of whiteflies), increase trap catches. Even large numbers of pest species in traps do not necessarily indicate that control action is needed. Always use traps in combination with plant inspection to determine whether economically damaging numbers of pests and stages susceptible to control actions are present. For more information, see ESTABLISHING ACTION THRESHOLDS. Sticky Tape Traps Crawlers, the mobile first instars of certain Sternorrhyncha (formerly Homoptera), are the life stage most susceptible to many pesticides. Traps made of double-sided clear sticky tape (available at stationery stores) are an efficient method of monitoring crawlers of armored scales, foliar-feeding mealybugs, soft scale insects, and certain other arthropods. On each of several plants infested with adult females, snugly wrap a stem with tape. Double over the loose end of the tape several times so you can pull the end to easily unwind it. Place a tag or flag near each tape so you can readily find each tape trap. Change the tapes at regular intervals, about weekly. After removing the old tape, wrap the stem at the same location with fresh tape. Preserve the old sticky tapes by sandwiching each tape unrolled between a sheet of pale-colored or white paper and a sheet of clear plastic. Label the tapes with the collection date, location, and host plant. Crawlers get stuck on the tapes and appear as yellow or orange specks. Examine the tapes with a hand lens to distinguish the crawlers (which are round or oblong, have very short appendages, and may have two dark eye spots) from contaminants such as dust, pollen, and spider mites. A contact insecticide and certain other pesticide types can be applied when crawlers are abundant. If a single application is planned, visually compare the tapes collected on each sample date. The best time for a single spray is after a sharp increase in crawlers in traps or soon after crawler numbers have peaked and begun to decline. Insects and Mites Monitoring with Sticky Traps (3/21) 112 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ESTABLISHING ACTION THRESHOLDS (3/21) The presence of a few pest insects or mites and some amount of arthropod damage commonly is unavoidable and can be tolerated. The number of pests or level of damage beyond which management action should be taken is known as the action threshold, a fundamental concept in integrated pest management. When management action should be taken (when a threshold is exceeded) is determined by the total cost of the action (including monitoring), the value of the crop, and the impact on the environment. Few thresholds have been established for flower and nursery crops, in part because of the lack of research in comparison with the large number of crop plants, pests, and growing situations. Specific thresholds or management action guidelines may be developed over the long term by growers who regularly monitor crops, keep good records, and evaluate and summarize outcomes for comparison over time. Consult the chapters "Integrated Pest Management" and "Insects, Mites, and Other Pests" in the Container Nursery Production and Business Management Manual and also Integrated Pest Management for Floriculture and Nurseries for more discussion and illustration of these techniques. Why Use Thresholds Pesticides sometimes are applied on a calendar schedule, when pest presence is only suspected, or when pest numbers are already high and difficult to control. Using thresholds can maintain or improve crop quality while reducing the cost and frequency of control measures. Less frequent applications help maintain pesticide efficacy by reducing the development of pesticide resistance. Fewer applications reduce the disruptions to cultural practices that occur during applications and the subsequent restricted entry interval (REI). In addition, fewer applications may improve plant growth and quality by minimizing phytotoxicity and increase profit by reducing costs of pesticide purchases, application labor, and regulatory compliance. When to Take Management Action Because crops are grown for profit, action thresholds are based largely on economics. Management action is warranted when the increased revenue expected from improved crop quality or yield will exceed the cost and adverse impacts (such as phytotoxicity, harvest disruption) of the action. The amount of pest damage or presence that can be economically tolerated is determined by many factors, including the type of pest and damage, crop species and cultivar, stage of plant development, time until harvest or sale, and market conditions. Tolerance to pests can be higher if infested plant parts are not marketed, such as older leaves on seed crops or cut flowers. Thresholds can often be higher if highly effective or quick-acting methods are available for controlling the problem. Conversely, if available controls are slow-acting or only partially effective, or crops are of an exceptionally high value, thresholds may be relatively low. In certain situations, regulations such as quarantines may impose zero tolerance for exotic organisms even when numbers are low or an organism does not directly damage the marketed crop. Mother stock and new plants should have virtually no pests. If pests are present at the beginning of the production cycle, many arthropods can develop through multiple generations resulting in large populations before plants are shipped. Abundant pests on young plants may require repeated management actions and greatly increase the likelihood of damaged, poor-quality plants. Action thresholds may be higher for mature plants of certain crops. More mature plants are often better able to tolerate some level of certain types of pests or their damage. It is unlikely that susceptible crops can always be maintained pest-free throughout their production cycle. As crops mature, they may be increasingly likely to become infested and are often more difficult to treat effectively because of the risk of phytotoxicity to colored bracts or flowers, increased difficulty in achieving good spray coverage on larger plants, and pesticide reentry intervals relative to crop harvest or shipping. If monitoring reveals very low pest abundance or damage near the end of production, it may not be necessary to take management actions because there may be insufficient time for populations to develop to problem levels before the crop is sold. How to Establish Thresholds Establish thresholds by regularly monitoring plants in a consistent and systematic manner. Keep good records and judge the acceptability of the finished crop in comparison with records of pest monitoring and management actions and the price received for the crop. Experiment over time to develop thresholds Insects and Mites Establishing Action Thresholds (3/21) 113 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES appropriate for your situation and market conditions. Be flexible in adjusting thresholds and adapt monitoring and management methods as appropriate. Thresholds should be quantitative or numerical to be useful. For example, thresholds could be based on the • average number of pests per trap each week • percent of leaves or plants found to be damaged or infested during visual inspection • number of pests dislodged per beat or shake sample Quantitative thresholds can be developed for most pest monitoring methods, such as treating when certain conditions are conducive to disease development or when invertebrate pests or damaged plant parts exceed specified numbers or percentages. For example, management action may be warranted for whiteflies early in production when more than about 5 adults per trap per week are captured on one well-maintained 3-by-5-inch yellow sticky trap deployed per 1,000 sq. ft. of production. Thresholds for your situations may be very different. Insects and Mites Establishing Action Thresholds (3/21) 114 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BIOLOGICAL CONTROL (3/21) Biological control is the beneficial action of parasites (technically parasitoids), pathogens, and predators in managing pests and preventing or reducing their damage. Biocontrol provided by these living organisms called “natural enemies” is especially important for reducing the abundance of pest insects and mites and their damage to crops. Conservation Preserve resident natural enemies by choosing cultural, mechanical, and selective chemical controls that do not kill these species or disrupt their beneficial activities. Many insect and mite pests in flower and nursery crops have natural enemies that can keep their populations below economically damaging levels. Conservation is the primary way to successfully use biological control. For example, using selective pesticides that do not kill natural enemies or disrupt their beneficial activities is a key component of integrated pest management. To enhance the effectiveness of biological control • Consult the Natural Enemies Gallery to become familiar with common and important parasites and predators of pests. • Control ants, which protect some pests from parasites and predators. • Exclude pests (e.g., bring only pest-free plants into growing areas, screen greenhouses) and use excellent sanitation (e.g., promptly remove infested crop debris and eliminate weeds and other nearby noncrop hosts of pests). These methods provide direct control and reduce or prevent the in-migration of abundant pests that can overwhelm the potential effectiveness of natural enemies that are resident or released. • Grow flowering insectary plants in or near outdoor nurseries to provide nectar and pollen to feed adult parasites and predators. Grow a series of plants that flower sequentially so blossoms are available throughout the growing season. Ideal insectary plants are those that can also be marketed, such as for culinary herbs and cut flowers. Avoid insectary-plant species that host arthropod pests or plant pathogens that can move to damage nearby crops. Consult Flowers; Fruit Trees, Nuts, Berries, and Grapevines; Trees and Shrubs; and Vegetables and Melons for lists of the pests reported on these plants. • Keep growing areas and plants clean and free of dust, which can impede parasites’ and predators’ ability to locate and attack prey. • Minimize or avoid the application of broad-spectrum, persistent (long-residual) acaricides and insecticides. • Rely on pesticides that do not kill natural enemies or disrupt their beneficial activities where this is feasible. • When pesticides are used, apply them in a selective manner. For example, spray only the more heavily infested portions of the crop (hot spots) and where needed to prevent crop damage. Conserving resident natural enemies elsewhere in the unsprayed growing area allows parasites and predators to reproduce and the adults to disperse and attack pests elsewhere in growing areas where the plant-feeding species are not currently abundant or causing noticeable damage. Augmentation When the desired natural enemies are not present, or they are not abundant enough to sufficiently reduce pest numbers, biological control can sometimes be augmented with the purchase and release of commercially reared natural enemies. Augmentative releases can be inoculative or inundative. As discussed below and in more detail in Natural Enemy Releases for Biological Control of Crop Pests, there are various release strategies (e.g., banker plants discussed below). Be aware that in most situations, employing practices that conserve resident natural enemies is more effective and less expensive and time consuming than purchasing and releasing them. Inoculative release When pest populations are low, relatively few natural enemies may be needed for effective release. The introduced parasites or predators are expected to reproduce, and it is their progeny that are expected to provide biological control. Releasing the mealybug destroyer lady beetle (Cryptolaemus montrouzieri) in late winter or spring to control foliar-feeding mealybugs is an example of inoculative release. The lady Insects and Mites Biological Control (3/21) 115 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES beetle is a highly effective predator of mealybug species that lay eggs in a cottony mass (ovisac). But this predator is native to the semi-tropics and does not survive cold weather, so to be effective it must be purchased and released early each growing season where mealybugs have been a problem. A parasitic wasp, Leptomastix dactylopii, can be released to kill nymphs of citrus mealybug. The mealybug destroyer and Leptomastix dactylopii parasite can be released in combination where citrus mealybug is a pest. Inundative release When releasing large numbers of natural enemies, often several times over a growing season, the individuals released are expected to provide biological control. Periodically releasing Trichogramma spp. egg parasitic wasps to destroy moth eggs is an example of inundative biological control. Trichogramma releases to kill moth eggs are compatible with applying Bacillus thuringiensis (Bt) to control the caterpillar stages and drenching soil with entomopathogenic nematodes (Heterorhabditis and Steinernema spp.) to kill the soildwelling, mature larvae and pupae of armyworms, cutworms, and European pepper moth (Dufo moth). Periodically releasing large numbers of convergent lady beetles (Hippodamia convergens) to temporarily control aphids is also inundative release. Each convergent lady beetle can consume several dozen aphids per day. Because the beetles will virtually all disperse within 1 or 2 days of being released, and generally will lay few eggs and not reproduce in the crop, releases must be repeated about weekly to provide control where aphids are an ongoing problem. Because the purchased beetles are field collected from mountainous foothills during their overwintering (diapause) phase, when collected, transported, and released, the convergent lady beetles are physiologically obliged to fly and disperse before settling to lay eggs among aphids. For more information, see Lady Beetle Releases for Aphid Control: How to Help Them Work (PDF ) from the newsletter UC IPM Retail Nursery and Garden Center IPM News. Banker plants One strategy for releases is to maintain natural enemies by rearing them on alternative insects that are not pests of the desirable crops. For example, barley, oats, or wheat infested with bird cherry-oat aphid might be used to maintain Aphidius colemani parasitic wasps in the greenhouse. This aphid is not a pest of many greenhouse bedding plants, but the wasps will feed on many other kinds of aphids (like green peach aphid) that are pests. These banker plants (e.g., planted in containers) with nonpest aphids and parasites or predators can be scattered throughout a greenhouse or nursery to provide a continual source of natural enemies that disperse to consume pest species on crops, such as for aphid control in greenhouses (PDF). Effectiveness of releases Augmentation is likely to be effective only in situations where researchers or other pest managers have previously demonstrated success. Guidelines for releasing natural enemies are provided in this publication in the sections on aphids, foliar-feeding mealybugs, fungus gnats, twospotted spider mite, and whiteflies. Because natural enemies are living organisms, they require food (adults of many species require nectar and pollen), shelter from harsh conditions, suitable environmental conditions, and water. Natural enemies may be adversely affected by low humidity or extreme conditions such as hot temperatures. Residues of certain pesticides can persist for weeks or months, harming natural enemies long after losing their effectiveness against pest species. Many beneficial species stop reproducing under short day length or prolonged cool conditions; supplemental light may be necessary for them to reproduce and be effective year-round. Environmental conditions required by natural enemies (such as long days) may not be compatible with production needs of certain crops. Desperate situations where pests are already abundant or damaging are not good opportunities for augmentation. Because pest presence is necessary to sustain natural enemies, choose crops where some levels of the target pests and their feeding can be tolerated (crops with moderate to high pest thresholds). Begin making releases early in the production cycle even before infestations are observed. Consider what other pests may occur in the crop and how they can be managed in ways that are compatible with conserving natural enemies. For more information, see Natural Enemies Handbook: The Illustrated Guide to Biological Pest Control, UC ANR 3386 (print edition), 9038 (ePub); and Natural Enemy Releases for Biological Control of Crop Pests. Insects and Mites Biological Control (3/21) 116 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Insect, Mite, and Other Invertebrate Management (Section reviewed 3/09) APHIDS (05/10) Melon aphid: Aphis gossypii Green peach aphid: Myzus persicae DESCRIPTION OF THE PESTS Aphids are distinguished from other insects by the presence of cornicles, tubelike appendages that protrude from the rear of the aphid. Numerous species of aphids attack California ornamental crops, but the two species most commonly encountered are the green peach aphid and the cotton or melon aphid. Melon aphids are typically dark green, but color variations do occur frequently. The cornicles are relatively short, stout, and always dark. Melon aphids have red eyes and antennae that only reach to the middle of the abdomen. Green peach aphid is characterized by a depression in the front of the head between the antennae (best seen with the use of a hand lens) and by long thin, translucent cornicles that extend beyond the tip of the body. Green peach aphids vary in color from yellowish green to rose pink. Winged adults have a dark blotch in the middle of the abdomen. Adult aphids may or may not have wings. Winged aphids are produced as a result of crowding. Green peach aphids produce winged adults at lower population densities than the melon aphid. The optimal temperature for green peach aphid development is 75°F, whereas optimal temperatures for development of melon aphids are above 75°F. Adult aphids give birth to live young. Generally, aphids begin giving birth when they are 7 to 10 days old, depending on temperature. DAMAGE Aphids excrete copious amounts of honeydew, a sweet, sticky substance that they produce as they feed on the plants. The honeydew can cover leaves and other plant parts and cause the plants to become sticky. Black sooty molds then grow on the honeydew. The white shed skins of the aphids frequently are stuck to the plant surfaces by the honeydew and further detract from the plant's appearance. Sufficient feeding can cause foliage to become yellowed, and feeding on newly developing tissues can cause those parts to become twisted as they grow. Melon aphids are known to transmit 44 plant viruses, while green peach aphids are known to transmit more than 100 plant viruses. MANAGEMENT Biological Control Predators such as lacewings (Chrysoperla spp.) and midges (Aphidoletes aphidimyza) are commercially available. Parasites, such as Aphidius spp., Lysiphlebus testaceipes, Diaeretiella rapae, and Aphelinus abdominalis, are also commercially available. For more information, see BIOLOGICAL CONTROL. Cultural Control Because aphids feed on a large variety of plant species, keep production areas free of weeds, which can serve as hosts of aphid populations. Exclusion of winged adults can be accomplished by covering openings to the greenhouse with screens that have a pore width of 355 microns or smaller. Before starting a new crop, carefully inspect plants to ensure that they are free of aphids and other pests. Treat or rogue any infested plants. Monitoring and Treatment Decisions Yellow sticky cards placed in greenhouses will capture winged adults. However, aphids produce winged individuals in response to crowding so monitoring plants for infestations is an essential component of managing and detecting these pests before populations get too high. Melon aphids tend to have a more uniform vertical distribution on plants than green peach aphids, which tends to be clustered around growing points, meaning that infestations of melon aphids under lower leaves can easily go undetected if these areas are not inspected. Green peach aphids will produce winged individuals at lower densities than melon aphids on crops such as chrysanthemums. Use at least one sticky trap per 10,000 square feet Major Insect and Mite Pests Aphids (5/10) 117 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES (900 sq m) of growing area for monitoring aphids. For more information, see MONITORING WITH STICKY TRAPS. Consider treating if an average of 5 to 10 aphids per card per week is present. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class biological botanical carbamate Pesticide (trade name) A. Beauveria bassiana# (BotaniGard 22 WP) (BotaniGard ES) Laverlam A. cinnamaldehyde (Cinnacure) oil4 REI1 Mode of action 2 Comments 4 — 4 — Proguard 4 — B. pyrethrin/PBO3 (PT Pyrethrum TR) Whitmire MicroGen 12 3 A. methiocarb* (Mesurol 75W) Gowan 24 1A Apply in 50 gal water. Repeat as necessary up to 2 applications/season. Do not apply with oil or foliar fertilizer. OHP 4 un B. azadirachtin (Ornazin 3%EC) C. pyriproxyfen (Distance) D. s-kinoprene (Enstar II) SePRO 12 un Must contact insect. Repeat applications as necessary. Aphid suppression only. Label permits low-volume application. Do not exceed 22.5 oz/acre/application. Valent 12 7C Wellmark 4 — A. imidacloprid (Marathon 1G) (Marathon II) OHP 12 4A B. imidacloprid (Marathon 60 WP) OHP 12 4A A. clarified hydrophobic ex- OHP tract of neem oil# (Triact 70) 4 un insect growth regu-A. azadirachtin lator (Azatin XL) neonicotinoid Manufacturer Treat every 7 days while insects are active. Do not tank mix with most fungicides and wait 48 hours after application to apply a fungicide. Do not apply to stressed plants or newly transplanted material before roots are established. An aerosol. Do not apply more than 2 times per cropping cycle or per 6 months. Apply prebloom. Also labeled for low volume use. Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. As above, but apply only as a drench. Do not spray plants under stress. Target pest must be completely covered with spray—this material may not effectively control melon aphid because it is often on the underside of lower leaves. Check label for list of plants that can be treated. May cause injury to flowers. Continued on next page . . . Major Insect and Mite Pests Aphids (5/10) 118 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class oil4 cont. Pesticide (trade name) B. horticultural oil5 (Ultra-Fine Oil) pyridine Whitmire MicroGen Brandt JMS Farms United Phosphorus REI1 Mode of action2 Comments Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. 12 — 4 4 24 — — 1B B. acephate Valent (Orthene T, T&O Spray) 24 1B C. acephate (PT 1300 Orthene TR) Whitmire MicroGen 24 1B A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) C. cyfluthrin (Decathlon 20 WP) D. deltamethrin* (DeltaGard) E. fenpropathrin* (Tame 2.4 EC) F. fluvalinate (Mavrik Aquaflow) G. lambda-cyhalothrin* (Scimitar) Whitmire MicroGen FMC 12 3 12 3 Check label. A fogger for greenhouse use only. Label permits low-volume application. OHP 12 3 Label permits low-volume application. Bayer 12 3 Valent 24 3 Label permits low-volume application. Wellmark 12 3 Syngenta 24 3 H. permethrin (Astro) FMC 12 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. For greenhouse and nursery use. Apply at 7-day intervals. Do not apply more than 52.4 fl oz of concentrate/acre/year. Do not mix with EC formulations or oils. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. A. pymetrozine (Endeavor) Syngenta 12 9B (SafTSide) (JMS Stylet Oil) organophosphate A. acephate (Acephate 97UP) pyrethroid6 Manufacturer A number of chrysanthemum varieties have exhibited phytotoxic reactions. Only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol that is only for greenhouse use. Apply as foliar spray at 7-14 day intervals. For outdoor use, do not apply more than 48 oz/acre/year; for indoor use, do not use more than 100 oz. Continued on next page . . . Major Insect and Mite Pests Aphids (5/10) 119 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class soap4 1 2 Pesticide (trade name) A. potash soap# (M-Pede) Manufacturer Dow Agro Sciences REI1 12 Mode of action2 Comments — Must contact insect, so thorough coverage is important. Repeat weekly as needed up to 3 times. Test for phytotoxicity. Do not spray new transplants or newly rooted cuttings. Do not add adjuvants. Restricted entry interval (REI is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://irac-online.org/. 3 PBO = piperonyl butoxide 4 Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. 5 Check with certifier to determine which products are organically acceptable. 6 Pyrethroids are generally not effective against green peach aphid. * Restricted use material. Permit required for purchase or use. — Unknown. # Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Aphids (5/10) 120 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ARMORED SCALES (5/10) Oystershell scale: Lepidosaphes ulmi Greedy scale: Hemiberlesia rapax California red scale: Aonidiella aurantii Oleander scale: Aspidiotus nerii San Jose scale: Diaspidiotus (=Quadraspidiotus) perniciosus DESCRIPTION OF THE PESTS The protective covering over armored scales is produced by molted skins and secretions from the scale. Unlike soft scales, the protective covering can be lifted off the body of the armored scale. High populations of these sucking insects give plant stems a crusty appearance. The first nymphal instar is called a crawler and has functional legs, while the remaining instars are attached to the leaf and do not move. Unlike soft scales, armored scales do not produce honeydew. Most armored scales have several generations a year. DAMAGE Along with the unsightly encrustations that are the bodies of the immobile scales, these scales inject toxic saliva that causes plants to decline. MANAGEMENT Biological Control Aphytis melinus is a commercially available parasite that is effective in controlling California red scale. For more information, see BIOLOGICAL CONTROL. Cultural Control Prune out and discard heavily infested plant parts. Exclusion of windblown crawlers can be accomplished by covering openings to the greenhouse with fine mesh screens. Monitoring and Treatment Decisions Carefully inspect new plants being brought into the production area to ensure that they are free of scales and other pests. Treat infested plants. Visual inspection of plants will help locate infestations and may permit localized treatments of hot spots. Treatment is generally warranted when scales are present. Optimum treatment timing is when crawlers are active; however, when there are overlapping, multiple generations, crawlers may emerge over a lengthy time, making multiple applications necessary. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Pesticide (trade name) A. pyrethrin+PBO3 (PT Pyrethrum TR) insect growth regu-A. pyriproxyfen lator (Distance) Class botanical B. s-kinoprene (Enstar II) Manufacturer Whitmire MicroGen Valent Wellmark REI1 12 Mode of action2 Comments 3/— An aerosol. 12 3 4 7A Do not apply more than 2 times per cropping cycle or per 6 months. Do not use through any type of irrigation system in California. Apply prebloom. Also labeled for low volume use. Continued on next page . . . Major Insect and Mite Pests Armored Scales (5/10) 121 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class oil4 Pesticide (trade name) Manufacturer A. clarified hydrophobic ex- OHP tract of neem oil# (Triact 70) B. horticultural oil5 (Ultra-Fine Oil) 12 United Phosphorus Valent 24 1B 24 1B C. acephate (PT 1300 Orthene TR) D. malathion (various) Whitmire MicroGen various 24 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouses only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. Do not use through any type of irrigation system. An aerosol for greenhouse use only. 12 1B Not for greenhouse use. A. cyfluthrin (Decathlon 20WP) B. fluvalinate (Mavrik Aquaflow) OHP 12 3 Label permits low-volume application. Wellmark 12 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. organophosphate A. acephate (Acephate 97UP) B. acephate (Orthene T, T&O Spray) 1 2 Mode of action2 Comments un Do not spray plants under stress. Target pest must be completely contacted with spray. Check label for list of plants that can be treated. May cause injury to flowers. Use as above for neem oil. Also, do not — use with sulfur fungicides; check label for tank mix restrictions. — — Whitmire MicroGen Brandt JMS Farms (Saf-T-Side) (JMS Stylet Oil) pyrethroid REI1 4 4 4 Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://irac-online.org/. 3 PBO = piperonyl butoxide 4 Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. 5 Check with certifier to determine which products are organically acceptable. * Restricted use material. Permit required for purchase or use. Acceptable for use on organically grown ornamentals. # Major Insect and Mite Pests Armored Scales (5/10) 122 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ARMYWORMS AND CUTWORMS (5/10) Beet armyworm: Spodoptera exigua Variegated cutworm: Peridroma saucia Yellowstriped armyworm: Spodoptera ornithogalli DESCRIPTIONS OF THE PESTS Beet armyworm Beet armyworm is the most frequently encountered of the three species listed above. Adults are heavy bodied moths (wingspread is about 1 inch, or 25–28 mm) with a characteristic mustard or orange colored liver-shaped spot on the forewings that is narrowly ringed with white. The female lays egg masses on the undersides of leaves, covering the eggs with felt made from her body hairs. The first through third instar larvae often feed gregariously, skeletonizing the undersides of leaves, or they feed on the insides of buds. Later instar larvae disperse and feed individually, chewing entirely through leaves or flowers. Early instar larvae are small and green, while late instar larval color may be green, brown, black, or gray. In all instars, there are fine lines along the length of the body, with a more conspicuous lateral stripe and a black spot just dorsal to the lateral stripe behind the head. Degree-days Calculate degree-days for beet armyworm in your location. Learn to use video presentation degree-days to time insecticide applications. Beet armyworm continually develops during winter in mild areas and builds up on weeds and in cotton, lettuce, and tomato fields. One generation can take as little as 31 days at 75°F or 24 days at 80°F. Egg to adult generation times can be calculated using degree-days (DD) based on a lower developmental temperature of 54°F. The egg stage requires the accumulation of about 94 DD from the time they are first laid until egg hatch. The larval and pupal stages require the accumulation of 470 DD and 318 DD respectively for females and 540 DD and 344 DD for males. Yellowstriped armyworm The yellowstriped armyworm larvae have a pair of black triangles on the back of most segments. Some larvae appear nearly completely black when viewed from above. The lateral stripe is bright orange or yellow. The adult has a complex and highly contrasting pattern of brown, yellow, and white on the front wings, and wingspread measure is about 1.5 inches. Variegated cutworm The variegated cutworm overwinters as a naked pupa in the soil. Adults have a distinct liver-shaped outline on the front wings and their wingspread can measure from 1.5 inches to a little over 2 inches. Larvae have yellow or orange spots or a broken longitudinal stripe at the top of the body, which is otherwise gray. Often there is a dark triangle or W-shaped mark on the top of the eighth body segment. DAMAGE Armyworms and cutworms mostly are a concern because they directly damage flowers as well as leaves that would normally be marketed with the flowers. Presence of late-instar larvae in seedling flats can also cause tremendous plant loss. On the other hand, moderate early-season feeding by armyworms on gypsophila may actually increase tillering and yields. MANAGEMENT Biological Control A number of parasites, both tachinid flies and parasitic wasps, attack Lepidoptera larvae and reduce their population growth rate. However, even if armyworm or cutworm larvae are parasitized, they continue feeding through to the last instar and still damage crops. Viruses also do not usually kill the larvae until later instars. Applying insecticides other than Bacillus thuringiensis (Bt) products are likely to exclude parasites because their residues are lethal to these beneficial insects. For more information, see BIOLOGICAL CONTROL. Cultural Control Because these pests feed on a large variety of plant species, keep production areas free of weeds, many of which serve as hosts to armyworms and cutworms. Exclusion of winged adults can be accomplished by Major Insect and Mite Pests Armyworms and Cutworms (5/10) 123 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES covering openings to the greenhouses with screens. Screens are especially important when lights are used at night in greenhouses to control flowering because lights attract moths. Individual seedling flats may also be covered with screens to exclude adults and larvae. Row covers can be a practical measure to exclude moths in field production as long as the mesh prevents entry of adults and the row cover is held above the plant surface to eliminate oviposition (egg laying) through the fabric. Monitoring and Treatment Decisions If Bt sprays are planned, use pheromone traps to determine adult flight activity and mating. Once adults are caught in traps, it is very likely that larvae are present and Bt should be applied as soon as possible because it is most effective against young larvae. Use regular visual inspections of plants to detect larvae and their damage. For guidelines on when to treat, see ESTABLISHING ACTION THRESHOLDS. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class biological botanical Pesticide (trade name) A. Bacillus thuringiensis ssp. kurstaki# (various products) A. pyrethrin+PBO3 (PT Pyrethrum TR) A. carbaryl* Manufacturer Valent REI1 4 Mode of action2 Comments 11 Most effective against early instar larvae; pheromone trapping recommended for timing applications. Whitmire MicroGen Bayer 12 3/— 12 1A OHP 4 un Chemtura 12 15 Chemtura 12 15 D. tebufenozide Dow Agro (Mimic) Sciences organophosphate A. acephate Valent (Orthene T, T&O Spray) 4 18 24 1B Whitmire MicroGen Whitmire MicroGen FMC 24 1B 12 3 12 3 Check label. A fogger for greenhouse use only. Label permits low-volume application. OHP 12 3 Label permits low-volume application. Bayer 12 3 Valent 24 3 carbamate insect growth regu-A. azadirachtin lator (Azatin XL) B. diflubenzuron (Adept 25WP) C. novaluron (Pedestal) pyrethroid B. acephate (PT 1300 Orthene TR) A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) C. cyfluthrin (Decathlon 20WP) D. deltamethrin* (DeltaGard) E. fenpropathrin* (Tame 2.4EC Spray) An aerosol. Must contact insect. Repeat applications as necessary. Label permits low-volume application. Use no more than twice per year and do not exceed 52 oz/acre/year. Do not use on poinsettia. A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse only labeled for greenhouse use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol only for greenhouse use. Label permits low-volume application. Continued on next page . . . Major Insect and Mite Pests Armyworms and Cutworms (5/10) 124 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class pyrethroid spinosyn Pesticide (trade name) F. fluvalinate (Mavrik Aquaflow) G. permethrin (Astro) A. spinosad (Conserve SC) Manufacturer Wellmark REI1 12 FMC 12 Dow Agro Sciences 4 Mode of action2 Comments 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. 3 Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. 5 Do not apply more than 10 times in a 12month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis. 1 Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. 2 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://irac-online.org/. 3 PBO = piperonyl butoxide # Acceptable for use on organically grown ornamentals. * Restricted use material. Permit required for purchase or use. Important Links • Degree-day model for Beet Armyworm in Floriculture • Video presentation Using degree-days to time insecticide applications Major Insect and Mite Pests Armyworms and Cutworms (5/10) 125 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BULB MITES (3/09) Rhizoglyphus spp. DESCRIPTION OF THE PEST Bulb mites are white with large amber spots, brown legs, and are 0.55 to 0.75 mm long when fully grown. They are slow moving and oval shaped, so are sometimes mistaken for insect eggs. These mites can be found in hollowed out and decomposing portions of bulbs. DAMAGE Bulb mites enter the bulb and feed in protected cavities, where fungi and bacteria may cause extensive decomposition of the bulb. They are associated with the spread of Fusarium, Stromatinia, and Pseudomonas diseases of bulbs. Species of bulbs attacked include freesia, hyacinth, lilies, narcissus, and onions, as well as underground peony rhizomes. Freesias are particularly affected because they require high temperature storage to break dormancy, which allows rapid growth of bulb mite populations. Lilies are attacked below ground, which stunts growth. Feeding at ground level causes the plants to topple. MANAGEMENT Biological Control Biological control has not been investigated. Cultural Control Bulbs may be disinfested by holding them for 24 hours at 100% relative humidity at 105.5°F. CO2 fumigation may be useful. TREATMENT Thoroughly clean bulbs, dip them in a sulfur fungicide solution, and dry them following harvest. The sulfur will control bulb mites as well as fungal diseases if the bulbs are being held at high temperatures. However, high rates of sulfur may be phytotoxic. Abamectin (Avid), dicofol (Kelthane), some pyrethroids, and pyridaben (Sanmite) are possibly effective, but have not been evaluated. Major Insect and Mite Pests Bulb Mites (3/09) 126 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CABBAGE LOOPER (5/10) Trichoplusia ni DESCRIPTION OF THE PEST Loopers arch their backs as they crawl. Cabbage loopers are light green and usually have a narrow, white stripe along each side and several narrow lines down the back. The dome-shaped eggs are laid singly on the undersurfaces of older leaves. Adult moths have brown, mottled forewings marked in the center with a small, silver figure 8. DAMAGE Young cabbage looper larvae feed primarily on the underside of lower leaves, skeletonizing them. Larger cabbage loopers chew entirely through leaves and flowers. MANAGEMENT Biological Control A number of parasites, both tachinid flies and parasitic wasps, attack Lepidoptera larvae and reduce their population growth rate. However, most of these larvae continue feeding through to the last instar, so parasitized larvae will still damage crops. Viruses also do not usually kill the larvae until later instars. Trichogramma spp. are commercially available egg parasites that can be effective against cabbage looper. Applying insecticides other than Bacillus thuringiensis (Bt) products are likely to exclude parasites because their residue are lethal to these beneficial insects. For more information, see BIOLOGICAL CONTROL. Cultural Control Because these pests feed on a large variety of plant species, keep production areas free of weeds (e.g., mustards) that serve as hosts to cabbage loopers. Exclusion of winged adults can be accomplished by covering openings to the greenhouses with screens. Screens are especially important when lights are used at night in greenhouses to control flowering because lights attract adult moths. Individual seedling flats may also be covered with screens to exclude adults and larvae. Row covers can be a practical measure to exclude moths in field production as long as the mesh prevents entry of adults and the row cover is held above the plant surface to eliminate oviposition through the fabric. Monitoring and Treatment Decisions If Bt sprays are planned, use pheromone traps to determine adult flight activity and mating. Once adults are caught in traps, it is very likely that larvae are present and Bt should be applied as soon as possible because it is most effective against young larvae. Use regular visual inspections of plants to detect larvae and their damage. For guidelines on when to treat, see ESTABLISHING ACTION THRESHOLDS. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class botanical Pesticide (trade name) A. pyrethrin+PBO3 (PT Pyrethrum TR) carbamate A. carbaryl* (various) insect growth regulator A. azadirachtin (Azatin XL) B. diflubenzuron (Adept 25WP) Manufacturer REI1 Mode of action2 Comments Whitmire MicroGen 12 3/— Bayer 12 1A OHP 4 un Chemtura 12 15 An aerosol. Must contact insect. Repeat applications as necessary. Label permits low-volume application. Continued on next page . . . Major Insect and Mite Pests Cabbage Looper (5/10) 127 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Pesticide Class (trade name) insect growth regula- C. novaluron tor, cont. (Pedestal) microbial organophosphate pyrethroid spinosyn 1 2 3 # * Manufacturer Chemtura REI1 12 Mode of action2 Comments 15 Use no more than twice per year and don't exceed 52 oz/acre/year. Don't use on poinsettia. 18 D. tebufenozide Dow Agro (Mimic, Confirm) Sciences A. Bacillus thuringiensis Valent ssp. kurstaki# (various products) 4 4 11 Most effective against early instar larvae; pheromone trapping recommended for timing applications. A. acephate (Orthene T, T&O Spray) Valent 24 1B B. acephate (PT 1300 Orthene TR) A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) C. cyfluthrin (Decathlon 20WP) D. deltamethrin* (DeltaGard) E. fenpropathrin* (Tame 2.4EC Spray) F. fluvalinate (Mavrik Aquaflow) Whitmire MicroGen 24 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse only labeled for greenhouse use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol only for greenhouse use. Whitmire MicroGen 12 3 Check label. A fogger for greenhouse use only. FMC 12 3 Label permits low-volume application. OHP 12 3 Label permits low-volume application. Bayer 12 3 Valent 24 3 Label permits low-volume application. Wellmark 12 3 G. permethrin (Astro) FMC 12 3 A. spinosad (Conserve SC) Dow Agro Sciences 4 5 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. Do not apply more than 10 times in a 12month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://irac-online.org/. PBO = piperonyl butoxide Acceptable for use on organically grown ornamentals. Restricted use material. Permit required for purchase or use. Major Insect and Mite Pests Cabbage Looper (5/10) 128 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DIAMONDBACK MOTH (5/10) Plutella xylostella DESCRIPTION OF THE PEST When at rest, the adult diamondback male moth's wings meet over its back to show three yellow diamonds. The female moths are about 0.4 inch long and lay minute eggs singly or in groups of two or three on the undersides of leaves. Each female lays an average of 75 eggs. First instar larvae mine leaves, then are external leaf feeders for the remaining three instars. Mature larvae are about 0.4 inch long, are pale green and wriggle actively when disturbed. An openly woven silk cocoon holds the pupa in place under leaves. Development from egg to adult is 29, 16, and 12 days at temperatures of 68°, 77°, and 87°F, with the greatest survival at 77°F. DAMAGE Diamondback moth larvae chew small circular holes in leaves from the undersides, giving the leaves a shot-hole appearance. Very high populations can defoliate plants. Affected flowers include sweet alyssum, stock, candytuft, wallflower, and other plants in the cruciferous family. MANAGEMENT Biological Control A number of parasites, both tachinid flies and parasitic wasps, attack Lepidoptera larvae and reduce their population growth rate. However, most of these larvae continue feeding through to the last instar, so parasitized larvae will still damage crops. Viruses also do not usually kill the larvae until later instars. The parasitic stingless wasps Cotesia plutellae, Diadegma insulare, and Microplitis plutellae are commercially available for control of diamondback moth. Applying insecticides other than Bacillus thuringiensis (Bt) products are likely to exclude parasites because the residues are lethal to these beneficial insects. For more information, see BIOLOGICAL CONTROL. Cultural Control Because these pests feed on a large variety of plant species, keep production areas free of weeds (e.g., mustards) that serve as hosts to diamondback moths. Exclusion of winged adults can be accomplished by covering openings to greenhouses with screens. Screens are especially important when lights are used at night in greenhouses to control flowering because lights attract adult moths. Individual seedling flats may also be covered with screens to exclude adults and larvae. Row covers can be a practical measure to exclude moths in field production as long as the mesh prevents entry of adults and the row cover is held above the plant surface to eliminate oviposition through the fabric. Also, intermittent overhead irrigation can disrupt oviposition by diamondback moth. Monitoring and Treatment Decisions If Bt sprays are planned, use pheromone traps to determine adult flight activity and mating. Once adults are caught in traps, it is very likely that larvae are present and Bt should be applied as soon as possible because it is most effective against young larvae. Use regular visual inspections of plants to detect larvae and their damage. Diamondback moth is resistant to many insecticides. For guidelines on when to treat, see ESTABLISHING ACTION THRESHOLDS. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class botanical carbamate Pesticide (trade name) A. pyrethrin+PBO3 (PT Pyrethrum TR) A. carbaryl* (various) Manufacturer Whitmire MicroGen Bayer REI1 Mode of action2 Comments 12 3/— 12 1A An aerosol. Continued on next page . . . Major Insect and Mite Pests Diamondback Moth (5/10) 129 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Pesticide Class (trade name) insect growth regula- A. azadirachtin tor (Azatin XL) microbial organophosphate pyrethroid spinosyn 1 2 3 * # Manufacturer OHP REI1 4 Mode of action2 Comments un Must contact insect. Repeat applications as necessary. Label permits low-volume application. 15 May damage poinsettias if used over labeled rate. 11 Most effective against early instar larvae; pheromone trapping recommended for timing applications. B. diflubenzuron Chemtura (Adept 25WP) A. Bacillus thuringiensis Valent ssp. kurstaki# (various products) 12 A. acephate (Orthene T, T&O Spray) 24 1B B. acephate Whitmire Micro(PT 1300 Orthene TR) Gen A. bifenthrin Whitmire Micro(Attain TR) Gen B. bifenthrin* FMC (Talstar Professional) C. cyfluthrin OHP (Decathlon 20WP) D. deltamethrin* Bayer (DeltaGard) E. fenpropathrin* Valent (Tame 2.4EC Spray) F. fluvalinate Wellmark (Mavrik Aquaflow) 24 1B 12 3 12 3 Check label. A fogger for greenhouse use only. Label permits low-volume application. 12 3 Label permits low-volume application. 12 3 24 3 Label permits low-volume application. 12 3 G. permethrin (Astro) FMC 12 3 A. spinosad (Conserve SC) Dow Agro Sciences 4 5 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. Do not apply more than 10 times in a 12month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis. Valent 4 A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse, only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol only for greenhouse use. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://irac-online.org/. PBO = piperonyl butoxide Restricted use material. Permit required for purchase or use. Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Diamondback Moth (5/10) 130 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FOLLIAR-FEEDING MEALYBUGS (5/10) Citrus mealybug: Planococcus citri Longtailed mealybug: Pseudococcus longispinus Madeira mealybug: Phenacoccus madeirensis DESCRIPTION OF THE PESTS Mealybugs are slow-moving sucking insects that have a loose, waxy coating on the body, which gives them their "mealy" appearance. The citrus mealybug is heavily and evenly covered with white, powdery wax, except for a faint narrow streak down the middle. It has short, wax filaments along the sides and hind filaments that are about one-fourth as long as the body. Both the citrus mealybug and the Mexican mealybug lay eggs in ovisacs (eggs are within masses of cottony wax). The Mexican mealybug can be distinguished from the citrus mealybug by four rows of thinly waxed depressions down the back. The longtailed mealybug has four long terminal wax filaments, which it holds parallel to the axis of the body; it also gives birth to live young. Mealybug infestations often occur underneath foliage and in hidden areas within dense foliage. DAMAGE Mealybugs remove sap from plants, which can cause yellowing of leaves and decline in vigor. Mealybug ovisacs and excreted honeydew are unsightly. Honeydew supports the growth of black sooty mold fungi and attracts ants; ants may then carry mealybugs to uninfested plants and tend them for honeydew, as well as protect them from natural enemies. MANAGEMENT Biological Control Cryptolaemus montrouzieri, the mealybug destroyer lady beetle, is an effective predator of many mealybugs and other ovisac-forming sucking insects (such as green shield scale). Larval mealybug destroyers themselves look like large, faster-moving mealybugs, but are readily distinguished by their chewing mouthparts. Leptomastix dactylopii, a parasite of citrus mealybugs, is also commercially available. Effective predators or parasites of longtailed mealybugs are not yet commercially available. For more information, see BIOLOGICAL CONTROL. Monitoring and Treatment Decisions Carefully inspect plants being brought in to start a new crop to ensure that they are free of mealybugs and other pests. If necessary, treat infested plants. Regularly inspect plants for signs of honeydew (i.e., glistening, sticky leaves) and ant activity. Well-established infestations containing females with ovisacs are much more difficult to control with either systemic or contact insecticides than new infestations because reproducing adults usually stop feeding and the females' bodies or the wax secretions help protect eggs or crawlers. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class biological Pesticide (trade name) A. Beauveria bassiana# (BotaniGard 22 WP) (BotaniGard ES) A. pyrethrin/PBO3 (PT Pyrethrum TR) insect growth regula- A. azadirachtin tor (Azatin XL) botanical Major Insect and Mite Pests Manufacturer Laverlam REI1 4 Whitmire MicroGen OHP 12 Mode of action2 Comments — Treat every 7 days while insects are active. Do not tank mix with most fungicides and wait 48 hours after application to apply a fungicide. 3/— An aerosol. 4 un Must contact insect. Repeat applications as necessary. Only effective on Foliar-Feeding Mealybugs (5/10) 131 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES neonicotinoid B. azadirachtin (Ornazin 3%EC) C. s-kinoprene (Enstar II) A. acetamiprid (TriStar) 70WSP B. dinotefuran (Safari) 20G C. imidacloprid (Marathon 1G) (Marathon II) SePRO 12 un Wellmark 4 7A Cleary 12 4A Valent 12 4A Can be applied as a drench or foliar spray. OHP 12 4A Syngenta 12 4A Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. As above. Apply only as a drench. Can be applied as a drench or foliar spray. OHP 4 un Do not spray plants under stress. Target pest must be completely covered with spray. Check label for list of plants that can be treated. May cause injury to flowers. Whitmire MicroGen Brandt JMS Farms 12 — 4 4 — — Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. A. acephate (Acephate 97UP) B. acephate (Orthene T, T&O Spray) United Phosphorus Valent 24 1B 24 1B C. acephate (PT 1300 Orthene TR) A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) C. cyfluthrin (Decathlon 20 WP) D. deltamethrin* (DeltaGard) E. fenpropathrin* (Tame 2.4 EC Spray) F. fluvalinate (Mavrik Aquaflow) Whitmire Micro- 24 Gen Whitmire Micro- 12 Gen FMC 12 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse, only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol for greenhouse use only. 3 A fogger for greenhouse use only. 3 Label permits low-volume application. OHP 12 3 Label permits low-volume application. Bayer 12 3 Valent 24 3 Label permits low-volume application. Wellmark 12 3 G. permethrin (Astro) FMC 12 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia and pteris fern. Label permits low-volume (Marathon 60 WP) D. thiamethoxam (Flagship) 25WG oil4 A. clarified hydrophobic extract of neem oil# (Triact 70) B. horticultural oil5 (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil) organophosphate pyrethroid immatures. Label permits low-volume application. Do not exceed 22.5 oz/acre/application. Major Insect and Mite Pests Apply prebloom. Only effective on immatures. Also labeled for low volume use. Apply as a foliar spray. Foliar-Feeding Mealybugs (5/10) 132 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES application. Do not apply more than 2 lb a.i./acre/year. 1 Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. 2 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. 3 PBO = piperonyl butoxide. 4 Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. 5 Check with certifier to determine which products are organically acceptable. * Restricted use pesticide. Permit required for purchase or use. # Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Foliar-Feeding Mealybugs (5/10) 133 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FUNGUS GNATS (3/09) Fungus Gnats: Bradysia coprophila, Bradysia impatiens DESCRIPTION OF THE PESTS Fungus gnats are small (2–5 mm long) mosquitolike flies with dark wings, delicate legs, and long antennae. They lay their eggs in soil, and the eggs hatch about 4 days later. There are four larval instars that increase in size up to about 0.33 inch (8 mm). Larvae are clear, with visible internal organs, and have shiny black head capsules. Initially larvae feed on root hairs and algae; later, larvae may feed on the insides of roots. When populations are high, larvae may bore into larger roots or stems that are in the soil. Larvae will also feed on leaves touching the soil. One generation may complete development in 21 (72°F) to 40 (61°F) days. DAMAGE Larvae usually feed on roots and algae within 1 inch of the soil surface. Root feeding by larvae can allow entry of plant pathogens. Direct damage through root feeding can cause wilting even though the plants are being sufficiently watered. Damage is particularly severe in propagation areas, in seedling flats, and with especially sensitive crops. Adult fungus gnats also disseminate soil-inhabiting pathogens on their bodies and in their feces. Fungus gnat adults can be a nuisance when present in large numbers. MANAGEMENT Biological Control Biological control agents include nematodes (Steinernema feltiae), soil-inhabiting predaceous mites (Hypoaspis miles), and the bacteria Bacillus thuringiensis (Gnatrol). For more information, see BIOLOGICAL CONTROL. Cultural Control Keep production areas free of weeds and algal scum, which can serve as breeding sites for fungus gnat populations. Maintaining overwatered conditions and using either incompletely composted organic matter or manure in potting media provides ideal conditions for fungus gnats. Commercial sources of peat may be infested with fungus gnats and should be steamed before use when growing crops sensitive to fungus gnats. Monitoring and Treatment Decisions Yellow sticky cards placed in greenhouses will capture adult fungus gnats. For more information, see MONITORING WITH STICKY TRAPS. Small emergence traps can also be used to determine precisely where adults are emerging. Larval populations can be monitored with cubes or slices of potatoes pressed just into the soil. Fungus gnat larvae can be readily seen feeding on the potato pieces. For more information on treatment decisions, see ESTABLISHING ACTIONTHRESHOLDS. Apply insecticide drenches to the top 1 inch of soil to kill larvae; avoid applying excessive spray volume that may leach or move insecticide too deeply into growing media. Pyrethrins and other adulticides such as aerosols, foggers, or sprays can quickly, but temporarily, reduce adult fungus gnat numbers. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class biological botanical Pesticide (trade name) Bacillus thuringiensis ssp. israelensis# A. (Gnatrol) pyrethrin/PBO3 A. (PT Pyrethrum TR) Major Insect and Mite Pests Manufacturer REI1 Valent Whitmire MicroGen 4 12 Mode of action2 Comments Do not apply with fertilizers or fungicides containing copper or chlorine. Not effec11 tive on shore flies. An aerosol. Also effective against adults. 3/— Fungus Gnats (5/10) 134 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES azadirachtin (Azatin XL) insect growth regulator A. azadirachtin B. (Ornazin 3%EC) 4 un SePRO 12 un Syngenta 12 17 Do not exceed 22.5 oz/acre/application Certification training required to use this product. Also effective against shore fly larvae. Chemtura 12 15 Apply as spray or drench to top 2 inches of soil. pyriproxyfen E. (Distance) Valent 12 7C Do not apply more than 2 times per cropping cycle or per 6 months. s-kinoprene F. (Enstar II) Wellmark 4 7A Apply prebloom. Also labeled for low volume use. Cleary 12 4A Valent 12 4A OHP 12 4A Syngenta 12 United Phosphorus 24 4A cyromazine C. (Citation 75 WP) diflubenzuron D. (Adept 25WP) neonicotinoid organophosphate pyrethroid Must contact insect. Repeat applications as necessary. Only effective on larvae. Label permits low-volume application. OHP acetamiprid A. (TriStar) 70WSP dinotefuran B. (Safari) 20G imidacloprid (Marathon 1G) C. (Marathon II) (Marathon 60 WP) thiamethoxam D. (Flagship) 25WG acephate A. (Acephate 97UP) Apply as a foliar spray. acephate (Orthene T, B. T&O Spray) Valent acephate Whitmire MicroC. (PT 1300 Orthene TR) Gen bifenthrin Whitmire MicroA. (Attain TR) Gen bifenthrin* B. (Talstar Professional) FMC cyfluthrin C. (Decathlon 20 WP) OHP D. deltamethrin* (DeltaGard) Bayer fenpropathrin* E. (Tame 2.4 EC Spray) Valent 1B 24 1B 24 1B 12 3 12 3 12 3 12 3 24 3 fluvalinate F. (Mavrik Aquaflow) Wellmark 12 3 permethrin G. (Astro) FMC 12 3 Major Insect and Mite Pests Can be applied as a drench or foliar spray. Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. As above. Apply only as a drench. Can be applied as a drench or foliar spray. A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouses only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol for greenhouse use only. Check label. A fogger for greenhouse use only. Also effective against adults. Label permits low-volume application. Also effective against adults. Label permits low-volume application. Also effective against adults. Label permits low-volume application. Also effective against adults. Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. Fungus Gnats (5/10) 135 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 1 Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. 2 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. 3 PBO = piperonyl butoxide * Restricted use pesticide. Permit required for purchase or use. # Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Fungus Gnats (5/10) 136 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES LEAFHOPPERS AND SHARPSHOOTERS (5/10) Aster leafhopper: Macrosteles quadrilineatus (=M. fascifrons) Blue-green sharpshooter: Graphocephala atropunctata Glassy-winged sharpshooter: Homalodisca vitripennis (=H. coagulata) Two-spotted leafhopper: Sophonia rufofascia DESCRIPTION OF THE PESTS Leafhoppers, including a subgroup called sharpshooters, are in the family Cicadellidae. All have mouthparts that allow them to pierce the plant tissue and feed on plant juices. Most leafhoppers are about 0.25 inch long and slender. Species may be brightly colored or similar in color to the host plant. They often jump away or move sideways when disturbed. Pale cast skins may be found on leaf surfaces. Leafhoppers have incomplete metamorphosis. Immatures (nymphs) are similar in structure to adults, but are smaller, wingless, and may differ in color. Glassy-winged sharpshooter Adult glassy-winged sharpshooters are about 0.5 inches long and dark brown in color. Wings are membranous and translucent, with reddish veins. The insects overwinter as adults and begin to lay egg masses about late February. There appear to be two generations of glassy-winged sharpshooters per year in California. Eggs are laid under the surface of the leaf epidermis. The gray-colored nymphs are smaller than the adults and wingless. There are 5 immature stages. As they feed on xylem tissue, they excrete a large amount of liquid substance that drops to the leaves or the ground below. The glassy-winged sharpshooter has a broad host range that includes many ornamental plant species. Aster leafhopper The aster leafhopper is also called the six-spotted leafhopper because it has three pairs of black spots on its head. The adults are small (about 0.12 inch long) and usually light green to yellow, with black marking on the thorax and abdomen. Their wings are transparent. Nymphs are usually dark green. Blue-green sharpshooter The blue-green sharpshooter has green to bright blue wings, head, and thorax, and yellow legs and abdomen, which are visible on the underside. It is about 0.4 inches long. There is one generation a year in most of California and a second generation in some southern areas of the state. Adults become active in late winter to early spring. They can become abundant in ornamental landscaping around homes. They also feed on numerous weeds mostly along stream banks or in ravines or canyons where there is dense vegetative growth. As natural vegetation dries up, adults disperse into crops and irrigated plantings. Eggs hatch from May through July with some of the nymphs becoming adults by mid-June. Two-spotted leafhopper Adults are about 0.25 inches long and pale yellow with a dark stripe down the center of the back. On the end of the wings are two prominent eye spots that make it appear that the leafhopper is walking backwards. This leafhopper feeds on a wide range of ornamental plants. Feeding may cause chlorosis of leaves in some species. DAMAGE Leafhoppers are pests primarily because some are vectors of plant pathogens. The glassy-winged sharpshooter and the blue-green sharpshooter transmit a bacterial pathogen Xylella fastidiosa that grows in the xylem, or water-conducting tissue, of certain plant species. Xylella fastidiosa can cause a number of plant diseases in a variety of hosts. Thus far, strains of X. fastidiosa that cause oleander leaf scorch, Pierce's disease of grapevines, almond leaf scorch, and alfalfa dwarf have been identified in California. The strains of the pathogen that infect oleander do not appear to infect grape and are genetically distinct from the other strains. The aster leafhopper is one of several leafhoppers that can transmit the phytoplasma pathogens that cause aster yellows disease in many plant hosts. In addition to the transmission of pathogens, leafhopper feeding can cause leaves to appear stippled, pale, or brown, and shoots may curl and die. Excrement exuded during feeding can serve as a substrate for the growth of sooty mold, or discolor leaves with a white chalky film. Glassy-winged sharpshooter is under quarantine in California and shipment from infested to noninfested areas requires specific treatments. Major Insect and Mite Pests Leafhoppers and Sharpshooters (5/10) 137 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MANAGEMENT Management of leafhoppers and sharpshooters in nursery crops is focused primarily on exclusion techniques. Plants can be protected from these pests and the transmission of pathogens with the use of row covers and screening; reflective mulches may also be useful. Good weed management is important in areas surrounding nurseries to prevent the buildup of populations and migration into the nursery when the surrounding vegetation dries. In nurseries that have had past problems with glassy-winged sharpshooters, a quarantine pest, preventive insecticide treatments are advisable. Otherwise, monitor these pests to detect an influx of populations into the nursery. Biological Control There are no commercial sources of biological control agents for leafhoppers currently available; however, there is a fairly high level of naturally occurring egg parasitism of glassy-winged sharpshooters late in the season. For more information, see BIOLOGICAL CONTROL. Cultural Control Leafhoppers can be excluded from growing areas using screening or row covers. Identify potential sources of pathogens that are near growing areas. Remove weeds to eliminate sources of leafhoppers or pathogens near growing areas. If such sources cannot be removed, avoid planting crops susceptible to disease near these alternate hosts. For open field flower or nursery production, silver reflective plastic mulches may be of value. Reflective mulches have been shown to repel leafhoppers in another crop (corn), thus reducing pest numbers in and around the plant canopies. In addition, Xylella transmission by the leafhopper vectors was greatly reduced, thus reducing corn stunt disease incidence. For best results, apply reflective mulches at the time of planting or transplanting the crop. Apart from reducing leafhopper and pathogen incidence, silver reflective mulch may increase cut-flower production and reduce the crop requirement for irrigation, water and fertilizer. Row covers, screening, and mulching are acceptable practices for organic production. Monitoring and Treatment Decisions Leafhoppers are dormant through the winter months and will require little attention. Activity and egg laying begin in early spring. Begin monitoring in February to March and continue through September. For nurseries with chronic glassy-winged sharpshooter problems, apply preventive treatments when adults are first detected. Otherwise, monitor nursery borders to detect the influx of leafhopper/sharpshooters and treat if necessary. Place yellow sticky traps around the nursery border and throughout the nursery at canopy height (4 cards per acre) to detect migration of sharpshooters and leafhoppers into the nursery. Check cards at least once a week for adult sharpshooters. Treat if any adult glassy-winged sharpshooters are detected in the traps. If glassy-winged sharpshooters are not present but five to ten leafhoppers or other sharpshooters are being caught in sticky traps, a treatment may be necessary to stem the influx of these other species. A major management consideration is that economic damage caused by the leafhopper should equal or exceed the cost of any necessary management. For more information, see MONITORING WITH STICKY TRAPS. Other monitoring methods, including beating samples and visual counts, can be used to detect the presence of leafhoppers and sharpshooters. Beat or sweep sampling for nymphs and adults is most effective when temperatures are cool (less than 60°F). At warmer temperatures the insects will fly away before they can be counted. To conduct a beat sample, place a 2-foot square sheet of white material underneath the canopy to be sampled. Strike the canopy with a stick or shake it vigorously to dislodge insects, and count the number on the sheet. A sweep net may be also used to sample foliage for the presence of adults and nymphs. Visual inspection of leaves, stems, and branches is perhaps the best method for detecting all stages. Insects may try to move to the far side of the stem to avoid detection. Placing a hand close behind the stem being observed will make the insects move to the front where they can be seen. (Glassy-winged sharpshooter egg masses can be easily detected by inspecting the undersides of leaves against a sunny sky.) For information on making treatment decisions, see ESTABLISHING ACTION THRESHOLDS. Major Insect and Mite Pests Leafhoppers and Sharpshooters (5/10) 138 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Quarantine Requirements. Nurseries are considered infested if 5 or more glassy-winged sharpshooters are collected on sticky cards that are within a 300-yard radius of each other (not less than one card per half acre). Shipment of nursery stock from glassy-winged sharpshooter-infested areas to noninfested areas within and outside of California requires additional treatments. Contact your county Agricultural Commissioner's office for more information. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class Pesticide (trade name) Manufacturer REI1 Mode of action2 Comments botanical pyrethrin/PBO3 A. (PT Pyrethrum TR) Whitmire MicroGen 12 3/— An aerosol. carbamate carbaryl* A. (Sevin SL) Bayer 12 1A May be applied through sprinkler irrigation systems only. Must contact insect. Repeat applications as necessary. Aphid suppression only. Label permits low-volume application. insect growth regulaazadirachtin tor A. (Azatin XL) azadirachtin B. (Ornazin 3%EC) s-kinoprene C. (Enstar II) neonicotinoid oil4 organophosphate acetamiprid A. (TriStar 70WSP) OHP 4 un SePRO 12 un Wellmark 4 7A Cleary 12 4A Do not exceed 22.5 oz/acre/application. Apply prebloom. Also labeled for low volume use. imidacloprid (Marathon 1G) B. (Marathon II) OHP 12 4A Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. imidacloprid C. (Marathon 60 WP) OHP 12 4A As above, but apply only as a drench. Do not spray plants under stress. Target pest must be completely covered with spray—this material may not effectively control melon aphid because it is often on the underside of lower leaves. Check label for list of plants that can be treated. May cause injury to flowers. clarified hydrophobic extract of neem oil# A. (Triact 70) horticultural oil5 (Ultra-Fine Oil) (SafTSide) B. (JMS Stylet Oil) acephate A. (Acephate 97UP) OHP 4 un Whitmire MicroGen Brandt JMS Farms United Phosphorus 12 — 4 4 — — 24 1B acephate (Orthene T, T&O B. Spray) Valent acephate Whitmire C. (PT 1300 Orthene TR) MicroGen Major Insect and Mite Pests 24 1B 24 1B Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. A number of chrysanthemum varieties have exhibited phytotoxic reactions. Only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol that is only for greenhouse use. Leafhoppers and Sharpshooters (5/10) 139 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES pyrethroid soap4 1 2 3 4 5 * # bifenthrin* A. (Talstar Professional) FMC cyfluthrin B. (Decathlon 20 WP) OHP deltamethrin C. (DeltaGard T&O) Aventis fenpropathrin* D. (Tame 2.4 EC) Valent 12 3 Label permits low-volume application. 12 3 Label permits low-volume application. 12 3 For outdoor use only. 24 3 Label permits low-volume application. Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. For greenhouse and nursery use. Apply at 7-day intervals. Do not apply more than 52.4 fl oz of concentrate/acre/year. Do not mix with EC formulations or oils. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. Must contact insect, so thorough coverage is important. Repeat weekly as needed up to 3 times. Test for phytotoxicity. Do not spray new transplants or newly rooted cuttings. Do not add adjuvants. fluvalinate E. (Mavrik Aquaflow) Wellmark 12 3 lambda-cyhalothrin* F. (Scimitar GC) Syngenta 24 3 permethrin G. (Astro) FMC 12 3 potash soap# A. (M-Pede) Dow Agro Sciences 12 — Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. PBO = piperonyl butoxide Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. Check with certifier to determine which products are organically acceptable. Restricted use material. Permit required for purchase or use. Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Leafhoppers and Sharpshooters (5/10) 140 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES LEAFMINERS (5/10) Pea leafminer: Liriomyza huidobrensis Serpentine leafminer: Liriomyza trifolii DESCRIPTION OF THE PESTS Adult leafminers are small (1.8 mm), yellow and black flies that are about the same size and shape as fruit flies. In contrast to shore flies, leafminer adults are brightly colored and have clear wings. They are often found on yellow flowers or objects. Females insert their eggs within leaves and also puncture the leaf surface with the ovipositor to feed on damaged plant tissue. Larvae have three instars, forming larger mines inside the leaves as they grow. Liriomyza trifolii mines are readily observed from the top of the leaf, while Liriomyza huidobrensis mines may only be visible from the underside of the leaf. Liriomyza huidobrensis mines tend to follow the veining pattern of the leaf. After completing their feeding, larvae drop from leaves to pupate in the soil. Liriomyza trifolii can complete one generation in 14 days at 95°F, 64 days at 59°F. DAMAGE When populations are high, stippling, caused by females puncturing the leaves with their ovipositor to feed and lay eggs, can be serious. However, most of the damage is caused by the larval mines that detract from the aesthetic value of the crop. MANAGEMENT Biological Control Biological control normally keeps these species in check in outdoor situations. Outbreaks of leafminers frequently occur following the disruption of their parasites with broad-spectrum insecticides. For this reason, try to use selective insecticides through the entire production cycle so that parasites can be conserved. The parasites Diglyphus spp. and Dacnusa sibirica are commercially available to control leafminers and may be useful in greenhouse situations, especially if greenhouses are screened to exclude adult leafminer movement into greenhouses. For more information, see BIOLOGICAL CONTROL. Cultural Control Because leafminers feed on a large variety of plant species, keep production areas free of weeds, which can serve as reservoirs for leafminer populations. Leafminers breed in weed or crop hosts outside of greenhouses, so weed management outside the greenhouse and exclusion of immigrating adults are especially valuable as management practices. Effective screens require a pore width of 600 microns or smaller. Carefully inspect plants being brought in to start a new crop to ensure that they are free of mines; discard infested plants or leaves. Steam planting beds immediately after removing infested plantings to eliminate leafminer pupae in the soil. Monitoring and Treatment Decisions Yellow sticky cards placed in greenhouses will capture adults. Place one trap per 10,000 sq. feet and monitor weekly. For more information, see MONITORING WITH STICKY TRAPS and ESTABLISHING ACTION THRESHOLDS. Insecticide resistance is so widespread that the effectiveness of each material depends on the tolerance of each treated population. Rotation to a new class of insecticides every 1 to 2 months is advised. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Pesticide Class (trade name) insect growth regula- A. azadirachtin (Azatin XL) tor B. azadirachtin (Ornazin 3%EC) Major Insect and Mite Pests Manufacturer REI1 OHP 4 SePRO 12 Mode of action2 Comments un Must contact insect. Repeat applications as necessary. Label permits low-volume application. un Do not exceed 22.5 oz/acre/application. Leafminers (5/10) 141 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES C. cyromazine (Citation 75 WP) Syngenta 12 17 D. novaluron (Pedestal) Chemtura 12 15 E. pyriproxyfen (Distance) Valent 12 7C macrocyclic lactone A. abamectin (Avid 0.15EC) Syngenta 12 6 Label permits low-volume application. neonicotinoid A. acetamiprid (TriStar 70WSP) Cleary 12 4A Apply as a foliar spray. B. dinotefuran (Safari) 20G C. imidacloprid (Marathon 1G) (Marathon II) Valent 12 4A OHP 12 4A Syngenta 12 4A Can be applied as a drench or foliar spray. Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. As above. Apply only as a drench. Can be applied as a drench or foliar spray. A. acephate (Orthene T, T&O Spray3) Valent 24 1B B. acephate (PT 1300) (Orthene TR) A. permethrin (Astro) Whitmire MicroGen 24 1B FMC 12 3 pyrrole A. chlorfenapyr (Pylon) OHP 12 13 spinosyn A. spinosad (Conserve SC) Dow Agro Sciences 4 5 (Marathon 60 WP) D. thiamethoxam (Flagship) 25WG organophosphate pyrethroid 1 2 3 * Certification training required to use this product. Also effective against fungus gnat larvae. Labeled for low volume applications. Use no more than twice per year and don't exceed 52 oz/acre/year. Don't use on poinsettia. Do not apply more than 2 times per cropping cycle or per 6 months. A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol for greenhouse use only. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. Greenhouse use only. Do not exceed 3 applications/growing cycle. Do not apply more than 10 times in a 12month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. This material is effective, but not specifically labeled for this pest. Restricted use pesticide. Permit required for purchase or use. Major Insect and Mite Pests Leafminers (5/10) 142 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES LEAFROLLERS (5/10) Fruittree leafroller: Archips argyrospila Light brown apple moth: Epiphyas postvittana Obliquebanded leafroller: Choristoneura rosaceana Omnivorous leafroller: Platynota stultana DESCRIPTION OF THE PESTS Fruittree leafroller and omnivorous leafroller are the primary leafrollers found in nursery stock, but obliquebanded leafroller and orange tortrix can also be found. There are other leafrollers such as Amorbia or western avocado leafroller, Amorbia cuneana, which attacks avocado primarily, and light brown apple moth (Epiphyas postvittana), which has been detected in California but is not established in the state. Fruittree leafrollers have one generation per year. Overwintering eggs hatch in spring, and larvae can be found feeding on leaves until about June. The larvae are dark green caterpillars with black heads. Adult moths appear in June or July and lay the overwintering eggs. The fruittree leafroller overwinters in flat egg masses on scaffold limbs and twigs. Eggs hatch in spring from March to as late as mid-May in cooler areas. Young larvae are dark green caterpillars with black heads. As the larva matures, its head turns dark brown and the plate immediately behind the head becomes a tan to olive-green color. Larvae roll a leaf and web it together to form a protective shelter. At maturity the larvae are 0.75 to 1 inch long. When disturbed, they wiggle backwards and drop to the ground on a silken thread. The pupa is just under 0.5 inch long, light to dark brown, and is usually formed within the rolled leaf. The adult moth has a wingspan of less than one inch. Like other leafrollers, its wings have a bell-shaped outline when viewed from above. The forewings are mottled shades of brown and tan with gold-colored flecks, while the hind wings are whitish to gray. Omnivorous leafrollers generally overwinter as adults, emerging in March. Caterpillars may differ in body color from cream to brown with light brown to black head capsules and resemble other tortricid species, except that they have white, slightly convex and oval tubercles at the base of each bristle on the upper side of the abdomen. Mature larvae are about 0.6 inch (1.5 cm) long and are green to cream colored but so translucent that you can see the main blood vessel running down their backs. Adults are small, dark brown moths, 0.375 to 0.5 inch long with a dark band on the wing and a long snout. Female moths lay overlapping eggs in clusters that resemble fish scales on the upper surface of leaves. Often eggs are laid on weed hosts such as horseweed, common lambsquarters, little mallow, curly dock, and legumes. Omnivorous leafroller has four to six generations per year depending on climatic conditions. Obliquebanded leafroller may be the most common leafroller found in the Sacramento Valley. It has two generations per year in the Sacramento Valley. Larvae are yellowish green caterpillars with brown to black heads. The obliquebanded leafroller appears about the same time in spring as the fruittree leafroller and resembles the fruittree leafroller as a larva. The obliquebanded leafroller, however, has multiple generations each year and is present throughout the summer. Adults (moths) of obliquebanded leafrollers are reddish brown and have alternating light and dark brown bands across their forewings. Obliquebanded leafroller overwinters as larvae in the bud scales of twigs. They begin emerging in mid-May in warmer districts to early June in cooler areas. There are two to three generations each year. Another leafrolling caterpillar, orange tortrix, occurs throughout the year. As a larva, it is about 0.5 inch long when mature and varies in color from light green to tan. The activities of orange tortrix and obliquebanded leafrollers are similar to those of the fruittree leafroller, but unlike the fruittree leafroller, which overwinters in the egg stage, these two species overwinter as larvae. Light brown apple moth, an exotic pest native to Australia, has been detected in California but has not been established here. Because it is a quarantine pest with special requirements regarding inspection and treatment, consult the University of California's online publication (PDF) and the California Department of Food and Agriculture (CDFA) website or a County Agricultural Commissioner. The light brown apple Major Insect and Mite Pests Leafrollers (5/10) 143 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES moth larvae cannot be reliably identified using morphological characters with our current knowledge. Deliver suspect larvae (see field identification guide PDF) to CDFA, usually via a county agricultural commissioner, for proper identification. The most efficient and reliable way of obtaining male adults is with the use of light brown apple moth pheromone traps. There are many native tortricids that can be confused with this pest. If you find a tortricid moth in a light brown apple moth pheromone trap, take it to your county agricultural commissioner's office for positive identification. DAMAGE Leafrollers, which can feed on leaves and flower buds, are generally minor pests in ornamental nursery crops but can be a serious defoliating pest when populations are high. In spring, small larvae spin webs and feed on new foliage. They can attack a wide variety of trees including deciduous and live oaks, ash, birch, California buckeye, box elder, elm, locust, maple, poplar, and willow. Roses can also be targets. MANAGEMENT Regular monitoring each season is important so that prompt action can be taken if damaging populations develop. Throughout the year, watch for the presence of leafrollers while monitoring for other pests. Biological Control A number of general predators, such as lacewing larvae, assassin bugs, tachinid flies, and wasp parasites attack leafroller larvae or eggs. These natural enemies help keep fruittree leafroller populations at low, nondamaging levels, but occasional outbreaks occur. Preservation of natural enemy populations is an important part of keeping leafroller numbers low. Use selective materials that are least disruptive of biological control when treating these and other pests. Monitoring Inspect plants during the winter period for egg masses. Egg masses are about the size of a thumbprint and laid on smooth wood. Also check blooms and leaves for the presence of the leafroller and other larvae. To monitor caterpillars, search the outer canopy. Begin checking once a week starting from the spring leaf flush. Closely examine blossoms and vegetative shoots in the nursery in the spring for the presence of caterpillars, webbed or rolled leaves, or feeding damage. Decisions to treat the larval stage of the leafrollers should be based on the presence of caterpillars observed from periodic visual inspection of the plants. Treatment Decisions If damaging populations are observed, a number of environmentally friendly chemicals are effective in controlling this pest, including Bacillus thuringiensis and spinosad (Entrust, Conserve). Bacillus thuringiensis (Bt) is only effective on fruittree leafroller larvae when they are small (less than 0.5 inch long) and usually requires more than one application. Caterpillars must ingest the pesticide to be killed. Spinosad is a material that is effective on young larvae and is often preferred over Bt because it has a longer residual and slightly more efficacious against older larvae. The stomach poison cryolite is specific to foliage-feeding pests. These insecticides are relatively nontoxic to parasites that attack the caterpillars and beneficial insects and mites that feed on other citrus pests. Carbaryl (Sevin) can be effective against leafroller larvae. Optimum control and a minimum amount of damage by fruittree leafrollers occur when a spray is applied at the time of larval hatching or shortly afterwards. To determine this time, inspect twigs showing flushes of new foliage and look for feeding injury and the small caterpillars. If egg masses are found, check them regularly for signs of larval exit holes. High-pressure spray is needed to force the material into the leaf rolls and other protected areas where larvae are found. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Major Insect and Mite Pests Leafrollers (5/10) 144 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class Pesticide (trade name) biological A. Bacillus thuringiensis ssp. kurstaki# (various products) carbamate A. carbaryl* (various) insect growth regula- A. diflubenzuron (Adept 25WP) tor mineral spinosyn 1 2 A. cryolite (ProKil Cryolite 96) (Kryocide 96WP) A. spinosad (Conserve SC) Manufacturer REI1 Mode of action2 Comments Valent 4 11 Bayer 12 1A Chemtura 12 15 Gowan Cerexagri Dow Agro Sciences 12 12 4 un un 5 Most effective against early instar larvae; pheromone trapping recommended for timing applications. Include vegetable oil at the rate of 1 qt/acre. Do not apply after petal fall. Do not exceed 2 applications in any given season. Allow 21 days between applications. Do not apply more than 10 times in a 12month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. # Acceptable for use on organically grown ornamentals. * Restricted use pesticide. Permit required for purchase or use. Major Insect and Mite Pests Leafrollers (5/10) 145 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ROOT MEALYBUGS (5/10) Rhizoecus spp. DESCRIPTION OF THE PESTS Root mealybugs are belowground dwelling mealybugs that feed on the roots of plants. These mealybugs have a thin, uniform waxy coating and lack the terminal wax filaments typical of their foliar-feeding relatives. DAMAGE The only outward sign of root mealybug feeding may be a decline in the health of infested plants. When plants are removed from the pot, the whitish mealybugs feeding on the roots are then observed. MANAGEMENT Biological Control Biological control has not been investigated. Cultural Control Discard infected and surrounding plants. Control ants. Monitoring and Treatment Decisions Examine plant root balls when monitoring and when plants are declining. The presence of ants climbing on the plant can also indicate a problem with mealybugs. Rogue and discard infected plants. Treat with a soil drench or discard the surrounding plants. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class botanical neonicotinoid organophosphate pyrethroid Pesticide (trade name) pyrethrin/PBO3 A. (PT Pyrethrum TR) imidacloprid (Marathon 1G) A. (Marathon II) (Marathon 60 WP) acephate A. (Acephate 97UP) Manufacturer Whitmire MicroGen REI1 Mode of action2 Comments 12 3/— OHP 12 4A United Phosphorus 24 1B acephate B. (Orthene T,T&O Spray) Valent bifenthrin A. (Talstar Professional) FMC cyfluthrin B. (Decathlon 20 WP) OHP fenpropathrin* C. (Tame 2.4 EC Spray) Valent Major Insect and Mite Pests An aerosol. Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. As above, but apply only as a drench. 24 1B A number of chrysanthemum varieties have exhibit ed phytotoxic reactions. In greenhouse, only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses. 12 3 Label permits low-volume application. 12 3 Label permits low-volume application. 24 3 Label permits low-volume application. Root Mealybugs (5/10) 146 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES pyrethroid/ neonicotinoid fluvalinate D. (Mavrik Aquaflow) Wellmark 12 3 permethrin E. (Astro) FMC 12 3 cyfluthrin/imidacloprid A. (Discus) OHP 12 3/4A Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. 1 Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. 2 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. 3 PBO = piperonyl butoxide. * Restricted use material. Permit required for purchase or use. Major Insect and Mite Pests Root Mealybugs (5/10) 147 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SHORE FLY (5/10) Scatella stagnalis DESCRIPTION OF THE PEST This fly breeds in overwatered conditions in association with algae. The adult is small (2 mm) and dark. The overall appearance is similar to a fruit fly; having short antennae and shorter legs than fungus gnats. The pair of dark wings has three white spots on each wing. When the fly is at rest, there appear to be five spots because the wings overlap. Small, oblong eggs are laid in algal scum where larvae feed. Shore fly larvae have no distinct head capsule, and the body is opaque yellow, white, or brown. Both the dark brown pupa and the larva have a forked air tube at the rear end. DAMAGE Large populations of shore flies can be a nuisance. Neither the adults nor larvae feed on plants. However, adult shore flies have been implicated in the spread of fungal spores in greenhouses. Fecal spots on leaves produced by resting adults can cause aesthetic damage to plants. MANAGEMENT Biological Control Biological control of shore flies has not been investigated. Cultural Control Do not overwater. Control algae growing underneath benches, along irrigation lines, and in drainage areas. Monitoring and Treatment Decisions Yellow sticky cards placed in greenhouses will capture adult shore flies, see MONITORING WITH STICKY TRAPS. Because these flies do not directly feed on plants, treatment may not be essential unless there is a large nuisance population. Foggers and aerosols may be better at controlling adults than sprays. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class botanical Manufacturer REI1 Mode of Comments action2 Whitmire MicroGen 12 3/— An aerosol. Also effective against adults. OHP 4 un B. cyromazine (Citation 75 WP) Syngenta 12 17 C. diflubenzuron (Adept 25WP) Chemtura 12 15 Must contact insect. Repeat applications as necessary. Only effective on larvae. Label permits low-volume application. Certification training required to use this product. Also effective against shore fly larvae. Apply as spray or drench to top 2 inches of soil. D. pyriproxyfen (Distance) Valent 12 7C Do not apply more than 2 times per cropping cycle or per 6 months. E. s-kinoprene (Enstar II) A. imidacloprid (Marathon 1G) Wellmark 4 7A OHP 12 4A Apply prebloom. Also labeled for low volume use. Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to Pesticide (trade name) A. pyrethrin/PBO3 (PT Pyrethrum TR) insect growth regula- A. azadirachtin (Azatin XL) tor neonicotinoid Major Insect and Mite Pests Shore Fly (5/10) 148 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES bedding plants intended to be used as food crops. organophosphate (Marathon 60 WP) A. acephate (Orthene T, T&O Spray) Valent B. acephate Whitmire (PT 1300 Orthene TR) MicroGen pyrethroid 1 2 3 * As above. Apply only as a drench. A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. 24 1B 24 1B An aerosol for greenhouse use only. A. bifenthrin (Attain TR) Whitmire Micro-12 Gen 3 Check label. A fogger for greenhouse use only. B. bifenthrin* (Talstar Professional) C. cyfluthrin (Decathlon 20 WP) D. fenpropathrin* (Tame 2.4 EC Spray) E. fluvalinate (Mavrik Aquaflow) FMC 12 3 OHP 12 3 Valent 24 3 Wellmark 12 3 F. permethrin (Astro) FMC 12 3 Also effective against adults. Label permits low-volume application. Also effective against adults. Label permits low-volume application. Also effective against adults. Label permits low-volume application. Also effective against adults. Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia, and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. PBO = piperonyl butoxide Restricted use pesticide. Permit required for purchase or use. Major Insect and Mite Pests Shore Fly (5/10) 149 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SNAILS AND SLUGS (3/21) Amber snail: Novisuccinea spp., Succinea spp. Brown garden snail: Cornu aspersum =Helix aspersa =Cantareus aspersus Cellar glass-snail: Oxychilus cellarius Garden slug: Arion hortensis Gray garden slug: Deroceras reticulatum =Agriolimax reticulatus Greenhouse slug: Milax gagates Threebanded garden slug: Ambigolimax valentianus =Lehmannia valentiana Tramp slug: Deroceras invadens White garden snail: Theba pisana DESCRIPTION OF THE PESTS Snails and slugs are mollusks with similar anatomy and biology, except slugs lack an external shell. As they feed and move, slugs and snails secrete mucus, which dries to form a silvery to whitish trail that indicates these pests' presence. Note that fungus gnat larvae also leave silvery trails on growing media, which when abundant can resemble trails of slugs and snails. Snails and slugs are active mostly at night and on cool, cloudy, damp, and foggy days. On sunny days, they hide from the heat and sunlight. The only daytime clues to their presence may be chewing damage to plants and silvery to whitish trails. In mild winter areas of Southern California and coastal locations, snails and slugs are active throughout the year. During cold weather, snails and slugs hibernate in the topsoil. During hot, dry periods, snails seal their shell opening with a parchment-like membrane, often attached to containers, fences, trunks, or walls. Snails and slugs are hermaphrodites; they have both female and male reproductive parts. But generally they must mate with another mollusk of the same species in order to lay viable eggs. Brown garden snails mature in about 2 years, whereas some slugs reach reproductive maturity in about 3 to 6 months. Brown garden snail is the most common snail pest. It has a spiraling shell up to 1-1/4 inches in diameter. The shell is patterned brown, gray, tan, and yellow in bands, flecks, and swirls. Where calcium is abundant in their food or soil, the shells will be hard. However, where calcium is low, shells may be quite fragile. Adult brown garden snails can lay about 80 eggs per month in shallow depressions in growing media and topsoil, but clutches (groups of eggs) may be smaller, often 10 to 20 eggs. The spherical to teardrop-shaped eggs are 1/8 inch in diameter and initially white, but become browner as they develop. The eggs may be mistaken for certain slow-release fertilizers. Amber snails have an elongate shell up to 4/5 inch long that is translucent and mostly brown or yellowish-orange (amber colored). These semiaquatic snails occur mostly in the wetter portions of growing areas. Several Novisuccinea and Succinea species can be present and they are not reliably distinguishable to species. These snails generally feed on algae on the bench or pot, but will also feed on tender leaves and petals. Cellar glass-snail has a shiny, pale brown, translucent shell up to 1/2 inch wide. The body on top is pale blue. Cellar glass-snail is an omnivore; its food includes dead and living plants, earthworms, fungi, other snails and slugs and their eggs, and sowbugs. White garden snail has coloration and a shell shaped similar to brown garden snail, but overall it is more pale and smaller at maturity. White garden snails are about 1/2 to 3/5 inch in diameter at maturity, and rarely grow up to 1 inch. In California this introduced pest is established in San Diego County and has been found in Los Angeles and Orange counties. Slugs of various species can be pests in greenhouses and nurseries. These include, garden slug, gray garden slug (gray field slug, or milky slug), greenhouse slug, threebanded garden slug, and tramp slug. For more information consult California Pest Snails and Slugs, Slugs: A Guide to the Invasive and Native Fauna of California, and Terrestrial Mollusc Tool. DAMAGE Snails and slugs chew and feed on algae, decaying organic matter, and various living plants. They chew irregular holes in leaves or entirely clip off succulent plant parts. They sometimes chew flowers, fruit, Snails and Slugs (XX/21) 150 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES roots, and tender bark. They make shiny to whitish trails on plants and other surfaces where their dark to pale feces may also be found. Because they prefer humid or moist conditions and prefer to feed on succulent plant parts, they are primarily pests of herbaceous and low-growing plants and seedlings. Quarantines prohibit the sale and shipment among counties and states of plants infested with the introduced brown garden snail, white garden snail, other exotic snails or slugs, and commonly all mollusks. MANAGEMENT Employ a combination of methods for effective snail and slug management: • Eliminate where feasible the places where snails and slugs can hide during the day. Boards, debris, stones, leafy branches growing close to the ground, weedy areas, and dense ground covers such as ivy are ideal sheltering spots. Reducing hiding places allows fewer snails and slugs to survive. • Inspect regularly the remaining places where slugs and snails seek shelter. The survivors will congregate there for spot control, such as by handpicking. Brown garden snails are often found on nursery containers. Slugs may be found under containers. • Switch from sprinkler to drip irrigation to reduce humidity and surface moisture, making the habitat less favorable for mollusks. • Where possible, do not grow plants on wooden benches and pallets. These stay moist for a long time, tend to be good sites for growth of algae on which mollusks feed, and provide snails and slugs places to hide between the bench or pallet and containers. Biological Control Snails and slugs have many natural enemies, including parasitic flies in the families Sciomyzidae and Phoridae, mites, nematodes, pathogens, Scaphinotus spp. and other predaceous ground beetles, staphylinid beetles such as devil's coach horse (Ocypus olens), and small vertebrates such as birds, snakes, toads, and turtles. But natural enemies do not provide satisfactory control of mollusks in production nurseries. The omnivorous decollate snail (Rumina decollata) is commercially available for biological control of pest snails in Fresno, Imperial, Kern, Los Angeles, Madera, Orange, Riverside, Santa Barbara, San Bernardino, San Diego, Ventura, and Tulare counties. Because of the potential impact of the decollate snail on certain endangered and native mollusks, it cannot be released outside of the above counties. Decollate snail release in commercial nurseries is not recommended because all plants must be snail-free. In addition to feeding on other snails, decollate snails feed on some seedlings and succulent, small plants. Before shipping plants, any decollate and other snails must be removed. Cultural Control Carefully inspect new plants and propagation stock to ensure they are pest free. Reduce hiding places that allow snails and slugs to survive and thrive. Use good sanitation and keep growing areas free of clutter and weeds. Grow plants off the ground and on metal benches and not on anything made of wood. Switch from overhead irrigation to drip to reduce the wetness of growing areas that favors pest mollusks. Increase the frequency between irrigations to the extent compatible with good plant growth. Irrigate early in the day so surfaces are drier by evening when mollusks become active. Apply copper bands or screens on benches to inhibit the movement of snails and slugs from the ground to plants on benches. Handpicking. Handpicking can be very effective if done thoroughly on a regular basis and in combination with reducing the places where mollusks can hide. Snails and slugs can be controlled and monitored using trap boards positioned throughout the nursery as discussed below. Crush and dispose of mollusks in covered containers away from crops. Snails and slugs may also be killed before disposal by dropping in a bucket with soapy water or diluted ammonia (5 to 10% solution). Do not apply salt to destroy snails and slugs as salt can increase soil salinity. Organically Acceptable Methods Biological and cultural controls are organically acceptable management methods. Bordeaux mixture, copper sulfate, and iron phosphate are organically acceptable molluscicides. Chemical Control Snails and Slugs (XX/21) 151 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Baits are effective when used properly in combination with cultural management practices. Note that baits will kill predatory decollate snails if they are present. The active ingredient of most baits is ferric sodium EDTA, iron phosphate, or metaldehyde. Growers report that iron phosphate appears to be more effective and persistent where humidity is commonly high, plants are watered overhead, or rainfall is common. Monitor to determine where to apply the bait. In commercial nurseries to be most effective bait is scattered throughout planting beds and places where snails hide. The timing of any baiting is critical; baiting is less effective during cold, dry, and hot times of the year because snails and slugs are less active then. Because snails and slugs are more likely to travel and encounter any bait when soil is moist, apply bait after an irrigation. Bordeaux mixture. Properly mixed copper sulfate and hydrated lime mixture (Bordeaux mixture) can be brushed or sprayed on trunks or bench legs to repel snails and slugs. One treatment should last about a year. Adding a commercial spreader-sticker may increase the persistence of Bordeaux mixture through two seasons. Copper barriers. Slugs and snails will not cross copper unless the surface is fouled with debris or becomes heavily oxidized. Copper flashing or vertical copper screens can be erected around planting beds to prevent in-migration of mollusks. The screen should be 6 inches tall and buried several inches below the soil to prevent slugs from crawling underneath. Copper screens can be placed between the bench-support legs and the bench to prevent snails and slugs under the bench from reaching the top where the pots are located. Copper foil or screen wrapped around planting boxes and bench legs can repel snails for months or longer. Monitoring and Treatment Decisions Regularly inspect growing areas for slugs and snails around chewed plants on cloudy, cool, damp days or around sunrise or sunset. During the day, scout beneath dense foliage, under benches and under and on pots, in nearby weeds, under edges of nursery mats, and other protected locations that are dark, moist, and near growing media, organic litter, or the ground. Slugs commonly are found under pots and in growing media. Snails are commonly found attached to the less-exposed sides of plant containers. Amber snails tend to remain on the surface of planting medium. Look for these on pot surfaces and where moist planting medium and dry areas (e.g., the container) meet, generally around the inner lip or head space of containers. Snails and slugs seek cover during daylight and can be trapped under slightly raised boards positioned throughout the nursery. Traps can be made of lumber about of 12 x 15 inches or any convenient size or similar material. Raise traps off the ground with 1-inch runners to facilitate pest movement to the shaded underside. After counting and recording the number of mollusks trapped, scrape off snails and slugs daily and dispose of them by crushing or killing in soapy water or dilute ammonia solution as described above. A method of both control and monitoring that is effective for the brown garden snail is to place an attractive bait (e.g., containing metaldehyde) in small piles strategically around the growing areas. Nearby snails will be drawn to the bait overnight and will quickly die. The next morning, the number of dead snails can be counted to help identify locations where snails are most abundant. As with the trapboard method above, repeated over time the use of bait piles allows comparisons of whether brown garden snail numbers are increasing or decreasing. If dogs wander the nursery, they may feed on and be poisoned by exposed metaldehyde bait; place the metaldehyde in a way that it is accessible to the snails but not the dogs, such as in a commercial bait trap. Snails and Slugs (XX/21) 152 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount per acre REI‡ (hours) PHI‡ (days) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used. A, IRON PHOSPHATE (Sluggo Slug and Snail Bait)# 24–44 lb 0 0 MODE OF ACTION GROUP NUMBER1: — COMMENTS: Can be more effective and persistent during prolonged wet conditions in comparison with metaldehyde. Reapply as bait is consumed or at least every 2 weeks while snails and slugs are active. B. METALDEHYDE (Durham Ornamental 3.5) 1 lb 12 NA ( Metarex 5) 8–25 lb 12 NA MODE OF ACTION GROUP NUMBER1: — COMMENTS: Reapply at 21 day intervals while snails and slugs are active. Broadcast per label instructions; do not apply in piles or strips unless using as a monitoring method. C. METHIOCARB* (Mesurol 75W) 2 lb/100 gal 24 0 MODE OF ACTION GROUP NUMBER1: carbamate (1A) COMMENTS: Danger signal word. Can only be applied twice in a cropping cycle. Do not apply or allow to drift to blooming crops or weeds. Should only be used as a rescue treatment. D. SODIUM FERRIC EDTA (Ferroxx) 5–20 lb 0 0 MODE OF ACTION GROUP NUMBER1: — COMMENTS: For terrestrial uses only. Do not allow water from treated fields that flooded to enter surface waters or drinking waters. Do not contaminate water when disposing of equipment wash water or rinse water. Spot apply near pots instead of broadcasting. May damage contacted, succulent leaves. E. BORDEAUX MIXTURE# 0.5:0.5:100 1 lb See label — MODE OF ACTION GROUP NUMBER1: Multi-site contact (M 01) COMMENTS: Apply only as a dilute spray to plant containers and nearby surfaces. Do not mix with microbial pesticides; contact with bacterial or fungal pesticides prevents efficacy of the microbial products. Can be phytotoxic to plant tissues. For how to prepare Bordeaux mixture see Pest Notes: Bordeaux Mixture. Check copper label to determine if acceptable in organic production. F. COPPER SULFATE (Cuproxat FL)# 1 pt/100 gal 48 — MODE OF ACTION GROUP NUMBER1: Multi-site contact (M 01) COMMENTS: Apply only as a dilute spray to plant containers and nearby surfaces. Do not mix with microbial pesticides; contact with bacterial or fungal pesticides prevents efficacy of the microbial products G. COPPER OXIDE (Nordox) 1 lb/100 gal 24 0 MODE OF ACTION GROUP NUMBER1: Multi-site contact (M 01) COMMENTS: Apply only as a dilute spray to plant containers and nearby surfaces. Do not mix with microbial pesticides; contact with bacterial or fungal pesticides prevents efficacy of the microbial products. ‡ Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode of action group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://irac-online.org/. Acceptable for organically grown produce. Permit required from county agricultural commissioner for purchase or use. Unknown 1 # * — Snails and Slugs (XX/21) 153 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SOFT SCALES (5/10) Black scale: Saissetia oleae Brown soft scale: Coccus hesperidum Green shield scale: Pulvinaria psidii Hemispherical scale: Saissetia coffeae DESCRIPTION OF THE PEST Soft scales are typically found on woody and foliage plants. The first nymphal instar is called a crawler and has functional legs, while the remaining instars are attached to the leaf or twig and (with the exception of green shield scale) do not move. These scales typically have a more conspicuous profile from the side view compared with armored scales and produce copious honeydew. The protective covering over a soft scale cannot be separated from its body. Brown soft scale adults are fairly flat in profile, range in color from yellowish green to brown, and are often spotted or mottled to uniform brown. Hemispherical scale adults are round, hard, brown, smooth and shiny. Black scale adults are globular and hardened with ridges on the back that look like the letter "H". Green shield scale, introduced into California in the early 1990s, has a light yellow-green color as an immature. Female green shield scales produce a mass of eggs in a cottony ovisac without mating (i.e., reproduction is parthenogenetic and there are no males). DAMAGE Soft scales remove sap from plants and cause yellowing of leaves and overall plant decline. Green shield scale ovisacs and the honeydew excreted by all the soft scales disfigure plants. Honeydew allows the growth of black sooty mold fungi and attracts ants. Ants may then carry scales to uninfested plants as well as protect them from natural enemies such as predators and parasites. MANAGEMENT Biological Control The black scale parasite, Metaphycus helvolus, has also been used for control of the closely related hemispherical scale. The mealybug destroyer, Cryptolaemus montrouzieri, is known to be an effective predator of green shield scale. Green shield scale, however, is a CDFA "B" rated quarantine pest, so plant material must be entirely free of the scale to be shipped. For more information, see BIOLOGICAL CONTROL. Cultural Control Exclusion of windblown crawlers can be accomplished by covering openings to the greenhouse with fine mesh screens. Prune out and discard heavily infested plant parts. Control ants. Monitoring and Treatment Decisions Visual inspection of plants will help locate infestations and may permit localized treatments of hot spots. The presence of ants climbing on the plant can also indicate a problem with scales. To monitor the crawler stage, place double-sided sticky tape around stems. Treatment is generally warranted when scales are present. Optimum treatment timing is when crawlers are active; however, this can be difficult when there are overlapping, multiple generations. Multiple applications are generally necessary. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class insect growth regulator Pesticide (trade name) pyriproxyfen A. (Distance) s-kinoprene B. (Enstar II) Major Insect and Mite Pests Manufacturer REI1 Valent 12 Wellmark 4 Mode of action2 Comments Do not apply more than 2 times per crop7C ping cycle or per 6 months. Apply prebloom. Also labeled for low vol3 ume use. Soft Scales (5/10) 154 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES neonicotinoid acetamiprid A. (TriStar 70WSP) imidacloprid (Marathon 1G) B. (Marathon II) oil3 Apply as a foliar spray. Cleary 12 4A OHP 12 4A (Marathon 60 WP) OHP 12 4A clarified hydrophobic extract of neem oil# A. (Triact 70) OHP 4 un Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. As above. Apply only as a drench. Do not spray plants under stress. Target pest must be completely covered with spray. Check label for list of plants that can be treated. May cause injury to flowers. 4 horticultural oil Ultra-Fine Oil organophosphate SafTSide B. JMS Stylet Oil acephate A. (Acephate 97UP) acephate (Orthene T, B. T&O Spray) acephate C. (PT 1300 Orthene TR) malathion D. (various) 1 2 Whitmire Micro-12 Gen 4 Brandt JMS Farms 4 United Phosphorus 24 — — — Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. 1B Valent 24 Whitmire MicroGen 24 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouses only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. 1B An aerosol for greenhouse use only. various 1B Not for greenhouse use. 12 Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. 3 Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. 4 Check with certifier to determine which products are organically acceptable. * Restricted use material. Permit required for purchase or use. # Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Soft Scales (5/10) 155 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES THREAD-FOOTED (TARSONEMID) MITES (5/10) Broad mite: Polyphagotarsonemus latus Bulb scale mite: Steneotarsonemus laticeps Cyclamen mite: Phytonemus pallidus DESCRIPTION OF THE PESTS Thread-footed mites are tiny and cannot be readily seen without magnification (20X to 40X). The life stages of these thread-footed mites are: egg, nymph, pseudopupa, and adult (one less stage than for spider mites). Eggs of the cyclamen mite are one-half the length of the adult and are oval shaped. Eggs of the closely related broad mite are distinguishable from cyclamen mite eggs by rows of white pegs on the egg's upper surface. Immature stages of these mites are white. These mites get the name "thread-footed" from the appearance of the hind pair of legs in the adult female, which is threadlike; adult males, on the other hand, have stout legs for clasping the female. Adult males carry female pseudopupae on their back. As soon as the adult female emerges, they mate. Cyclamen mite is generally found feeding on growing terminals, in buds, or on unfolding leaflets. Their development is optimal under moderately warm (60° to 80°F) temperatures and high humidity (80 to 90%). Broad mite is similar to cyclamen mite, but is generally found mostly on the undersides of plant leaves. Mites disperse between plants on air currents and by mechanical transport such as on worker's clothing. These mites can complete one generation in 7 to 21 days, depending on temperature. Female bulb scale mites lay up to 28 eggs. Adults are usually found between the scales of the bulb and the neck region. Bulb mites overwinter in bulbs between the scales, emerging as the leaves grow. They re-enter bulbs as the bulbs dry in the field. One generation can be completed in about 7 weeks under field conditions. DAMAGE Feeding by cyclamen and broad mites is easily recognized on all hosts because affected leaves become characteristically cupped, dwarfed and thickened, and the internodes are greatly shortened. Broad mite damage occurs more generally over the plant than cyclamen mite damage. Bulb scale mites feeding in developing shoots can cause longitudinal bronze streaks of discoloration, horizontal cracks, distortion, and death of leaves and flowers. MANAGEMENT Use good sanitation practices and biological and chemical controls to manage thread-footed mites. Biological Control Neoseiulus californicus and other species of predatory mites have been used for broad mite and cyclamen mite control. For more information, see BIOLOGICAL CONTROL. Cultural Control Because these mites feed on a large variety of plant species, keep production areas free of weeds that can serve as hosts for mite populations. Carefully inspect plants being brought in to start a new crop to ensure that they are free of pests, and disinfest the plants if needed. Disinfestation can be accomplished by immersing propagation stock in 110.3°F water for 30 minutes, or treatment at 100% relative humidity and 110.3°F for 1 hour. If hot spots of these mites are found in production areas, consider roguing affected plants and treating the surrounding plants. Monitoring and Treatment Decisions Visually inspect plants for typical damage symptoms as part of a weekly scouting program. Major Insect and Mite Pests Thread-footed (Tarsonemid) Mites (5/10) 156 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Pesticide Class (trade name) macrocyclic lactone A. abamectin (Avid 0.15EC) oil3 A. clarified hydrophobic extract of neem oil# (Triact 70) B. horticultural oil4 (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil) Manufacturer REI1 Syngenta 12 Mode of action2 Comments 6 Label permits low-volume application. OHP 4 un Whitmire MicroGen Brandt JMS Farms 12 — 4 4 — — pyridazinone A. pyridaben (Sanmite 75WP) BASF 12 21A soap3 A. potash soap# (M-Pede) Dow Agro Sciences 12 — 1 2 3 4 * # Do not spray plants under stress. Target pest must be completely covered with spray. Check label for list of plants that can be treated. May cause injury to flowers. Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. Use at least 2 different chemicals between applications of Sanmite. Do not use fertilizers containing boron or apply through any type of irrigation system. Do not exceed 10.67 oz/acre/application. Must contact insect, so thorough coverage is important. Repeat weekly as needed up to 3 times. Test for phytotoxicity. Do not spray new transplants or newly rooted cuttings. Do not add adjuvants. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. Check with certifier to determine which products are organically acceptable. Restricted use pesticide. Permit require for purchase or use. Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Thread-footed (Tarsonemid) Mites (5/10) 157 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES THRIPS (5/10) Greenhouse thrips: Heliothrips haemorrhoidalis Western flower thrips: Frankliniella occidentalis DESCRIPTION OF THE PESTS Thrips are tiny insects that have four featherlike wings, each consisting of a thick supporting strut with fine hairs on the front and hind edges. Thrips go through six life stages: egg, first instar, second instar, prepupa, pupa, and adult. Thrips insert eggs into plant tissue. The first two instars and the adults feed by piercing and removing the contents of individual plant cells. Western flower thrips. This thrips has three color forms that vary in abundance depending on the time of year. There is a pale form that is white and yellow, except for slight brown spots or blemishes on the top of the abdomen; an intermediate color form with a dark orange thorax and brown abdomen; and a dark form that is dark brown. The intermediate form is present throughout the year, but in spring the dark form predominates while the pale form is most abundant at other times throughout the year. The dark form is an overwintering form that is usually found in foothill or mountain areas. Its presence in greenhouses in spring indicates thrips are migrating into the houses. Western flower thrips usually feed in enclosed tissues such as flowers, buds, or growing tips. Adults also feed on pollen and on spider mites. The prepupa and pupal stages take place in the soil beneath infested plants. Females will lay male eggs if unmated and female eggs are produced once mating has occurred. Development times to complete one generation of western flower thrips varies from 11 days (77° to 87°F), to 44 days (50° to 60°F). Greenhouse thrips. Adult greenhouse thrips are tiny, black, insects with whitish to translucent wings folded back over their thorax and abdomen. Legs are also a whitish color. Nymphs are whitish to slightly yellowish in color and produce a globule of fecal fluid at the tip of their abdomen. These globules of fluid increase in size until they fall off and another one begins to form, resulting in a characteristic spotting of the infestation area with black specks of fecal material. DAMAGE Western flower thrips primarily feeds on flowers but also sometimes on new vegetative growth, whereas greenhouse thrips feeds primarily on foliage. Direct feeding damage includes streaking, spotting, and tissue distortion. On leaves, feeding often occurs along veins and appears as an outlining of the veins. Western flower thrips can vector Tomato spotted wilt virus as well as many other viruses. Western flower thrips may cause premature senescence of flowers, such as African violets, because they prematurely pollinate the flowers. On orchids, western flower thrips feeding and egg laying will leave translucent 'pimpling' spots on petals and leaves. Greenhouse thrips stipple the foliage of numerous field and greenhouse grown plants. The stippling damage caused by thrips feeding on individual cells is often confused with mite stippling. Thrips feeding is often accompanied, however, by black, varnishlike flecks of dried excrement whereas mite stippling is often accompanied by webbing or shed skins. MANAGEMENT Prevention is a good strategy in a thrips management program. Treat plants with an effective insecticide and move them to a holding area for inspection and potting. Biological Control Three commercially available predators to help control western flower thrips are the minute pirate bug, Orius tristicolor, and two predatory mites, Neoseiulus cucumeris, and Hypoaspis miles. Minute pirate bugs are polyphagous and will also feed on aphids, mites, and small caterpillars. Orius are released at a rate of 2000 to 4000 per acre, while Neoseiulus cucumeris are released at a rate of 10 to 50 mites per plant for each of 2 to 3 weeks. These mites will also feed on spider mite eggs, pollen, and fungi. Hypoaspis miles are soilinhabiting predators that feed on thrips prepupae and pupae in the soil. These mites are generally released in the soil at planting and are most successful at controlling thrips when there is plant-to-plant contact that facilitates movement of the predators between plants. A commercially available parasite of greenhouse thrips is Thripoctenus javae =Thripobius semiluteus. For more information, see BIOLOGICAL CONTROL. Cultural Control Because western flower thrips and greenhouse thrips feed on a large variety of plant species, keep production areas free of weeds, which can serve as hosts for thrips populations. Most commercially available screens Major Insect and Mite Pests Thrips (5/10) 158 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES have pore sizes slightly larger than the width of the western flower thrips thorax (145 microns), meaning that some winged adults can penetrate these openings. However, covering openings to the greenhouse with fine screens does exclude most thrips. Be sure that the ventilation system on an existing greenhouse can accommodate the reduced flow caused by a fine screen or else the system will need to be modified. Monitoring and Treatment Decisions Blue sticky cards are most attractive to western flower thrips. However, yellow cards are good predictors of western flower thrips populations, are easier to count and are more commonly used for general-purpose insect monitoring. Place yellow sticky cards vertically in the crop canopy, with the lower one-third of the trap in the leaves and the upper two-thirds above the leaves. As the crop grows, the traps will need to be raised. For more information, see MONITORING WITH STICKY TRAPS. There is little research on the most effective trap density to use or on action thresholds. Research in California greenhouse roses suggests that three traps per cultivar is adequate. In greenhouses with many different cultivars, place traps in the most sensitive varieties, usually yellow or white flowers. In large greenhouses of the same or similar cultivars, there should be at least eight traps per 100,000 square feet. The treatment threshold for roses is 25 to 50 thrips per card per week (25 for more sensitive yellow- and white-flowered varieties, 50 for reds). In other crops place one card per 10,000 square feet. Consider treating if an average of 5 to 10 thrips per card per week is present. It is important to note that correct identification of pest thrips is essential in a monitoring program. There may be several species of thrips present on a sticky card but only the western flower thrips and greenhouse thrips should be counted when making treatment decisions. Most insecticides must be applied at least two times, 5 to 7 days apart, for efficacy against western flower thrips. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class Pesticide (trade name) Manufacturer REI1 Mode of action2 Comments biological A. Beauveria bassiana# (BotaniGard 22WP) (BotaniGard ES) Laverlam 4 — botanical A. cinnamaldehyde (Cinnacure) Proguard 4 — B. pyrethrin/PBO3 (PT Pyrethrum TR) Whitmire MicroGen 12 3/— A. methiocarb* (Mesurol 75W) Gowan 24 1A OHP 4 un (Ornazin 3%EC) B. novaluron (Pedestal) SePRO Chemtura 12 12 un 15 A. abamectin (Avid 0.15EC) Syngenta 12 6 carbamate insect growth regula- A. azadirachtin tor (Azatin XL) macrocyclic lactone Major Insect and Mite Pests Treat every 7 days while insects are active. Do not tank mix with most fungicides and wait 48 hours after application to apply a fungicide. Use product within 10 days of breaking seal. Do not apply to stressed plants or newly transplanted material before roots are established. An aerosol synthetic pyrethroid that is some-times used as an irritant when mixed with other pesticides. Apply in 50 gal water. Repeat as necessary up to 4 applications/season. Do not apply with oil or foliar fertilizer. Do not use through any type of irrigation system. Must contact insect. Repeated applications as necessary. Label permits lowvolume application. Do not exceed 22.5 oz/acre/application Use no more than twice per year and don't exceed 52 oz/acre/year. Don't use on poinsettia. Label permits low-volume application. Do not use through any type of irrigation system. Thrips (5/10) 159 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES neonicotinoid A. acetamiprid (TriStar 70WSP) B. imidacloprid (Marathon 1G) (Marathon II) Cleary 12 4A OHP 12 4A Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. As above, but apply only as a drench. Must contact insect. Repeat applications as necessary. Difficult to get coverage in flowers, best for thrips on foliage. (Marathon 60 WP) 4 oil A. clarified hydrophobic extract of neem oil# (Triact 70) OHP 4 un organophosphate A. acephate (Acephate 97UP) B. acephate (Orthene T, T&O Spray) United Phosphorus Valent 24 1B 24 1B C. acephate Whitmire Mi(PT 1300 Orthene TR) croGen A. potash soap# (M-Pede) Dow Agro Sciences 24 1B 12 — A. spinosad (Conserve SC) 4 5 soap4 spinosyn 1 2 3 4 * # Dow Agro Sciences A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouses only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia, and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol for greenhouse use only. Must contact insect, so thorough coverage is important. Repeat weekly as needed up to 3 times. Test for phytotoxicity. Do not spray new transplants or newly rooted cuttings. Do not add adjuvants. Do not apply more than 10 times in a 12month period. Compatible with most beneficials, but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. PBO = piperonyl butoxide Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. Restricted use material. Permit required for purchase or use. Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Thrips (5/10) 160 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TWOSPOTTED SPIDER MITES (5/10) Tetranychus urticae DESCRIPTION OF THE PEST Twospotted spider mites are web-forming mites that pierce plant cells and remove their contents. All spider mites have two body segments and four pairs of legs as adults. Twospotted spider mite adults, as the name suggests, have two large dark spots on the sides of their yellowish green bodies. These mites lay round eggs that hatch into six-legged larvae. The subsequent stages, the protonymph and deutonymph stages, are eight-legged as are the adults. Since the entire life cycle can take as little as 8 (77° to 95°F) to 28 (50° to 68°F) days, spider mites have many generations per year and can rapidly increase in number. DAMAGE Twospotted mites suck cell contents from leaves, initially stippling leaves with a fine pale green mottling. As feeding continues, the stippling increases and leaves turn yellow with bronzed or brown areas; damaged leaves frequently fall. Undersides of leaves may have many cast skins of mites, and the webbing on foliage is unaesthetic. Plants may become severely stunted when large mite populations are allowed to feed and the plants may die. MANAGEMENT Biological Control Many different species of predatory mites are available for control of these mites under different conditions. Phytoseiulus persimilis is a commercially available predator of twospotted spider mite, and it has been used to control mite populations in greenhouses and field situations. It can reproduce faster than its prey, yet best results have been obtained when it is released into the crop well before the spider mite populations have built up. For more information, see BIOLOGICAL CONTROL. Cultural Control Because spider mites feed on a large variety of plants, keep production areas free of weeds, which can serve as hosts to the mites. Carefully inspect plants being brought in to start a new crop to ensure that they are free of mites. Rogue or treat infested plants. Monitoring and Treatment Decisions Monitor the crop regularly, as indirect sampling methods (such as sticky cards) are ineffective. Observe the undersides of leaves with a 10X hand lens, and watch for changes in plant foliage that are characteristic of mite feeding. Except as noted, the materials listed only kill active stages of mites, so more than one treatment may be necessary to break the life cycle. Follow label directions regarding reapplication times. For guidelines on when to treat, see ESTABLISHING ACTION THRESHOLDS. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class Pesticide (trade name) Manufacturer REI1 Mode of action2 Comments botanical A. cinnamaldehyde (Cinnacure) Proguard 4 — carbamate A. methiocarb* (Mesurol 75W) Gowan 24 1A Gowan 12 carboximide A. hexythiazox (Hexygon 50DF) Major Insect and Mite Pests Use product within 10 days of breaking seal. May cause phytotoxicity to tender tissue growth on plants. Do not apply to stressed plants or newly transplanted material before roots are established. Apply in 50 gal water. Repeat as necessary up to 4 applications/season. Do not apply with oil or foliar fertilizer. 10A No chemigation. Ovicidal/larvicidal action. Use only 1 time per crop or once a year. Twospotted Spider Mites (5/10) 161 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES carboxylic acid A. bifenazate (Floramite) Chemtura 12 un macrocyclic lactone A. abamectin (Avid 0.15EC) Novartis 12 6 oil3 OHP 4 un Do not spray plants under stress. Target pest must be completely covered with spray. Check label for list of plants that can be treated. May cause injury to flowers. Whitmire MicroGen Brandt JMS Farms 12 — 4 4 — — Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. A. clarified hydrophobic extract of neem oil# (Triact 70) B. horticultural oil4 (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil) Do not use in successive applications; apply at least two alternative products between treatments of bifenazate. Primarily effective against motile stages but has some ovicidal activity. Label permits low-volume application. phenoxypyrazole A. fenpyroximate (Akari) SePRO 12 21A Do not apply more than 10 gal spray/1000 sq ft/application. Do not exceed 48 oz/crop cycle or growing season, whichever is longer. pyrethroid A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) C. fenpropathrin* (Tame 2.4EC Spray) D. fluvalinate (Mavrik Aquaflow) Whitmire MicroGen Whitmire MicroGen Valent 12 3 12 3 Check label. A fogger for greenhouse use only. Label permits low-volume application. 24 3 Label permits low-volume application. Wellmark 12 3 pyridazinone A. pyridaben (Sanmite 75WP) BASF 12 21A pyrrole A. chlorfenapyr (Pylon) A. potash soap# (M-Pede) OHP 12 13 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Use at least 2 different chemicals between applications of Sanmite. Do not use fertilizers containing boron. Do not exceed 10.67 oz/acre/application. Greenhouse use only. Do not exceed 3 applications/growing cycle. Dow Agro Sciences 12 — soap3 spinosyn 1 2 A. spinosad (Conserve SC) Dow Agro Sciences 4 5 Must contact mite, so thorough coverage is important. Repeat weekly as needed up to 3 times. Test for phytotoxicity. Do not spray new transplants or newly rooted cuttings. Do not add adjuvants. Miticidal activity of this material is due mainly to the surfactants and other inert ingredients. This material is not recommended for use against mites unless control is also needed for other pests (caterpillars, leafminers, thrips) against which the active ingredient in this product is effective. Do not apply more than 10 times in a 12-month period. Compatible with most beneficials but highly toxic to bees and hymenopteran parasites. Direct contact can cause significant mortality to Phytoseiulus persimilis. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should Major Insect and Mite Pests Twospotted Spider Mites (5/10) 162 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 3 4 * # be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. Check with certifier to determine which products are organically acceptable. Restricted use pesticide. Permit require for purchase or use. Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Twospotted Spider Mites (5/10) 163 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES WHITEFLIES (5/10) Greenhouse whitefly: Trialeurodes vaporariorum Silverleaf whitefly: Bemisia argentifolii (=Bemisia tabaci B-biotype) DESCRIPTION OF THE PESTS Greenhouse whitefly. The greenhouse whitefly adult is 0.9 (male) to 1.1 mm (female) long, with four wings, sucking mouthparts, a powdery waxy coating over the body, and wings that give the otherwise yellow body a white color. The wings are held nearly parallel to the leaf and cover the abdomen when the adult is at rest. There are seven life stages: egg, four nymphal instars, pupal stage, and the adult. Females occasionally lay eggs in circles on the undersides of leaves of plants with smooth leaves. Egg laying on plants with pubescent leaves results in random placement of the eggs. Eggs are partially inserted into the leaf, initially they are yellowish, but close to hatching they turn a purplish brown. The first nymphal instar is called a crawler and has functional legs, while the remaining instars are attached to the underside of the leaf and do not move. The end of the fourth instar is called a pupa. The pupal stage is the most important for determining whitefly species identification. Greenhouse whitefly pupae are oval and have vertical sides, giving the pupa a cakelike appearance from the side. Along the perimeter of the upper surface is a fringe of filaments and relatively large wax filaments project above the upper surface of the body. The greenhouse whitefly can complete one generation in 21 to 26 days at 81°F. Silverleaf whitefly. The silverleaf whitefly adult is 0.8 (male) to 1.0 mm (female) long, with four wings, and sucking mouthparts. The white, waxy coating covering its body and wings is not as thick as it is on the greenhouse whitefly and its yellow body has a whitish hue from the wax rather than a white color. The wings are held at the sides of the body, partially exposing the back of the abdomen when the adult is at rest. There are seven life stages: egg, four nymphal instars, pupa, and the adult. Eggs are not laid in a circular pattern, are partially inserted into the leaf, and remain yellowish until they hatch. The first nymphal instar is called a crawler and has functional legs, while the remaining instars are attached to the leaf and do not move. The end of the fourth instar is called a pupa. Silverleaf whitefly pupae are ovoid, but with a slightly pointed hind end and red eye spots easily visible from above. The pupa is fairly flat and does not have a marginal fringe of filaments. The length of wax filaments projecting above the upper surface of the body varies on different hosts. Silverleaf whiteflies can complete development in 16 (86°F) to 31 (68°F) days. DAMAGE Whitefly adults and immatures feed on sap. As they feed, they excrete honeydew, a sticky substance that causes unsightly glistening and supports the growth of black sooty mold. Very large populations of whiteflies cause stunting of plant growth, and leaves may senesce and die. Physiological abnormalities, such as white stem on poinsettia, may also occur. Usually populations are not high enough to stunt ornamentals, and damage is mostly caused by honeydew, sooty mold, and nuisance populations of flying adults. MANAGEMENT Biological Control Encarsia formosa, a tiny, stingless parasitic wasp, is as an effective biological control for greenhouse whiteflies. Wasps are released once a week at a rate of two to five parasites per plant for 8 to 10 weeks of the growing season. This sort of release program can be effective if long residual insecticides have not been applied in advance of the parasite release, and where the initial population of whiteflies is quite low (only a few whiteflies per plant). Greenhouse whitefly pupae turn black when parasitized by Encarsia, which emerge as adults through circular exit holes. Delphastus pusillus, a whitefly predator, has been used against silverleaf whiteflies. Eretmocerus eremicus is a commercially available whitefly parasite for silverleaf whitefly. It will also attack greenhouse whitefly, whereas Encarsia is ineffective against silverleaf whitefly. For more information, see BIOLOGICAL CONTROL. Cultural Control Because whiteflies feed on a large variety of plant species, keep production areas free of weeds, which can serve as hosts for whitefly populations. Exclusion of winged adults can be accomplished by covering openings to the greenhouse with screens that have a pore width of 405 microns or smaller. Before starting a new crop, carefully inspect plants to ensure that they are free of whiteflies and other pests. Treat or discard any infested plants. Major Insect and Mite Pests Whiteflies (5/10) 164 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES In open field production, mulching with silver reflective plastic has been shown to repel whiteflies, thus greatly reducing their presence in and around the plant canopy. Apply the plastic mulch at the time of planting or transplanting for best results. In addition to repelling insects and reducing the incidence of insect-transmitted diseases, reflective mulch may increase plant growth, cut-flower yield, and reduce the irrigation water and fertilizer requirement. This control method is acceptable for organic production. Monitoring and Treatment Decisions Yellow sticky cards placed in greenhouses will capture adult whiteflies. However, traps need to be used at a greater density, one per 1,000 sq. ft., than for other pests. Trap monitoring should be supplemented with inspection of leaves for nymphs and pupae. When monitoring plant samples, it is imperative to look on the undersides of leaves for adults and nymphs. For more information, see MONITORING WITH STICKY TRAPS. Treatment thresholds vary with the crop. For example, cut flowers such as gerberas can tolerate more whiteflies than poinsettias because only the flowers are harvested in the cut flower crop whereas the entire poinsettia plant is marketed. For more information, see ESTABLISHING ACTION THRESHOLDS. TREATMENT Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact. Class biological Pesticide (trade name) A. Beauveria bassiana# (BotaniGard 22WP) B. (BotaniGard ES) A. pyrethrin/PBO3 (PT Pyrethrum TR) insect growth regula- A. azadirachtin (Azatin XL) tor botanical Manufacturer REI1 Laverlam 4 Laverlam 4 Whitmire Micro-12 Gen OHP 4 Mode of Comments action2 — Treat every 7 days while insects are active. Do not tank mix with most fungicides and wait 48 hours after application to apply a fungicide. — 3/— An aerosol. un Must contact insect. Repeat applications as necessary. Label permits low-volume application. Do not exceed 22.5 oz/acre/application. B. azadirachtin (Ornazin 3%EC) C. diflubenzuron (Adept 25WP) SePRO 12 un Chemtura 12 15 Whitefly suppression. May damage poinsettias if used over labeled rate. Also effective on fungus gnat larvae and lepidopteran larvae. D. novaluron (Pedestal) Chemtura 12 15 Use no more than twice per year and don't exceed 52 oz/acre/year. Don't use on poinsettia. E. pyriproxyfen (Distance) F. s-kinoprene (Enstar II) Valent 12 7C Wellmark 4 7A Do not apply more than 2 times per cropping cycle or per 6 months. Apply prebloom. Also labeled for low volume use. Syngenta 12 6 Cleary 12 4A OHP 12 4A macrocyclic lactone A. abamectin (Avid 0.15EC) neonicotinoid A. acetamiprid (TriStar 70WSP) B. imidacloprid (Marathon 1G) (Marathon II) Major Insect and Mite Pests Label permits low-volume application. Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. Whiteflies (5/10) 165 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES oil4 organophosphate pyrethroid pyridazinone pyridine soap4 1 2 3 4 (Marathon 60 WP) A. clarified hydrophobic extract of neem oil# (Triact 70) OHP 12 4 4A un B. horticultural oil5 (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil) A. acephate (Acephate 97UP) As above. Apply only as a drench. Do not spray plants under stress. Target pest must be completely covered with spray. Repeat application as necessary. Check label for list of plants that can be treated. May cause injury to flowers. Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. Whitmire MicroGen Brandt JMS Farms United Phosphorus 12 — 4 4 24 — — 1B B. acephate (Orthene T, T&O Spray) Valent 24 1B C. acephate (PT 1300 Orthene TR) D. malathion (various) A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) Whitmire MicroGen various 24 1B A number of chrysanthemum varieties have exhibited phytotoxic reactions. In the greenhouse, only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses. An aerosol for greenhouse use only. 12 1B Not for greenhouse use. Whitmire MicroGen FMC 12 3 12 3 Check label. A fogger for greenhouse use only. Label permits low-volume application. C. cyfluthrin (Decathlon 20WP) D. fenpropathrin* (Tame 2.4EC) E. fluvalinate (Mavrik Aquaflow) OHP 12 3 Label permits low-volume application. Valent 24 3 Label permits low-volume application. Wellmark 12 3 F. permethrin (Astro) FMC 12 3 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, dieffenbachia and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. A. pyridaben (Sanmite 75WP) A. pymetrozine (Endeavor) BASF 12 21A Syngenta 12 9B A. potash soap# (M-Pede) Dow Agro Sciences 12 — Apply as foliar spray at 7-14 day intervals. For outdoor use, do not apply more than 48 oz/acre/year; for indoor use, do not use more than 100 oz. Must contact insect, so thorough coverage is important. Repeat weekly as needed up to 3 times. Test for phytotoxicity. Do not spray new transplants or newly rooted cuttings. Do not add adjuvants. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/. PBO = piperonyl butoxide Note that single doses of soaps or oils can be used at anytime in a pesticide rotation scheme without negatively impacting resistance management programs. Major Insect and Mite Pests Whiteflies (5/10) 166 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 5 * # Check with certifier to determine which products are organically acceptable. Restricted use pesticide. Permit required for purchase or use. Acceptable for use on organically grown ornamentals. Major Insect and Mite Pests Whiteflies (5/10) 167 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Nematodes (Section reviewed 3/21) Foliar nematodes: Aphelenchoides fragariae and A. ritzemabosi Root-knot nematode: Meloidogyne spp. DESCRIPTION OF THE PESTS Nematodes are typically tiny (usually microscopic), unsegmented roundworms. At maturity, they commonly are 1/100 to 1/25 inch (0.25 to 1 mm) long. Depending on the type of nematode, they feed on or inside bulbs, leaves, seeds, stems, or roots. Root-knot nematodes (Meloidogyne spp.) are the most prevalent nematodes attacking floricultural and nursery crops. Foliar nematodes (Aphelenchoides spp.) and lesion nematodes (Pratylenchus spp.) can also cause problems. However, there are numerous other nematodes, both ectoparasitic (feed externally on plants) and endoparasitic (enter plant tissues to feed and reproduce) that can attack floricultural and nursery crops. Because growing media used in containers is commonly pasteurized, soil-dwelling nematodes primarily cause problems in field crops. Plant-parasitic nematodes generally hatch from an egg and develop through four juvenile stages before maturing into adults. Most species are active at temperatures from about 60° to 85°F. Feeding stages pierce plant cells and withdraw the contents. They also inject enzymes and other chemicals that breakdown cells and can change the appearance and physiology of plants. Tissues injured by nematode feeding become increasingly susceptible to infection by pathogenic bacteria, fungi, and oomycetes. Certain species of plant-parasitic nematodes vector some plant viruses. Root-knot Nematodes Root-knot nematodes occur throughout California and most of the United States. The second-stage larvae occur in soil, are mobile, and can enter roots. Once inside the roots, they become immobile near vascular cells where they induce feeding sites (giant cells). While the root swells to form galls, within those structures the nematodes further develop through three molts into mature females. Each of those pear-shaped females can produce up to 400 eggs in a protective gelatinous mass that protrudes from the surface of roots. Second-stage larvae hatch from eggs to repeat the cycle, or eggs can remain viable in the soil and hatch during the next crop or growing season. The time from root invasion to egg development is determined mostly by temperature, but also depends on the nematode species and host crop. Root-knot nematodes are the most common pests of plants grown in warm, sandy, irrigated soils. The particular Meloidogyne species that are active can depend on cropping history, geographical location, and seasonal temperature. Although Meloidogyne species generally have a broad host range, there are differences between species, so cropping history can influence the species of root-knot nematodes present. See the University of California (UC), Davis Nemaplex website for more information. To tentatively diagnose an infestation, dig the plants up after they have grown for about 4 to 6 weeks in soil above 65°F. Wash or gently tap the soil from their roots and examine the roots for swellings and gnarled, restricted root growth. Cut open any galls and use a hand lens or binocular microscope to examine galls for the presence of pinhead-sized, shiny white females that look like tiny pearls. For confirmation of infection by root-knot nematodes, send roots or soil or both to a nematology laboratory. Foliar Nematodes Foliar nematodes, also called bud and leaf nematodes, prefer moderate temperatures and moist or humid conditions. Aphelenchoides fragariae and A. ritzemabosi are the leaf-infesting nematodes that attack ornamental plants in California. Ferns, strawberries, tropical foliage plants, and vegetatively propagated ornamentals are important hosts of A. fragariae. Foliar nematode damage in California occurs mostly in certain greenhouses and in fields along coastal areas where humidity is high and ornamental hosts and strawberries are grown. Foliar nematodes are tiny, about 1/50 to 1/25 inch (0.5–1 mm) long, and samples must be sent to a nematode diagnostic laboratory to confirm an infestation. Foliar nematodes infest new plants by swimming in a water film up stems and along the surface of moist plant tissue. After entering leaves through stomata, females lay their eggs in intracellular spaces in leaves. Nematodes (3/21) 168 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Foliar nematodes can mature from egg to adult in about 2 weeks, allowing many generations to develop during one growing season. Foliar nematodes can also live for a few months in soil or decomposing organic material by feeding on fungi. They typically overwinter in dormant buds, plant terminals, and soil in dead leaves that drop from infested plants. In slowly drying leaf tissue, adults of A. ritzemabosi can enter a desiccated, resting stage that allows them to survive for several years until moist conditions induce them to resume activity. See the UC Davis Nemaplex website for more information. To make an initial diagnosis, tear symptomatic tissue into small pieces and place it in a glass dish. Add just enough water to immerse the plant tissue, then cover the dish to reduce evaporation. After 24 hours, carefully examine the water under strong light using a 10X hand lens or, preferably, a binocular microscope providing higher magnification. Nematodes will appear as tiny strands moving in the water. SYMPTOMS AND DAMAGE Root-knot nematodes Root-knot nematodes cause galls or swellings on the roots of many broadleaf plants. Many weeds host root-knot nematodes. Some grasses and cereals (monocots) can be infested and are suitable hosts, but root symptoms (galls) on these crops are generally not obvious. Severely infected roots may subsequently be attacked by a variety of decay- or disease-causing microorganisms, including bacteria, fungi, and oomycetes. Aboveground symptoms are usually nonspecific, characteristic of a poorly functioning root system, and may include stunted growth, wilting, and yellowing. Although beneficial nitrogen-fixing bacteria often form nodules on the roots of legumes such as cassia, sweet pea, and vinca, these nodules rub off roots easily, whereas galls caused by root-knot nematodes are truly swellings of the roots. Also, a thumbnail can easily be pressed into a bacterial gall, but not into a gall of root-knot nematodes. To provide identification, collect galled roots and surrounding soil and send them to a nematode diagnostic laboratory. Foliar nematodes Foliar nematode damage can be confused with symptoms caused by certain bacteria, fungi, viruses, nutrient deficiencies, or chemical injuries. Nematodes may interact with certain bacteria or fungi to cause severe foliar blight. Foliar nematode damage usually begins as yellowish leaf spots that eventually turn dark green to blackish brown. Discoloring typically starts near the leaf base and spreads outward. The lesions are often angular because nematodes in leaves are initially contained between the veins. Because monocots have parallel veins, discoloring on them occurs in streaks. If young leaves or shoots are infested, they may remain undersized, become bushy or distorted, and produce little or no marketable foliage or flowers. Damaged foliage may become brittle or shrivel and drop prematurely. Damage usually appears beginning in spring (or winter in coastal areas) and becomes most severe by summer. SAMPLING NEMATODES The best time to sample nematodes for the next crop is at or around the harvest of the current crop when plants with damage symptoms are available for testing. Nematodes of most pest species are usually concentrated near or in plant roots. Unless your nematology laboratory recommends other procedures, the following method can be used. Divide the field into areas of uniform plant growth and similar soil characteristics and cropping history. Take several soil subsamples from locations scattered throughout each uniform field area. Each subsample can be about 1 pint of soil. Collect moist (not soggy) soil from the plant root zone or the upper 6 to 18 inches of soil if no crop is present. Thoroughly mix the subsamples to make a composite sample and send about 1 pint of soil for testing. Repeat this sampling procedure for each field area. If plants have symptoms, dig them up along with their roots and surrounding soil and place them in a bag for testing. Also, bag separately at least one or two plants and soil sampled from a healthy-looking part of the field and send them for comparison testing. Label each sample with field location, current crop, cropping history, crop injury observed, and your name, address, and phone number. Seal samples in plastic to prevent them from drying out and keep them cool at about 50° to 60°F until the material reaches the laboratory. Laboratories should report the genus of the nematodes that were found, the number of nematodes per unit of soil, and the extraction Nematodes (3/21) 169 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES efficiency. It is important to know the laboratory's method (and the method's efficiency) for extracting nematodes from soil. Certain techniques are not adequate for detecting the presence of specific genera of nematodes, or they provide only qualitative results, which tell you that nematodes are present but not whether they are abundant enough to cause damage. MANAGEMENT OF FOLIAR NEMATODES Grow plants in soilless media or pasteurize media before use. Propagate only nematode-free stock. Foliar nematodes are typically introduced into growing areas in cuttings, seedlings, and other vegetative propagation material that may be asymptomatic. Take cuttings only from the tops of long, vigorous growth to reduce the likelihood that it is infested. If the plants tolerate heat without damage, cuttings can be disinfected by dipping them in hot water at 122°F for 5 minutes or at 111°F for 30 minutes. Foliar nematodes infesting Easter lilies may be controlled by dipping bulblets in 125°F water for 10 minutes before planting. However, treatment at the same temperature for 20 minutes results in severe damage to the crop. Thus, to avoid damage to plants, it is critical to control both temperature and exposure time accurately. Employ proper sanitation by removing plant debris, promptly disposing of all infested plants, and eliminating weeds that can host foliar nematodes (e.g., goldenrod, groundsel, and sneezeweed) from around growing areas. To reduce the risk that foliar nematodes will spread throughout the crop by traveling in a water film on plant surfaces, avoid crowding plants and using overhead irrigation . MANAGEMENT OF ROOT KNOT AND OTHER SOIL-DWELLING NEMATODES Rotating crops, employing good cultural practices and excellent sanitation, pasteurizing growing media, and fumigating field soil before planting are the most important strategies for preventing and managing most soil-dwelling nematodes. Soil amendments and biological control products may sometimes suppress nematode populations. Post-plant nematicides for use in soil around established plants may be permissible (check the label). But it is generally more effective to employ preventive measures before planting. Sanitation and Cultural Practices Avoid introducing nematode-infested plants into growing areas. To minimize the risk of introducing nematodes with the planting stock, use only good-quality stock from a reliable supplier and, if available, from participants in the California Department of Food and Agriculture (CDFA) Nursery Services Program. Use growing media known to be free of nematodes or pasteurize growing media before use. Dispose of infested plants when found and avoid moving soil from around infested plants to healthy plants. Do not allow irrigation water from around infested plants to run off onto healthy plants, as this spreads nematodes. Unless the soil is treated first, do not plant susceptible crops in field soils where nematodes have previously been a problem. In particular, do not replant the same plant genera into the old site; rotate crops by replanting with different genera more tolerant of, or resistant to, the specific nematodes present. Provide crops with proper cultural care so that they are vigorous and better able to tolerate feeding by nematodes and other pests. More frequent irrigation of drought-stressed plants can reduce damage caused by root-knot nematodes, but it does not reduce the abundance of nematodes. Heat Pasteurization Pasteurizing media with heat, such as aerated steam, can control nematodes and other pests or pathogens in container mix and greenhouse beds. Special tractor-drawn steam rakes are available, but except for raised beds, steam is difficult to use in field soils. The heat generated by decomposer microorganisms during composting of container media can control certain nematodes, but preparing pathogen-free compost requires careful management and monitoring. Solarization In sunny, warm climates, field solarization before planting can temporarily reduce nematode populations in the upper 12 inches of soil. Solarization involves covering moist, bare soil or container mix with single or double layers of clear plastic for several weeks during hot weather. In some cases, incorporating amendments (such as compost or green manure) or applying lower than normal rates of fumigant Nematodes (3/21) 170 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES pesticides in combination with solarization can provide better control than using any single method. Correct use of "double-tent" solarization can completely eradicate plant-parasitic nematodes, most other pathogens, and weed seeds from containerized growth media. See the table of Some Flower and Nursery Crop Nematodes Controlled by Solarization of Container Mix for which nematodes are controlled in this situation. See CDFA's Nursery Inspection Procedures Manual (NIPM Item 7) and UC's Using Solarization to Disinfect Soil for Containerized Production (PDF) for details. Some Flower and Nursery Crop Nematodes Controlled by Solarization of Container Mix Common name Scientific name citrus Tylenchulus semipenetrans dagger Xiphinema spp. ring Criconemella (=Criconemoides) xenoplax root knot Meloidogyne hapla root knot Meloidogyne incognita root knot Meloidogyne javanica root lesion Pratylenchus spp. stem and bulb Ditylenchus dipsaci Source: Stapleton, J., L. Ferguson, and M. McKenry. 1998. Using solarization to disinfect soil for containerized production (PDF). U.C. Plant Protection Qtr. 8(1 & 2): 7-9 (https://ucanr.edu/sites/kac/files/123909.pdf). Hot Water Dips Hot water dips can reduce the number of nematodes and certain other pests infesting bulbs, corms, and rhizomes of crops such as amaryllis, daffodil, gladiolus, lily, and tulip. The temperature and time needed to provide sufficient control depend on the nematode species and crop variety. Exceeding the proper temperature or exposure time can damage plants, but insufficient temperatures or exposure time may not kill the nematodes. Cool plants immediately afterward with clean, cold water, then dry thoroughly in warm air or sunshine. Consider making a fungicide application after the heat treatment. After heat treatment, store the plant material under cool, low-humidity conditions until plants are used. Amendments and Biological Control Although amendments and biological control microorganisms reduce plant-parasitic nematodes in certain situations, sufficient control has been unreliable. The reasons for this variable effectiveness are not well known. To provide a basis for comparison, growers using amendments and biological control products should consider leaving several randomly selected areas of their fields untreated or treated with more conventional methods or both. Soil amendments used for nematode control can be placed into four categories: animal-based, inorganics, plant-based, and microbial. Except for inorganics (such as ammonium sulfate fertilizer and powdered rock), nematode suppression from most amendments is at least partly the result of biological control. Incorporating animal manure, compost, crop residue, and organic fertilizers increases the organic matter content of the soil. It improves water and nutrient availability to plants, reduces plant stress, and can encourage higher numbers of nematode predators and parasites. Some residues can produce by-products with nematicidal properties upon degradation. However, organic amendments sometimes contain contaminants such as weed seeds, especially in non-composted or incompletely composted materials, and their effectiveness is largely limited to the depth of material incorporation. Barley, certain legumes such as clover and vetch, French marigold, perennial rye, and other plants with bioactive properties are grown as crop rotations, cover crops, or trap crops in some row crops. These plants may sometimes reduce populations of certain soil-dwelling plant-parasitic nematodes by producing chemicals that kill or repel nematodes, stimulate premature egg hatch, suppress nematode growth, or disrupt the attraction between nematodes seeking to mate. However, crops suppressive to one species of nematode often host other nematode species. Rotating specific marigold cultivars with crops such as lilies grown for bulb production has been somewhat successful in controlling certain nematodes. The marigolds must be left in the soil, either through cultivation or by mowing the tops and leaving the roots underground. However, this practice is generally not recommended because phytotoxicity to lilies and other crops is commonly observed when they are grown in rotation after incorporating marigolds into the soil. Nematodes (3/21) 171 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Several biologically-based (microbial) nematicides are registered in California. Their efficacy for controlling root-knot nematodes has been studied in vegetable crops in Southern California. These field experiments found their effectiveness to be inconsistent at best. Organically Acceptable Methods Certain amendments and biological control products, anaerobic soil disinfestation, cultural practices, heat pasteurization, hot water dips, sanitation, and solarization are organically acceptable management methods. Fumigants A soil fumigant can be used in certain situations to reduce nematode populations before planting. Before using a fumigant, be sure that nematodes or other soil pests are the cause of your problem by having a laboratory test performed or by having an expert examine your plants and soil. Consider alternatives before using a nematicide. Be sure the nematicide is registered for that crop or growing situation. Follow label directions strictly; the improper application is not only illegal but often ineffective and may be hazardous. Fumigants such as 1,3-dichloropropene* and metam sodium* are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. (*Permit required from county agricultural commissioner for purchase or use.) Fumigate only as a last resort when other management strategies have not been successful or are not available. Soil fumigants may only be applied by a regulated, commercial applicator. Consult UC's Field Fumigation: Pesticide Application Compendium, Vol. 9, the Department of Pesticide Regulation's Addendum to the Field Fumigation Study Guide (PDF), and the office of the local county agricultural commissioner for more information. Common name Amount to use REI‡ PHI‡ (Example trade name) (hours) (days) Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used. Preplant A. 1,3-DICHLOROPROPENE*§/CHLOROPICRIN*§ (InLine, Telone C-35) Label rates See label NA COMMENTS: Multipurpose liquid fumigant for the preplant treatment of soil to control plant-parasitic nematodes, symphylans, and certain soil-borne pathogens using drip irrigation systems only. Use of a tarp seal is mandatory for all applications of this product. B. 1,3-DICHLOROPROPENE*§ (Telone EC) Label rates 5 days NA COMMENTS: Liquid fumigant for the preplant treatment of soil against plant-parasitic nematodes and certain other soil pests in cropland using drip irrigation systems only. C. CHLOROPICRIN*§ (Tri-Clor, Tri-Clor EC) Label rates See label NA D. METAM SODIUM*§ (Vapam HL, Sectagon-42) Label rates See label NA COMMENTS: Contact your farm advisor for advice on the most effective application method for a particular situation. E. METAM POTASSIUM*§ (K-PAM HL ) Label rates See label NA COMMENTS: Contact your farm advisor for advice on the most effective application method for a particular situation. F. ETHOPROP*§ (Mocap EC) Label rates COMMENTS: Apply just before planting. Make only one application per crop. 72 NA Nematodes (3/21) 172 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES G. 1,3-DICHLOROPROPENE*§ (Telone II) Label rates 5 days NA COMMENTS: Liquid fumigant for the preplant treatment of soil against plant-parasitic nematodes and certain other soil pests in cropland using drip irrigation systems only. H. DAZOMET (Basamid G) Label rates See label NA COMMENTS: Granular fumigant for preplant treatment of soil or substrates against (some) plant-parasitic nematodes. I. CHLORFENAPYR (Pylon) Label rates 12 hrs NA COMMENTS: Nematicide and Miticide only for greenhouse ornamentals and vegetables. For managing foliar nematodes (Aphelenchoides spp.) ONLY; not for control of other plant-parasitic nematodes. ‡ Restricted entry interval (REI) is the number of hours or days from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of these two intervals is the minimum time that must elapse before harvest may occur. * Permit required from county agricultural commissioner for purchase or use. § Do not exceed the maximum rates allowed under the California Code of Regulations Restricted Materials Use Requirements, which may be lower than maximum label rates. NA Not applicable. Nematodes (3/21) 173 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Weeds (Section reviewed 7/20) COMMON AND SCIENTIFIC NAMES OF WEEDS IN FLORICULTURE AND NURSERIES (7/20) Weeds are broadly divided into broadleaf plants (dicotyledons) or narrowleaf plants (monocotyledons). Most narrowleaf plants are grasses, but this group also includes sedges, such as yellow nutsedge, which are important weeds. Another way to classify weeds is by when they germinate and grow. Many common weed species are winter annuals, germinating mainly in fall, growing through winter and spring, and dying as summer approaches. Summer annuals germinate in spring, grow through summer and die as the temperature drops in the fall. Irrigation can alter the germination time of weeds and prolong the life span of some annuals and delay their senescence. A few weeds complete a life cycle in 2 years and are referred to as biennials (e.g., bristly oxtongue). Some of the worst weed species are perennials; weeds that live for 2 years or more. These include bermudagrass, creeping woodsorrel, and nutsedge that persist through their vegetative propagules (stolons, rhizomes, or tubers). See the Common Weeds in Floriculture and Ornamental Nurseries table for a list of these and links to photographs and more information on them. Common Weeds in Floriculture and Ornamental Nurseries. COMMON NAME WINTER ANNUALS bittercress bluegrass, annual burclover, California chickweed, common cudweeds filarees goosefoot, nettleleaf groundsel, common lettuce, prickly mallow, little (cheeseweed) mustard, wild nettles pearlwort radish, wild rocket, London shepherd's-purse sowthistle, annual spurry, corn SCIENTIFIC NAME‡ Cardamine spp. Poa annua Medicago polymorpha Stellaria media Gnaphalium spp. Erodium spp. Chenopodium murale Senecio vulgaris Lactuca serriola Malva parviflora Brassica sp. Urtica spp. Sagina sp. Raphanus raphanistrum Sisymbrium irio Capsella bursa-pastoris Sonchus oleraceus Spergula arvensis Continued on next page . . . Weeds Common and Scientific Names of Weeds in Floriculture and Nurseries (7/20) 174 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common Weeds in Floriculture and Ornamental Nurseries, continued COMMON NAME SCIENTIFIC NAME‡ SUMMER ANNUALS barnyardgrass Echinochloa crus-galli buttercup, yellow Ranunculus sp. crabgrasses Digitaria spp. fleabane, hairy Conyza bonariensis henbit Lamium amplexicaule horseweed Conyza canadensis junglerice Echinochloa colona lambsquarters, common Chenopodium album nightshade, black Solanum nigrum nightshade, hairy Solanum physalifolium pigweed, prostrate Amaranthus blitoides pigweed, rough Amaranthus retroflexus pigweed, tumble Amaranthus albus puncturevine Tribulus terrestris purslane, common Portulaca oleracea sprangletops Leptochloa spp. spurges; prostrate, creeping, or Euphorbia (=Chamaesyce) spp. spotted willowherbs Epilobium spp. COMMON BIENNIALS AND PERENNIALS bermudagrass Cynodon dactylon bindweed, field Convolvulus arvensis johnsongrass Sorghum halepense kyllinga, green Kyllinga brevifolia nutsedge, purple Cyperus rotundus nutsedge, yellow Cyperus esculentus oxtongue, bristly (biennial) Picris echioides woodsorrel, creeping Oxalis corniculata MISCELLANEOUS liverwort Marchantia polymorpha mosses Bryophytes (a division taxon) ‡ Scientific names are genus and specific epithet except where noted. Growing site and production practices largely determine which weeds are likely to become problems at a site. For example, weeds commonly associated with container nursery production include creeping woodsorrel, common groundsel, lesser-seeded bittercress, northern willowherb, and prostrate and spotted spurge. Sometimes annual bluegrass, liverwort, or pearlwort are a problem. In greenhouses, weeds that thrive in moist conditions often proliferate. These include liverwort, mosses, and pearlwort. In field sites, weed species vary greatly but the weed spectrum can be influenced by management practices in the field and by the environment. Because of these variations, each type of production situation is addressed separately in this guideline. After the section on general methods of weed management, there are special sections for weed management in • container nurseries • field-grown trees and shrubs • field-grown flowers • greenhouse-grown crops Weeds Common and Scientific Names of Weeds in Floriculture and Nurseries (7/20) 175 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GENERAL METHODS OF WEED MANAGEMENT (7/20) Managing weeds in ornamental plant production, whether in field soil, greenhouses, or outdoor containers, can be difficult but is essential to successful production. Weeds not only compete with the crop for plant nutrients and sunlight but are also unsightly and do not meet clean nursery quality standards. In addition, ornamental plants infested with certain noxious weeds cannot be sold because of quarantine regulations. Because of the high value of ornamental crops and the limited number of herbicides available, growers often resort to costly hand-weeding. However, many of the strategies used in vegetable row crops or tree crops can be adapted for use in field-grown trees and cut flower production. For example, planting in rows allows the field to be more easily cultivated by hand or mechanically. The use of drip irrigation in tree or shrub production greatly reduces excessively wet areas, thus reducing the germination and growth of weeds. Whether ornamentals are grown in containers, fields, or greenhouses, there are some control practices common to many methods of production that can reduce the impact of weeds on the crop as listed below in no particular order. Prevention The most important factor in overall weed control is to prevent weeds from developing seed and perpetuating the weed problem. Sources of weed introduction include weedy stock, weed seeds in the growing area or nearby, or plant propagules in manure, soil, uncomposted yardwaste, or other organic matter sources. Many growers cultivate or treat the margins of the property with herbicides to reduce the number of windborne or water-carried seeds that can move to the growing area. Screens on open-water inflow sources can be installed to keep out water-borne seeds. When using fine-mesh screens, increasing the surface area of the water intake and periodic debris removal may be needed to avoid clogging of the water flow. Cultivation Weed management systems for field-grown ornamentals start with mechanical cultivation. Begin this process by irrigating the field to induce weeds to germinate and then cultivate the new seedlings. Alternatively, the field can be sprayed with a postemergence herbicide after weed emergence so that the soil will not be disturbed by cultivation before planting. Each time cultivation occurs, new weed seeds can be brought close to the soil surface and germinate. This method reduces the soil seed bank so fewer weed seeds will be present to germinate when the crop is planted. After planting (and crop emergence if a seeded crop), preemergence herbicides can be used before weed emergence or the field can be cultivated between rows after new weeds germinate or both. After harvest, cultivate again to kill emerged weeds so they do not seed and replenish the weed seed bank. Cover Crops Cover crops can be used between rows and at field edges to improve weed management and to allow for another crop to grow instead of weeds. See the Potential Cover Crops for Field-Grown Ornamentals for the desirability of species for cover crops. The cover crop selected will depend on soil type, environmental conditions, and the ornamental crop. The cover crop can be a living mulch that is repeatedly mowed to minimize competition, or it can be sprayed with herbicides and used as a nonliving mulch. Certain cover crops can be hard to suppress with herbicides, such as white or strawberry clovers. An annual cover crop can be established and allowed to senesce naturally or (where freezing temperatures occur) be killed back by exposure to frost. Weeds Potential Cover Crops for Field-Grown Ornamentals. DESIRABLE INTERMEDIATE LESS DESIRABLE WINTER ANNUALS beans, bell or fava clover, rose or crimson mustard,1 wild or black bromegrass, blando fescue, zorro ryegrass, annual pea, Austrian winter field brome, California rye, cereal oat (forage) vetch, hairy or purple SUMMER ANNUALS General Methods of Weed Management (7/20) 176 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES beans, dry sorghum sudangrass sudangrass/sorghum hybrids PERENNIALS perennial ryegrass/hard fescue orchardgrass, berber bermudagrass clover, strawberry or white 1 Mustards can be undesirable cover crops because they can be invasive weeds in wildlands. Mowing Mowing is used to prevent rampant growth of the weeds, reduce the formation of seed, and reduce the spread of weed seed into cultivated areas. Properly timed mowing can also suppress some perennial weeds such as established johnsongrass. However, repeated mowing over a period of time (seasons or years) without any other means of weed control tends to favor the establishment of low-growing perennial grasses, which are very competitive for water and nutrients. Also, species that have flower heads below the level of the blade are not effectively controlled. If performed after seed set, mowing can spread weed seed and exacerbate weed problems. Flaming Flaming can be used before planting or on weeds between crop rows. To avoid injuring the crop, direct the flame at young weeds between the rows or use shields. Broadleaf weeds are controlled more effectively than grasses by flaming, and young weeds are better controlled than older ones. Because of the cost of fuel, the time required to pass over the beds, potential injury to workers, and fire hazard, flaming is not a widely used method of weed control for field-grown flowers or nurseries. Hand-removal Hand-hoeing or hand-pulling of weeds is always a part of crop management because cultivation does not remove all of the weeds. In some crops there may not be any other method of control. By removing the few remaining weeds in the crop, not only will there be less competition, but fewer weed seeds will be produced. Mulches Various kinds of bark, composted yardwaste, and other organic material can be used to help suppress annual weeds by covering the soil surface and preventing weed seed germination and establishment. Only 2 to 3 inches of fine organic mulch (finished yardwaste) may be required to totally eliminate light on the soil and suppress the growth of weeds. An advantage of the fine mulches is that after the crop is harvested, the mulch can be worked into the soil to improve drainage, soil structure, and water-holding capacity of the soil. A disadvantage of fine mulch is that weed seeds that fall on it will germinate and grow. Coarse wood chips or bark may require 3 to 6 inches of material to eliminate light. Synthetic materials (geotextiles, landscape fabrics) made of polypropylene or polyester can also be used as mulches but because of cost, they generally are used only with perennial shrubs or trees or under containers. Because they last several years, they can be left on for the life of the tree or shrub, or they can be removed and reused. Dark plastic mulches can be used for weed control when using drip or furrow irrigation. Soil Solarization Heating soil to high temperatures can kill many weed seeds. Solarization is done by covering bare, moist soil with clear plastic during periods of high solar radiation and temperature. In California's interior valleys, this is generally during June to August. Before placing the plastic on the site to be treated, cultivate or closely mow any established plants and remove the clippings, then smooth the soil surface and irrigate the area well. Place clear polyethylene that is ultraviolet (UV) resistant over the area and extend it about 2 feet beyond the infested area on all sides and pull it tightly so it is close to the soil. The plastic must be left in place and maintained intact for 4 to 6 weeks for control of weeds. Many annual weeds can be controlled using this method. Weeds not well controlled include clovers, field bindweed, and purple and yellow nutsedge. Media for containers or for use in greenhouses can be solarized using clear bags or flats or small, low mounds of soil covered with clear polyethylene. In greenhouses, beds can be solarized before planting. See Soil Solarization: A Nonpesticidal Method for Controlling Diseases, Nematodes, and Weeds, UC ANR Weeds General Methods of Weed Management (7/20) 177 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Publication 21377 and UC IPM Pest Notes: Soil Solarization for Gardens and Landscapes, UC ANR Publication 74145, for more details. Transplants Using transplants rather than direct-seeding a crop allows the crop to establish more quickly and be more competitive with weeds. Also, a transplant is generally more tolerant to soil-applied (preemergence) herbicides than are germinating crop seeds. Herbicides Herbicides are used in many ornamental production areas as an economical option to control weeds. By using herbicides before weeds emerge, weed competition with the ornamental crop can be reduced or eliminated, resulting in higher quality ornamental plants and less labor costs. Herbicides are generally classified according to when they are used in relation to crop and weed growth stage. Preplant herbicides are applied before planting. These herbicides are used before the desirable plants are present because some can control both germinating seedlings and established plants. Preemergence herbicides kill weeds at the seed germination stage. These herbicides are applied before weeds emerge. Postemergence herbicides are applied after the weeds have emerged. Preemergence and postemergence herbicides may be applied before or after the crop is planted depending on the crop and the herbicide selected. See the section SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTROL to guide herbicide choice based on the weed species present. Preplant herbicides Herbicides that are applied before planting the crop may be fumigants, nonselective or selective postemergence herbicides, or preemergence herbicides, which are selective because they are generally safe for use around established plants. The fumigant herbicides, such as metam potassium* and metam sodium*, are often applied as an injection to cultivated soil. They are generally covered with a polyethylene tarp to seal in moisture and slow the escape of fumigant gas. Dazomet is a powder that is incorporated into the soil. All of these materials must be applied by licensed applicators. Nonselective postemergence herbicides can be used preplant as well. Certain preemergence herbicides can be applied and incorporated mechanically into soil before direct seeding or transplanting if the crop is tolerant to that herbicide. (*Requires a permit from the county agricultural commissioner for purchase or use.) Preemergence herbicides Preemergence herbicides must be applied before the weed seeds germinate. These herbicides comprise the largest number of herbicides available to ornamental growers because they are generally safest for the crop and the weed seedling stage is the easiest part of the plant cycle to interrupt. Examples of these herbicides are dimethphenamid-d, flumioxazin, indaziflam, isoxaben, napropamide, oryzalin, oxadiazon, oxyfluorfen, pendimethalin, prodiamine, and trifluralin. There are a number of preemergence herbicides sold as combinations such as dimethenamid-p/pendimethalin (Freehand), oryzalin/isoxaben (Snapshot), oxyfluorfen/oryzalin (Rout), and oxyfluorfen/pendimethalin (OH2). Apply preemergence herbicides to the soil after cultivating or hand-weeding to remove emerged weeds. Follow the application with an irrigation or rain to move the herbicide in the top 1/2 inch of media or soil where the seeds are germinating. A second handweeding 7 to 10 days after an herbicide application may be needed to ensure elimination of previously germinated seedlings. However, read the label to learn if doing so will affect the chemical barrier. For example, oxadiazon and oxyfluorfen are taken up by the seedling as it emerges; disturbing the soil may create some gaps in the herbicide barrier. Because of the varied germination periods of the weed species and the selectivity and sometimes limited persistence of the herbicides, it can be necessary to use different preemergence herbicides at different times of the year or repeat application of a particular herbicide to achieve the best control. For example, common groundsel and lesser-seeded bittercress can germinate at almost any time during the year, but their maximum germination in a field situation occurs in a cool, moist environment. Thus, a late summer herbicide treatment for control of winter annual seedlings is most desirable. For summer weeds such as crabgrass and purslane, apply herbicides in late winter. Keep in mind that where artificial conditions for germination can occur, such as in a container nursery where irrigation may occur daily, these weeds can germinate at any time. The length of time a preemergence herbicide stays active is also an important Weeds General Methods of Weed Management (7/20) 178 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES consideration in application frequency and timing. For example, because of frequent irrigation herbicides may not control weeds for as long as stated on the label. Postemergence herbicide Postemergence herbicides are applied after weeds have emerged. Some are very selective and control only a narrow range of weed species. Examples of selective postemergence herbicides include clethodim, fluazifop-p-butyl, and sethoxydim. Fluazifop-p-butyl and sethoxydim control most annual grasses, except annual bluegrass and fine fescue. Clethodim will control annual bluegrass as well as other grasses. Products containing phenoxy herbicides, such as 2,4-D, will selectively control broadleaf weeds in monocots but will injure a broadleaf crop. There are no selective postemergence herbicides that can be used over a wide spectrum of ornamental species for broadleaf weed control. Nonselective herbicides are those containing diquat, glufosinate, glyphosate, pelargonic acid, and plant oils such as eugenol. Nonselective herbicides can be used around the field to keep weeds from seeding but must be kept away from the crop. Apply postemergence contact herbicides when weeds are in the seedling stage, the stage when they are the most susceptible and require the least amount of herbicide for effective control. Translocated herbicides such as glyphosate and the grass selective herbicides can be effective on bigger weeds. In some field-grown flowers, shrubs, or trees, control of grasses with the postemergence herbicides clethodim, fluazifop-p-butyl, or sethoxydim can be very effective. Many postemergence herbicides need addition of an adjuvant (surfactant oil) for maximum control. Check the herbicide label for information about whether a surfactant should be added and which type of surfactant to use and the rate. By using preemergence or postemergence herbicides or, where possible, mulches instead of cultivation or hand-weeding, the root system of desirable plants is not disturbed. Roots are not cut off with a hoe or crop plants pulled accidentally. And because new weed seeds are not brought to the soil surface, as they would be with cultivation, fewer weeds will germinate to start a new weed crop. Application of Herbicides Calibration of the equipment is essential for proper application regardless of whether the herbicide is sprayed or applied dry as granules. Granules and wettable powder formulations can cause severe wear to the application equipment, so the equipment will need to be calibrated more frequently. Most liquid herbicides are applied at 20 to 60 gallons of solution per acre at pressures of 30 to 40 pounds per square inch (psi). Applying liquids with a single nozzle hand wand does not give as uniform distribution as multiple nozzles on a boom. Because the effectiveness of preemergence herbicide applications is highly dependent on even soil coverage, make applications as uniformly as possible. When applying to container plants be aware that the media surface may be blocked by plant foliage. Where the crop makes it difficult for the herbicide to reach the media, a granular can be more effective. Granules are applied to dry foliage and if the foliage restricts the movement to the media surface, the foliage can be lightly brushed or shaken with a broomstick or similar tool to dislodge granules. Recalibration of the application equipment is important when changing herbicides as granule size and weight differ among herbicides. Weeds General Methods of Weed Management (7/20) 179 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTROL (7/20) Mode of Action ANNUAL WEEDS barnyardgrass bittercress, lesserseeded bluegrass, annual burclover, California chickweed, common crabgrasses cudweeds filarees fleabane goosefoot, nettleleaf groundsel, common henbit horseweed junglerice lambsquarters, common lettuce, prickly mallow, little (cheeseweed) mustard nettle, stinging nightshade, black nightshade, hairy pearlwort pigweeds purslane, common radish, wild rocket, London shepherd's-purse sowthistle, common sprangletops spurge, prostrate or spotted spurry, corn willowherbs BIENNIAL WEEDS oxtongue, bristly PERENNIAL WEEDS bermudagrass (plant) bermudagrass (seedling) bindweed, field (plant) bindweed, field (seedling) buttercup, yellow johnsongrass (plant) johnsongrass (seedling) nutsedge, yellow nutsedge, purple woodsorrel, creeping (plant) Weeds PREEMERGENCE DIH DIM D/P FLM IND ISO I/T MCH NAP ORY O/O OXA OXY O/P PEN PRD TRI 14 15 15/3 14 29 21 21/3 15 15 3 3/14 14 14 14/3 3 3 3 C — C — C — C — C — N C C C C P C P C P C C C C P C C C C P C P C P — — P P C — C C C — C — C C — C C — — — — — — — — C C — C C — — — C — C — C C — — C P — C C — C C C — C C C — C C C C C P C C — C N C C N C C P C C C P N C C C C C C C P C C C P C C C N C C N N N P N N N C P C N C C P C N C C N P C C C N C C N P N C P C N C C C C C C C C P C C C P C C C N N C C C P C P C P C C P C P N C C P C C C P P C C C C C C C P C C C P C C C N C C N N N C N C N C C C N C C N N N C N C N C C C N C C N N N C N C N C C C — — — — P — C P C C C C C N N C P P P C C P C C C C C N P N P N P — C C C — P C — — — C — C — C P P — C C — — — — — — — C P P C C C — — — — C C C C C C — — C — — C C — — C C C C — C C C C C C — C C C C C C C C C C C C N C C C C C C C C C C C C C C N C C C P C C N N P P C N P P N N C C C N C P C C N N P N N C C C N N N N C C C C C C C C C C C C C C C C C C C N C C C C C C P C C C C C P C C C C C C N C C C C C C C C C C C C C C N P N N C C C N N N N C C N P N N C C C N N N N C C N P N N C C C N N N N C C — — — — C — — C — C C P C P C N C N C P C C N P P C C C C N C N C N — — — — — N N N N N N N N N N N N N — — — N N N N N N N N N N N N N C — C — — N C C C C C P N N C C C P N N — N N N N N N N P N N N N N C — P — — N C N N P C C C C P P C — N C P — C P — C — — — — N — N N N N N C N N C N N C N N C N N N N N N N N N N N P N N P N N C N N C P — — P — — P — — P N — N N — N N N N N N P P N P N N N N N N N N N N N N N N N N N N N N N N N N N N Susceptibility of Weeds to Herbicide Control (7/20) 180 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES woodsorrel, creeping (seedling) MISCELLANEOUS liverwort C = control — — C — C C C — — — C — — DIH DIM D/P FLM IND ISO P = partial control DIH DIM D/P FLM = dichlobenil (Casoron) = dimethenamid-P (Tower) = dimethenamid/pendimethalin = flumioxazin (Broadstar, Sureguard) IND = indaziflam (Marengo G) ISO = isoxaben (Gallery) I/T = isoxaben/trifluralin MCH = metolachlor (Pennant) N = no control — I/T N N C C C C C C C — — — P P P P — — — MCH NAP ORY O/O OXA OXY O/P PEN PRD TRI — = Information not available or not presented NAP ORY O/O OXA = napropamide (Devrinol) = oryzalin (Surflan) = oryzalin/oxyfluorfen = oxadiazon (Ronstar) OXY O/P PEN PRD TRI = oxyfluorfen (Goal) = oxyfluorfen/pendimethalin = pendimethalin (Pre-M, Pendulum) = prodiamine (Barricade) = trifluralin (Treflan) Susceptibility of Weeds to Herbicide Control, continued Mode of Action ANNUAL WEEDS barnyardgrass bittercress, lesser-seeded bluegrass, annual burclover, California chickweed, common crabgrasses cudweeds filarees fleabane goosefoot, nettleleaf groundsel, common henbit horseweed junglerice lambsquarters, common lettuce, prickly mallow, little (cheeseweed) mustard nettle, stinging nightshade, black nightshade, hairy pearlwort pigweeds purslane, common radish, wild rocket, London shepherd's-purse sowthistle, common sprangletops spurge, prostrate or spotted spurry, corn willowherbs BIENNIAL WEEDS oxtongue, bristly PERENNIAL WEEDS bermudagrass (plant) bermudagrass (seedling) bindweed, field (plant) bindweed, field (seedling) Weeds C POSTEMERGENCE FLU GLU GLY PAR 1 10 9 22 CLE 1 DIQ 22 C N C N N C N N N N N N N C N N N N N N N N N N N N N N N N N N C P C P C P P N N N N N N P P N N P P P P N P C C N P P N C P P C N N N N C N N N N N N N C N N N N N N N N N N N N N N N N N N C C C C C C C C C C C C C C C C P C C C C C C C C C C C C C C C C C C C C C C P C C C C C C C C P C C C C C C C C C C C C C C C N N N P C C C N N N C N C P C N N PEL 26 SET 1 P — C P C C N P P C C C C P P P N C P C C — C N P C C C P C — P C P C P C P P N N N N N N P P N N P P P P N P C C N P P N C P P C N N N N C N N N N N N N C N N N N N N N N N N N N N N N N N N — N N P C P N P C C C C C P P P N N C C C P N Susceptibility of Weeds to Herbicide Control (7/20) 181 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES buttercup, yellow johnsongrass (plant) johnsongrass (seedling) nutsedge, yellow nutsedge, purple woodsorrel, creeping (plant) woodsorrel, creeping (seedling) C = control P = partial control CLE = clethodim (Envoy) DIQ = diquat (Reward) FLU = fluazifop-p-butyl (Fusilade) GLU = glufosinate (Finale) Weeds N C C N N N N CLE N N C N N N C DIQ N = no control N P C N N N N FLU P P C N N P C GLU C C C P P C C GLY — N C P P — — PAR N N C N N N C PEL N P C N N N N SET — = Information not available or not presented GLY = glyphosate (Roundup Pro) PAR = paraquat (Gramoxone) PEL = pelargonic acid (Scythe) SET = sethoxydim (Vantage) Susceptibility of Weeds to Herbicide Control (7/20) 182 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Container Nurseries INTEGRATED WEED MANAGEMENT FOR CONTAINER NURSERIES (7/20) The growth and vigor of nursery stock can be reduced when weeds are allowed to grow in the container for any length of time. Slow-growing crops that do not cover the surface of the media in the container quickly are particularly vulnerable to weed infestations. Managing weeds in container nurseries involves eliminating weeds and their seed and preventing the introduction of new weed seeds into the nursery. Although growing medial is usually weed-free at planting, weed seeds can be blown in from other areas or may be brought in with the liner (transplant). Frequently, preemergence herbicides are applied to the surface of potting mix in containers of 1 gallon or larger to prevent the establishment of weed seeds. Mulches may also be applied after canning or after weeding. After container plants are established, preemergence herbicides are applied one or more times per year for weed management. Hand-pulling of weeds that have escaped the herbicide treatments is necessary to prevent them from setting seed and reestablishing a weed population. Most weeds in a container nursery come from • contaminated liners • equipment • irrigation water • movement of soil • plants growing between, in, or near pots • potting mix, if it is stored uncovered where weed seed can blow in • vehicles • windborne seeds Transplants produced in the nursery or purchased from others should be free of weeds and weed seed and moved into larger, weed-free containers. Use preemergence herbicides in and between the containers to reduce contamination or reinfestation, but take care so that herbicides are not carried off-site in water runoff. The most effective way to manage weeds is to start with a clean area and to keep it clean by creating a weed-free, well-drained site for containers. Covering the nursery site with concrete, a geotextile (landscape fabric), or gravel helps control weeds under and between containers. Control perennial weeds before grading and installing irrigation equipment because they are nearly impossible to control after a nursery is established. Soil Mixture Although potting mix is usually weed-free, it can become contaminated with weed seed if stored uncovered where seeds can blow in from neighboring areas. Fumigate, solarize, or steam sterilize any seed-contaminated soil mix. Check the soil mix periodically for weed seeds by placing samples of soil mix in a flat or two. Keep the flats moist and check for weed germination for 1 to 2 weeks. If weeds grow, consider fumigation or solarization of the soil mix. For fumigation to be most effective, the soil mixture needs to be uniformly wet for 3 to 4 days before fumigation treatment so that the weed seeds absorb water and begin to germinate. If the mix is too dry or too wet or there are large clods of soil, fumigation will not be uniform. Fumigation is most successful when the soil is placed on a concrete pad or in a container and the fumigant or steam is introduced at several locations in the mix. There are two main methods to fumigate a soil mix: 1. Steam fumigation. The steam is usually mixed with air and injected into a loose soil mix to heat the mix to at least 140°F for 30 minutes. Length of time and temperature are critical if weed seeds are to be controlled. Cover the pile so that the entire pile, including the outer edges, reaches 140°F. A major problem of steam fumigation is that equipment, such as a boiler and blower, are required. Weeds Integrated Weed Management for Container Nurseries (7/20) 183 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 2. Chemical fumigation. Fumigation with pesticides such as dazomet (Basamid), metam potassium*, or metam sodium* is sometimes used as a preplant treatment in potting mixes. For recommended fumigants, see MANAGEMENT OF ROOT-KNOT AND OTHER SOIL-DWELLING NEMATODES. Dazomet is a dry formulation that is mixed into the potting mix before wetting the pile. The pile is then covered for about 2 weeks as the dazomet degrades into the active fumigant, methyl isothiocyanate. The cover is removed and the soil allowed to air for 2 weeks before using the mix for potting. Metam potassium and metam sodium are liquids that can be applied in water to the mix and then tarped for 2 weeks. Air out the soil for 2 weeks before planting the crop. Fumigants such as metam potassium and metam sodium are sources of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. (*Requires a permit from the county agricultural commissioner for purchase or use.) Although less commonly used, soil solarization can also be used to control weeds in the potting mix before planting. See the discussion of soil solarization in GENERAL METHODS OF WEED MANAGEMENT at the beginning of the weeds section. Monitoring Container Nurseries See the Common Weeds in Container-Production Nurseries table for links to photographs and more information on these species. Because many of these weeds can germinate year-round in the nursery, check the containers regularly. Some weed species can flower and produce seed in only a month from the seedling stage, so monitoring followed by hand-weeding is needed at least monthly to remove any weeds that were missed by herbicide treatments or from the last hand-weeding. It is essential to monitor for winter annual weeds germinating in late summer and for summer annuals germinating in late winter. Common Weeds in Container-Production Nurseries. Common name Scientific name bittercress Cardamine spp. cudweed Gnaphalium stramineum groundsel, common Senecio vulgaris lettuce, prickly Lactuca serriola liverwort Marchantia polymorpha pearlwort, birdseye Sagina procumbens sowthistle, annual Sonchus oleraceus spurge, prostrate or spotted Chamaesyce maculata willowherbs Epilobium spp. woodsorrel, creeping Oxalis corniculata Identifying the weeds present in a given situation is an important factor in deciding which weed control strategies to employ. Use the Weeds of California, UC ANR Publication 3488, and the UC IPM Weed Photo Gallery to help identify weeds. University of California Cooperative Extension advisors or county agricultural commissioners, botanic gardens, or arboretum personnel can also help with weed identification. Once the weed is identified, the herbicide labels and tables of SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTROL will help you determine the best herbicide or combinations of herbicides to supplement a weed management program and provide optimum control of the weed species present. Herbicides Preemergence herbicides are used extensively in container-grown ornamentals, usually in conjunction with handweeding to control any weeds that escape the chemical treatment. The herbicides used depend on the weed species expected (see monitoring section), the time of year, the stage of the ornamental plants, and the tolerance of the ornamental plants to the herbicides. The weed species present at a particular site must be properly identified in order to select the effective herbicide. Apply the herbicide as soon as possible to achieve optimal weed control but keep in mind that some plants may be injured if applied before the soil has settled around the roots. Herbicides used in container production will not harm the ornamental species listed on the label if care is taken to use them properly. A number of factors determine if the ornamental plant will be adversely affected. These include the Weeds Integrated Weed Management for Container Nurseries (7/20) 184 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES • • • • • • • • • Degree of plant establishment. Newly-planted plants are more sensitive because generally they have smaller root systems than established plants. Dosage of the herbicide. Higher dosages can cause crop injury; rates above the label are illegal. Use the lowest dose that will control the weeds targeted. Note that using too low of rate can promote the development of resistance to herbicide. Formulation. Granular formulations are generally safer with some products than the emulsifiable concentrate or wettable powder formulations. However, injury can result if the granules collect in the whorl of the plant. Plant size. The younger the crop plant the greater the sensitivity to herbicides, and therefore, the greater the likelihood of it being injured. Rate of plant growth. Actively growing plants often are more sensitive to injury from certain herbicides than dormant plants. Soil texture and organic matter content. These properties can affect an herbicide's tendency to leach into the root zone. Some herbicides can be more strongly adsorbed on soil particles than others. As clay and organic matter content increase, binding increases and usually there is less leaching. Spray techniques. The method of application will affect distribution of the herbicide on the target. For most herbicides, the height of the spray boom should be adjusted so that the top of the ornamental plant receives uniform spray distribution. This means that with normal spray booms equipped with fan type nozzles, the nozzles should be at least 20 to 24 inches above the top of the plants. Spray booms adjusted too low can cause plant injury with certain herbicides. Individual nozzles should be checked for proper flow rate and spray pattern. Tank mixing of products. Mixing in wetting agents (chemicals that reduce the surface tension of liquids) or another herbicide that has wetting agents in it with an herbicide that has postemergence activity can greatly increase the activity and perhaps also increase crop injury and reduce selectivity. Check the label and follow any instructions regarding adding adjuvants or tank-mixing products. Temperature. Temperature affects rates of chemical reactions in plants. Higher temperatures can greatly increase the speed of chemical reactions, which can result in greater injury to plants as well as to weeds. Higher temperatures may also increase herbicide absorption through leaves and roots. Herbicide runoff can be a serious problem in some situations, so observe the following precautions to reduce runoff: • Spot treat. • Use herbicides with water solubility of less than 3.5 ppm as listed in the Herbicide Handbook and certain online guides (PDF). • Use low-volume applications. Use only as much water as needed to move the herbicide into soil with the first irrigation following an application. Container spacing can also affect herbicide loss when granular herbicides are applied. Tight spacing of containers can keep 50% more of the herbicide in the container rather than on the ground compared to containers that are spaced 8 inches apart. Additionally, herbicide loss can be reduced if drop spreaders are used rather than rotary spreaders. However, herbicide that falls on the ground is not totally lost because it helps control weeds between containers and thus contributes to the total weed management. Weeds Integrated Weed Management for Container Nurseries (7/20) 185 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SPECIAL WEED PROBLEMS FOR CONTAINER NURSERIES (7/20) BITTERCRESS (hairy bittercress, lesser-seeded bittercress, popweed) Bittercress is a small winter annual that will germinate almost any time in container production. It grows upright when the seed stalk starts to form and is easy to hand-weed at that stage, but as a seedling it is very difficult to remove easily. It produces hundreds of seed per plant, and when the capsule matures it expels the seed some distance from the original plant. Remove this weed before it flowers to reduce seed production and new infestations. Herbicides that are effective against bittercress are those that contain isoxaben, oxadiazon, or oxyfluorfen. Sanitation is also important to reduce the spread of this weed. Because the seed of this weed adheres to soil on the outside of the pots, wash pots before reuse or moving them from an infested area. The seeds are also easily carried in irrigation water. Avoid overwatering or allowing water to runoff from an infested area to a clean one. COMMON GROUNDSEL Common groundsel is probably the most difficult weed to control in container nurseries in California. It is a hardy weed that grows rapidly and germinates anytime during the year in container nurseries, whereas in the field it usually germinates in fall and early winter. Preemergence herbicides suppress the rooting, making the weed easier to pull. Also, because the seedling is smaller after the use of a preemergence herbicide, competition with the desirable plant is not very significant. Remove this weed before it flowers because its seeds are easily spread by wind. Preemergence herbicide combinations containing dichlobenil, dimethenamid-P + pendimethalin, flumioxazin, isoxaben, napropamide, or oxyfluorfen have given good control. CREEPING WOODSORREL (Oxalis) Creeping woodsorrel is a perennial plant that grows in a prostrate manner and forms roots along its stems where nodes contact the soil. It is a prolific seed producer. When its seed pods mature, they burst open and forcefully expel seeds, which may land several feet from the plant. Because the seeds are rough, they adhere to clothing or the surfaces of machinery and are easily dispersed. The primary method of managing creeping woodsorrel is to hand-pull established plants before they set seed, being careful to remove as much of the creeping stolons as possible, and to control germinating seeds with mulch or the preemergence herbicides indaziflam, isoxaben, oryzalin, oxadiazon, oxyfluorfen, pendimethalin, prodiamine, or trifluralin. CUDWEED Cudweed is an annual that germinates in fall and grows through the winter and spring. It is a whitish, hairy plant that has small inconspicuous flower heads. The preemergence herbicides dichlobenil, indaziflam, isoxaben, and oxyfluorfen have been effective in controlling the seedlings of this weed as they germinate. LIVERWORT Liverworts are nonvascular, primitive plants that reproduce vegetatively and through spores. Their flat leaf-like structure is called a thallus and their root-like structure is a rhizoid. These plants can form dense colonies in ornamental containers resulting in crop damage and reduced marketability. Preemergence herbicides containing flumioxazin or oxyfluorfen provide limited control of this weed, but are not labeled for use in greenhouses. There are no selective postemergence herbicides available. PEARLWORT Pearlwort is a low-growing winter annual that roots on the stems and forms mosslike mats in the container. It reproduces by seed. If oxadiazon has been used repeatedly without rotation to other herbicides it becomes a dominant weed in the nursery. A preemergence application of isoxaben, napropamide, oryzalin, pendimethalin, prodiamine, or trifluralin will control pearlwort. SPURGE Creeping and prostrate (spotted) spurge are low-growing annuals that grow rapidly and quickly produce seed. They are more easily removed when older, but by then the seeds have usually been produced and fall off the plant into the container when the weed is removed. Mulching reduces establishment. The Weeds Special Weed Problems for Container Nurseries (7/20) 186 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES preemergence herbicides dichlobenil, indaziflam, isoxaben, oryzalin, oxadiazon, oxyfluorfen, pendimethalin, prodiamine, and trifluralin will control spurge. WILLOWHERB There are at least two species of willowherb found in nursery containers, Epilobium paniculatum and E. ciliatum. Willowherb seeds profusely and the seed blows in the wind. Preemergence herbicides that have been effective in controlling germinating seeds include dimethenamid-P + pendimethalin, flumioxazin, oxadiazon, and oxyfluorfen. Weeds Special Weed Problems for Container Nurseries (7/20) 187 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES HERBICIDE TREATMENT TABLE FOR CONTAINERS AND FIELD-GROWN TREES AND SHRUBS (7/20) Common name (Example trade name) Amount to use REI‡ (hours) PHI‡ (days) Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to resistance management, the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see the table SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTOL for information on control of specific weeds. Always read the label of the product being used. Note: Not all ornamentals will tolerate each herbicide. Check the label for species selectivity. PREEMERGENCE HERBICIDES A. DICHLOBENIL (Casoron 4G) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: Not for container-grown ornamentals. Check label carefully for sensitive crops. A dormant season application of dichlobenil can control many seed-propagated, perennial, broadleaf weeds and provide residual control through early summer. Good for control of Equisetum and mugwort. B. DIMETHENAMID-P (Tower) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1:15 COMMENTS: Mix with isoxaben or pendimethalin to expand the weed spectrum controlled. Can be used over the top on well-rooted plants. Check label for sensitive crops and test on a small group of each crop before applying widely. C. DITHIOPYR (Dimension 2EW) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: For application to established container and field-grown, tolerant ornamentals as listed on the label. D. FLUMIOXAZIN (Broadstar, granular) See label 12 NA (Sureguard, sprayable) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: Avoid contact with foliage of young crop plants. Wash foliage as soon as possible after application. Can cause stem dieback or leaf burn on sensitive plants. Has some postemergence activity. Provides moderate liverwort control. Helps provide preemergence control of annual grasses, chickweed, hairy fleabane, horseweed, and other annual broadleaves. Test on a small number of plants before using widely. E. INDAZIFLAM (Marengo G) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 29 COMMENTS: Not for use on certain field-grown trees and shrubs; check label for permitted uses. Long residual. Irrigate immediately following application for best activity. Can be used on many ornamentals and also used around beds and greenhouses for long-term, preemergence, weed control. F. ISOXABEN (Gallery SC) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 21 COMMENTS: Excellent herbicide for broadleaf weed control. Does not control annual grasses and willowherb, therefore often it is mixed with oryzalin or trifluralin to control grasses. It is safe on a wide range of woody ornamentals. G. METOLACHLOR (Pennant Magnum) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 15 COMMENTS: Controls yellow nutsedge as well as some annual grasses, but to be effective it must be incorporated into the soil where nutsedge germinates and grows through the treated area. Check label for crop safety. This herbicide is one of the more soluble products (solubility 490 ppm) – make sure that it does not move with irrigation or rainwater. Weeds Herbicide Treatment Table for Containers and Field Grown Trees and Shrubs (7/20) 188 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES H. NAPROPAMIDE (Devrinol DF-XT) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 15 COMMENTS: Needs mechanical incorporation (such as a power tiller, adequate irrigation, or 1 to 2 inches of rainfall within 2 to 3 days) for optimum results. The first irrigation seems to be critical for maximum activity. Safe on many woody plants but is weak in controlling some broadleaf weeds such as members of the aster and nightshade families, oxalis, and spurge. An excellent grass herbicide and can suppress common groundsel. Generally less efficacious but often safer than the combination herbicides, it is useful in herbaceous crops. Unless it is applied before rooted liners are established, injury is rare. If placed in the container around the newly planted liner before an irrigation settled the soil or if placed in the root zone, injury (stunting) may result. If the soil is moist and there is no rainfall or irrigation within 7 days following application, an appreciable amount of the herbicide is lost and weed control will be lessened. I. ORYZALIN (Surflan AS) See label See label NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: A relatively broad-spectrum preemergence herbicide that does not need mechanical incorporation. Controls germinating seeds of annual grasses and many broadleaf weeds and can be used safely around many herbaceous and woody ornamentals. Leaches slightly into the soil from rainfall or irrigation. Can cause girdling of certain gymnosperms at the soil line: young hemlocks or firs (Abies spp.) up to about 3 years of age are affected, but arborvitae, junipers, pines, and Taxus are more tolerant. Stems of Monterey pines may exhibit some swelling. Oryzalin is a strong root inhibitor but most broadleaf ornamentals are very tolerant to oryzalin if the herbicide is not in the root zone. Commonly used in combination with other herbicides to widen the weed spectrum controlled. J. OXADIAZON (Ronstar G) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: Not for use in conifer nurseries or on certain weeds species; see label. A broad-spectrum preemergence shoot-girdling herbicide. In containers, granular oxadiazon plus napropamide is a good combination with a broad range of safety in woody plants. The wettable powder formulation should not be applied over young growth. Oxadiazon does not control weeds in the chickweed family but napropamide controls those. Has a relatively long residual, 12–16 weeks. Oxadiazon is not very effective on certain broadleaves including chickweed, horseweed, and pearlwort. Oxadiazon is very effective when applied in fall or spring. Oxadiazon does not leach readily in the soil, is not a root inhibitor, and thus is less likely to injure established species. Injury may occur if oxadiazon is applied to wet foliage, is not washed from the foliage, or the granules collect in leaf bases or crowns. If treated soil is cultivated, weed control effectiveness is reduced. K. OXYFLUORFEN (Goal 2XL) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: For use only around conifers and selected deciduous trees grown in the field. Excellent in dormant or hardened conifers where groundsel, malva, mustards, or purslane are found. Controls these weeds in a few days and provides residual, broadleaf control. Oxyfluorfen cannot be safely sprayed over most deciduous plants. Safest to the conifers when applied as granules. Weak on common chickweed, grasses, and horseweed. Oxyfluorfen acts by girdling the stem of seedlings; thus in soil, oxyfluorfen is most effective with frequent irrigation. If treated soil is cultivated, weed control is reduced. L. PENDIMETHALIN (Pendulum 2G, Pendulum AquaCap) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Do not apply Pendulum AquaCap over the top of transplants; see label. Gives excellent grass control and controls many broadleaf weeds. Weed spectrum controlled is similar to that of oryzalin. Often combined with an additional herbicide to widen spectrum of weeds controlled. Controls oxalis and spotted spurge. An encapsulated formulation (AquaCap) has no odor and less persistent orange color. Though it is a root inhibitor, it is less injurious to roots than oryzalin or prodiamine. M. PRODIAMINE (Barricade) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER: 3. COMMENTS: Stable on the soil surface. Does not provide as long of weed control as oryzalin at the maximum label rates for both. Has been less effective for groundsel and spurge suppression than some other dinitroaniline herbicides. Inhibits root growth. Low water solubility and does not move deeply in the soil. N. TRIFLURALIN Weeds Herbicide Treatment Table for Containers and Field Grown Trees and Shrubs (7/20) 189 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES (Lebanon Treflan) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: In the same class of herbicides as oryzalin (dinitroanilines), but it is not as stable on the soil surface. Must be incorporated with cultivation or irrigation or covered with a mulch very soon after application. Inhibits root growth. Often mixed with other herbicides (benefin or isoxaben) to widen the weed spectrum controlled. PREEMERGENCE COMBINATIONS Note: For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum active ingredient (a.i.) on any label when tank mixing products that contain the same a.i. A. DIMETHENAMID-P/PENDIMETHALIN (FreeHand 1.75G) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBERS1: 15/3 COMMENTS: Controls many common nursery weeds such as eclipta, oxalis, spurges, and willowherbs. Can be applied very soon after potting. Provides preemergence control or suppression of yellow nutsedge. B. ISOXABEN/TRIFLURALIN (Snapshot 2.5 TG) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBERS1: 21/3 COMMENTS: Gives broad-spectrum control of annual broadleaf and grass weeds. Apply only to soil where established weeds have been removed. If the soil has been freshly cultivated, apply only after the soil has settled, then follow with an irrigation. C. ORYZALIN/OXYFLUORFEN (Rout) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBERS1: 3/14 COMMENTS: Provides excellent broad-spectrum control of annual broadleaf and grass weeds. Can be applied after a cultivation to reduce subsequent germination. Water in after application. If granules remain in plants at the base of the leaf or in whorls, burn will occur. Residual control is 3–4 months. D. OXYFLUORFEN/PENDIMETHALIN (OH2) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBERS1: 14/3 COMMENTS: Provides excellent broad-spectrum control of annual broadleaf and grass weeds. Should be watered-in immediately after application. Slightly less root pruning than the oryzalin/oxyfluorfen formulation (Rout). Residual control is about 3 months. E. OXYFLUORFEN (Goal 2XL) See label 24 NA . . . PLUS . . . OXADIAZON (Ronstar Flo) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBERS1: 14/14 COMMENTS: Not currently registered in California for use on annual bluegrass, annual sedge, bristly oxtongue, cheeseweed, fiddleneck, fireweed, shepherd's-purse, sow thistle, ripgut bromegrass, and wild oats. Gives broadspectrum control of grasses and broadleaf weeds. Soil should be thoroughly settled after cultivation and rainfall or irrigation because the products form a surface barrier that controls seedlings as they germinate and grow through the herbicides. Cultivation after treatment destroys the control. F. PRODIAMINE/OXYFLUORFEN (Biathlon) See label WSSA MODE-OF-ACTION GROUP NUMBERS1: 3/14 COMMENTS: See the comments above on these herbicides individually. Weeds See label NA Herbicide Treatment Table for Containers and Field Grown Trees and Shrubs (7/20) 190 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (Example trade name) Amount to use REI‡ (hours) PHI‡ (days) Selective (broadleaves) A. OXYFLUORFEN (Goal 2XL) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: For use only around conifers and selected deciduous trees grown in the field. Postemergence applications of oxyfluorfen will control certain annual broadleaf weeds. Effective only on certain young seedling weeds, especially little mallow. Perennial broadleaf weeds will be burned but not controlled. Activity is enhanced if a surfactant or crop oil is added. Spruces and true firs are injured by oxyfluorfen during their early flush but after about 5 weeks of new growth, they are tolerant. Dormant applications do not cause injury. Selective (grasses) A. B. CLETHODIM (Envoy Plus) See label WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: Controls most annual grasses, including annual bluegrass. 24 NA FLUAZIFOP-P-BUTYL (Fusilade II) See label 12 NA (Ornamec Over-The-Top) See label 4 See COMMENTS WSSA MODE-OF-ACTION GROUP NUMBER1: NC COMMENTS: Do not apply to ornamentals that may be harvested for food within 1 year after application. Kills most annual and perennial grasses; however, it will not control annual bluegrass or hard fescue. Most effective on young, actively growing grasses and less effective on mature grasses. Has injured certain azalea cultivars, especially at high rates, causing spotting and necrosis on leaves. Certain junipers also are sensitive to fluazifop-p-butyl; consult the label carefully. Nonselective A. CAPRYLIC ACID/CAPRIC ACID (Suppress) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: NC COMMENTS: Works best on newly emerged weeds. Do not apply through any type of irrigation system. B. CITRIC ACID/CLOVE OIL (BurnOut) See label WSSA MODE-OF-ACTION GROUP NUMBER1: NC COMMENTS: Do not directly spray or allow to drift to desirable plants. 0 NA C. CLOVE OIL (Matratec) See label 0 NA WSSA MODE-OF-ACTION GROUP NUMBER1: NC COMMENTS: For use in and around greenhouses. Do not directly spray or allow to drift to desirable plants. D. DIQUAT (Reward) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 22 COMMENTS: Not for use in ornamental seed crops in California. Labeled for use around container-grown ornamentals. Kills annual weeds, but only burns off the top of perennials. Contact activity only; affects only green tissue. Good for weed control in winter. E. FATTY ACIDS/AMINE SALTS (Finalsan Herbicidal Soap) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: NC COMMENTS: For around field-grown ornamentals. Do not directly spray or allow to drift to desirable plants. F. GLUFOSINATE (Finale) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 10 COMMENTS: For use as a directed spray around container-grown ornamentals and established fieldgrown ornamentals. Do not apply directly to or allow to drift to desirable green tissue or thin or Weeds Herbicide Treatment Table for Containers and Field Grown Trees and Shrubs (7/20) 191 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES uncalloused bark. Contact herbicide with a limited amount of systemic activity; kills annual weeds, but only burns off the tops of perennials. G. GLYPHOSATE (Roundup Pro) See label 4 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 9 COMMENTS: Labeled for use around container-grown ornamentals and established woody ornamentals. A systemic herbicide that translocates to the roots and growing point of plants and kills the entire plant. Effective on both annual and perennial weeds. Contact with leaves of the ornamentals will result in injury to the plant. Glyphosate activity is increased in low water volumes. For example, greater activity is obtained at 20 gal/acre than at 50 gal/acre. This herbicide can be used alone or combined with a preemergence herbicide. H. PARAQUAT* (Gramoxone SL 2.0) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 22 COMMENTS: For use as a directed around established field-grown ornamental trees. Do not apply directly to or allow to drift to desirable green tissue or bark. Kills annual weeds, but only burns tops off perennials. Controls young annual weeds with contact activity only and affects only green tissue. I. PELARGONIC ACID (Scythe) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 26 COMMENTS: Labeled for use around container-grown ornamentals. Works by contact activity only (does not move in plants) and affects only green tissue. Good control of young annual weeds, but only burns off the top of perennials. Must be applied at high rates in high volumes of water. Very rapid activity. 1 Group numbers are assigned by the Weed Science Society of America (WSSA) according to different modes of action. Although weeds may exhibit multiple resistance across many groups, mode-of-action numbers are useful in planning mixtures or rotations of herbicides with different modes of action. For more information, see http://www.hracglobal.com. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. Permit required from county agricultural commissioner for purchase or use. Not applicable. ‡ * NA Weeds Herbicide Treatment Table for Containers and Field Grown Trees and Shrubs (7/20) 192 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Field-Grown Trees and Shrubs INTEGRATED WEED MANAGEMENT FOR FIELD-GROWN TREES AND SHRUBS (7/20) Field-grown trees and shrubs are generally grown in rows to facilitate planting, weeding by hand or mechanical cultivation, and cultural operations such as grafting and pruning. Most weeds are controlled in established plantings by cultivation and application of preemergence herbicides, but perennial weeds need to be controlled before the crop is planted. Crop Rotation Sometimes the field is fumigated before planting. During the growing season, cultivation, herbicides, or other control methods are used. After the crop is harvested (either bareroot in winter or potted in spring), the field is planted to a cereal crop in fall (barley, oats, or wheat) and harvested the following spring. Herbicides can be used in the cereal crop that will reduce weed problems in the next crop of trees and shrubs. Solarization Soil solarization is a valuable tool to clean up a site before a fall planting (see "Solarization" under GENERAL METHODS OF WEED MANAGMENT. Cover Crops Cover crops, especially winter annuals such as barley, oat, wheat, or combinations of these with rose clover, may be planted between tree rows in early fall. Cover crops reduce erosion and help maintain soil organic matter when the cover is worked into the soil in the spring. Mow the cover crop and work it into the soil before it seeds to reduce competition with the marketed crop. Mulches To reduce weeds in field rows, cuttings can be planted through holes in paper mulch. After planting, organic mulches (e.g., bark chips) can be applied around the plants and between the rows. Organic mulch must be deep enough to shade out all weed seedlings as they germinate. Keep organic mulch back some from basal stems of the crop to avoid promoting crown decay. Geotextile can be placed along the sides of newly planted stock. The geotextile materials must be placed close to the plant to reduce the number weeds will grow around the base of the plant. It is often beneficial to combine geotextile and organic mulches to achieve good coverage and reduce ultraviolet degradation of the geotextile. Weeds Integrated Weed Management for Field-Grown Trees and Shrubs (7/20) 193 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SPECIAL WEED PROBLEMS FOR FIELD-GROWN TREES AND SHRUBS (7/20) LITTLE MALLOW (Cheeseweed) Cheeseweed is a winter annual or biennial that forms hard seed that can remain dormant for long periods of time. It generally germinates in fall after rainfall or an irrigation, but it may germinate any time during winter and spring. The germinating seed is controlled by most preemergence herbicides, especially oxadiazon and oxyfluorfen. Flumioxazin, indaziflam, and isoxaben are also effective. Oxyfluorfen is also effective applied postemergence to the young plant. Glyphosate is not very effective against this weed. YELLOW NUTSEDGE Yellow nutsedge, sometimes call nutgrass, is a perennial sedge that is often confused with a grass. Fumigation before planting is usually effective in controlling this weed. Repeat applications of glyphosate (before the five-leaf stage when new tubers are formed) will reduce populations over time. Bentazon (Broadloom T&O) may be used around some tree species. If the area is left fallow, halosulfuron can be used and then the crop can be planted the next season. Most preemergence herbicides do not control nutsedge, but metolachlor (Pennant) will suppress sprouting of the tubers. Soil solarization will reduce yellow nutsedge but will not eradicate it. Weeds Special Weed Problems for Field-Grown Trees and Shrubs (7/20) 194 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES HERBICIDE TREATMENT TABLE FOR CONTAINERS AND FIELD-GROWN TREES AND SHRUBS (7/20) See table in the previous section. Weeds Herbicide Treatment Table for Field-Grown Trees and Shrubs (7/20) 195 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Field-Grown Flowers INTEGRATED WEED MANAGEMENT FOR FIELD-GROWN FLOWERS (7/20) Most weeds are controlled in field-grown flower crops with cultivation, hand-hoeing, preplant fumigation, and herbicides where there is crop safety. Crops are planted in rows to make cultivation easier and to reduce crop damage from the cultivators. The crops may be direct seeded, but are often transplanted as bulbs or plugs; transplants are more tolerant to handling and herbicides than direct-seeded crops. After establishment, the crops can be cultivated two or three times before the crop canopy closes and the crop begins to compete with the weeds. Some handweeding is usually required to remove all of the weeds. Crop rotation is beneficial to reduce weeds in the crop. When the same crop is grown year after year, the population of weed species that escape normal cultural practices increases. Good rotation crops are barley, oats, or wheat in winter and corn or sudangrass in summer. Mulch Unless the crop is sprinkler irrigated, a dust mulch often is created that keeps the soil surface dry and reduces the germination and establishment of annual weeds. Organic mulches used around transplants can reduce weeds if the light cannot reach the soil. Fine mulches (composted yardwaste) applied 1-1/2 to 2 inches deep before the weed seeds germinate or when weeds are still in the seedling stage will control most of the weeds. If the mulch is coarse, 3 to 6 inches may be required to completely eliminate light from the soil, but unlike fine mulch, they do not allow weed seed germination in the mulch. Bulbs such as Dutch iris may be good candidates for mulching for weed control. They have a large food reserve to push through the mulch and may have better growth after mulching. With some crop species, having a fine mulch right around the base of the plant may result in disease damage to plants. Mulches should not be used if they contain weed seed or plant propagules (e.g., bulbs, rhizomes, or tubers). Soil Solarization Solarization effectively controls many weed species before planting. Solarization must be done during periods of high solar radiation and temperature. Before placing the plastic on the site to be treated, closely mow any established plants, remove the clippings, and then water the area well. Place clear polyethylene that is ultraviolet (UV) resistant over the area, extend it about 2 feet beyond the infested area on all sides, and pull it tightly close to the soil. The plastic must be left in place and maintained intact for 4 to 6 weeks for control of weeds. Many annual weeds can be controlled using this method. Weeds not well controlled include field bindweed, purple and yellow nutsedge, and sweet clover. In areas where solar radiation and temperatures are low and marginal for solarization, purslane is not controlled well. Flaming Shielded propane burners effectively control young weeds between rows without disturbing the soil and bringing weed seeds to the soil surface as cultivation would do. Flaming controls broadleaf weeds better than grasses. Herbicides Most crops have one or more selective preemergence herbicides available for use. See the table TREATMENT FOR FIELD-GROWN FLOWERS for selective herbicides that are registered on flower crops. Postemergence herbicides (fluazifop-p-butyl, sethoxydim) can be used to control some grasses in broadleaved crops. These are applied after the weeds emerge but while they are still small (1–3 inches in height). If weeds are larger than 3 inches, more herbicide will be required and some weeds may not be controlled. Broadleaf herbicides are generally not safe enough to use over flower crops. Even some selective grass herbicides may injure the crop if treated during the flowering stage. Control weeds when they are small and before they flower and set seed. If a few weeds remain, hand weed them. Herbicides can be used before the crop is planted. The broad-spectrum fumigants dazomet, metam potassium*, and metam sodium* can be used on prepared beds to control weeds and other soilborne pests. Depending on which fumigant is used, crops can be planted within days or in 2 to 4 weeks to allow time for the fumigant to dissipate. (* Permit required from county agricultural commissioner.) Weeds Integrated Weed Management for Field-Grown Flowers (7/20) 196 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Another method before planting is called a "stale seedbed" treatment. Beds are prepared for planting and irrigated to germinate weeds. After most of the weeds have germinated, a postemergence herbicide like diquat or glyphosate is applied to kill the weeds. Because no cultivation is done before planting, no new weed seeds are brought to the surface. This "irrigate, germinate, eliminate" approach may be repeated two or more times before planting the crop to reduce the seed populations in the soil. Preemergence herbicides also can be applied after seeding or transplanting a crop but before the weeds emerge. These herbicides generally must be incorporated mechanically along the planted row or leached slightly into the soil by rainfall or 1/2 inch irrigation after application. See specific comments on the herbicides in the table TREATMENT FOR FIELD-GROWN FLOWERS. After the annual flower crop has been harvested, clean up any weeds before they set seed. This can be done most effectively by cultivating. If the field is not needed until the next season, it may be beneficial to plant a cover crop to reduce weeds, keep the soil from eroding, reduce dust, and maintain organic matter in the soil. Weeds Integrated Weed Management for Field-Grown Flowers (7/20) 197 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES HERBICIDE TREATMENT TABLE FOR FIELD-GROWN FLOWERS (7/20) Amount to use Common name (Example trade name) REI‡ (hours) PHI‡ (days) Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see the table SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTROL for information on specific weed control. Always read the label of the product being used. PREEMERGENCE HERBICIDES A. ISOXABEN (Gallery 75DF) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 21 COMMENTS: Excellent herbicide for broadleaf weed control. Major weakness is annual grass control. Therefore, it is often mixed with oryzalin or trifluralin. Some broadleaf weed species can be controlled for up to 18 months with the labeled rates. Isoxaben does not effectively control Malvaceae (mallows). Some herbaceous ornamentals such as Digitalis, snapdragon, and Veronica may be killed by postplant, preemergence applications of isoxaben. B. NAPROPAMIDE (Devrinol DF-TX Ornamental) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 15 COMMENTS: Works best if mechanically incorporated or followed by rainfall or a sprinkler irrigation of 1/2 inch within 7 days after application. The first irrigation seems to be critical for maximum activity. It is an excellent grass herbicide and can suppress common groundsel. Generally less efficacious but often safer than the combination herbicides. Is safer if applied after transplanting. If the soil is moist and there is no rainfall or irrigation within 7 days following application, an appreciable amount of the herbicide is lost and weed control will be lessened. C. ORYZALIN (Surflan AS Specialty) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: A relatively broad-spectrum preemergence herbicide. Can be applied up to 21 days prior to rainfall or before irrigation that is needed to move it into seed zone. Needs 1/2 inch of irrigation or rain to move it to appropriate depth. Controls annual grasses and many broadleaf weeds and can be used safely on some crops after transplanting. Leaches slightly into the soil with irrigation or rainfall. A strong root inhibitor. Many broadleaf ornamentals are tolerant to oryzalin if the herbicide is not in the root zone. Even when applied at rates of 4 lb a.i./acre, sometimes weeds in the aster family (common groundsel, fleabane, prickly lettuce, sowthistle), mustard family (bittercress), and legume family (burclover) are not completely controlled. For most labeled weeds, control usually is effective for 2–3 months. Oryzalin can control spotted oxalis and spurge from seed for about 4 months. Tolerance is marginal on some crops; thus, use low rates until familiar with the herbicide and crop combination. D. OXADIAZON (Ronstar G) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 14 COMMENTS: A broad-spectrum preemergence herbicide that is used during the growing season from spring until fall. It is moved off crop foliage and into the soil by a sprinkler irrigation following application. Oxadiazon is a shoot-girdling herbicide. The granular formulation is safer than the wettable powder. It is weak on all of the chickweed family and on certain broadleaves including chickweed, horseweed, and pearlwort. Has a relatively long residual, 12–16 weeks, but if cultivated control will be lost. It is very effective when applied in fall or spring. Does not leach readily in the soil, is not a root inhibitor, and thus is less likely to injure established species. Injury may occur if applied to wet foliage, if it is not washed from the foliage, or if the granules collect in leaf bases or crowns. E. PENDIMETHALIN (Pendulum 2G) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Gives excellent grass control and will control many broadleaf weeds. Controls a broad-spectrum of broadleaf and grass weeds that is similar to what oryzalin controls. It is often combined with an additional herbicide to widen the spectrum of weeds controlled. Though it is a root inhibitor, it is less injurious to roots than oryzalin or prodiamine. Weeds Herbicide Treatment Table for Field-grown Flowers (7/20) 198 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES F. PRODIAMINE (Barricade) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Prodiamine is stable on the soil surface. It also has been less effective for spurge and groundsel suppression than some other dinitroaniline herbicides. Inhibits root growth. G. TRIFLURALIN (Lebanon Treflan) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: In the same class of herbicides as oryzalin (dinitroanilines), but it is not as stable on the soil surface and must be incorporated with cultivation or irrigation. At low rates trifluralin has been used as a preplant incorporated herbicide for some direct-seeded crops but is safer for use before transplanting. PREEMERGENCE COMBINATIONS Note: For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum active ingredient (a.i.) on any label when tank mixing products that contain the same a.i. A. ORYZALIN/OXYFLUORFEN (Rout) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBERS1: 3/14 COMMENTS: Limited registrations for field-grown flowers. Woody plants are more tolerant than herbaceous plants. Provides excellent broad-spectrum control of annual broadleaf and grass weeds. If granules remain in plants at the base of the leaf or in whorls, burn will occur. Residual control is 3–4 months. POSTEMERGENCE HERBICIDES Nonselective A. DIQUAT (Reward) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 22 COMMENTS: Labeled for use as a preplant treatment and directed postemergence use in field grown ornamentals. Kills annuals weeds, but only burns off the top of perennials. Controls young annual weeds with contact activity only; affects only green tissue. B. GLYPHOSATE (Roundup Pro) See label 4 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 9 COMMENTS: Labeled for use before planting. A systemic herbicide that translocates to the roots and growing point of the plants and kills the entire plant. Effective on both annual and perennial weeds. Contact with leaves of the ornamentals will result in injury to the plant. Glyphosate activity is increased in low water volumes. For example, greater activity is obtained at 20 gal/acre than at 50 gal/acre. Can be used alone or combined with a preemergence herbicide. Often takes 7 or more days after application for complete control. Avoid drift. C. PARAQUAT* (Gramoxone SL 2.0) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 22 COMMENTS: For harvest aid and desiccation applications, preplant or preemergence (broadcast or banded), and postemergence directed spray. Controls young annual weeds with contact activity only; affects only green tissue. D. PELARGONIC ACID (Scythe) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 26 COMMENTS: Labeled for use preplant. Controls young annual weeds by contact activity only; affects only green tissue. Must be applied at high rates in high volumes of water. Kills annual weeds, but only burns off the top of perennials. Does not move in plant. Very rapid activity (minutes in high sunlight). Selective (grasses) A. CLETHODIM (Envoy Plus) See label 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: Controls most annual grasses, including annual bluegrass. Safe to use over most broadleaf ornamentals. B. FLUAZIFOP-P-BUTYL (Fusilade II) Weeds See label 12 NA Herbicide Treatment Table for Field-grown Flowers (7/20) 199 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES (Ornamec) See label 4 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: Postemergence contact selective herbicide for use in field grown ornamentals. Kills most annual and perennial grasses, however it will not control annual bluegrass or hard fescue. It is most effective on young actively growing grasses and less effective on mature grasses. Ornamec Over-The-Top not for use on certain ornamental species in California; see label. C. SETHOXYDIM (Poast) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 1 COMMENTS: Controls most annual grasses, except annual bluegrass or hard fescue. Most effective on young, actively growing grasses. A nonphytotoxic oil or nonionic surfactant must be added for best control. * Permit required from county agricultural commissioner for purchase or use. Group numbers are assigned by the Weed Science Society of America (WSSA) according to different modes of action. Although weeds may exhibit multiple resistance across many groups, mode-of-action numbers are useful in planning mixtures or rotations of herbicides with different modes of action. For more information, see http://www.hracglobal.com. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. Not applicable. 1 ‡ NA Weeds Herbicide Treatment Table for Field-grown Flowers (7/20) 200 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Greenhouse-Grown Crops INTEGRATED WEED MANAGEMENT INSIDE GREENHOUSES (7/20) It is difficult to control weeds in greenhouses because the types of plants grown are generally sensitive to herbicides and weeds are often hard to reach with an herbicide application. Only one preemergence herbicide is registered for use in greenhouses (indaziflam) and that is for beneath benches and greenhouse floors only. Only a few weed species are common problems in greenhouses. They are all closely associated with high moisture and nutrients and spread rapidly if they are allowed to become established. The most common weeds in and around greenhouses include annual bluegrass, common chickweed, creeping woodsorrel, lesser-seeded bittercress, liverwort, moss, and pearlwort. Others that may be present include cheeseweed, cudweed, fireweed, prostrate and spotted spurge, sowthistle, and willowherb. Controlling these weeds will also help reduce the reservoir of insects and plant pathogens that are often associated with weeds. Reducing standing water or high moisture around the interior perimeter of the greenhouse will help control these weeds as they often become established there and can spread from those habitats. Cultural Control Sanitation is the best method for weed control. Weeds may be brought into the greenhouse in potting mix or with cuttings, bulbs, or other plant material or on dirty pots and tools. If weeds do get in, they should never be allowed to flower and seed. This is especially true of bittercress and creeping woodsorrel (oxalis). Maintain trash cans in the greenhouse for weeds that are pulled during maintenance, so they can be readily removed before flowering. Hand-weed frequently (daily or weekly) so no weeds go to seed. If the floors are concrete, regularly wash or sweep away soil that drops to the floor so that weeds will not establish or seed. When crops are rotated, clean weeds out of the greenhouse and clean benches, tubing, and walls to remove seeds that may be sticking to them. Irrigate with water that is free of fungal spores and weed seeds. If using raised or self-contained beds, pasteurize the soil before planting by either steaming or solarizing. Solarization is described in GENERAL METHODS OF WEED MANAGEMENT and steam fumigation in CONTAINER NURSERIES. Herbicides Only Marengo (indaziflam) is currently available for preemergence use in greenhouses and only under benches or on the floor, not in the container. Many of the other preemergence herbicides are quite volatile at greenhouse temperatures and can move or accumulate or both in greenhouses to levels toxic to crop plants. Even though some herbicides may be labeled for use in a crop, the label must specifically state that it can be used in greenhouses to be legal and safe. On the greenhouse floor and under the benches a postemergence herbicide can be used to reduce weed populations and to keep the weeds from flowering and seeding. Provide good drainage and level the gravel or soil under the benches to reduce water collecting in low areas. Wet areas increase the chance of liverwort and moss infestations. Air movement at the floor level will help dry off the floor and will also reduce the chance of infestations of weeds favored by wet areas. After a crop has been harvested, remove any weeds to keep them from seeding so new seeds will not be added to the seedbank in soil. Weeds Integrated Weed Management Inside Greenhouses (7/20) 201 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SPECIAL WEED PROBLEMS INSIDE GREENHOUSES (7/20) LIVERWORT AND MOSSES Liverwort and mosses can be found in many greenhouses where plants are highly irrigated and fertilized. Their presence is exacerbated when there is high nitrogen in the upper soil surface, such as by top-dressing. These types of plants reproduce by spores and vegetatively and are easily spread throughout a greenhouse. They can compete with the crop for nutrients and water and can also create a barrier on the potting media surface that restricts water movement into the container resulting in poor irrigation efficiency and increased runoff. Decreasing the amount of water applied and avoiding top-dressing, as well as inspecting plants before they come into the greenhouse, can reduce the presence and impact of liverwort and mosses. Weeds Special Weed Problems Inside Greenhouses (7/20) 202 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES HERBICIDE TREATMENT TABLE FOR INSIDE GREENHOUSES (7/20) Common name (Example trade name) Amount to use REI‡ (hours) PHI‡ (days) Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see the table SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTOL for information on specific weed control. Always read the label of the product being used. PREEMERGENCE HERBICIDES A. Indaziflam (Marengo) 7.5-15.5 fl oz/acre 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 29 COMMENTS: Very long residual. For use under benches and greenhouse floors only. Do not exceed 18.5 fl oz in a 12 month period. POSTEMERGENCE HERBICIDES A. DIQUAT (Reward) Spot application: 1–2 qt plus 8–16 oz nonionic surfac24 NA tant/100 gal water Broadcast: 1–2 pt plus 16–32 oz nonionic surfactant/100 gal water WSSA MODE-OF-ACTION GROUP NUMBER1: 22 COMMENTS: Apply in 15–40 gal water/acre. Do not allow contact of spray or drift to desirable foliage. B. GLUFOSINATE (Finale) Spot application: 1.5 fl oz/1 gal water 12 NA Broadcast application: 3 qt when weeds less than 6 inches tall or 4 qt when weeds are 6 inches or taller WSSA MODE-OF-ACTION GROUP NUMBER1: 10 COMMENTS: Apply as directed spray under benches or on floors of the greenhouse or around the periphery of the greenhouse. Do not have air circulation fans running. Apply using large droplets and low pressure to avoid drift or contact with green leaves or stems of crop. Do not use in greenhouses with edible crops. C. GLYPHOSATE (Roundup Pro) Spot application: 0.66–1.33 oz product/1 gal water 4 NA Broadcast application: (annuals) 2 qt–1 gal/100 gal water (perennials) up to 2 gal/100 gal water WSSA MODE-OF-ACTION GROUP NUMBER1: 9 COMMENTS: Apply to young weeds under benches along walkways or along the edge of the greenhouses. Use low pressure and large droplets to reduce chance of drift of spray on to leaves of the crop. Do not apply to any runoff water. Turn off air circulation fans during application. Desirable vegetation should not be present during application. D. PELARGONIC ACID (Scythe) See label 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 26 COMMENTS: Apply to young weeds under benches, along walkways, or along the edge of greenhouses. 1 Group numbers are assigned by the Weed Science Society of America (WSSA) according to different modes of action. Although weeds may exhibit multiple resistance across many groups, mode-of-action numbers are useful in planning mixtures or rotations of herbicides with different modes of action. For more information, see http://www.hracglobal.com. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. Not applicable. ‡ NA Weeds Herbicide Treatment Table for Inside Greenhouses (7/20) 203 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES INTEGRATED WEED MANAGEMENT OUTSIDE GREENHOUSES (7/20) Control weeds outside the greenhouse to help prevent movement of their seeds into the greenhouse. Weed control in the area around the greenhouse will also reduce the chances that insects and plant pathogens that may live and reproduce on weeds will move into the greenhouse. If insects such as aphids, leafhoppers, lygus bugs, thrips, or whiteflies are abundant on the weeds outside the greenhouse, it may be desirable to control them before the weeds are removed or these insects may move into the greenhouse when the weed host dies. Weeds outside the greenhouse can be controlled by cultivation or mowing where feasible and with herbicides. Take care when applying herbicide so that it does not move into the greenhouse by drift or runoff. Preemergence herbicides can be used if the soil slopes away from the greenhouse so no soil or water that may contain an herbicide gets into the greenhouse. Vents in the greenhouse and fans should be closed or shut off while herbicide applications are being made so that the herbicide will not be drawn into the greenhouse. Also, volatile herbicides (e.g., oxyfluorfen) should not be used around the outside of a greenhouse. Weeds Integrated Weed Management Outside Greenhouses (7/20) 204 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES HERBICIDE TREATMENT TABLE FOR OUTSIDE GREENHOUSES (7/20) Common name (Example trade name) Amount per Acre REI‡ (hours) PHI‡ (days) Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see the table SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTOL for information on specific weed control. Always read the label of the product being used. PREEMERGENCE HERBICIDES A. ISOXABEN (Gallery 75 DF) 0.9975 lb 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 21 COMMENTS: Apply preemergence or combine with a postemergence herbicide if young weeds are established. May be combined with other preemergence herbicides to control additional broadleaf weeds. B. ORYZALIN (Surflan AS) 2–4 qt 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Combine with a postemergence herbicide if young weeds are present. May be combined with other preemergence herbicides to control a broader spectrum of grasses and broadleaf weeds. C. PENDIMETHALIN (Pendulum 3.3 EC) 2–3.96 lb a.i. 24 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Apply preemergence. May be combined with a postemergence herbicide if young weeds are present. May be combined with other preemergence herbicides to control grasses and certain broadleaf weeds. D. PRODIAMINE (Barricade) 0.65–1.495 lb 12 NA WSSA MODE-OF-ACTION GROUP NUMBER1: 3 COMMENTS: Apply preemergence. May be combined with a postemergence herbicide if young weeds are present. May be combined with other preemergence herbicides to control grasses and certain broadleaf weeds. POSTEMERGENCE HERBICIDES A. DIQUAT (Reward) 1–2 pt plus 16–32 oz nonionic 24 NA surfactant/100 gal water WSSA MODE-OF-ACTION GROUP NUMBER1: 22 COMMENTS: Apply 15–40 gal/acre or enough to wet young weeds. Apply when weeds are young for improved control. B. GLUFOSINATE (Finale) Spot application: 1.5 fl oz/1 gal water 12 NA Broadcast application: 3 qt when weeds are less than 6 inches tall or 5 qt when weeds are 6 inches or taller. WSSA MODE-OF-ACTION GROUP NUMBER1: 10 COMMENTS: Apply as directed spray under benches or on floors of the greenhouse or around the periphery of the greenhouse. Do not have air circulation fans running. Apply using large droplets and low pressure to avoid drift or contact with green leaves or stems. Do not use in greenhouses with edible crops. C. GLYPHOSATE (Roundup Pro) Annuals: 2 qt–1 gal/100gal water 4 NA or 0.66–1.33 oz/gal water Perennials: see comments WSSA MODE-OF-ACTION GROUP NUMBER1: 9 COMMENTS: Apply lower rates to young weeds. Apply to perennials when in flower stage and the soil moisture is sufficient to maintain active growth of the weeds. Weeds Herbicide Treatment Table for Outside Greenhouses (7/20) 205 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 1 ‡ NA Group numbers are assigned by the Weed Science Society of America (WSSA) according to different modes of action. Although weeds may exhibit multiple resistance across many groups, mode-of-action numbers are useful in planning mixtures or rotations of herbicides with different modes of action. For more information, see http://www.hracglobal.com. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. Not applicable. Weeds Herbicide Treatment Table for Outside Greenhouses (7/20) 206 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES This material is partially based upon work supported by the Extension Service, U.S. Department of Agriculture, under special project Section 3(d), Integrated Pest Management. PRECAUTIONS FOR USING PESTICIDES Pesticides are poisonous and must be used with caution. READ THE LABEL BEFORE OPENING A PESTICIDE CONTAINER. Follow all label precautions and directions, including requirements for protective equipment. Apply pesticides only on the crops or in the situations listed on the label. Apply pesticides at the rates specified on the label or at lower rates if suggested in this publication. In California, all agricultural uses of pesticides must be reported. Contact your county agricultural commissioner for further details. Laws, regulations, and information concerning pesticides change frequently. This publication reflects legal restrictions current on the date next to each pest's name. Legal Responsibility. The user is legally responsible for any damage due to misuse of pesticides. Responsibility extends to effects caused by drift, runoff, or residues. Transportation. Do not ship or carry pesticides together with food or feed in a way that allows contamination of the edible items. Never transport pesticides in a closed passenger vehicle or in a closed cab. Storage. Keep pesticides in original containers until used. Store them in a locked cabinet, building, or fenced area where they are not accessible to children, unauthorized persons, pets, or livestock. DO NOT store pesticides with foods, feed, fertilizers, or other materials that may become contaminated by the pesticides. Container Disposal. Dispose of empty containers carefully. Never reuse them. Make sure empty containers are not accessible to children or animals. Never dispose of containers where they may contaminate water supplies or natural waterways. Consult your county agricultural commissioner for correct procedures for handling and disposal of large quantities of empty containers. Protection of Nonpest Animals and Plants. Many pesticides are toxic to useful or desirable animals, including honey bees, natural enemies, fish, domestic animals, and birds. Crops and other plants may also be damaged by misapplied pesticides. Take precautions to protect nonpest species from direct exposure to pesticides and from contamination due to drift, runoff, or residues. Certain rodenticides may pose a special hazard to animals that eat poisoned rodents. Posting Treated Fields. For some materials, restricted entry intervals are established to protect field workers. Keep workers out of the field for the required time after application and, when required by regulations, post the treated areas with signs indicating the safe re-entry date. Check with your county agricultural commissioner for latest restricted entry interval. Preharvest intervals. Some materials or rates cannot be used in certain crops within a specified time before harvest. Follow pesticide label instructions and allow the required time between application and harvest. Permit Requirements. Many pesticides require a permit from the county agricultural commissioner before possession or use. When such materials are recommended, they are marked with an asterisk (*) in the treatment tables or chemical sections of this publication. Processed Crops. Some processors will not accept a crop treated with certain chemicals. If your crop is going to a processor, be sure to check with the processor before applying a pesticide. Crop Injury. Certain chemicals may cause injury to crops (phytotoxicity) under certain conditions. Always consult the label for limitations. Before applying any pesticide, take into account the stage of plant development, the soil type and condition, the temperature, moisture, and wind. Injury may also result from the use of incompatible materials. Personal Safety. Follow label directions carefully. Avoid splashing, spilling, leaks, spray drift, and contamination of clothing. NEVER eat, smoke, drink, or chew while using pesticides. Provide for emergency medical care IN ADVANCE as required by regulation. ANR NONDISCRIMINATION AND AFFIRMATIVE ACTION POLICY STATEMENT FOR UNIVERSITY OF CALIFORNIA PUBLICATIONS REGARDING PROGRAM PRACTICES The University of California prohibits discrimination or harassment of any person on the basis of race, color, national origin, religion, sex, gender identity, pregnancy (including childbirth, and medical conditions related to pregnancy or childbirth), physical or mental disability, medical condition (cancerrelated or genetic characteristics), ancestry, marital status, age, sexual orientation, citizenship, or service in the uniformed services (as defined by the Uniformed Services Employment and Reemployment Rights Act of 1994: service in the uniformed services includes membership, application for membership, performance of service, application for service, or obligation for service in the uniformed services) in any of its programs or activities. University policy also prohibits reprisal or retaliation against any person in any of its programs or activities for making a complaint of discrimination or sexual harassment or for using or participating in the investigation or resolution process of any such complaint. University policy is intended to be consistent with the provisions of applicable State and Federal laws. Inquiries regarding the University's nondiscrimination policies may be directed to the Affirmative Action/Equal Opportunity Director, University of California, Agriculture and Natural Resources, 1111 Franklin Street, 6th Floor, Oakland, CA 94607, (510) 987-0096. Precautions for Using Pesticides (7/20) 207 Illustrated version at http://ipm.ucanr.edu/PMG/selectnewpest.floriculture.html

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