UC IPM Pest Management Guidelines: Floriculture & Ornamental Nurseries April 2013 Contents (Dates in parenthesis indicate when each topic was updated) DISEASES General information (Section reviewed 3/09) Management of Soilborne Pathogens (3/09) ...................................................................................................................................... 1 General Properties of Fungicides (3/09) ............................................................................................................................................. 4 Key Diseases (Section reviewed 3/09) Cottony Rot (3/09) ................................................................................................................................................................................. 5 Crown Gall (3/09) .................................................................................................................................................................................. 7 Damping-Off (3/09) ............................................................................................................................................................................... 9 Downy Mildew (3/09) ......................................................................................................................................................................... 11 Fusarium Wilt (3/09) ........................................................................................................................................................................... 12 Gray Mold (3/09) ................................................................................................................................................................................. 14 Phytophthora Root and Crown Rots (3/09) ..................................................................................................................................... 16 Phytoplasmas (3/09) ............................................................................................................................................................................ 18 Powdery Mildew (3/09) ...................................................................................................................................................................... 19 Pythium Root Rot (3/09) ..................................................................................................................................................................... 22 Rust (3/09) ............................................................................................................................................................................................. 24 Southern Blight (3/09) ......................................................................................................................................................................... 26 Sudden Oak Death (3/09) ................................................................................................................................................................... 28 Thielaviopsis Root Rot (3/09) ............................................................................................................................................................. 31 Verticillium Wilt (3/09) ....................................................................................................................................................................... 32 Viruses and Viroid Diseases (3/09) .................................................................................................................................................. 33 Disease Control Outlines (Section reviewed 3/09) Aster, China (Callistephus chinensis) (3/09) ...................................................................................................................................... 35 Azalea (Rhododendron spp.) (3/09) .................................................................................................................................................... 36 Begonia (Begonia spp.) (3/09) ............................................................................................................................................................ 37 Calla (Zantedeschia spp.) (3/09) ........................................................................................................................................................... 38 Camellia (Camellia spp.) (3/09)........................................................................................................................................................... 39 Carnation (Dianthus caryophyllus) (3/09) ........................................................................................................................................... 40 Cattleya (Cattleya spp.) (3/09) ............................................................................................................................................................. 42 Chrysanthemum (Chrysanthemum grandiflora) (3/09) ...................................................................................................................... 44 Cyclamen (Cyclamen spp.) (3/09) ........................................................................................................................................................ 47 Cymbidium Orchid (Cymbidium spp.) (3/09) ................................................................................................................................... 48 Dahlia (Dahlia spp.) (3/09) ................................................................................................................................................................... 49 Delphinium (Delphinium spp. and hybrids) (3/09) .......................................................................................................................... 51 Easter Lily (Lilium longiflorum) (3/09) ................................................................................................................................................ 52 Fuchsia (Fuchsia spp.) (3/09)................................................................................................................................................................ 53 Geranium (Pelargonium spp.) (3/09) ................................................................................................................................................... 54 Gladiolus (Gladiolus spp.) (3/09) ......................................................................................................................................................... 56 Gypsophila (Gypsophila paniculata) (3/09) ......................................................................................................................................... 58 Heather (Calluna vulgaris, Erica spp.) (3/09)...................................................................................................................................... 59 Iris (Bulbous) (3/09) .............................................................................................................................................................................. 60 (continued next page) An illustrated version of this guideline is available online at www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html Publication 3392 UC Statewide Integrated Pest Management Program Table of Contents, continued Iris (Rhizomatous) (3/09) ..................................................................................................................................................................... 62 Marguerite Daisy (Chrysanthemum frutescens) (3/09) ....................................................................................................................... 63 Pot Marigold (Calendula officinalis) (3/09).......................................................................................................................................... 64 Narcissus (Narcissus spp.) (3/09) ........................................................................................................................................................ 65 Peony (Paeonia spp.) (3/09) .................................................................................................................................................................. 67 Poinsettia (Poinsettia spp.) (3/09) ........................................................................................................................................................ 68 Rose (Rosa spp.) (3/09) ......................................................................................................................................................................... 69 Shasta Daisy (Chrysanthemum maximum) (3/09) ............................................................................................................................... 71 Snapdragon (Antirrhinum majus) (3/09) ............................................................................................................................................ 72 Statice (Limonium spp.) (3/09) ............................................................................................................................................................. 73 Stock (Matthiola spp.) (3/09) ................................................................................................................................................................ 74 Strawflower (Helichrysum bracteatum) (3/09) .................................................................................................................................... 76 Sweet Pea (Lathyrus odoratus) (3/09)................................................................................................................................................... 77 Sweet William (Dianthus barbatus) (3/09) .......................................................................................................................................... 78 Host-Pathogen Index (3/09) .................................................................................................................................................................... 79 INSECTS & MITES General information (Section reviewed 3/09) Managing Pesticide Resistance (3/09) .............................................................................................................................................. 82 Monitoring With Sticky Traps (3/09) ................................................................................................................................................ 84 Establishing Treatment Thresholds (3/09) ....................................................................................................................................... 85 Biological Control (3/09) ..................................................................................................................................................................... 86 Major Insect and Mite Pests (3/09) Aphids (6/10) ........................................................................................................................................................................................ 91 Armored Scales (6/10) ......................................................................................................................................................................... 95 Armyworms and Cutworms (6/10) .................................................................................................................................................. 97 Bulb Mites (3/09) ................................................................................................................................................................................ 100 Cabbage Looper (6/10) ...................................................................................................................................................................... 101 Diamondback Moth (6/10) ............................................................................................................................................................... 104 Foliar-Feeding Mealybugs (6/10) .................................................................................................................................................... 107 Fungus Gnats (6/10) .......................................................................................................................................................................... 110 Leafhoppers and Sharpshooters (6/10)........................................................................................................................................... 113 Leafminers (6/10) ............................................................................................................................................................................... 117 Leafrollers (6/10) ................................................................................................................................................................................ 119 Root Mealybugs (6/10) ...................................................................................................................................................................... 122 Shore Fly (6/10) .................................................................................................................................................................................. 124 Soft Scales (6/10) ................................................................................................................................................................................ 126 Thread-Footed (Tarsonemid) Mites (6/10) ..................................................................................................................................... 128 Thrips (6/10) ....................................................................................................................................................................................... 130 Twospotted Spider Mites (6/10) ...................................................................................................................................................... 133 Whiteflies (6/10) ................................................................................................................................................................................. 136 OTHER INVERTEBRATES Mollusks Snails and Slugs (4/13) ...................................................................................................................................................................... 140 Nematodes (3/09).................................................................................................................................................................................... 143 WEEDS General information (Section reviewed 3/09) Weed Classifications (3/09) .............................................................................................................................................................. 148 General Methods of Weed Management (3/09) ............................................................................................................................. 150 Susceptibility of Weeds to Herbicide Control (3/09) ...................................................................................................................... 154 Container Nurseries (3/09) Weeds in Container Nurseries (3/09) ............................................................................................................................................. 156 Special Weed Problems for Container Nurseries (3/09) .............................................................................................................. 159 Treatment for Container Nurseries (6/10) ..................................................................................................................................... 160 (continued next page) April 2013 ii Table of Contents, continued Field-Grown Trees, Shrubs, and Flowers (3/09) General Information on Field-Grown Trees and Shrubs ............................................................................................................... 164 Special Weed Problems for Field-Grown Trees and Shrubs (3/09) ............................................................................................ 164 Treatment for Field-Grown Trees and Shrubs (3/09) ................................................................................................................... 165 Field-Grown Flowers (3/09) ............................................................................................................................................................. 169 Treatment for Field-Grown Flowers (3/09).................................................................................................................................... 171 Greenhouses (3/09) Greenhouse-Grown Crops (Inside Greenhouses) (3/09) ............................................................................................................. 174 Treatment (Inside Greenhouses) (3/09) .......................................................................................................................................... 175 Greenhouse-Grown Crops (Outside Greenhouses) (3/09) .......................................................................................................... 176 Treatment (Outside Greenhouses) (3/09) ....................................................................................................................................... 177 Precautions for Using Pesticides .............................................................................................................................................................. 178 April 2013 iii Authors Diseases: S. T. Koike, UCCE Monterey Co.; C. A. Wilen, UC IPM Program, UCCE San Diego Co. Insects and Mites: J. A. Bethke, UCCE San Diego Co. Nematodes: J. J. Stapleton, UC IPM Program, Kearny Agricultural Center; M. V. McKenry, Kearney Agricultural Center, Parlier; A. T. Ploeg, Nematology, UC Riverside Weeds: C. A. Wilen, UC IPM Program, UCCE San Diego Co. Acknowledgment for contributions to Diseases: R. D. Raabe, (emeritus) ESPM, UC Berkeley; A. H. McCain, (emeritus) ESPM, UC Berkeley; M. E. Grebus, Plant Pathology, UC Riverside Acknowledgment for contributions to Sudden Oak Death: S. A. Tjosvold, UCCE Santa Cruz Co. 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, Entomology, UC Davis Acknowledgment for contributions to Weeds: C. L. Elmore, Vegetable Crops/Weed Science, UC Davis About this publication Produced and edited by: UC Statewide IPM Program University of California, Davis Guidelines Coordinator: R. Basler Production: C. Laning 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://www.ipm.ucdavis.edu • UC Cooperative Extension County Offices • University of California ANR Communication Services Richmond, CA 94804 510-665-2195; 800-994-8849 Updates: These guidelines are updated regularly. Check with your University of California Cooperative Extension Office or the UC IPM World Wide Web site for information on updates. Note to readers: 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 formulations or registered materials are listed and the products listed in these guidelines are not all equally efficacious. Most of the pests listed in these guidelines have a propensity to develop resistance to insecticides or miticides. Pesticide resistance in many of the pests can be localized and is dependent on the pesticide use patterns to which the pest population has been exposed. Therefore, what works for one grower may not be effective for a neighboring grower. These guidelines have been written to assist in developing an IPM program and to delay or prevent the development of pesticide resistance. In the Insect and Mite section, classes of pesticides are listed alphabetically and materials are listed alphabetically within the class of pesticide to which they belong. Always check the label and 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. Note that some products may not be labeled for both greenhouse and field production uses. To be used with UC ANR Publication 3402, Integrated Pest Management for Floriculture and Nurseries April 2013 iii UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DISEASES (Section reviewed 3/09) General information MANAGEMENT OF SOILBORNE PATHOGENS (3/09) Soil is a reservoir for many plant pathogens and plants are under constant attack by these soilborne organisms. If conditions become favorable for infection, plants will develop disease. Population 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, select a few plants from different locations and remove plants from their containers or gently scrape or wash away soil. Examine roots and crowns for browning, softness, or other early indications of disease. Also look for discolored or wilted plants and fungal growths aboveground, which may indicate more advanced stages of disease. Test kits are available for detecting Pythium, Rhizoctonia, and Phytophthora fungi infecting greenhouse and container-grown nursery plants. However, keep in mind that some test kits do not specifically test for pathogenic species; in such cases, nonpathogens could result in a false positive result. Use test kits in combination with other information to make good pest management. Understand the conditions and practices that promote disease and regularly examine for and remedy diseasepromoting 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 and soil in cold frames, as well as soil in open fields. For soil in containers, monitor the temperatures of the growing medium closely to ensure that it is high enough to control pests by placing a soil thermometer into the center of the mass of the soil mix. Planting media can be solarized either in bags or flats covered with transparent plastic or in layers 3- to 9-inches wide sandwiched between two sheets of plastic. A double layer of plastic can increase soil temperature by up to 50°F. 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 plastic. Soil temperatures will be lower except at the surface, so plastic should 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. Solarization is acceptable for organic production. Heat. Heating the soil is very effective and has the advantage over chemical treatment in that the soil can be planted immediately after cooling. Many plant pathogens are killed by short exposures to high temperatures; however, experience has shown that the soil temperatures should be maintained for approximately 30 minutes. Most plant pathogens can be killed by temperatures of 140°F (60°C) for 30 minutes; however, some viruses (as well as weed seeds) may survive this treatment. (Where weed seeds are a problem, a higher treatment temperature is required, but the tobacco mosaic virus [TMV] and some weed seeds still will not be killed by the higher temperature.) Although pure steam at sea level is at 212°F (100°C), the temperature at which steam is used to treat soil is usually about 180°F because of air that is present in the steam or in the 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 at just what temperature to treat soil. 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. DISEASES: GENERAL INFORMATION Management of Soilborne Pathogens (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 11 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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 to insure even distribution of heat is important. 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 insure that there is good circulation of steam air. Soil Fumigants. The most useful soil fumigants are methyl bromide and chloropicrin. (The 2007 Critical Use Exemption list allows use of methyl bromide for moderate-to-severe pathogen infestation.) Although registered for use, metam-sodium (Vapam), and dazomet (Basamid) are not very effective for controlling many soilborne pathogens, including Verticillium and Fusarium oxysporum. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone; methyl bromide depletes ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. Methyl bromide is a gas at temperatures over 40°F. It escapes rapidly from soil if not applied under a gas-proof cover. Polyethylene sheeting is commonly used to confine methyl bromide, although the gas does slowly escape through polyethylene. Methyl bromide is probably the most versatile of the soil fumigants because of its ability to diffuse rapidly through the soil and kill many kinds of organisms, weeds, and many seeds. Soil generally can be planted in just a few days after removal of plastic covers, although there are exceptions. A few plants such as Allium spp., carnations, and snapdragons are sensitive to and may be damaged by inorganic bromide that remains in the soil following fumigation. Leaching the soil with water before planting is helpful in reducing the amount of bromide in the rooting area. Methyl bromide alone usually does not kill all of the microsclerotia of Verticillium dahliae, the fungus that is the causal agent of Verticillium wilt. When this fungus occurs it is often necessary to include chloropicrin in the fumigant. Methyl bromide may be injected by chisels if the soil is covered immediately by plastic. It is the only soil fumigant that needs to be applied under plastic covers. This is a restricted use material and requires a permit from the county agricultural commissioner to be purchased and/or applied. With the impending loss of methyl bromide as a registered fumigant, research is being conducted to find viable alternatives because of ozone depletion concerns. Chloropicrin (trichloronitromethane) must be injected into soil. It is the best fumigant for controlling Verticillium dahliae. It generally is 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. This is a restricted use material and requires a permit from the county agricultural commissioner to be purchased and/or applied. 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. Fosetyl-Al (Aliette) is active against Phytophthora species and some Pythium species. It is applied as a soil drench or as a foliar spray but is more effective as a foliar spray. It is absorbed by foliage and moves into roots. It is used as a drench at 0.8 to 1.6 lb a.i./1000 square feet using 0.5 to 1.5 pt water/square foot. As a foliar spray it is applied at 2 to 4 lb a.i./100 gal water. The active ingredient in SoilGard is Gliocladium virens, a soilborne fungus that under certain conditions helps provide control of Pythium and Rhizoctonia fungi. Iprodione (Chipco 26019) is used at 0.2 lb a.i./100 gal water applied as a drench (1–2 pt/square foot) at seeding or transplanting. It is effective against Rhizoctonia damping-off, Sclerotinia, and gray mold. Some iprodione is absorbed by plant parts. Mefenoxam (Subdue Maxx) is active against Pythium, Phytophthora, and downy mildews but is not effective against pathogens outside of this group of organisms. This material replaces the fungicide metalaxyl. It is applied at planting as a drench and periodically thereafter as needed. Mefenoxam is also available in a granular formulation to use before planting. It is water-soluble and readily leached from soil. It is absorbed by plant parts DISEASES: GENERAL INFORMATION Management of Soilborne Pathogens (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 12 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES including roots; movement in the plant is primarily in the xylem. Use of this material over a period of time may lead to resistance. PCNB (Terraclor), also called quintozene, is very active against diseases caused by Rhizoctonia solani and Sclerotinia spp. and is the best available material for southern wilt caused by Sclerotium rolfsii. It is insoluble in water and must be thoroughly mixed with soil to reach its desired depth of control. It works through vapor action and has good residual action. It is inactive against Pythium pathogens. It is used at 0.5 to 1 lb a.i./1000 square feet and mixed into the top 2 inches of soil for control of Rhizoctonia damping-off. Germination of some seeds may be inhibited and small plants may be stunted by this fungicide. Streptomyces griseoviridis (Mycostop) is a biological fungicide reported to help control seed rot, root and stem rot, and wilt caused by Alternaria and Phomopsis in container-grown ornamentals. In the greenhouse it may suppress Botrytis gray molds and root rots of Pythium, Phytophthora, and Rhizoctonia. Thiophanate-methyl (FungoFlo, Cleary's 3336, Zyban, Systec, etc.) is generally applied after sowing. It helps to control Rhizoctonia diseases, cottony rot, Thielaviopsis rots, and some Cylindrocladium diseases. It is not effective against Pythium spp., Phytophthora spp., Sclerotium rolfsii, Botrytis spp., or Fusarium spp. It is used at 0.5 lb a.i. or less/100 gal water and applied as a drench or heavy spray (1-2 pt/sq ft). 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. Trichoderma spp. (Garden Solutions, Root Guardian) is a biological fungicide reported to help provide control of root diseases caused by Pythium, Rhizoctonia, and Fusarium in nursery and greenhouse crops. It is formulated as a seed protectant, a soil drench, and as granules. Triflumizole (TerraGuard) is a protectant fungicide used as a cutting soak, soil drench, foliar spray, or through chemigation for control of Cylindrocladium spp. Its use is restricted to enclosed commercial structures such as greenhouses and shade houses. 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 and thiram are also seed treatments; they are generally applied at rates of 1 to 4 oz/100 lb seed, but they offer only a small degree of protection. Materials used for bulb or corm dips include thiabendazole (Mertect), which controls Fusarium basal rot and Penicillium blue mold. 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 some types of fungal spores and bacteria. 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 10 parts water. For known contaminated materials, a stronger solution diluted 1 part bleach to 5 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. Debris, potting mix, and other residues left over in bleach washes will also reduce bleach concentration. 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 13 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GENERAL PROPERTIES OF FUNGICIDES Common name (trade name) azoxystrobin (Heritage) Bacillus subtilis (Rhapsody) chlorothalonil (Daconil) dicloran dimethomorph (Stature) etridiazole (Terrazole CA) fenarimol (Rubigan) fenhexamid (Decree) fixed copper (Kocide, etc.) fludioxonil (Medallion) flutolanil (Prostar) fosetyl-al (Aliette) Gliocladium virens (SoilGard) iprodione (Chipco 26019) lime sulfur Chemical class Activity Qol2 biological chloronitrile aromatic hydrocarbon carboxylic acid amines heteroaromatic DMI3-pyrimidine hydroxyanilide inorganic phenylpyrroles carboxamides phosphonate biological dicarboximide inorganic mancozeb (Dithane) mefenoxam (Subdue Maxx) myclobutanil (Hoist) neem oil (Triact) PCNB (Terraclor) piperalin (Pipron) potassium bicarbonate (Kaligreen) potassium phosphate (Fosphite) propiconazole (Banner Maxx) Streptomyces griseoviridis (Mycostop) stylet oil (JMS) thiophanate-methyl (FungoFlo, etc.) triadimefon (Strike, etc.) Trichoderma spp. (Garden Solutions, etc.) trifloxystrobin (Compass) triflumizole (TerraGuard) wettable sulfur (3/09) single-site contact multi-site systemic (local) — — single-site — multi-site — — multi-site — multi-site multi-site Mode of action1 11 NC M5 14 40 14 3 17 M1 12 7 33 NC 2 M2 Resistance potential high low low medium low-medium low-medium medium low-medium low low-medium medium low low medium-high low dithio-carbamate (EBDC)3 acylalanine DMI3-triazole oil aromatic hydrocarbon amines inorganic inorganic DMI3-triazole biological multi-site single-site single-site — single-site — — contact single-site — M3 4 3 NC 14 5 NC NC 3 NC low high medium none low-medium low-medium none low medium low oil benzimidazole DMI3-triazole biological — single-site single-site — NC 1 3 NC none high medium low Qol2 DMI3-imidazole inorganic single-site single-site multi-site 11 3 M2 high medium low Comments incompatible with most other pesticides — = no information NC = not classified 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. 2 Qol = quinone outside inhibitor 3 DMI = demethylation (sterol) inhibitor 4 EBDC = ethylene bisdithiocarbamate DISEASES: GENERAL INFORMATION General Properties of Fungicides (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 4 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Key Diseases COTTONY ROT (3/09) (3/09) Pathogen: Sclerotinia sclerotiorum SYMPTOMS Under high humidity the fungus produces a mass of cottony hyphae or mycelia on the soil or plant surface. Later, large (5–10 mm), black sclerotia (hard, dark masses of hyphae) are formed on infected plant parts. Frequently the sclerotia are found inside dead 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 smaller than those of Sclerotinia; it also doesn't produce 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 primarily a disease of vegetables, such as beans, carrots, celery, and lettuce. The fungus often infects the plant near the soil line but infections can occur on any aboveground part. 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. Sclerotinia sclerotiorum does not produce 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, the sclerotia germinate to form apothecia (saucer-shaped, dime-sized structures on stalks) that produce spores. The spores 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 occurs. 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. Infections frequently occur at the soil level because plants can be infected directly by sclerotia in the soil that germinate to produce vegetative strands (hyphae). MANAGEMENT Protective fungicides, as well as steam, solarization, or fumigation can be helpful. 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 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 (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. A. IPRODIONE (Chipco 26019) 0.4 lb/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. B. THIOPHANATE-METHYL (FungoFlo, etc.) 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). 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. KEY DISEASES Cottony Rot (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 5 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) C. PCNB (Terraclor) 0.5–1 lb a.i./1000 sq ft 12 MODE OF ACTION GROUP NAME (NUMBER1): Aromatic hydrocarbon (14) COMMENTS: Inhibits germination of sclerotia when incorporated into top 2 inches of soil. 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 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. Restricted entry interval (R.E.I.) 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 6 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CROWN GALL (3/09) Pathogen: Agrobacterium tumefaciens SYMPTOMS Crown gall is a disease resulting from infection by a bacterium that causes galls to form at the base of the stem or root crown or on other plant parts. The bacterium infects only through fresh wounds. 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. 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 population 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. CONTROL 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. KEY DISEASES Crown Gall (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 7 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) When choosing a product, consider information relating to environmental impact. A. AGROBACTERIUM TUMEFACIENS K-84# (Galltrol) Label rates 12 . . . or . . . AGROBACTERIUM TUMEFACIENS K-1026# (Nogall) Label rates 4 COMMENTS: Products may list biological agent 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. GALLEX Label rates COMMENTS: For killing of existing galls; apply directly to galls winter through spring. # Acceptable for use on organically grown ornamentals. + Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. KEY DISEASES 0 Crown Gall (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 8 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DAMPING-OFF (3/09) Pathogens: Rhizoctonia solani, Pythium spp., and others SYMPTOMS 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. As the name implies, the disease is associated with damp conditions. Some Pythium species are favored by cool, wet conditions while Rhizoctonia can cause disease under somewhat drier and warmer conditions. ELISA test kits are available for detecting Pythium and Rhizoctonia pathogens. MANAGEMENT Vigorous seedlings grown from the best seed and 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, leveled 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 (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. SEED TREATMENT A. STREPTOMYCES GRISEOVIRIDIS# (Mycostop) 0.08 oz/lb of seed or 5g/kg of seed 4 COMMENTS: For control of seed rots, root and stem rots, and wilt diseases of ornamental crops caused by Alternaria, Fusarium, and Phomopsis; also suppresses Botrytis, Pythium, and Phytophthora. May be used for both field-grown and greenhouse ornamentals. SOIL FUNGICIDE – Pythium spp. A. MEFENOXAM (Subdue Maxx) Label rates 48 MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (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 is translocated in the plant through the xylem. SOIL FUNGICIDE – Rhizoctonia solani A. IPRODIONE (Chipco 26019) 0.4 lb/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 B. 12 PCNB (Terraclor) 0.5–1 lb a.i./1000 sq ft 12 MODE OF ACTION GROUP NAME (NUMBER1): Aromatic hydrocarbon (14) COMMENTS: Insoluble in water and must be thoroughly mixed into the top 2 inches of soil. Some seeds may be inhibited by this fungicide. KEY DISEASES Damping-off (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 9 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) C. Amount to Use THIOPHANATE-METHYL (FungoFlo, etc.) 20 fl oz/100 gal for 800 sq ft bench area MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) R.E.I.+ (hours) 12 D. TRIFLUMIZOLE (TerraGuard) 50W 4–8 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 3–4 week intervals as needed. SOIL FUNGICIDE – Pythium spp. and Rhizoctonia solani A. TRICHODERMA spp.# (Garden Solutions, Root Guardian) Label rates NA COMMENTS: Formulated as a seed treatment, a soil fungicide, and a nursery drench. 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 actions (for more information, see http://www.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. Acceptable for use on organically grown ornamentals. + Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. NA Not applicable. KEY DISEASES Damping-off (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 10 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DOWNY MILDEW (3/09) Pathogens: Peronospora spp., Plasmopara spp., and Bremia sp. SYMPTOMS The name downy mildew is somewhat descriptive of the appearance of the white, lavender, or purple sporulation that occurs usually on the undersides of leaves. Downy mildew leaf lesions are often angular in shape and delimited by veins. Pale yellow 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 with powdery mildews, the downy mildews are more host specific and require very wet 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 and there is free water, germination and infection occurs, generally in 8 to 12 hours. Some downy mildews also produce a sexual spore that can survive dry conditions, which enables the pathogen to survive in the absence of the host. Downy mildews are favored by moist and cool conditions (40° to 60°F). Common name (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. A. MANCOZEB (Dithane) 75 1–1.5 lb/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M3) COMMENTS: A protectant fungicide. Thorough coverage is important for control. B. C. MEFENOXAM (Subdue Maxx) 1-2 oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (4) COMMENTS: Use allowed in California under a 24(c) registration. 24 48 COPPER 50%# 1–2 lb/100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M1) 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. FOSETYL-AL (Aliette) 2.5 lb/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (33) COMMENTS: For control of downy mildew on roses. Spray to wet using no more than 400 gal/acre. 1 # + Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. Acceptable for use on organically grown ornamentals. Restricted entry interval (R.E.I.) 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 11 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FUSARIUM WILT (3/09) Pathogen: Fusarium oxysporum SYMPTOMS Symptoms include yellowing and stunting of older plants and yellowing, stunting, and death of seedlings. 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. Thus, the fungus that causes wilt of carnations is Fusarium oxysporum f. sp. dianthi, specific only to 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 use of plant breeding in developing resistant cultivars. There are many saprophytic forms of F. oxysporum and recovery of the fungus from diseased plant material does not guarantee that a wilt fungus is present. 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. The fungus produces two kinds of spores. Chlamydospores are resistant to drying and adverse conditions, and enable the fungus to survive extended periods in soil. Conidia are produced in a sporodochium, which is a mass of conidiophores (conidia-bearing stalks) placed tightly together. Sporodochia are sometimes visible as small, pink-to-orange cushions on dead tissue as well as along hyphae. Conidia are spread by splashing water and can contaminate tools and hands. There are two types of conidia: macroconidia (large, multi-celled spores) and microconidia (small, one-celled spores). Conidia generally are not airborne, but the fungus can become airborne in bits of infected plant debris, in dust, or in splashing water. 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) and disease may not occur at low soil temperatures (below 68°F). An infected plant may remain symptomless at lower temperatures. The fungus can be spread through the use of 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. It is always prudent to treat seed with a fungicide or heat to destroy the fungus on the seed and to protect the emerging seedlings from infection. Fungus populations can be reduced from soil by heat treatments and by chemical fumigation. These treatments, while effective in controlling the fungus in annual plantings, leave much to be desired in perennial plantings. In field crops, Fusarium wilt diseases are controlled by selection and plant breeding. In perennial ornamental crops such as carnations, the best way to deal with the disease is through the use of resistant cultivars; however, the most popular cultivars are not resistant. Liming soils and using nitrate nitrogen fertilizer have been effective for management of Fusarium oxysporum on chrysanthemum, aster, gladiolus, cucumber, tomato, and watermelon. KEY DISEASES Fusarium Wilt (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 12 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. SOIL FUMIGATION (Note: The 2007 Critical Use Exemption List allows fumigation with methyl bromide for moderate-to-severe disease infestation.) A. METHYL BROMIDE* Label rates 48 COMMENTS: Allowed for use under a Critical Use Exemption only. Methyl bromide is a gas at temperatures over 40°F. It escapes rapidly from soil if not applied under a gas-proof cover. Polyethylene sheeting is commonly used to confine methyl bromide, although the gas does slowly escape through polyethylene. Diffuses rapidly through the soil and kills many kinds of organisms, weeds, and many seeds. Soil generally can be planted a few days after removal of plastic covers, although there are exceptions. A few plants such as Allium spp., carnations, and snapdragons are sensitive to and may be damaged by inorganic bromide that remains in the soil following fumigation. Leaching the soil with water before planting is helpful in reducing the amount of bromide in the rooting area. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone: methyl bromide depletes ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. B. METHYL BROMIDE*/CHLOROPICRIN* Label rates 48 COMMENTS: Inject into soil and cover immediately with plastic tarps. See Comments above regarding the use of methyl bromide, which is allowable for use under a Critical Use Exemption only. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone: methyl bromide depletes ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. SOIL FUNGICIDE A. THIOPHANATE-METHYL (FungoFlo, etc.) 20 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: Apply as a drench at planting. Not very effective in controlling Fusarium. B. 12 STREPTOMYCES GRISEOVIRIDIS# (Mycostop) 0.08 oz/lb of seed or 5g/kg of seed 4 COMMENTS: Good for Fusarium wilt on asters. May be used on both field-grown and greenhouse plants. C. * 1 # + IPRODIONE (Chipco 26019) 0.4 lb/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2) COMMENTS: Apply as a drench (1–2 pt/sq ft) at seeding or transplanting. 12 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 (for more information, see http://www.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. Acceptable for use on organically grown ornamentals. Restricted entry interval (R.E.I.) 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 13 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GRAY MOLD (3/09) Pathogen: Botrytis cinerea SYMPTOMS Gray mold is one of the more 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 also may be infected, and young seedlings of several crops can be killed. Under conditions of high relative humidity, the fungus may sporulate on infected tissues and produce masses of characteristic gray or brownish spores that become airborne and are the primary means by which 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 tissues. A food base is not required by the fungus for invasion of flower petals of African violet, asters, begonia, carnation, chrysanthemum, cyclamen, cymbidium, gerbera, geranium, gladiolus, hydrangea, marigolds, orchids, 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 about 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. Also, removing old flowers before they become infected and function as spore sources can be important and sometimes essential to control. The fungus can develop and sporulate at low temperatures, so do not overlook old flowers and foliage in refrigerators. Because free moisture is necessary for germination and infection, great emphasis is placed on avoiding condensation of water on susceptible plant parts. 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. Also, maximize the period between irrigations to further enhance drying of foliage and flowers. Wider plant spacings to increase ventilation and minimize leaf wetness can also help reduce disease incidence. Chemical Control Numerous fungicides are effective against Botrytis 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. KEY DISEASES Gray Mold (3/09) 14 Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. A. FENHEXAMID (Decree) 16 oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Hydroxyanilide (17) COMMENTS: Apply as a spray; very effective and can be applied after infection. 4 B. 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. C. IPRODIONE (Chipco 26019) 0.4 lb/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. Some resistance has been reported with this material. Effective against Rhizoctonia damping-off, Sclerotinia, and gray mold. Some iprodione is absorbed by plant parts. D. THIOPHANATE-METHYL (FungoFlo, etc.) 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). Some resistance has been reported with this material. Helps to control gray mold, Rhizoctonia diseases, cottony rot, Thielaviopsis rots, and some Cylindrocladium diseases. 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. E. CHLOROTHALONIL (Daconil WeatherStik) 54% 1.375 pt/100 gal water 12 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) 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. F. MANCOZEB (Dithane) 75DF 1–1.5 lb/100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M3) COMMENTS: Protects against leaf spots, Botrytis, rusts, and blight. Not systemic so thorough coverage is important for control. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. Restricted entry interval (R.E.I.) 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 (3/09) 15 Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PHYTOPHTHORA ROOT AND CROWN ROTS (3/09) Pathogen: Phytophthora spp. SYMPTOMS Many, if not most, Phytophthora species can infect roots in the same manner as Pythium species. In addition, Phytophthora species infect larger roots and stems, particularly in woody plants. Infection of the bases of stems or root crowns is very common under wet conditions. Aerial parts, including branches and shoots, also can be infected under wet conditions if soil water or airborne spores are splashed on these aboveground parts. Plants become stunted, low in vigor, and appear as if they were water stressed. Foliage yellows and the plant may wilt and die. Roots rot and stem is girdled by the fungi at or below the soil line, resulting in a dark brown rot. 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. Ideal soil conditions for the growth of Phytophthora are wet soils (70% moisture or higher) 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 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 of 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 at 20% in potting mixed is reported to provide some control of Pythium and Phytophthora root rots. For flower production in open fields, solarization in warmer climates has been successful for control of 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 (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. A. MEFENOXAM (Subdue Maxx) Label rates 48 MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (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 is translocated in the plant through the xylem. KEY DISEASES Phytophthora Root and Crown Rots (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 16 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) B. FOSETYL-AL (Aliette) 2.5–5 lb/100 gal water for foliar spray 12 MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (33) 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. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. Restricted entry interval (R.E.I.) 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 17 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PHYTOPLASMAS (3/09) SYMPTOMS Symptoms of phytoplasma (previously known as mycoplasmalike organisms) diseases include yellowing and dwarfing, distorted foliage, and the abnormal production of shoots. Flowers may not develop normally and are often replaced by green leafy structures. COMMENTS ON THE DISEASE Phytoplasmas are microscopic organisms that are somewhat smaller than bacteria. They do not have a cell wall as do bacteria. The cytoplasm is bounded by a three-layered membrane. For many years the aster yellows phytoplasma was considered a virus. This phytoplasma is vectored by leafhoppers, in which it can multiply, and has a very wide host range. In general, phytoplasmas are vectored by leafhoppers, plant hoppers, and psyllids and invade the phloem of infected plants. PHYTOPLASMA ORGANISMS Virus Aster yellows (aster yellows phytoplasma) KEY DISEASES Transmission leafhoppers 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 Weeds and native Crop plant hosts plant hosts buckwheat, carrots, celery, California poppy, dandelion, lettuce, onion, parsley, pars- plantain, and many others nip, potato, safflower, spinach, tomato, and many others Phytoplasmas (3/09 Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 18 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES POWDERY MILDEW (3/09) Pathogen: Erysiphe spp., Leveillula (= Oidiopsis) taurica, Oidium sp., Sphaerotheca spp. SYMPTOMS Powdery mildew is the name given to diseases resulting from infection by fungi that produce a white, 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 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 cleistothecia (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 are unique in that they require no external moisture for germination; most other fungi require free water in the form of dew, guttation, rain, or water from overhead irrigation for germination and infection or growth whereas the 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 (cleistothecium) 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 (infections) are killed. Shade or low light intensities also 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 development of resistant cultivars of flower crops. Because high relative humidity (greater than 95%) favors some powdery mildew fungi, increased air movement around the plants in the greenhouse tends to reduce infection potential in these mildews. 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 fungal strains that are resistant to the fungicides. Plants that have been treated with antitranspirants are less likely to develop powdery mildew infections. KEY DISEASES Powdery Mildew (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 19 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. PROTECTANTS (Must be applied to healthy tissues before infection takes place) A. WETTABLE SULFUR# 3 lb /100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) 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. B. MYCLOBUTANIL (Hoist) 40WSP 4 oz/100 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, crepe myrtle, gerbera, roses, and snapdragons. C. 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. D. FENARIMOL (Rubigan) AS 3–10 fl oz/100 gal water 12 MODE OF ACTION: A DMI (Group 3)1 pyrimidine fungicide. COMMENTS: Apply on a 10- to 14-day interval. A systemic fungicide used for prevention or eradication of powdery mildew on roses and field and container-grown ornamentals. E. TRIADIMEFON (Strike, Bayleton) Label rates 12 MODE OF ACTION: A 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. F. THIOPHANATE-METHYL (FungoFlo, Cleary's 3336F, etc.) Label rates MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) COMMENTS: Not as effective against powdery mildew as other materials. G. PROPICONAZOLE (Banner Maxx) 5 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: A preventive fungicide. 12 24 H. POTASSIUM BICARBONATE# (Kaligreen) 1–1.5 lb/half-acre 4 MODE OF ACTION: An inorganic salt. COMMENTS: Primarily a protectant but it eradicates some existing infections with thorough coverage. Apply in 75–100 gal water/half-acre at first signs of infection. Thorough coverage is essential for good protection. Labeled for use on roses, field ornamentals, and greenhouse ornamentals; make no more than 8 applications/season. KEY DISEASES Powdery Mildew (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 20 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) ERADICANTS A. STYLET OIL# (Organic JMS Stylet Oil) 1 oz/gal water 4 MODE OF ACTION: A contact fungicide with smothering and barrier effects. 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 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. B. NEEM OIL# (Triact) 70 Label rates 4 MODE OF ACTION: Unknown. 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. Never apply any oil within 2 weeks of a sulfur spray or plants may be injured. C. PIPERALIN (Pipron) 84.4 Ec 4–8 fl oz/100 gal water 12 MODE OF ACTION: An amine (Group 5)1 piperidine fungicide. 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. LIME SULFUR 28%# 1.5–3 pt/100 gal water 48 MODE OF ACTION: A multi-site contact (Group M2)1 inorganic fungicide. 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. 1 # + Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. Acceptable for use on organically grown ornamentals. Restricted entry interval (R.E.I.) 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 21 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PYTHIUM ROOT ROT (3/09) Pathogen: Pythium spp. SYMPTOMS Pythium attacks juvenile tissues such as the root tip. After gaining entrance to the root the fungus may cause a rapid, 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 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 mold, 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. 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 are conducive to infection by Pythium. Soil from a given field may contain 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 resting structures. Sporangia and zoospores in general do not survive in air or dry soil for long periods of time. ELISA test kits are available for detecting Pythium. 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 growing medium. Sanitation is important 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 at 20% in a potting mixture is reported to provide some control of Pythium and Phytophthora root rots; also the mycoparasite, Gliocladium virens, is used as a Pythium biocontrol agent. 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 (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. A. MEFENOXAM (Subdue Maxx) Label rates 48 MODE OF ACTION GROUP NAME (NUMBER1): Phenylamide (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. B. FOSETYL-AL (Aliette) 2.5–5 lb/100 gal water for foliar spray 12 MODE OF ACTION GROUP NAME (NUMBER1): Phosphonate (33) 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. KEY DISEASES Pythium Root Rot (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 22 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) C. 1 # + NA GLIOCLADIUM VIRENS# (SoilGard) 12G Amount to Use R.E.I.+ (hours) Label rates NA Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. Acceptable for use on organically grown ornamentals. Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Not applicable. KEY DISEASES Pythium Root Rot (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 23 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES RUST (3/09) Pathogens: Puccinia spp. and others SYMPTOMS Rust pustules appear as powdery masses of yellow, orange, purple, black, or brown spores on leaves and sometimes on stems. Pustules are usually found on the undersides of leaves. COMMENTS ON THE DISEASE The rust fungi are obligate parasites in the order Uredinales. Many have complicated life cycles that include up to four different spore stages and one or possibly two distinctly different hosts. Other rusts produce all 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 four spore stages are produced. Rose rust also produces all 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. 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 rust (Phragmidium mucronatum), may survive the winter on leaves that do not fall off the plant. Rose rust also survives as teliospores (dark, overwintering spores) that form in fall. These spores survive in a dormant stage on fallen leaves. It is recommended that leaves with teliospores be removed, rapid composted, or buried. 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 pelargoni-zonalis), can be eradicated by hot water treatment of cuttings, but some damage to the host can occur. Because water is necessary for infection, overhead irrigation should be avoided when rust is a problem. If possible, eliminate alternate hosts if they occur and prune off infected stalks. It is recommended that leaves with teliospores be removed, rapid composted, or buried. Chrysanthemum white rust, caused by Puccinia horiana, is under an eradication program in California. If you have this disease contact your agricultural commissioner. See specific guidelines under the DISEASE CONTROL OUTLINE FOR CHRYSANTHEMUM. 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 (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. A. MANCOZEB (Dithane) 75W 1–1.5 lb/100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M3) COMMENTS: Provides protection only; must be applied before infection. Protects against leaf spots, Botrytis, rusts, and blight. Thorough coverage is important for control. B. MYCLOBUTANIL (Hoist) 40WSP 4 oz/100 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, crepe myrtle, gerbera, roses, and snapdragons. KEY DISEASES Rust (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 24 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) C. Amount to Use R.E.I.+ (hours) TRIADIMEFON (Strike, Bayleton) 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. D. 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. E. WETTABLE SULFUR# 1–3 lb/100 gal water 24 MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M2) COMMENTS: Use a wetting agent. Not as effective as other materials. Apply this material with caution when temperatures exceed 85°F. F. CHLOROTHALONIL (Quali-Pro) 38.5% 23–32 fl oz/100 gal water MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) COMMENTS: Provides protection only; must be applied before infection. 12 G. PROPICONAZOLE (Banner Maxx) 2-24 fl oz/100 gal 24 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Controls white rust of chrysanthemums but may cause phytotoxic symptoms on some cultivars. H. NEEM OIL# (Triact) 70 Label rates 4 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 actions (for more information, see http://www.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. Acceptable for use on organically grown ornamentals. Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. KEY DISEASES Rust (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 25 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SOUTHERN BLIGHT (3/09) Pathogen: Sclerotium rolfsii SYMPTOMS Southern blight, also called southern wilt, southern stem rot, southern root rot and several 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. 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.): 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. 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 open 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 (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider information relating to environmental impact. SOIL FUMIGATION Note: The 2007 Critical Use Exemption List allows fumigation with methyl bromide for moderate-to-severe disease infestation. A. METHYL BROMIDE* Label rates 48 COMMENTS: Allowable for use under a Critical Use Exemption only. Methyl bromide is a gas at temperatures over 40°F. It escapes rapidly from soil if not applied under a gas-proof cover. Polyethylene sheeting is commonly used to confine methyl bromide, although the gas does slowly escape through polyethylene. Diffuses rapidly through the soil and kills many kinds of organisms, weeds, and many seeds. Soil generally can be planted a few days after removal of plastic covers, although there are exceptions. A few plants such as Allium spp., carnations, and snapdragons are sensitive to and may be damaged by inorganic bromide that remains in the soil following fumigation. Leaching the soil with water before planting is helpful in reducing the amount of bromide in the rooting area. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone: methyl bromide depletes ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. B. METHYL BROMIDE*/CHLOROPICRIN* Label rates 48 COMMENTS: Inject into soil and cover immediately with plastic tarps. See Comments above regarding the use of methyl bromide, which is allowable for use under a Critical Use Exemption only. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone: methyl bromide depletes ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. KEY DISEASEs Southern Blight (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 26 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Common name (trade name) Amount to Use R.E.I.+ (hours) SOIL FUNGICIDE A. PCNB (Terraclor) 0.5–1 lb a.i./1000 sq ft 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 actions (for more information, see http://www.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. Restricted entry interval (R.E.I.) 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 27 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SUDDEN OAK DEATH (3/09) Pathogen: Phytophthora ramorum SYMPTOMS Although hosts of P. ramorum show a range of symptoms, the disease is generally characterized by irregular, necrotic leaf lesions, instead of distinct leaf spots. Leaf infections can develop down into the petiole and twigs. Often, infected leaves fall before the lesion develops to the petiole. Sometimes infections occur initially on stems or develop into stems and cause blights, where stems and associated leaves wilt, become necrotic, and die. A distinct dark line can mark the advance of the infection on some species such as California bay laurel. Under natural conditions, California bay laurel tends to get infected on the tip of the leaf, where the leaf hangs down and water accumulates. This characteristic is seen in some nursery hosts as well. Infection often occurs on leaf tissue where free water remains on leaves for long periods, such as deep in the leaf canopy, near or touching the soil, and between overlapping or cupped leaves. While not commonly seen on nursery hosts, bark cankers on the trunks of trees are also associated with this disease. Cankers have red-brown to black discoloration, seep 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 look similar to P. ramorum infection. Abiotic injury is often found distributed over the entire plant, while P. ramorum leaf spots are often found on only a few leaves or on one portion of the plant. COMMENTS ON THE DISEASE Tens of thousands of tanoaks (Lithocarpus densiflorus), California black oaks (Quercus kelloggii) and coast live oaks (Quercus agrifolia) have died as a result of P. ramorum infection. In Marin, Santa Cruz and Monterey Counties, portions of the wildland-urban interface forest changed dramatically; tree crowns turned brown in a few weeks, giving the impression of instantaneous mortality, giving rise to the name sudden oak death. Camellias, rhododendrons 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, and if the pathogen is found, affected nursery stock must be destroyed as a means of eradication. For a current host list and additional information, see the California Oak Mortality Task Force Web site (http://nature.berkeley.edu/comtf/). 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. 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. In California forests the pathogen sporulates prolifically on California bay laurel trees (Umbellularia californica) that serve as reservoirs for inoculum. Infected California bay laurel can also be an important source of inoculum when in close proximity to nursery stock. MANAGEMENT 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 or other means. This can be partly accomplished by careful inspection of all incoming host propagative material and stock. Monitor the outside source stock weekly, and intensify monitoring a few weeks after bud break, especially in rainy periods when environmental conditions are highly conducive to pathogen infection and development. Disease symptoms might take weeks to several months to develop and become apparent, so plants may appear healthy. 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. KEY DISEASES Sudden Oak Death (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 28 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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. 1. 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. 2. Consider building berms to prevent water and soil movement into production areas from surrounding hillsides the nursery that may contain infected hosts. 3. 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 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, which is available online at http://anrcatalog.ucdavis.edu. Cultural Practices Cultural practices that can be useful to reduce disease risk: 1. Avoid irrigation practices where the foliage is wet for prolonged periods. If sprinklers are used, irrigate in the morning to allow for thorough and quick drying of foliage. 2. 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. 3. Monitor irrigation-water sources, other than well water, for P. ramorum. Use disinfection systems if using recycled water. 4. 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. 5. 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. 6. 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 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. 7. Propagate cuttings only from disease-free hosts. 8. 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. 9. Disinfect tools and shoes that have been in contact with contaminated plants or soil. Fungicides. Fungicides used to protect nursery stock from P. ramorum function are preventive treatments only; currently, even the most active fungicides do not stop the development of P. ramorum once foliar lesions are present. Whether or not to use Phytophthora-specific fungicides for the sole control of P. ramorum is a complex question and should be reserved for special cases, such as where a nursery is exposed to local inoculum sources from surrounding infected native hosts or when the nursery has no choice but to use irrigation water that could contain P. ramorum inoculum. When fungicide applications are made to control other Phytophthora species, it may be appropriate to select fungicides and application intervals that can also control P. ramorum. Regardless of the reasons to use fungicides, these chemicals should only be used after other management strategies and preventive steps have been fully implemented. Although fungicides might help prevent the spread of the disease if infested plants are introduced in the nursery, they might also hinder the detection of the disease. The masking of symptoms with fungicide use might eventually lead to the sale and movement of infected plants to nurseries or customers in noninfested areas. Such an occurrence might circumvent the quarantine program that intends to limit the spread of sudden oak death. Finally, Phytophthora-specific fungicides used continuously may lead to fungicide resistance. KEY DISEASES Sudden Oak Death (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 29 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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 adsorbed 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. 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. KEY DISEASES Sudden Oak Death (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 30 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES THIELAVIOPSIS ROOT ROT (3/09) Pathogen: Thielaviopsis basicola SYMPTOMS Thielaviopsis root rot is also called black root rot after one of the major symptoms. Plants are stunted and roots are 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 3 to 7 and rectangularshaped endoconidia. The fungus can be spread in water, soil, by infected plants or vectored by fungus gnats and shore flies. MANAGEMENT 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 open fields, solarization in warmer climates has been successful for control of most Thielaviopsis in many crops. Solarization and steaming are acceptable for organic production. For more information, see MANAGEMENT OF SOILBORNE PATHOGENS. Common name (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider the general properties of the fungicide as well as information relating to environmental impact. A. THIOPHANATE-METHYL (FungoFlo, etc.) 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). Generally applied after sowing. Helps to control gray mold, Rhizoctonia diseases, cottony rot, Thielaviopsis rots, and some Cylindrocladium diseases. 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) 50W 4–8 oz/100 gal 12 MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) COMMENTS: Apply as a soil drench at 3–4 week intervals as needed on potted plants. A protectant fungicide; use is restricted to enclosed commercial structures such as greenhouses and shade houses. 1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.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. Restricted entry interval (R.E.I.)is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. + KEY DISEASES Thielaviopsis Root Rot (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 31 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES VERTICILLIUM WILT (3/09) Pathogen: Verticillium dahliae and V. albo-atrum SYMPTOMS 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 usually fall; sometimes they remain attached. Woody plants often are affected first on one side, and affected branches usually die. The water-conducting tissues (sapwood) of infected plants are often discolored with dark streaks occurring in the xylem tissue; discoloration varies with the species but frequently is an olive green, dark brown, or black. In some plants there is little or no discoloration (including olive, ash, and roses). 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 long-lived. 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 open field 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 disinfested. Soil fumigation or soil solarization (in warmer climatic areas) can be useful. During the season, remove and destroy any plants that exhibit symptoms of Verticillium wilt. Common name (trade name) Amount to Use R.E.I.+ (hours) When choosing a fungicide, consider information relating to environmental impact. SOIL FUMIGATION Note: The 2007 Critical Use Exemption List allows fumigation with methyl bromide for moderate-to-severe disease infestation. A. METHYL BROMIDE*/CHLOROPICRIN* Label rates 48 Allowable for use under a Critical Use Exemption only. Methyl bromide is a gas at temperatures over 40°F. It escapes rapidly from soil if not applied under a gas-proof cover. Polyethylene sheeting is commonly used to confine methyl bromide, although the gas does slowly escape through polyethylene. Diffuses rapidly through the soil and kills many kinds of organisms, weeds, and many seeds. Soil generally can be planted a few days after removal of plastic covers, although there are exceptions. A few plants such as Allium spp., carnations, and snapdragons are sensitive to and may be damaged by inorganic bromide that remains in the soil following fumigation. Leaching the soil with water before planting is helpful in reducing the amount of bromide in the rooting area. Fumigants such as methyl bromide are a source of volatile organic compounds (VOCs) but are not reactive with other air contaminants that form ozone: methyl bromide depletes ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available. * + Permit required from county agricultural commissioner for purchase or use. Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. KEY DISEASES Verticilium Wilt (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 32 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES VIRUSES and VIROID DISEASES (3/09) SYMPTOMS Virus diseases are recognized by several characteristic symptoms. Light and dark green mosaic patterns, mottles, ringspots, vein clearing, and vein enations are some of the symptoms seen in the leaves. Deformed yellow, stunted growth or overall stunting are additional symptoms that can be encountered. 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 but no protein coat. Chrysanthemum stunt and chrysanthemum chlorotic mottle are examples of diseases caused by viroids. Positive identification of virus infection involves 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 a large number of viruses. Thrips vector tomato spotted wilt and other Tospoviruses. Mites, nematodes, and lower fungi also serve as vectors of a few viruses. Once an insect has acquired a virus, it may retain it in a persistent (for its lifetime) or nonpersistent (usually means minutes to hours only) manner. 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 virus in muskmelons, tomato mosaic virus in tomato, and others). Many are transmitted by vegetative propagation of plant material from infected plants. MANAGEMENT Control of virus diseases is a matter of prevention and the use of virus-free planting stock. Once a plant is infected by a virus it usually remains infected for the life of the plant. Plants vegetatively propagated from such material are usually infected. However, virus-free plants can be obtained from infected plants by a combination of heat treatment and shoot tip 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 only) 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. In any case, remove weeds that may harbor the virus; sometimes nematode control may reduce spread as well. Disinfection of pruning or propagation tools between plants or at least between different varieties or species and the use of disposable gloves can help reduce the cross contamination of virus diseases in a greenhouse operation. The use of a 1 to 5 dilution of household bleach in water (1% sodium hypochlorite) for 5 minutes acts as an effective disinfectant for virus-contaminated materials (tools, benches, etc.). Bleach solutions must be rinsed off using clean water to avoid toxicity to plants. See MANAGEMENT OF SOILBORNE PATHOGENS section for more details. Cultural Control In open 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. KEY DISEASES Viruses and Viroid Diseases (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 33 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES VIRUSES WITH WIDE HOST RANGES Transmission Bean yellow mosaic (potyvirus group) aphids; mechanically to gladiolus, sweet pea, violets an extent in gladiolus legumes, bean, clovers, fava legumes, Chenopodium, clovers, bean, pea, soybean, sweet clo- sweet clover ver Beet curly top (rhabdovirus 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, Polygonium spp., Rumex spp., Russian thistle, shepherd's-purse Cauliflower mosaic (caulimovirus group) aphids honesty (lunaria), stock crucifers, broccoli, cabbage, cauliflower, Chinese cabbage, mustard mustard, Raphanus spp., shepherd's-purse Cucumber mosaic (cucumovirus group) aphids; mechanically in begonia, buddleia, calendula, buckwheat, carrot, celery, cua few hosts china aster, columbine, dahlia, curbits, cowpea, pepper, podaphne, delphinium, geranium, tato, tobacco, tomato 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 apple, hops, Prunus spp. Prunus spp. Tobacco mosaic (tobamovirus group) mechanical; seeds may delphinium, petunia, phlox, be externally contami- wisteria, flowering tobacco nated, can be soilborne beans, tobacco, tomato Emilia, tree tobacco Impatiens necrotic spot virus and tomato spotted wilt (tospovirus group) thrips amaryllis, aster, ageratum, begonia, calendula, calla, chrysanthemum, coreopsis, cosmos, dahlia, forget-me-not, gerbera, gladiolus, gloxinia, gypsophila, impatiens, kalanchoe, lily, nasturtium, papaver, petunia, phlox, primula, ranunculus, salvia, stock, sweet pea, tagetes, verbena, zinnia, and others artichoke, bean, cauliflower, 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'spurse, and others Turnip mosaic (potyvirus group) aphids anemone, nasturtium, petunia, statice, stock, sweet william, wallflower, zinnia Brussels sprouts, cabbage, cruciferous weeds cauliflower, cress, horseradish, mustard, radish, rape, rhubarb, swede turnip KEY DISEASES Ornamental hosts Prunus spp., rose Crop plant hosts Weed and native plant hosts Virus Viruses and Viroid Diseases (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 34 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Disease Control Outlines (3/09) ASTER, CHINA (Callistephus chinensis) Disease (causal agent) Symptoms (3/09) Survival of pathogen and effect of environment Comments on control Fusarium wilt Plants yellow and wilt, often on one side. Brown dis- Commonly seedborne. In soil for many years. Disease (Fusarium oxysporum f. sp. cal- coloration of vascular system develops. Disease is most severe when soil and/or air temperatures are listephi) also causes damping-off of young seedlings at soil high. temperatures of 75° to 80°F. Use disease-free seed. Fumigate the seedbed with chloropicrin-methyl bromide combination or solarize soil. Grow on clean land, or only once every 5 years on infested land. Treat seed with a fungicide. (More info*) Gray mold (Botrytis cinerea) Brown, water-soaked decay of flowers. Woolly 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. (More info</a>*) Leaf spots (Stemphylium callistephi) Circular, irregular, brown spots appear on lower leaves. Leaves may die. 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. 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). In plant debris. Airborne spores require long (48 hours), Avoid low-lying areas where air movement is poor. Do not damp periods for infection. use overhead irrigation. Protect foliage with a fungicide such as mancozeb. Avoid planting in poorly drained fields. Plant on raised beds. In soil. Favored by heavy, waterlogged soils. Do not overirrigate and keep hose ends off the ground. Drench seedlings with mefenoxam. more info: Pythium Root Rot, Phytophthora Root and Crown Rots* Favored by free moisture from rain, dew, or fog. Very Avoid overhead irrigation. Treat at the first signs of rust and common in cut-flower-growing areas around San Jose. continue until conditions are no longer favorable for the disease. Grow seedlings away from main crop. more info* Sclerotinia rot or Cottony rot (Sclerotinia sclerotiorum) Infection girdles stems. Cottony, white fungal growth Airborne spores produced by sclerotia in soil, but infecand large, black sclerotia develop on and inside tion more common from growth of hyphae from sclerostems. Stems take on a bleached-white color. tia. Favored by wet weather. Stem rot A brown decay develops at the soil line and affects (Rhizoctonia solani, Botrytis ci- the basal leaves and stem. nerea) 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. more info: Cottony Rot, Southern Blight* Soilborne and in plant debris. Gray mold (B. cinerea) fa- Before planting or transplanting, mix PCNB or Trichoderma vored by cold, damp conditions. Disease development spp. into top inch of soil. Spray bases of seedlings with thican be rapid under high temperature conditions. ophanate-methyl, iprodione, or Trichoderma spp. Verticillium wilt (Verticillium dahliae) Symptoms are almost identical to Fusarium wilt. Not In soil for many years. Symptoms most severe during a common disease of asters in California. warm weather that follows a cool period. Avoid planting in fields where fungus has occurred or fumigate soil as described for Fusarium wilt. (More info</a>*) 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. Vec- Locate seedbed away from weedy areas. Control weeds and tored by leafhoppers. leafhoppers in noncropped areas. (More info</a>*) DISEASE CONTROL OUTLINES Aster, China (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 35 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES AZALEA (Rhododendron spp.) (3/09) Disease (causal agent) Symptoms Cutting rot and graft decay (Rhizoctonia solani and Cylindrocladium scoparium) Basal rot of cuttings occurs. Under humid conditions, In soil and plant debris. Favored by moist conditions and Steam or chemically treat propagating media, flats, etc. tops are rotted and covered with fungal strands (my- temperatures of 75° to 80°F. Grow stock plants in treated media and observe strict sanitacelium). tion. 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. Leaf gall (Exobasidium vaccinii) All or part of leaf becomes greatly thickened, disOn living plants. Airborne spores produced only during torted, and crisp. Also affects flowers. Infected parts wet weather. are covered with a white or pinkish bloom of fungal spores. Hand-pick galls where practical before they turn white. Avoid overhead irrigation. Protect foliage with a fungicide, such as mancozeb, during wet weather. Root rot (Pythium and Phytophthora spp.) Plants are low in vigor. Leaves wilt and turn dull Water molds occur in soil. Favored by overwatering, green and fall, so only a few terminal leaves remain poor drainage, and other factors that weaken plants. 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). Treat growing media with methyl bromide. Select cuttings from high on stock plants. Drench plants with mefenoxam, or spray with fosetyl-al. more info: Pythium Root Rot, Phytophthora Root and Crown Rots* Septoria leaf spot or leaf scorch Dark, reddish brown, angular spots appear on (Septoria azaleae) leaves, which fall prematurely. Leaves yellow on some cultivars. Survival of pathogen and effect of environment 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. On living and dead leaves. Favored by wet weather. Fungal spores spread in splashing water. Comments on control 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. 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* (Microsphaera sp.), and web blight (Rhizoctonia solani). * For additional information, see section on Key Diseases. DISEASE CONTROL OUTLINES Azalea (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 36 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BEGONIA (Begonia spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Bacterial leaf spot (Xanthomonas campestris pv. begoniae) Circular, necrotic spots start as small, watersoaked, blisterlike spots. Premature abscission occurs when spots are numerous. Systemic as well as in dead begonia leaves. Favored by Keep humidity low. Avoid wetting foliage. Do not crowd splashing water or overhead irrigation and high temper- plants. Remove and destroy infected plants. atures (80° to 90°F). Gray mold (Botrytis cinerea) Soft, brown rot of leaves, stem, and flowers occurs. In plant debris; common on any dead plant material on Woolly gray fungal spores form on decayed tissues. soil if moist. Resting sclerotia favored by high moisture Fungus is common on weakened plants. Botrytis conditions and low temperatures. may also start in powdery mildew spots, sunburned tissues, tissues injured by other means, or in ligules. Control root rot and powdery mildew. Pick up dead flowers and leaves. Keep humidity low. Protect plants with fungicide such as fenhexamid. Avoid overhead irrigation. (More info</a>*) Powdery mildew (Erysiphe cichoracearum, Oidium begoniae) 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. Increase air movement; some resistant cultivars available. Spray at the first sign of mildew and at 2- to 3-week intervals thereafter. Use fenarimol, myclobutanil, or triadimefon. Triadimefon is very effective but expect stunting of some plants. (More info</a>*) Root and stem rot (Pythium spp.) Plants are stunted, unthrifty, and may die. Root sys- In soil. Spores spread in water and when infested soil is Steam or chemically treat soil. Observe strict sanitary tem is small and discolored. Also invades tubers of moved to uninfested areas. Favored by excess water. measures. Drench plants with mefenoxam. Do not drench tuberous begonias. Stem rot phase: stems become very young seedlings. (More info</a>*) water soaked and discolored, and collapse. Disease also causes damping-off of seedlings. Plants are predisposed to sunburning. 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. In living begonias, nasturtiums, callas, dahlias, and some weeds. Transmitted by thrips. Eliminate nearby weeds and susceptible ornamental plants. Control thrips. On living begonia leaves; rarely as resistant fungal structures (cleistothecia). 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. Comments on control Begonias are also susceptible to Armillaria root rot (Armillaria mellea), anthracnose (Gloeosporium sp.), black root rot (Chalara elegans), 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 (Erwinia carotovora), and Verticillium wilt* (Verticillium dahliae). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. DISEASE CONTROL OUTLINES Begonia (3/09) IIllustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 37 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CALLA (Zantedeschia spp.) (3/09) 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 Avoid deep planting and overwatering. Treat soil with PCNB most field soils. 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. Root rot (Phytophthora cryptogea) Yellowing of leaf margins of outer leaves followed by Pathogen is present in some field soils. Several other general yellowing and wilting. Feeder rootlets are types of plants may be infected. Favored by wet soil rotted. conditions. Soft rot (Erwinia carotovora) A soft rot of the rhizomes. Plants may rot off at the Bacterium is present in some field soils. Favored by Avoid injuries to the rhizomes. Do not overwater. Yellow calsoil line. Bacterium is a common secondary invader warm, moist conditions and plant parts attacked by other las are more susceptible than others, but there are new yelof succulent plant parts and generally requires some organisms. low cultivars that are more resistant. sort of injury to cause disease. Has odor. Virus or viruslike diseases Symptoms Host range and natural spread Dasheen mosaic (Dasheen mosaic virus) Mosaic patterns in leaves, which may be severely distorted. Infects plants low in vigor. Common because callas frequently propagated vegeta- Obtain or develop virus-free plants by heat treatment and tistively, which spreads the virus. Virus is also spread by sue culture. Control aphids. Remove infected plants. aphids. Spread in a planting can be rapid. Can be transmitted by sap but not by seed. 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. 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. (More info</a>*) Grow on raised beds and provide good drainage. Do not overirrigate. Treat with mefenoxam. (More info</a>*) Comments on control 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 (Armilliaria 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 38 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CAMELLIA (Camellia spp.) (3/09) 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, Prune diseased tissues and protect wounds with a fungicide warm conditions, weakened plants, and injuries. Fungus such as captan. Avoid overwatering. spores (conidia) are spread by splashing water. Fungus has a wide host range. Flower blight (Ciborinia camelliae) Flowers have dry rot with accented veins. Only petal Sclerotia survive on or in soil and germinate for several tissues are infected. First symptoms are small tan or years producing fruiting bodies (apothecia) that disbrown necrotic spots in the center of the flower that charge spores (ascospores) forcibly into the air. 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. 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 Favored by cool wet weather. Spores are airborne. Funbase of the flower as rapidly as the flower blight fun- gus survives on and in old flowers. gus. Woolly gray fungus spores form on decayed blossoms under high humidity. Avoid overhead irrigation. Clean up plant debris, especially floral tissues. Protect flowers with a fungicide effective against Botrytis such as fenhexamid. (More info</a>*) Sudden Oak Death1 (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 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 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 cinnamoni is often involved but other species also infect camellias. Phytophthora spp. survive in soil as resting spores. They Heat or chemically treat propagation and growing media. are common in stream and ditch water. Infective spores Drench plants on a preventative basis with mefenoxam. (zoospores) swim very short distances in soil water. Dis- (More info</a>*) ease is favored by poor drainage, long wet periods, and standing water. 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 Popular camellia cultivars where P. ramorum was isolated from nursery stock on two or more occasions: C. japonica 'Bob Hope',C. japonica 'Mrs. Charles Cobb', C. japonica 'Daikagura' Var. C. japonica 'Debutante', C. japonica ''Elegans Splendor', C. japonica 'Glen 40', C. japonica 'Kumasaka', C. japonica 'Kramer's Supreme', C. japonica 'Mathotiana Supreme', C. japonica 'Nuccio's Gem', C. japonica 'Nuccio's Pearl', C. japonica 'Silver Waves', C. japonica 'Shiro Chan', C. japonica 'Tom Knudsen', C. oleifera 'Winter's Fire', C. sasanqua 'Apple Blossom', C. sasanqua 'Cleopatra', C. sasanqua 'Hana Jiman', C. sasanqua 'Jean May', C. sasanqua 'Kanjiro', C. sasanqua 'Setsugekka', C. sasanqua 'Yuletide' DISEASE CONTROL OUTLINES Camellia (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 39 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CARNATION (Dianthus caryophyllus) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Alternaria leaf spot and branch rot (Alternaria dianthi, A. dianthicola) 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 Infected plants and debris. Bacteria spread in water. stem cracks. Roots may be rotted. Vascular discolora- Favored by high temperatures. tion in stems is yellowish to brown. The outer layer (epidermis) separates easily from stem, which is sticky to the touch. 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 (Pleospora herbarum) Rot starts at tip of calyx and progresses towards base. In old leaves, stems, and debris. Favored by high humidity. 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 Provide good air circulation and keep humidity low. Irrigate wet weather. 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. Same as Greasy blotch. Harvest regularly. Destroy infected buds. Control mites. Do not bring field-grown carnations into greenhouse. Control weeds outside growing area. Fusarium stem rot Stem rotted at soil line and high up on plant. Roots and In soil and plant debris. Spores spread in water. Also fa- Use clean cuttings and rooting medium. Spray cuttings in (Fusarium avenacearum, base of stem rotted. Tops wilt and die. Pink cushions of vored by warm, humid conditions. Also favored by high rooting medium with thiophanate-methyl. F. culmorum, F. graminearum) spores may form at base of plant on decayed tissues. N fertilization and high N:K ratio. Common as a cutting rot. Fusarium wilt (Fusarium oxysporum f. sp. dianthi) Yellow, wilted branches frequently occur on one side at Soil and infected plants. Spores spread in water. Fafirst. Vascular discoloration is dark brown. Root system vored by soil temperatures 75°F and above. Restricted usually remains intact. In late stages, stem develops a below 60°F. dry, shredded rot. Infected parts die. 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 methyl bromide alone or with chloropicrin. Residual bromides should be leached by irrigation before planting. Adjust soil pH to 6.5 to 7.0. (More info</a>*) Moderately resistant: 'Ace', 'Apache', 'Barsemi Yasmino', 'Big Red', 'Comache', 'Corona', 'Exquisite Select', 'Felicia', 'Fiesta', 'Georgia Ann', 'Jolievette', 'Lucy Carrier', 'Maman', 'Mei-Sciang', 'Orchid Beauty', 'Pallas', 'Shiro', 'Silvery Pink', 'Sweetheart', 'White Elegance Highly resistant: Gray mold (Botrytis cinerea) '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' Woolly gray fungal spores form on soft, brown, decayed In plant debris. Airborne spores. Favored by high moisblossoms and can move into plant parts wherever blos- ture conditions and low temperatures. soms touch them. Remove old flowers from growing area. Maintain horizontal air movement. Lower humidity where possible. Mist blooms with iprodione or fenhexamid. (More info</a>*) Continued on next page . . . DISEASE CONTROL OUTLINES Carnation (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 40 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Carnation, continued Disease (causal agent) Symptoms Survival of pathogen and effect of environment 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. Provide good air circulation and keep humidity low. Irrigate Not too common. in early morning. Do not wet foliage with irrigation water. Phialophora wilt (Phialophora cinerescens) Gradual wilting of plants; leaves become straw colored. Soil and infected plants. Spores spread in water. FaNot one-sided as Fusarium wilt may be. Brown discolor- vored by cool soil temperatures. ation of vascular system. Little or no tissue rotting in late stages. Uncommon. 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 mefenoxam. (More info</a>*) 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 mefenoxam periodically, depending on severity of disease. Make first application at planting. (More info</a>*) 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 diantha) 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. (More info</a>*) Virus or viruslike diseases Symptoms Comments on control 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 Aphids. in leaves. Symptoms are masked at low temperatures. Obtain virus-free plants. Control aphids. Ring spot Small 0.5- to 1-inch (1- to 2-cm) rings; sometimes concentric. Chlorosis, mottling, and distortion of young leaves. Plants obviously stunted. Cutting knife and handling. Insect vectors unknown. Same as 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. * For additional information, see section on Key Diseases. DISEASE CONTROL OUTLINES Carnation (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 41 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CATTLEYA (Cattleya spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial soft rot (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. Soilborne fungi. Spores spread in water. Favored by Decay may progress rapidly. Affected tissues turn black warm moist conditions (above 65°F). and are sometimes soft. Drench plants with mefenoxam. Steam or chemically treat growing media and used pots. Remove badly infected plants. More info: Pythium Root Rot, Phytophthora Root and Crown Rots* Botrytis flower brown speck or rot (Botrytis cinerea) Tiny, light-brown spots on blossoms may enlarge to rot On plant debris. Spores airborne. Favored by cool, entire flower. Woolly gray fungal spores develop on moist conditions. flowers if kept moist. 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 In infected plants. Spores spread in water. Favored by margins. Spots may coalesce and kill entire leaf. Spots moist conditions and unfavorable growing conditions. start as minute, dark areas, often at leaf tips. Provide better growing conditions. Avoid wetting foliage. Remove infected tissues. Rust (Sphenospira sp.) 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. (More info</a>*) Virus or viruslike disease Symptoms Natural spread and host range Comments on control Can be spread on cutting tools. Use clean cutting tools. Destroy infected plants. Blossom necrotic streak Blossoms open without evidence of brown spots or (a strain of Cymbidium mosaic streaks, which become visible after about 1 week or virus) longer. Long, yellowish, irregular streaks may develop on leaves. Leaf necrosis (Cymbidium mosaic virus) Irregular, elongated streaks of dead tissue on undersur- Spread by pruning tools. Cattleya and its hybrids, Cymface of older leaves. Some leaves may be killed or vari- bidium, Epidendrum, Zygopetalum, Angraceum, Laelia, ous patterns of sunken, black tissue may develop. InOncidium, Spathoglottis. fected plants may show no symptoms. 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. Severe flower break Variegation of flower color. May also distort sepals and Spread by green peach aphid. Cattleya and its hybrids, Same control for all viruses. petals. Leaves mottled with streaks of light and dark Cymbidium. green tissue. Dark green areas somewhat raised, producing ridges and bumps. Unknown, but can be transmitted by juice inoculations. Isolate or destroy infected plants. Disinfect tools between Cattleya and its hybrids, Cymbidium, Odontoglossum, cuts with a quaternary ammonium disinfectant. Phalaenopsis. Continued on next page . . . DISEASE CONTROL OUTLINES Cattleya (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 42 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Cattleya, continued Virus or viruslike disease Symptoms Symmetrical flower break A symmetrical variegation in which pigment occurs Unknown, but can be transmitted by juice inoculations. along sepal margins and over most of petals, except in Cattleya. middle areas that have little or no pigment. Leaves may develop an inconspicuous mosaic mottle. Natural spread and host range Comments on control Cattleya orchids are also susceptible to gray mold* (Botrytis cinerea). * For additional information, see section on Key Diseases. DISEASE CONTROL OUTLINES Cattleya (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 43 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CHRYSANTHEMUM (Chrysanthemum grandiflora) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Bacterial blight (Erwinia 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, Sclerotia in soil. Spores produced from sclerotia are white fungal mass may occur on rotted tissues. Black airborne but infect only through flowers and dead tissclerotia may form inside or outside stems. sues. Favored by high humidity. Same as for gray mold. Also, treat soil with PCNB before planting and spray foliage with iprodione or thiophanatemethyl. (More info</a>*) 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 ritzema-bosi) 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 Soilborne and carried in cuttings. Favored by high soil apex, followed by curvature of the stem towards the af- temperatures (80°F). fected side. As the disease progresses, there is a general chlorosis and wilt and stunting of leaves. The vascular system becomes a reddish brown. Gray mold (Botrytis cinerea) Brown, water-soaked spots on petals. Woolly gray fun- In plant debris. Favored by high humidity, low tempera- Keep humidity low; avoid overhead irrigation. Protect foligal spores form on decayed tissues. Rotting of lower tures (50° to 60°F), and water on plant. age with a fungicide, especially lower-dense foliage. Mist leaves. Fungus may enter and girdle stem. blooms with chlorothalonil, iprodione, or fenhexamid. (More info</a>*) Hollow stem (Erwinia carotovora) 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. Bacteria may be present in vascular bundles of symp- Use disease-free cuttings. Reduce humidity in growing artomless chrysanthemums. Bacteria also present in un- eas. Streptomycin dips may be helpful. decomposed debris. Favored by high temperatures and high moisture. Powdery mildew (Erysiphe 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, fenarimol, or triadimefon. (More info</a>*) Pythium root rot and basal stem rot (Pythium spp.) Girdling black lesions occur near soil line. Plants stunted as a result 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 mefenoxam. (More info</a>*) 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 mum refuse. Waterborne spores. Favored by rainy weather. Use disease-free cuttings. Avoid wetting foliage and keep humidity low. Protect foliage with chlorothalonil. 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'). (More info</a>*) Continued on next page . . . DISEASE CONTROL OUTLINES Chrysanthemum (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 44 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 Airborne spores produced only on living plants. Free undersides of leaves and on stems. 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 In plant debris and in soil debris for 2 years. Spores progressively upward from base of plant. Tiny black spread in splashing water. Favored by wet weather. fungal fruiting bodies in centers of spots. 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-methyl bromide combination. In sunny climates, soil solarization might be considered. (More info</a>*) 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 an inch in diameter. Raised, waxy, pink-colored pustules are formed on lower leaf surface. 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. Not all cultivars are susceptible. White rust is under an eradication program in California. Check with your Agricultural Commissioner about its status in your county. Once the disease is confirmed, CDFA requires a control program of 3 to 5 applications of myclobutanil (Eagle or Hoist); the number of applications depends on whether or not the crop is in an infested or noninfested area or if it is propagative material. Repeated treatments with myclobutanil can cause stunting of growth, so don't apply it weekly throughout the winter if white rust is not present and treatment not required by law. Growers in nonregulated areas can rotate with mancozeb (Dithane) and chlorothalonil (Daconil) as a protectant treatment program. Combine fungicide treatments with destruction of infected plants and crop free periods of 8 weeks. Propiconazole, previously recommended as the treatment for eradication programs, may cause phytotoxic symptoms on some cultivars. Details concerning approved CDFA treatments can be found at http://pi.cdfa.ca.gov/pqm/ manual/411.htm. Infected plants or flowers cannot be moved or sold and cleanup of infestations in quarantined areas must be done to CDFA's satisfaction. Continued on next page . . . DISEASE CONTROL OUTLINES Chrysanthemum (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 45 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 prop- Use disease-free cuttings. Remove infected plants. agation. 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 Eliminate nearby susceptible ornamental plants and be spread by vegetative propagation. Many weeds and weeds. Control thrips inside and outside growing areas. perennial ornamental plants act as reservoirs of virus Use virus-free cuttings. (dahlia, calla, nasturtium, mallow, knotweed, plantain, and others). 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 (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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 46 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CYCLAMEN (Cyclamen spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Gray mold (Botrytis cinerea) Spotting of flowers. Decay of emerging flower stems and leaf petioles under leaf canopy. Woolly 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. (More info</a>*) Soft rot (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 Heat-treat growing medium at 140°F for 30 minutes or fuis favored by poor drainage and overwatering. migate. Drench plants with mefenoxam. More info: Pythium Root Rot, Phytophthora Root and Crown Rots* 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 Discard infected plants and soil; don't save seed from inother plants are infected. Disease is favored by tempera- fected plants. Good sanitation generally provides adetures above 70°F. May be seedborne. quate 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. (More info</a>*) 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. (Cryptocline [=Gloeosporium] cyclaminis) Distinctly zonate, pale green and circular spots. Orange to pink-colored spores on stems and leaves. (Septoria cyclaminis) Red concentric spots turn gray with red borders. Stunt (Ramularia cyclamanicola) Conspicuous stunt. Flower peduncles shortened so Infected plants and debris. Spores are airborne. Favored Dispose of infected plants, keep humidity low. Keep seedthat flowers open below surrounding leaves. Reddish by warm, moist conditions. lings away from older plants. Protect plants with thiophanbrown necrosis in tuber. Brown irregular leaf spots. ate-methyl. Frosty appearance on underside of lower yellowed leaves. Control is same as for gray mold. Protect foliage with a fungicide. 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 47 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CYMBIDIUM ORCHID (Cymbidium spp.) (3/09) 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 mefenoxam. Steam or chemically treat growing medium. (More info</a>*) 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 Sclerotia survive in soil for many years. No spores form. Destroy infected plants. Heat-treat soil, fumigate with methyl stem. White fungus growth and small resting strucFavored by warm, moist soil. Fungus has a wide host bromide-chloropicrin mixture, or mix granular PCNB with tures (sclerotia) that resemble mustard seeds usually range. planting medium before planting. present on plant and planting medium. 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 Elongated chlorotic areas are sometimes diamond(Odontoglossum ringspot virus) shaped. Older leaves sometimes develop (Tobacco mosaic virus, orchid brown-to-black flecks and streaks. strain) Can be transmitted by juice inoculations. Cymbidium, Cattleya, Odontoglossum, Phalenopsis. 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, Epi- All virus diseases are propagated with plant. Once infected, dendrum, Zygopetalum, Angraceum, Laelia, Oncidium, plant remains so for life. Destroy infected plants. Disinfect Spathoglottis. 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 48 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DAHLIA (Dahlia spp.) (3/09) 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 Avoid wounding plants. Do not grow plants in infested soil wounds and can survive on infected roots. Gall develop- for 3 years, or fumigate soil. Discard infected roots. Rotate ment favored by rapidly growing host. with non-woody crops, such as cereals and legumes. (More info</a>*) Fusarium wilt (Fusarium oxysporum) Symptoms are almost identical to those of Verticillium Soilborne for many years. Disease most severe when wilt. Not common in California. soil temperatures are high. Destroy infected plants. Grow plants in new areas or fumigate soil; see above for control of Verticillium wilt. (More info</a>*) Gray mold (Botrytis cinerea) Brown, water-soaked spots appear on petals. Woolly Plant debris. Favored by cool, wet conditions and congray fungus spores form on soft, brown, decayed tis- densed moisture on plants. sues; fungus may invade plant tissue that touches infected petals. Remove withered or diseased flowers promptly. During cool, wet weather, spray with iprodione, mancozeb, or fenhexamid. (More info</a>*) Powdery mildew (Erysiphe 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 struc- Protect foliage with myclobutanil, fenarimol, or sulfur. (More tures (cleistothecia) on old leaves. Free water is not info</a>*) necessary for infection. 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. (More info</a>*) 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, Erwinia carotovora, 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 humidities. 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-methyl bromide combination (tarped). Fumigation also controls most other fungi, bacteria, weeds, nematodes, and soil insects. Soil solarization might be considered in sunny climates. (More info</a>*) Continued on next page . . . DISEASE CONTROL OUTLINES Dahlia (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 49 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 irreguAphids. Spread vegetatively by cuttings and roots. In larly. Bands adjacent to the veins remain pale green some cultivars, the virus is almost symptomless. (vein-clearing). Leaves may be distorted. Shortening of internodes (stunt) occurs in some cultivars. Flower color is usually normal. 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 Destroy infected plants. Control aphids and weeds. plants: cucurbits, tomato, pepper, legumes. 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 Eliminate reservoir hosts and weeds. Destroy infected plants. plants. Control thrips. Eliminate virus by taking small, stem-tip cuttings from rapidly growing plants. Destroy infected plants. Control aphids. Dahlias are also susceptible to southern blight* (Sclerotium rolfsii) and foliar nematodes.** * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. DISEASE CONTROL OUTLINES Dahlia (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 50 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DELPHINIUM (Delphinium spp. and hybrids) (3/09) 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 delphinRotate field to a different crop. In perennial plantings, reium crop. Disease is favored by cool, wet weather. Bac- move old leaves and stems from field. Avoid overhead irriteria are spread in splashing water. gation. Diplodina disease (Diplodina delphinii) Brown to black stem cankers often at stem bases of Fungus survives on delphinium debris and in crowns of older plants. Basal canker may girdle the stem, caus- living plants. Spores are spread in splashing water. ing the tops to die and break over. Tiny, black fungus fruiting structures (pycnidia) may be visible in necrotic tissues. Uncommon. 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. Powdery mildew White powdery patches on surface of leaves and (Erysiphe polygoni and Sphaer- stems. Basal leaves yellow, then brown and die. otheca humili) 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. (More info</a>*) Soft crown rot and Black leg (Erwinia carotovora ssp. atroseptica) 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 agriculImprove drainage. Grow on raised beds. Do not overirrigate. tural soils. Spores (zoospores) are spread in water. Fa- Fungicides used to control Pythium and Phytophthora vored by wet weather, poor drainage, and overwatering. should be useful. more info: Pythium Root Rot, Phytophthora Root and Crown Rots* 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 51 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES EASTER LILY (Lilium longiflorum) (3/09) 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 In plant debris. Spores are airborne. Favored by cool, Keep humidity below 85% by heating and ventilation. Do not appear on older leaves. Under damp conditions, wet conditions and condensed moisture on plant parts. use overhead irrigation. Mist blooms and foliage with iprodiwoolly gray fungal spores form on spots. Brown spotone, mancozeb, or fenhexamid. (More info</a>*) ting of blooms occurs. Botrytis elliptica infects healthy tissue whereas B. cinerea invades only dead or dying tissue. Bulb rots (Rhizopus spp., Penicillium spp.) Bulb rot may be soft and mushy (Rhizopus spp.) or dry In plant debris. Spores are airborne. Favored by warm Do not injure bulbs. Store bulbs under cool and dry condiand punky (Penicillium spp.) storage temperatures. tions. Thiabendazole bulb dips usually prevents Penicillium decay. Fusarium bulb rot Lower leaves become yellow or purple and die. Plants In diseased bulbs and soil. Favored by warm tempera- Do not plant bulbs that show any signs of infection. Dip (Fusarium oxysporum f. sp. lilii) are stunted and of poor quality. Brown basal rot of tures. bulbs in thiabendazole. Plant deep in pot to force stem bulb occurs, causing the scales to fall off. roots. Leaf scorch (nonparasitic) Semicircular brown areas develop along leaf margins. Most severe in high-acid and low-fertility soils. Leaf tips turn brown. 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 Drench plants with mefenoxam in combination with thidrainage. ophanate-methyl. Mefenoxam at high rates may cause yellowing of leaf margins of Easter lilies. (More info</a>*) 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. Mefenoxam 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 Many hosts; transmitted by aphids. veins mostly on older leaves. Flowers are smaller and fewer than on healthy plant Remove infected plants and control aphids. Mosaic (Tulip breaking virus) Foliage shows a slight, dark and light green mottling. Plants are usually salable. 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 Symptoms tend to be masked at high temperatures shortened, giving plants a flat rosette or cylindrical ap- (above 75°F). pearance in contrast to pyramid shape of a healthy plant. Flowers fail to open correctly. Spread by aphids. Adjust soil pH to 6.5 or 7.0. Maintain adequate levels of nitrogen and calcium. Easter Lilies are also susceptible to bunchy top (Aphelenchoides olesistis)** 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 52 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FUCHSIA (Fuchsia spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Fuchsia rust (Pucciniastrum epilobii) Initially, small brown areas appear on underside of Overwinters as teliospores on fireweed or as basidioRemove fireweed and infected plants. Applications of manleaves. Later, large circular areas of chlorosis occur spores on fir. Urediospores on fuchsia can reinfect fuch- cozeb are effective. Avoid wetting leaves. Prune back to and yellow-orange urediospores appear on the under- sia. stems and remove cuttings. (More info</a>*) side of leaves. Older leaves may have green tissue around infected areas. Eventually urediospores appear on both sides of leaf. Infected leaves usually drop. 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* (Phytophthora spp.), various viruses* (TSWV), 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 53 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GERANIUM (Pelargonium spp.) (3/09) Disease (causal agent) Symptoms Alternaria leaf spot (Alternaria tenuis) Water-soaked areas occur on undersides of leaves. In plant debris and leaf spots. Favored by cool wet condi- Protect foliage with mancozeb. Iprodione sprays applied for Spots enlarge to 0.25 to 0.5 inch and have a slightly tions. gray mold also may help. sunken center surrounded by concentric rings of darker brown or red tissue. Common on Pelargonium domesticum. Bacterial blight Round sunken leaf spots or angular dead areas ap(Xanthomonas campestris pv. pear and are followed by wilting and death of leaf. pelargoni) 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. Survival of pathogen and effect of environment 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. Comments on control 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 Infected plants. Many kinds of plants are susceptible. Fa1 inch in diameter). Margins are water-soaked. Spots vored by warm temperatures, rain, and overhead irrigamay develop tan centers and have a yellow halo. tion. 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 mefenoxam. Remove and destroy infected plants. (More info</a>*) 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. Woolly 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. (More info</a>*) Rust (Puccinia pelargoni-zonalis) Pustules of orange-brown spores form on undersides On living leaves. Favored by moist conditions and water of leaves. 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. (More info</a>*) 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. Use pathogen-free cuttings. Steam treat or fumigate soil with methyl bromide-chloropicrin combination. Avoid soil previously planted to tomatoes, strawberries, potatoes, chrysanthemums, or other susceptible crops. (More info</a>*) 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. Continued on next page . . . DISEASE CONTROL OUTLINES Geranium (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 54 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. (More info</a>*) Line pattern (Pelargonium line pattern virus) Mosaic (Cucumber mosaic virus) Ringspot (Tomato ringspot virus and/or Tobacco ringspot virus) Yellow net (virus suspected) 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 55 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GLADIOLUS (Gladiolus spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Botrytis disease (Botrytis blight, Neck rot, Corm disease) (Botrytis gladiolorum, B. cinerea) Tiny brown leaf spots develop; spots may expand or In corms and on crop refuse. Spores are airborne. Facoalesce. Brown water-soaked spots appear on flower vored by moist conditions and low temperatures (50° to petals. Basal stem infections (neck rot)may penetrate 70°F). corm; corm decay may continue in cold storage. Woolly gray fungus spores may form on decayed tissues. Black seedlike sclerotia may form on underground parts. 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. (More info</a>*) 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. 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 methyl bromide- 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 On corms and corm debris and as spores on storCure and treat corms as outlined at end of this section. in association with other corm rots. If conditions are age-room equipment. Rot develops rapidly when humidmoist, greenish blue spore masses appear over rot- ity is high. ted areas. 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. 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. Stemphyllium leaf spot (Stemphyllium spp.) Small round or angular yellow spots with a red dot in Carried over on gladiolus foliage and refuse. Favored by Spray mancozeb at 10- to 14-day intervals. Plow under the center appear on green parts of plants. Spots are warm, wet weather, especially sprinkler irrigation and gladiolus crop residues. larger on some cultivars. Cultivars differ in susceptibil- rain. ity. 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. In diseased corms and in infested soil for many years. Favored by temperatures of 70°F or above. Comments on control On diseased corms and in soil for 10 years or more. Fa- Cure and treat corms as outlined at end of this section. Use vored by wet soil. uninfested or chemically treated land. Fumigate soil with methyl bromide-chloropicrin combination. * For additional information, see section on Key Diseases. Continued on next page . . . DISEASE CONTROL OUTLINES Gladiolus (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 56 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Gladiolus, continued 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 Aphids. Mechanically transmitted by harvesting tools. break of blossoms. Disease is common in nearly all Legumes (beans, peas, vetch). gladiolus cultivars but symptoms are more severe in some cultivars. Blossoms may fail to open all the way. Ringspot (Tobacco ringspot virus, Tomato ringspot virus) Yellow or white ring patterns and blotches on leaves. Stunt Plants are stunted and produce short spikes. Virus nature not proved. Disease commonly affects 'Chamouny', 'Spic and Span', 'Elizabeth the Queen' cultivars. White break White blotches on flowers. Flowers open poorly and may shrivel prematurely. White break (Cucumber mosaic virus) White streaking or flecking of leaves and a white Aphids. Sometimes transmitted by harvesting tools. Cu- Rogue infected plants at flowering time, or as soon as virus blotch or color break in petals. Flowers sometimes fail curbits (melons, cucumber, squash). symptoms appears. Control aphids. to open completely. Propagate from selected disease-free plants grown in isolated areas. Nematodes. Mechanically transmitted by harvesting tools. Many kinds of plants, including weeds. Destroy infected plants. Corm-propagated. Vector unknown. Propagate from selected disease-free plants grown in isolated areas. Rogue infected plants at flowering time, or as soon as virus symptoms appear. Septoria leafspot (Septoria gladioli) and leaf smut (Urocystis gladiolicola) are rare diseases in California. Curvularia leafspot (Curvularia lunata) appears occasionally as a neck rot, particularly in cormel stocks. 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 6–8 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 70–80% 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 4–6 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 70–80% relative humidity. DISEASE CONTROL OUTLINES Gladiolus (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 57 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GYPSOPHILA (Gypsophila paniculata) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Bacterial gall (Erwinia herbicola) Soft, light brown galls up to 2 inches (5 cm) in diame- Bacteria survive in galls and in aerial parts of the plant. ter develop at or below soil line. Galled plants are of- Infection is favored by warm conditions. ten stunted and some die. 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. Avoid overhead irrigation during flowering. Protective sprays of iprodione or chlorotholonil may be helpful in severe situations. Phytophthora crown rot (Phytophthora parasitica) Leaves wilt and turn light green. Entire plant may col- Pathogen is soilborne and may be present in many lapse and die. Crown tissue is discolored and a soft, fields. Disease is favored by warm temperatures 90°F, wet decay develops. Secondary bacteria cause the moist conditions, and poor drainage. diseased tissue to putrefy. Root rot (Pythium spp.) Soft wet decay of seedlings and plants in propagaSeveral species of Pythium are involved. Pythium apha- Mefenoxam is helpful when used in preventative programs. tion. Leaves of infected plants turn grey-green. In the nidermatum is favored by warm or hot conditions while (More info</a>*) field, roots are rotted and plants are stunted. P. ultimum develops at lower temperatures. Both pathogens are present in many field soils. Disease is favored by overwatering and poor drainage. Stem rot (Rhizoctonia solani) All stages of growth may be affected. Stems are inFungus occurs naturally in many soils. Favored by fected at or just beneath the soil line. Sunken dark le- warm, wet conditions and deep planting. sions are dry in the early stages but later the decay becomes soft and wet. Favored by moist conditions. Comments on control Improve drainage by planting on raised beds. Do not moisture-stress plants, but do not overwater. Soil drenches of mefenoxam are helpful in preventing the disease. (More info</a>*) 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 (12/98) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 58 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES HEATHER (Calluna vulgaris, Erica spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment 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 Avoid fields just cleared of oaks or other susceptible woody in soil. Infection is favored by the same conditions that plants. This is not a common disease of heather. are favorable for plant growth. 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. Powdery mildew (Erysiphe polygoni) Shoot tips are reddened, then yellow and turn brown On living heather foliage. Fungus is favored by moderand fall off. A side bud develops into the new terminal ate temperatures, partial shade, and dry foliage. 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. 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. (More info</a>*) 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 mefenoxam. Careful water management will provide some relief in field plantings. Mefenoxam applied as a drench also helps. more info: Pythium Root Rot, Phytophthora Root and Crown Rots* Rust (Uredo ericae) Small pustules of powdery orange spores occur on On foliage. Spores are airborne and may be carried by leaves. Infected leaves usually turn yellow and abthe wind for many miles. Pathogen is favored by moderscise. Erica hirtiflora and E. persoluta var. alba are in- ately low temperature and dew or rain. fected. 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. (More info</a>*) 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. Avoid fields that have been in susceptible crops or weeds such as tomato, chrysanthemum, strawflowers, nightshade, and others. Propagate plants, using heat or chemicallytreated medium. The fungus can be eliminated from field soil by fumigation with methyl bromide-chloropicrin mixture. (More info</a>*) 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. Comments on control 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. * For additional information, see section on Key Diseases. DISEASE CONTROL OUTLINES Heather (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 59 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES IRIS (Bulbous) (3/09) 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. Avoid excessive overhead irrigation. Space plants wide Rhizomatous iris also is susceptible. Disease is favored enough to promote air circulation and rapid drying of foliage. by warm, moist conditions and by injuries and frost Discard infected plants. Use pathogen-free planting stock. damage. 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 methyl bromide-chloropicrin mixture. 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 prema- Wounds caused by insects, harvesting, sunburn, etc. turely die. Blue-green mold on rotted bulbs. Also com- are necessary for infection. Late or early digging favors mon as on stored bulbs. 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 Disease is favored by mild temperatures (50° to 70°F) brown borders. As the spots become old, centers turn and wet conditions. Spores are airborne. Fungus also tan. Spots are often near tips of leaves. Flower buds, infects rhizomatous iris. stems, and bulbs may be infected. Dark green spores may be seen in the spots. 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 Disease is favored by mild (68° to 77°F), moist condimargins. Older leaves develop gray centers. Dark tions. Fungus survives on infected bulbs and debris. spore masses may be visible on lesions. Usually Not common. older leaves are infected. Irregular inky-black stains occur on Iris reticulata bulbs. Disease may be severe on plants undug for 2 years. 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 Nematodes survive in bulbs. Damage is worse in cool, the outer husks. Outer husks become shredded at the moist climates. Other hosts include alfalfa, potato, sugbase and the basal plate becomes honeycombed and arbeet, tulips, and some weeds and fungi. grayish. 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) (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 60 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Iris (Bulbous), continued Disease (causal agent) Symptoms Rust (Pucciniairidis) Reddish brown powdery pustules on leaves. Cultivars Fungus survives on living iris leaves. Spores are airdiffer in susceptibility. borne. Favored by condensed moisture and overhead irrigation. Survival of pathogen and effect of environment Comments on control 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. (More info</a>*) Southern blight (Sclerotium rolfsii) This disease is also called crown rot or southern wilt. Sclerotia survive in soil. Disease is favored by warm Outer leaves turn yellow. Eventually all leaves are af- (77° to 95°F), moist soil. May be spread by infected fected. Leaf bases and bulb are affected by a soft rot. bulbs and anything that moves infested soil. White mycelium is present on bulbs and in soil. Small, tan to reddish brown sclerotia are found in and on bulbs and soil. PCNB mixed with soil before planting helps. (More info</a>*) 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) (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 61 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES IRIS (Rhizomatous) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Bacterial soft rot (Pseudomonas spp.) Wilting and dying of fans accompanied by a soft, wet, In infected tissue. Favored by warm, wet weather, but Bacteria enter through wounds, so prevent injuries to plant. foul-smelling rot of rhizome. Fans separate easily rot may continue when conditions are dry. More serious Remove infected plants, cut away rotted tissues, and allow from rotted rhizome or topple over. when rhizomes are buried when planted. 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 diOn living and dead leaves. Favored by wet weather. ameter and up to 1 inch in length. At first, yellowish Fungus also infects bulbous iris and other iris species. 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. 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 On living iris leaves. Spores are airborne. Favored by areas frequently surrounded by yellow tissues. Culti- atmospheric moisture (rain, dew, overhead irrigation). vars differ greatly in susceptibility to rust. 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. (More info</a>*) Sclerotium rot (Sclerotium rolfsii) Rhizomes and leaf bases become rotted. The fungus In soil as sclerotia. Favored by high temperatures and is visible as a white, cottony growth on the surface wet soil. and in the soil, and as small, brown resting structures (sclerotia). 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. Scorch (Cause unknown) Central leaves, beginning at leaf tips, wither and die Favored by moist soil at 60°F. back. Affected leaves may turn reddish brown. Rhizome remains firm. Cortical tissues of roots are rotted, leaving only central water-conducting tissues and tubelike outer tissues. Plants can recover, but some may die. No sure method of control available. Thorough cleaning and drying before replanting sometimes is effective. Dip in 0.5% sodium hypochlorite after cleaning. Sometimes replanting with no treatment gives uninfected plants. Virus or viruslike disease Symptoms Comments on control Mosaic (Iris virus 1) Light and dark green mottling and yellow stippling of Iris family (Iridaceae). Transmitted by aphids. Oncocyfoliage. Mottling and stippling are especially promilus iris and their hybrids can be severely damaged. Senent on young leaves. Mosaic is most severe on bulb- rious on Tagridias. ous iris and some rhizomatous species. Iris germanica and its hybrids are only slightly stunted and sometimes exhibit no symptoms. Host range and natural spread Comments on control 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) (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 62 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MARGUERITE DAISY (Chrysanthemum frutescens) (3/09) 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. (More info</a>*) 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 Plant disease-free plants. Propagate from clean plants. Dip soil for several years. or spray cuttings with Agrobacterium radiobacter 'K84' immediately if wounded. Avoid wounds, especially when plants are wet. (More info</a>*) 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. Avoid poorly drained soils. Plant on raised beds. Reduce Favored by excess soil moisture and poor drainage. amount of irrigation water. Mefenoxam applied at transplanting will help get plants started. (More info</a>*) 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 Preplant fumigate with methyl bromide-chloropicrin mixture most severe in sandy soils. Also prevalent in cooler cli- or solarize soil.** mates: 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). 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. 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. Avoid fields where the disease has occurred or fumigate with Sclerotia germinate and infect susceptible plants. Fun- methyl bromide-chloropicrin mixture. PCNB applied to the gus has a wide host range. base of plants or as a preplant treatment will help. (More info</a>*) Preplant fumigate with methyl bromide-chloropicrin mixture or solarize soil. Marguerite Daisy is also susceptible to downy mildew* (Peronospora radii), powdery mildew* (Erysiphe cichoracearum), Verticillium wilt* (Verticillium dahliae), leaf spot (Ramularia sp.), curly top (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 Marguerite Daisy (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 63 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES POT MARIGOLD (Calendula officinalis) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Powdery mildew (Erysiphe cichoracearum, Sphaerotheca fuliginea) 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. (More info</a>*) 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 mefenoxam. (More info</a>*) 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 wind 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 (Sclerotina sclerotiorum), and Verticillium wilt* (Verticillium dahliae). * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. DISEASE CONTROL OUTLINES Pot Marigold (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 64 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES NARCISSUS (Narcissus spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Basal rot (Fusarium oxysporum f. sp. narcissii) 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. Basal rot susceptibility: 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 (Sclerotium rolfsii) A bulb rot that is at first wet and later becomes dry and woody. A white fungus mat and small (0.03 to 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. 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 Remove flowers before fungus produces apothecia in germinate in spring to produce fruiting bodies (apothe- March/April. Protect flowers and foliage with a fungicide. cia), which produce airborne spores (ascospores). Conidia, which are also airborne, cause secondary spread. The disease is favored by mild, humid conditions. Scorch (Stagonospora curtsii) Yellow to brown lesions at leaf tips. Elongate reddish The fungus survives in the neck and between scales. Treat bulbs with hot water. Protect plants in the field with funbrown leaf spots. Small black pycnidia form in neDisease is favored by mild, moist conditions. Spores gicides. Make first application as leaves emerge. crotic areas. are spread in splashing water. The fungus infects members of the Amaryllidaceae. Smoulder (Botrytis narcissicola) A dark brown lesion first appears on leaf tips. Infected leaves may curl when infection occurs on inner edge. Masses of woolly 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. 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. 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 65 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 Do not replant for 1 year in fields where the disease has ocbulbs. Sclerotia germinate to produce conidia as leaves curred. Protect foliage with mancozeb. Copper fungicides emerge. Disease is favored by warm, moist conditions. are also helpful. Virus or viruslike disease Symptoms Host range and natural spread White streak (Narcissus white streak virus) Narrow, dark green to purple streaks, which later be- Narcissus is the only host of the virus, which is transcome white to yellow-white, appear in leaves and mitted by aphids. Symptoms do not occur until air temflower stalk after flowering. Bulb size and yields are peratures exceed 64°F. reduced by premature senescence. 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. Eliminate infected plants. Control aphids. The virus infects only narcissus and is spread by aphids. Symptoms appear early in growing season. Comments on control 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 stolonifera), bacterial streak (Pseudomonas sp.) and root lesion nematode** (Pratylenchus penetrans). ** For additional information, see section on Nematodes. DISEASE CONTROL OUTLINES Narcissus (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 66 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PEONY (Paeonia spp.) (3/09) 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 Disease is favored by wet weather and injured tissue. the base. Woolly gray fungus sporulation is usually Fungus survives on plant debris and as sclerotia in or visible on infected tissues. Flower buds darken and on soil. wither; leaves also may be attacked. Leaf blotch (Cladosporium paeoniae) Small (0.02 to 0.04 inch), oval leaf spots that reach a Fungus survives on infected peony debris and probably Burn or remove plant residues in fall. Protect foliage in spring diameter of 0.08 to 0.12 inch before they penetrate on infected scales of crown buds. Disease is favored by with a fungicide starting as soon as green shoots appear. through the thickness of leaf. As spots enlarge, they rainy weather in spring. merge giving the leaf an irregular, blotchy appearance. The upper surface of spots become purple while the lower surface is a dull brown. Phytophthora blight (Phytophthora cactorum) Young shoots turn black and die or cankers appear Favored by cool, wet conditions such as very heavy along stems and cause them to collapse. Crown in- rains, excessive irrigation, and poor drainage. fections produce a wet rot that often destroys the entire plant. 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 methyl bromide-chloropicrin mixture. Do not propagate from plants that exhibit any symptoms of the disease. (More info</a>*) 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 Plants are systemically affected and do not recover. to form flowers. Roots of affected plants are often irregularly swollen. The disease slowly spreads in plantings in a manner suggesting a soilborne vector. Ringspot (Peony ringspot virus) A marked yellow mottle that is in the form of chlorotic Virus is systemic in infected plants. The virus is meDestroy infected plants. rings occasionally accompanied by small necrotic chanically transmitted but little else is known about natspots. Growth is probably reduced but not obviously. ural transmission. Remove or burn old growth in fall. Cut stalks below the ground level. Planting on raised beds also is helpful. Treat with fenhexamid. (More info</a>*) Destroy infected plants. Peonies are also susceptible to Armillaria root rot (Armillaria mellea), crown gall* (Agrobacterium tumefaciens), and Chalara root and crown rot (Thielaviopsis basicola). * For additional information, see section on Key Diseases. DISEASE CONTROL OUTLINES Peony (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 67 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES POINSETTIA (Poinsettia spp.) (3/09) 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. Bacterial stem rot (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 temper- Avoid high temperatures and practices that produce succuatures (73° to 86°F) and succulent plants. lent 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. Woolly 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. (More info</a>*) 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 humidities, high temperatures, and condensed moisture on plants. Reduce humidity. Sanitize pruning tools. Avoid wetting foliage. Powdery mildew (Oidium pp.) 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. (More info</a>*) 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. (More info</a>*) 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. (More info</a>*) 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 (Poinsettia mosaic virus) Distortion of leaves and bracts. Some bracts may fail to May be symptomless in poinsettias. Mechanically color normally. Mild mottling of leaves. Angular leaf spot- transmitted. ting, 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. Plant pathogen-free cuttings. Avoid overhead irrigation and syringing. Steam soil and disinfect benches with copper naphthenate; disinfect tools. Obtain virus-free plants. Grow at higher temperatures. Discard plants with symptoms. Poinsettias are also susceptible to Rhizopus soft rot (Rhizopus stolonifera). * For additional information, see section on Key Diseases. DISEASE CONTROL OUTLINES Poinsettia (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 68 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ROSE (Rosa spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Armillaria root rot (Armillaria mellea) A general decline and eventual death. White plaques In infected wood buried in soil. Could be introduced with Fumigate infested soil with methyl bromide/chloropicrin comof fungal growth develop between bark and wood. leaf mold if there are woody branches or roots present bination. or in incipient infection on plant. Black spot (Diplocarpon rosae) Black spots with fringed margins mainly on both On living and dead leaves, and on infected stems. Wasides of leaves and on succulent stems. Yellowed ar- terborne spores are spread by splashing water. eas develop around spots. Causes defoliation. 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. Woolly 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. Keep plants in vigorous condition. Prune diseased portions. Spores are waterborne. Infection occurs mainly through When pruning, cut back to node. wounds. Crown gall (Agrobacterim tumefaciens) Overgrowths or galls form on stem and roots. Infection occurs mainly through wounds. In soil. Bacteria spread in water. Gall development is fa- Avoid injuring base of plant and roots. Paint galls with Gallex vored by rapidly growing host. to eradicate them. Use good sanitation in propagating areas. (More info</a>*) Downy mildew (Peronospora sparsa) Purplish red to dark brown, irregular angular spots on Spores produced only on living plants. Resistant spores Protect foliage with mancozeb, fosetyl-al, or mefenoxam. leaves. Lower surface covered with sparse, downy (oospores) carry fungus over unfavorable periods. (More info</a>*) fungal growth that may be hard to see. Leaves turn Moist, humid conditions. yellow and fall. Powdery mildew (Sphaerotheca 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%). Comments on control Protect foliage with fenarimol, myclobutanil, neem oil, propiconazole, stylet oil, potassium bicarbonate, or sulfur. Eradicate infections with horticultural oils, neem oil, or jojoba oil.* Rust Small orange pustules on undersides of leaves and On living leaves; rarely on stems. Favored by cool, Avoid overhead irrigation. Protect foliage with myclobutanil, (Phragmidium disciflorum or other green parts. Leaves frequently are yellow. May moist weather, and condensed water on leaves. Spores triadimefon, or mancozeb. Remove and destroy all leaves P. speciosum, P. mucronatum) cause defoliation. Cultivars differ widely in suscepti- are airborne. during winter months. (More info</a>*) bility. In fall, black teliospores form on leaves. 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. (More info</a>*) Continued on next page . . . DISEASE CONTROL OUTLINES Rose (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 69 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 Symptoms vary with rose cultivar and virus. Symp(Prunus necrotic ringspot virus) toms 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 Obtain virus-free plants. Heat treatment helps control the vigrafting and by rooting cuttings from infected plants. No rus in rose stocks; 100°F temperatures for 4 weeks inactiinsect vectors known. Symptoms appear at moderate- vates virus in 99% of cuttings taken from treated plants. to-low temperatures and are masked at high temperatures. 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. Rose ring pattern (probably a virus) Symptomless or inconspicuous in some cultivars, es- Infected rose plants. No natural spread. Readily transpecially floribunda types. Rosa multiflora 'Burr' is se- mitted by grafting. verely 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. Obtain virus-free plants. Virus is sensitive to thermal inactivation. (See Mosaic.) Rose spring dwarf (probably a virus) 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. Obtain virus-free plants. Infected rose plants. No natural spread. Obtain virus-free plants. Destroy infected 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 70 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SHASTA DAISY (Chrysanthemum maximum) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Comments on control Acremonium wilt (Acremonium strictum) Wilting, stunting, chlorosis and necrosis, often unilat- Soilborne fungus. Disease is intensified if plants are Plant disease-free plants. Fumigate soil with methyl broeral, of lower leaves. Vascular browning. Symptoms stressed by excessive soil moisture. Fungus has a wide mide-chloropicrin combination. often develop with the onset of flowering. 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. Fasciation (Rhodococcus fascians) Short, swollen clumps of distorted shoots that do not Bacteria survive on infected plants and debris. Bacteelongate at the base of plants. Vigor of plant is rerium has a wide host range. Spreads in water. duced. Secondary rotting of clumps may kill plant. 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 Fungus survives on infected plants and debris. Spores infected leaves yellow and die. Minute black dots are spread by splashing water. Pathogen needs con(pycnidia) are visible in the center of spots. densed 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 thiophanate-methyl. 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. Avoid poorly drained soils. Plant on raised beds. Reduce Favored by excess soil moisture and poor drainage. amount of irrigation water. Mefenoxam applied at transplanting will help get plants started. (More info</a>*) 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. Fungus survives in soil as sclerotia that germinate after a Avoid planting in infested fields or fumigate soil. Carrots, celcold-dormancy period and produce airborne spores, ery, and lettuce are common hosts. Treat soil with PCNB bewhich infect only dead or dying tissue. Direct infection fore planting. Protect plants with thiophanate-methyl. (More from sclerotia may occur. Fungus has a wide host range. info</a>*) Optimum temperature for germination of fungus is 56° to 59°F and needs high soil moisture for at least 10 days. Preplant fumigate soil with methyl bromide-chloropicrin 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 71 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SNAPDRAGON (Antirrhinum majus) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment 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. In greenhouse, steam or chemically treat soil. Before plantSpores are spread in water. Favored by cool, wet soils. ing, 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. (More info</a>*) 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 mefenoxam in preplant treatment or use later as a drench to protect against Pythium and Phytophthora spp. (More info</a>*) Downy mildew (Peronospora antirrhini) Young tip leaves are dull green, severely stunted, Thick-walled resting spores (oospores) in dead plant and roll downward. Gray-purple fungus grows on un- parts. Airborne spores. Favored by cool (40° to 60°F), dersides of leaves. Disease is common on seedling wet weather. phase; large plants are less frequently attacked. Infected plants fail to produce flowers. In greenhouse, reduce humidity. Drench seedlings with mefenoxam. Do not replant in fields where disease has been severe. Steam treat to kill resting spores. Protect foliage with mancozeb. (More info</a>*) Gray mold (Botrytis cinerea) Brown, water-soaked decay of flowers, leaves, and stems. Woolly 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. (More info</a>*) Powdery mildew (Erisyphe cichoracearum) 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. (More info</a>*) Rust (Puccinia antirrhini) Pustules of dark brown to purple powdery spores de- On living snapdragon plants and spores on seed. Does velop on leaves and stems. Rapid water loss from not survive in soil, but does in plant refuse. Airborne severely rusted leaves causes them to dry up. spores. Favored by abundant dew, cool nights (50° to 55°F), and warm days (70° to 75°F). Verticillium wilt (Verticillium dahliae) Plants wilt, frequently on one side. Wilting is more In soil for many years. Favored by cool weather. Plants Steam treat or fumigate soil with a methyl bromide-chloropicpronounced near time of bloom. Problem is most im- wilt during hot weather. rin combination or solarize soil. (More info</a>*) portant in seed fields. Water mold root rots (Pythium 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. Comments on control 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. (More info</a>*) Avoid planting on poorly drained soils. Do not overirrigate. Steam treat or fumigate greenhouse soil. Drench plants with mefenoxam. More info: Pythium Root Rot, Phytophthora Root and Crown Rots* Snapdragons are also susceptible to anthracnose (Colletotrichum antirrhini), 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 72 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES STATICE (Limonium spp.) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Anthracnose (Colletotrichum gloeosporioide) Plants wilt and become mildly chlorotic. Crown tisThe fungus survives on infected plants and debris. The sues decay and plant may die. In initial stages, roots disease is favored by wet weather and overhead irrigaare not affected. The fungus also causes leaf, stem, tion. Spores are spread by splashing water. and flower spots, but this phase of the disease is not common in California. `Gold Coast' is highly susceptible; blue and white cultivars are more tolerant. Cercospora leaf spot (Cercospora insulana) Small, dull red lesions that enlarge up to 0.67 inch (15 Spores are airborne. Disease is favored by warm, moist Avoid overhead irrigation. Protect foliage with chlorothamm) and become tan and membranous in the center conditions and condensed water on foliage. lonil. with reddish borders. 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. Gray mold (Botrytis cinerea) Rot of leaves, stems, and flowers. Rot may enter Fungus has a wide host range and develops on dead crowns and kill plants. Woolly gray fungus sporulation plant parts. Spores are airborne. The disease is prevadevelops on decayed tissues. Flower stubs remaining lent in California in cool (below 77°F) rainy weather. after flower harvest are particularly susceptible. The fungus also may kill seedlings. 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. (More info</a>*) 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 methyl bromide to chloropicrin combination. Heat, fumigate, or solarize soil used in production of transplants. (More info</a>*) 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 are transmitted by leafhoppers. Control insects. Destroy infected plants. Mosaic (Turnip mosaic virus) Plants are stunted and have a mosaic pattern of light Virus is transmitted by several different aphids and is and dark green in leaves. Plants infected when young common in many weedy plants in the mustard family often die. Leaves may be distorted. (Cruciferae). 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. Comments on control Avoid overhead irrigation. Protect plants with chlorothalonil or copper. Chlorothalonil may cause blackening of flowers. 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.* 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 73 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES STOCK (Matthiola spp.) (3/09) 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 black- Seedborne and in plant debris; also in soil for 2 years. ened. Soft, water-soaked stem cankers later become Favored by cool, wet weather. Bacteria are spread by dark and sunken. Plant stems may break and fall over water. because they are weakened by the cankers. Black discoloration of the vascular system occurs. 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. (More info</a>*) 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. (More info</a>*) Fusarium wilt (Fusarium oxysporum f. sp. mathioli) (Important in seed fields) Lower leaf veins turn yellow, then entire leaf becomes Soilborne for many years; also seedborne. A yellow, withers, and drops. Basal leaves are affected warm-weather disease; rarely a problem in the winter first. Plants are stunted. Seed pods turn a light-tan grown cut-flower crop. color. Brown vascular discoloration occurs. Gray mold (Botrytis cinerea) A soft, brown decay that occurs on flowers or entire flower heads. Woolly 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 Protect flowers with thiophanate-methyl in combination condensed moisture on plants. Spores (conidia) are air- with mancozeb or treat with iprodione. Avoid overhead irriborne. gation. (More info</a>*) 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 methyl bromide-chloropicrin combination (tarped). This combination also controls most weeds, nematodes, soil insects, and other fungi and bacteria. (More info</a>*) Water mold root rots (Phytophthora 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 treatment helps control damping-off phase. Mefenoxam also effective. more info: Pythium Root Rot, Phytophthora Root and Crown Rots* No control necessary for the cut-flower crop grown in cool, coastal areas. Fumigate soil with a methyl bromide-chlorpicrin combination (tarped). (More info</a>*) Continued on next page . . . DISEASE CONTROL OUTLINES Stock (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 74 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Stock, continued Virus or viruslike disease Symptoms Mosaic (several viruses) Leaf mottling and flower breaking occur. Leaf symp- In cruciferous weeds (mustard, wild radish, shepherd'stoms vary with different viruses. White and yellow va- purse, etc.). Spread by aphids. Not seedborne. Symprieties do not show flower breaking. toms favored by cool weather. Host range and natural spread Comments on control 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 75 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES STRAWFLOWER (Helichrysum bracteatum) (3/09) 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 Control tarweed for some distance away if possible. Protec(sporangia) are airborne. Chilean tarweed (Madia sative fungicides should be effective but few if any are labeled tiva) and other members of the family Compositae are for strawflower. (More info</a>*) hosts of P. halstedii. 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 Avoid fields that are known to be infested. Soil fumigation hot weather at flowering. Fungus survives in soil for long with methyl bromide-chloropicrin combination is effective. periods as microsclerotia. Many plants are infected in- (More info</a>*) cluding weeds, crop plants, and ornamentals. 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 76 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SWEET PEA (Lathyrus odoratus) (3/09) 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 Avoid fields previously planted in legumes. Avoid overirrigacondition that weakens the plant. tion and overfertilization. Plant on raised beds. Powdery mildew (Erysiphe polygoni) 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 actually 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. (More info</a>*) 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 ("winVirus is spread by aphids. Host plants include many leg- Control nearby weeds, especially legumes. Control aphids. dows"). Foliage may be crumbled and stunted. There umes. may be "windows" in the flowers. 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 leg- Control nearby weeds, especially legumes. Control aphids. umes. 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 Control nearby weeds including grasses. Control thrips. many weeds. Juvenile thrips (nymphs) acquire the virus and transmit it as adults. Sweet peas are also susceptible to Ascochyta blight (Ascochyta lathyri), bacterial streak (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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 77 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SWEET WILLIAM (Dianthus barbatus) (3/09) Disease (causal agent) Symptoms Survival of pathogen and effect of environment Fusarium wilt (Fusarium oxysporum f. sp. dianthi) Yellowing of new growth. Plants stunted and leaves Fungus survives in soil for many years as chlamydoFumigate soil with methyl bromide to chloropicrin combinapoint downward instead of upward as in a healthy spores. Disease is favored by warm soils and high tem- tion. Grow seedlings in heat-treated, solarized, or fumigated plant. Leaves gradually turn yellow and die. The vas- peratures. soil or growing medium. (More info</a>*) cular system of the lower stem and roots is brown. 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. Comments on control Avoid overhead irrigation. Protect foliage with a fungicide. Sweet Williams are also susceptible to rust* (Uromyces caryophyllinus and Puccinia areneriae), root rot* (Pythium ultimum), gray mold* (Botrytis cinerea), stem rot (Rhizoctonia solani), southern blight* (Sclerotium rolfsii), Septoria leafspot (Septoria dianthi), anther smut (Ustilago violucea), 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 (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 78 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Host-Pathogen Index (3/09) 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 Erwinia chrysanthemi Aphelenchoides ritzemabosi Botrytis cinerea Phytophthora parasitica Erysiphe cichoracearum Sphaerotheca fuliginea Pythium spp. Rhizoctonia solani physiological (cold water and light) Christmas cactus (Schlumbergera bridgesii) Crown rot* Phytophthora parasitica Pythium aphanidermatum Fusarium rot* Fusarium oxysporum Gray mold* Botrytis cinerea Root and stem rot Rhizoctonia solani Root rot* Pythium irregulare Stem rot Phytophthora spp. Stem rot and leaf spot Bipolaris cactivora Virus Cactus virus X Candytuft (Iberis amara) Alternaria leaf spot Basal stem rot Club root Gray mold* Phytophthora root rot Powdery mildew* Pythium root rot* Root knot nematode** White rust Alternaria brassicae Phoma lingum Plasmodiophora brassicae Botrytis cinerea Phytophthora spp. Erysiphe polygoni Pythium spp. Meloidogyne sp. Albugo candida Cineraria (Senecio cruentis) Collar rot Downy mildew* Gray mold* Powdery mildew* Impatiens necrotic spot/spotted wilt Leaf spot Powdery mildew* Root and collar rot* Root rot* Spotted wilt Stem rot Rhizoctonia solani Plasmopara halstedii Botrytis cinerea Erysiphe cichoracearum Impatiens necrotic spot virus Alternaria cinerariae Sphaerotheca fulginea Phytophthora spp. Pythium ultimum Tomato spotted wilt virus Sclerotinia sclerotiorum * For additional information, see section on Key Diseases. ** For additional information, see section on Nematodes. DISEASES Host Pathogen Index (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 79 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* Sclerotina 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 Erysiphe 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 Erysiphe polygoni 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. DISEASES Host Pathogen Index (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 80 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Impatiens (Impatiens wallerana) Bacterial fasciation Bacterial leaf spot Black root rot Brown crown canker Crown rot* Gray mold* Impatiens necrotic spot/spotted wilt Leaf spot Root rot* Southern blight* Verticillium wilt* Rhodococcus fascians Pseudomonas syringae Thielaviopsis basicola Rhizoctonia solani Pythium ultimum Rhizoctonia solani Botrytis cinerea Impatiens necrotic spot virus Phyllosticta sp. Pythium sp. Sclerotium rolfsii Verticillium dahliae Kalanchoe (Kalanchoe blossfeldiana) Aster yellows Edema Leaf and stem blight Leaf spots Fasciation Powdery mildew* Root and crown rot* Spotted wilt Stem rot Top-spotting Aster yellows phytoplasma Nonparasitic; cause unknown Botrytis cinerea Stemphylium spp. Cercospora sp. Erysiphe polygoni Phytophthora spp. Tomato spotted wilt virus Myrothecium roridum Top-spotting virus 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 Pouch Flower (Calceolaria herbeohybrida) Cottony rot* Sclerotinia sclerotiorum Gray mold* Botrytis cinerea Root and crown rot* Phytophthora spp. Root rot* Pythium spp. Spotted wilt Tomato spotted wilt virus Stem rot Myrothecium sp. Verticillium wilt* 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 * For additional information see section on Key Diseases. DISEASES Host Pathogen Index (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 81 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES INSECTS & MITES General information (Section reviewed 3/09) 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 INSECTS & MITES: GENERAL INFORMATION Managing Pesticide Resistance (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 82 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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 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. INSECTS & MITES: GENERAL INFORMATION Managing Pesticide Resistance (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 83 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MONITORING WITH STICKY TRAPS (3/09) Adults of whiteflies, thrips, fungus gnats, leafminers, psyllids, shore flies, winged aphids, and parasites can be monitored with yellow sticky traps. Traps warn of pest presence, hot spots, and migration. Traps provide a relative measure of insect density; comparisons of the number of adults caught among sample dates may indicate whether pest density is changing or remaining relatively constant over the long term. Traps are often a very efficient and important monitoring tool, alerting growers to pests early, before damage is observed in crops. Traps may not be a good tool for deciding treatment need or timing. Immature stages in crops commonly cause most damage, and traps typically capture only airborne adults. Adult trapping sometimes is not a reliable indicator of pest presence or abundance on the crop, and traps must be used in combination with visual inspection of plants. Unless other guidelines are recommended, use at least one sticky trap per 10,000 square feet (900 sq m) of growing area. When monitoring whiteflies, use about one trap per 1,000 square feet (90 sq m) of growing area. Although actual trap density will be dictated by the growing area and the time and effort devoted to trapping, each pest management unit should have at least one trap. In addition, put one trap by vents and by doors to detect populations migrating in. Also, put a trap in very susceptible crops and do not locate these crops near doors. Use bright yellow traps, each 3 by 5 inches or larger. If western flower thrips is the primary species of concern, consider using blue sticky traps. Orienting traps horizontally (facing the soil) is sometimes recommended when monitoring pests such as fungus gnats emerging from media. However, in most programs, to catch the most insects, orient the longest part of the trap vertically (up and down). Place each trap so that the bottom of the trap is even with the top of the plant canopy. For rapidly growing crops, locate the trap's bottom a few inches above the canopy so that the plants don't overgrow the traps. As plants grow, move each trap up so that its bottom remains about even with the top of the canopy. Use one or two clothespins to attach each trap to a bamboo post or wood dowel embedded in the growing media or 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. Traps can then be wrapped in clear plastic and taken to a more comfortable location for counting. Alternatively, replace traps when they become too fouled to count insects quickly. If traps are reused, note this because catches become cumulative and you must subtract the number of insects present last time the traps were checked. Because many insects in TRAPS may be harmless or beneficial, carefully identify insects before taking action. High-quality color photographs and line drawings of commonly trapped insects are available in Sticky Trap Monitoring of Insect Pests, ANR Publication 21572. You can also wrap used traps in clear plastic (such as Saran Wrap) to preserve them and take the traps containing unknown pests to a Cooperative Extension or county agricultural department expert for help in identification. Count the number of each type of pest caught and keep a record of these data. It is not necessary to count all insects on the entire trap; counting the insects in a vertical, 1-inch-wide (2.5-cm-wide) column on both sides of the trap will give results that are representative of the entire trap. Do not reduce traps to 1-inch vertical strips, as smaller traps may be less attractive to insects. Interpreting Trap Information. Regularly summarize trap data to facilitate comparison, for example, by graphing the average of all traps from each sample date. Interpreting trap information requires knowledge, skill, and practice and may be more art than science. 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 populations on foliage. 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 should not be used when comparing adult densities among sample dates. Foliage disturbances, such as sprinkling with water or shaking plants to promote pollination or monitor adults, increase trap catches. Even large numbers of pest species in traps do not necessarily indicate that control action is needed. For more information, see ESTABLISHING TREATMENT THRESHOLDS. Always use traps in combination with foliage inspection to confirm presence of an economically damaging population. INSECTS & MITES: GENERAL INFORMATION Monitoring with Sticky Traps (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 84 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ESTABLISHING TREATMENT THRESHOLDS (3/09) The presence of a few pest insect or mites and some amount of damage usually can be tolerated. The number of pests and level of damage beyond which treatment should be taken is known as the treatment threshold, a fundamental concept in integrated pest management. 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 crops, pests, and different growing situations. Specific thresholds or control action guidelines may be difficult to determine, but thresholds can be developed over the long term by growers who regularly monitor crops and keep and evaluate good records. Why Use Thresholds. Pesticides sometimes are applied on a calendar schedule, when pest presence is only suspected or when populations are already high and difficult to control. Using thresholds can maintain or improve crop quality while reducing the frequency of pesticide applications. Less frequent applications help maintain pesticide efficacy by reducing the development of pesticide resistance. They also reduce disruptions to cultural practices that occur during applications and reentry intervals. In addition, fewer applications may improve plant growth and quality by minimizing phytotoxicity. Finally, they increase profit by reducing costs of pesticide purchases, application labor, and regulatory compliance. When to Treat. Because crops are grown for profit, treatment thresholds are based largely on economics. Control action is warranted when the increased revenue expected from improved crop quality or yield will exceed the cost and adverse impacts (such as phytotoxicity) of control. The amount of pest presence or damage that can be 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 terminal 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, thresholds may be relatively low for that pest. In certain situations, regulations such as quarantines may impose zero pest tolerance even when populations are low and pests do 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 crop production cycle, pests can develop through many generations before plants are shipped. Abundant pests on young plants may require repeated management actions and greatly increase the likelihood of damaged, poor-quality plants. Treatment 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 be maintained pest-free throughout their production cycle. As crops mature, they are 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. If monitoring reveals very low pest problems near the end of production, it may not be necessary to take control 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 systematically monitoring plants, keeping good records, and judging the acceptability of the finished crop in comparison with pest monitoring and control records. Experiment over time to develop thresholds appropriate for your situation. 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, the percent of plants or leaves found to be damaged or infested during visual inspection, or the number of pests dislodged per 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, control action may be warranted for whiteflies when more than about five adults per trap per week are captured on one well-maintained 3-by-5-inch (7.5-by-12.5 cm) yellow sticky trap deployed per 1,000 square feet (90 sq m) of production. Thresholds for other situations may be very different from this. INSECTS & MITES: GENERAL INFORMATION Establishing Treatment Thresholds (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 85 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BIOLOGICAL CONTROL (3/09) Many insect and mite pests in floricultural crops have natural enemies that can sometimes keep their populations below economically damaging levels. Using pesticides that do not disrupt natural enemy activity is a key component of integrated pest management programs. Two other important features of a good biological program are clean, dust-free plants and the absence of ant activity. Dust and ants can severely interfere with control by natural enemies. When natural enemy populations are not present or are not high enough to reduce pests, they can sometimes be augmented with releases of commercially reared natural enemies. There are two types of augmentative releases: inoculative releases and inundative releases. Inoculative releases are made when pest populations are low and relatively few natural enemies are released, usually just once or twice a season. The introduced predators or parasites reproduce, and it is their progeny, not the released individuals that are expected to provide biological control. Releasing the mealybug destroyer lady beetle (Cryptolaemus montrouzieri) in spring to control mealybugs is an example of inoculative release. Inundative releases involve releasing large numbers of natural enemies often several times over a growing season. The released natural enemies are expected to provide biological control. Although they may reproduce, progeny of release individuals generally are not relied on for control. Periodically releasing Trichogramma species (parasitic wasps) to destroy moth eggs is an example of inundative biological control. A good place to start with augmentation is in situations similar to those where researchers or other pest managers have previously demonstrated success. Guidelines for releasing natural enemies are given for many pests in the individual pest sections of this guideline. Desperate situations where pests are already abundant or damage is common are not a good opportunity for augmentation. Because pest presence is necessary to sustain natural enemies, choose crops where some levels of the target pests and their damage can be tolerated. Begin making releases early in the production cycle. Consider what other pests may occur in the crop and how they can be managed in ways that are compatible with biological control. Make other necessary changes in production practices, for example, by avoiding use of pesticides that harm natural enemies (Table 1). Increase the likelihood that natural enemy releases will be effective by accurately identifying the pest and its life stages. Parasites and many predators attack only certain pest stages; release the beneficial species when the pest is in its vulnerable life stage or stages. The pest life stage that can be effectively controlled with natural enemies may be different from the pest stage that damages plants. For example, Trichogramma species kill only eggs of moths and butterflies; they are not effective against caterpillars. Trichogramma must be released when moths are laying eggs, before the caterpillars become abundant. The quality of commercially available natural enemies is not regulated and may sometimes be poor because of production practices, inadequate packaging, or unsuitable conditions during shipping. Evaluate the quantity and quality of each shipment of natural enemies. If beneficials arrive in parasitized hosts, count parasite exit holes in a small sample immediately after parasites arrive. Keep the sample in a suitable place and recount and compare the number of emergence holes about 10 days after deploying the parasite. If natural enemies (typically predators) arrive in a shaker-type container, estimate their numbers and calibrate your application rate by making one shake over a sheet of white paper and counting the number of apparently alive or active natural enemies. Repeat this several times to estimate the average number of predators per shake. If predators or parasitized hosts arrive on leaves, use a hand lens or dissecting binocular microscope to examine the underside of several leaves and estimate the natural enemies per leaf. Contact the supplier immediately if natural enemy quality is unsatisfactory. Remember that natural enemies are living organisms that require water, food, shelter, and suitable growing conditions. Natural enemies may be adversely affected by 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. Overhead irrigation may drown natural enemies. Many beneficial species stop reproducing under short day length or prolonged cool conditions. Supplemental light may be necessary for some predators and parasites to be effective year-round. Environmental conditions required by natural enemies (such as long days) may not be compatible with production needs of certain crops. Many natural enemies are commercially available (Table 2) through mail order. A publication listing sources, Suppliers of Beneficial Organisms in North America, can be obtained from the Environmental Monitoring and Pest INSECTS & MITES: GENERAL INFORMATION Biological Control (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 86 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Management Branch of the California Department of Pesticide Regulation online at www.cdpr.ca.gov or as a printed publication by calling (916) 324-4100 or writing the Department of Pesticide Regulation, Environmental Monitoring and Pest Management Branch, 830 K St., Room 200, Sacramento, CA 95814. TABLE 1. Pesticide Use Compatibility with Biological Control.1 Chemical name (trade name) abamectin (Avid) Range of activity (affected groups) intermediate (mites, leafminers) Immediate impact on natural enemies2 high to predatory mites, low for many insects Duration of impact on natural enemies2 long to predatory mites and affected insects acephate (Acephate) (Orthene 75WP) (PT 1300 Orthene TR) acetamiprid (Tristar 70WSP) azadirachtin (Azatin XL) (Ornazin) Bacillus thuringiensis# (Gnatrol) broad (insects & mites) high intermediate broad (insects) broad (insects & mites) moderate intermediate moderate short narrow (larvae of flies such as fungus gnats, mosquitoes) narrow (caterpillars) narrow (caterpillars) none none narrow (kills some softbodied predators) broad (insects & mites) low short high long narrow (mites) low short broad (insects & mites) narrow (mites) high long low intermediate intermediate (aphids, thrips & mites) broad (insects & mites) narrow (leafminers) broad (insects) low short high intermediate low short high long (Dipel DF) (Xentari) Beauveria bassiana# (BotaniGard WP) (BotaniGard ES) bifenthrin* (Attain TR) (Talstar Flowable) bifenazate (Floramite) carbaryl* (various) chlorfenapyr (Pylon) cinnamaldehyde (Cinnacure) cyfluthrin (Decathlon 20WP) cyromazine (Citation) deltamethrin (DeltaGard) Continued on next page . . . INSECTS & MITES: GENERAL INFORMATION Biological Control (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 87 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Table 1. Pesticide Use Compatibility with Biological Control, continued Chemical name (trade name) dicofol (Kelthane) diflubenzuron (Adept) endosulfan* (Endosulfon 3EC) (Endosulfon 50WSB) fenbutatin-oxide* (Vendex) fenpropathrin* (Tame) fenpyroximate (Akari) fluvalinate (Mavrik Aquaflow) hexythiazox (Hexygon) horticultural oil# (various) imidacloprid (Marathon 1%G) (Marathon 60 WP) (Marathon II) lambda-cyhalothrin* (Scimitar) malathion (various) methiocarb* (Mesurol) neem oil# (various) novaluron (Pedestal) permethrin (Astro) potash soap# (M-Pede) pymetrozine (Endeavor) pyrethrin/PBO4 (PT Pyrethrum TR) pyrethrin/rotenone (Pyrellin E.C. ) pyridaben (Sanmite) pyriproxyfen (Distance) Range of activity (affected groups) narrow (pest mites & mites) narrow (fungus gnats) broad (insects & mites) Immediate impact on natural enemies2 high to beneficial mites Duration of impact on natural enemies2 long to beneficial mites none none high long narrow (mites) low short broad (insects & mites) narrow (mites) high intermediate moderate short broad (insects & mites) narrow (mite nymphs & eggs) broad (exposed insects and mites) narrow (sucking insects) high long high to predatory mites long moderate short to none low (soil applications) high3 (foliar applications) short broad (plant bugs, beetles, caterpillars) broad (insects & mites) broad (insects) high intermediate high intermediate high long narrow (soft-bodied insects) intermediate (thrips, whiteflies, army-worms, leafminers) broad (insects & mites) broad (insects & mites) narrow (aphids, whiteflies) moderate short low short high long moderate short to none low short broad (insects) broad (insects & mites) narrow (mites) intermediate (aphids, scale, whiteflies, leafminers, gnats) high short high short high to predatory mites intermediate low short Continued on next page . . . INSECTS & MITES: GENERAL INFORMATION Biological Control (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 88 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Table 1. Pesticide Use Compatibility with Biological Control, continued Chemical name (trade name) Range of activity (affected groups) Immediate impact on natural enemies2 Duration of impact on natural enemies2 s-kinoprene (Enstar II) intermediate (immature insects) moderate short spinosad (Conserve SC) intermediate (thrips, caterpillars, leafminers) high to adult wasp parasites; low to predators intermediate tebufenozide (Mimic) narrow (caterpillars) low short 1 Adapted from Flint, M. L., S. H. Dreistadt, and J. K. Clark. 1998. Natural Enemies Handbook: An Illustrated Guide to Biological Pest Control, ANR Publication 3386. 2 The immediate impact of pesticides on natural enemies is the killing of natural enemies resulting from spraying the pest or its habitat (contact toxicity). Duration of the impact on natural enemies refers to persistent residues that kill natural enemies that migrate in and contact previously treated areas (residual toxicity). Use stated toxicities only as a general guide. The actual toxicity of specific chemicals depends on environmental conditions, application rate and exposure, and the species of natural enemy. 3 High toxicity to hymenopteran insects (honey bees and parasitic wasps) 4 PBO = piperonyl butoxide * Restricted use material. Permit required for purchase or use. # Acceptable for use on organically grown ornamentals. INSECTS & MITES: GENERAL INFORMATION Biological Control (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 89 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TABLE 2. Some Commercially Available Natural Enemies of Floriculture and Nursery Pests. TARGET PEST ------------------------------------ NATURAL ENEMY -------------------------------------------Common name Scientific name aphids aphid midge convergent lady beetle lacewings microbial insecticide minute pirate bugs parasitic wasps Aphidoletes aphidimyza Hippodamia convergens Chrysoperla spp. Beauveria bassiana1 Orius insidiosus, O. tristicolor Aphelinus, Aphidius spp., Diaeretiella rapae, others broad mites predaceous mites Neoseiulus spp. caterpillars egg parasites parasitic nematodes Trichogramma spp. Steinernema carpocapsae, Heterorhabditis bacteriophora several host-specific ssp. Bacillus thuringiensis ssp. kurstaki, Bt ssp. aizawai; Beauveria bassiana; spinosyn (spinosad)1 larval parasites microbial insecticides fungus gnats parasitic nematodes microbial insecticide predaceous mite Steinernema carpocapsae, S. feltiae Bacillus thuringiensis ssp. israelensis1 Hypoaspis miles mealybugs citrus mealybug parasite lacewings mealybug destroyer microbial insecticides Leptomastix dactylopii Chrysoperla spp. Cryptolaemus montrouzieri Beauveria bassiana1 scale insects predaceous lady beetle red scale parasite soft scale parasites Rhyzobius (=Lindorus) lophanthae Aphytis melinus Metaphycus helvolus, Microterys flavus serpentine leafminer parasitic nematode parasitic wasps Steinernema carpocapsae Dacnusa, Diglyphus spp. spider mites lacewings predatory cecidomyiid predatory mites Chrysoperla spp. Feltiella sp. Amblyseius, Metaseiulus, Neoseiulus, Phytoseiulus spp. thrips greenhouse thrips parasite lacewings microbial insecticide minute pirate bug predatory mites Thripobius semiluteus Chrysoperla spp. Beauveria bassiana1 Orius insidiosus, O. tristicolor Amblyseius, Euseius, Iphiseius, Neoseiulus spp., Hypoaspis miles weevils parasitic nematodes Steinernema carpocapsae, Heterorhabditis bacteriophora whiteflies lacewings microbial insecticide parasitic wasps predaceous lady beetle Chrysoperla spp. Beauveria bassiana1 Encarsia, Eretmocerus spp. and others Delphastus pusillus white grubs parasitic nematodes Steinernema carpocapsae, Heterorhabditis bacteriophora 1 These microbial products are registered insecticides. INSECTS & MITES: GENERAL INFORMATION Biological Control (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 90 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Major Insect and Mite Pests (3/09) APHIDS Scientific Names: (5/10) 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 (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. MAJOR INSECT AND MITE PESTS Aphids (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 91 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. Class biological botanical carbamate Pesticide (commercial name) A. Beauveria bassiana# (BotaniGard 22 WP) (BotaniGard ES) oil4 4 Mode of action 2 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. — Do not apply to stressed plants or newly transplanted material before roots are established. 3 An aerosol. A. cinnamaldehyde (Cinnacure) Proguard 4 B. pyrethrin/PBO3 (PT Pyrethrum TR) C. pyrethrin/rotenone (Pyrellin EC) Whitmire MicroGen Webb Wright 12 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) A. imidacloprid (Marathon 1G) (Marathon II) SePRO 12 un Must contact insect. Repeated applications as necessary. Aphid suppression only. Label permits low-volume application. Do not exceed 22.5 oz/acre/application. Valent 12 7C Wellmark 4 — OHP 12 4A B imidacloprid . (Marathon 60 WP) OHP 12 4A A. clarified hydrophobic extract of neem oil# (Triact 70) OHP 4 un insect growth reg- A. azadirachtin ulator (Azatin XL) neonicotinoid Manufacturer R.E.I.1 Laverlam 4 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 92 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class oil4 cont. Pesticide (commercial name) B. horticultural oil5 (Ultra-Fine Oil) Manufacturer 12 — 4 4 — — Drexel 48 2A United Phosphorus 24 1B B. acephate Valent (Orthene T, T&O Spray) 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) F. fluvalinate (Mavrik Aquaflow) G. lambda-cyhalothrin* (Scimitar) 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 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 A. endosulfan* (Endosulfan 3EC) organophosphate A. acephate (Acephate 97UP) pyrethroid6 pyridine Mode of action2 Comments Whitmire MicroGen Brandt JMS Farms (SafTSide) (JMS Stylet Oil) organochlorine R.E.I.1 Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. Check local water/runoff restrictions. Some varieties of chrysanthemum exhibit phytotoxicity. Do not apply more than 3 lb a.i./ acre/season. 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 93 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class soap4 1 2 Pesticide (commercial name) A. potash soap# (M-Pede) Manufacturer Dow Agro Sciences R.E.I.1 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 (R.E.I.) 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/. 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 94 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ARMORED SCALES Scientific Names: (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. Class botanical Pesticide (commercial name) A. pyrethrin/PBO3 (PT Pyrethrum TR) insect growth reg- A. pyriproxyfen ulator (Distance) B. s-kinoprene (Enstar II) Class oil4 Pesticide (commercial name) A. clarified hydrophobic extract of neem oil# (Triact 70) MAJOR INSECT AND MITE PESTS Manufacturer R.E.I.1 Mode of action2 Comments Whitmire MicroGen 12 3/— Valent 12 3 Wellmark 4 7A Manufacturer R.E.I.1 OHP 4 An aerosol. 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. 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 Armored Scales (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 95 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES can be treated. May cause injury to flowers. B. horticultural oil5 (Ultra-Fine Oil) Whitmire MicroGen Brandt JMS Farms 12 — 4 4 — — Drexel 48 2A 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. (Saf-T-Side) (JMS Stylet Oil) organochlorine A. endosulfan* (Endosulfan 3EC) organophosphate A. acephate (Acephate 97UP) B. acephate (Orthene T, T&O Spray) pyrethroid 1 2 Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. Do not apply to 'Bonnaton Deluxe,' 'Fred Shoesmith,' or 'White Knight' chrysanthemums. Check local water/runoff restrictions. Do not apply more than 3 lb a.i./acre/season. Restricted entry interval (R.E.I.) 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/. 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 96 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ARMYWORMS and CUTWORMS Scientific Names: (5/10) Beet armyworm: Spodoptera exigua Yellowstriped armyworm: Spodoptera ornithigalli Variegated cutworm: Peridroma saucia 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. 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. (To calculate degree-days, see "Degree-days" on the UC IPM Web site at http://www.ipm.ucdavis.edu.) 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 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 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 MAJOR INSECT AND MITE PESTS Armyworms and Cutworms (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 97 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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 TREATMENT 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 (commercial name) Mode of action2 Comments Valent 4 11 Whitmire MicroGen Webb Wright 12 3/— 12 3/21B Bayer 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 botanical carbamate A. Bacillus thuringiensis ssp. kurstaki# (various products) A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) A. carbaryl* Manufacturer R.E.I.1 insect growth reg- A. azadirachtin ulator (Azatin) XL B. diflubenzuron (Adept 25WP) C. novaluron (Pedestal) pyrethroid Most effective against early instar larvae; pheromone trapping recommended for timing applications. An aerosol. Must contact insect. Repeat applications as necessary. Label permits low-volume application. Use no more than twice per year and don't exceed 52 oz/acre/year. Don't 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. 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 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 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 application. Do not apply more than 2 lb a.i./acre/year. MAJOR INSECT AND MITE PESTS Armyworms and Cutworms (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 98 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES spinosyn A. spinosad (Conserve SC) Dow Agro Sciences 4 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 (R.E.I.) 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 # Acceptable for use on organically grown ornamentals. * Restricted use material. Permit required for purchase or use. MAJOR INSECT AND MITE PESTS Armyworms and Cutworms (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 99 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES BULB MITES (3/09) Scientific Name: 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, pyridaben (Sanmite), and endosulfan* (Thionex) are possibly effective, but have not been evaluated. * Restricted-use pesticide. Permit required for purchase or use. MAJOR INSECT AND MITE PESTS Bulb Mites (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 100 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES CABBAGE LOOPER (5/10) Scientific Name: 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 TREATMENT 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 insect growth regulator Pesticide Mode of (commercial name) Manufacturer R.E.I.1 action2 Comments A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) Whitmire MicroGen Webb Wright 12 3/— 12 3/21B A. carbaryl* (various) A. azadirachtin (Azatin XL) Bayer 12 1A OHP 4 un B. diflubenzuron (Adept 25WP) Chemtura 12 15 MAJOR INSECT AND MITE PESTS An aerosol. Must contact insect. Repeat applications as necessary. Label permits low-volume application. Cabbage Looper (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 101 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES microbial organophosphate pyrethroid spinosyn C. novaluron (Pedestal) Chemtura 12 15 D. tebufenozide (Mimic, Confirm) A. Bacillus thuringiensis ssp. Kurstaki# (various products) A. acephate (Orthene T, T&O Spray) Dow Agro Sciences Valent 4 18 4 11 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 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. MAJOR INSECT AND MITE PESTS Use no more than twice per year and don't exceed 52 oz/acre/year. Don't use on poinsettia. Most effective against early instar larvae; pheromone trapping recommended for timing applications. 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. Cabbage Looper (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 102 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class 1 2 3 # * Pesticide (commercial name) Mode of Manufacturer R.E.I.1 action2 Comments Restricted entry interval (R.E.I.) 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 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 103 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES DIAMONDBACK MOTH (5/10) Scientific Name: 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 TREATMENT 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. MAJOR INSECT AND MITE PESTS Diamondback Moth (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 104 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Class botanical Pesticide (commercial name) A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) Whitmire MicroGen Webb Wright 12 3/— 12 3/21B Bayer 12 1A 4 un B. diflubenzuron Chemtura (Adept 25WP) A. Bacillus thuringiensis Valent ssp. Kurstaki# (various products) 12 15 4 11 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 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 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. carbamate A. carbaryl* (various) insect growth regula- A. azadirachtin tor (Azatin XL) microbial organophosphate pyrethroid spinosyn Mode of Manufacturer R.E.I.1 action2 Comments MAJOR INSECT AND MITE PESTS OHP An aerosol. Must contact insect. Repeat applications as necessary. Label permits low-volume application. May damage poinsettias if used over labeled rate. Most effective against early instar larvae; pheromone trapping recommended for timing applications. 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. Diamondback Moth (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 105 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Class 1 2 3 * # Pesticide (commercial name) Mode of Manufacturer R.E.I.1 action2 Comments Restricted entry interval (R.E.I.) 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 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 106 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FOLIAR-FEEDING MEALYBUGS Scientific Names: (5/10) Citrus mealybug: Planococcus citri Madeira mealybug: Phenacoccus madeirensis Longtailed mealybug: Pseudococcus longispinus 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 (commercial name) A. Beauveria bassiana# (BotaniGard 22 WP) (BotaniGard ES) A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) insect growth regu- A. azadirachtin lator (Azatin XL) botanical MAJOR INSECT AND MITE PESTS Manufacturer Laverlam Mode of R.E.I.1 action2 Comments 4 — 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. Whitmire MicroGen Webb Wright 12 3/— 12 3/21B OHP 4 un An aerosol. Must contact insect. Repeat applications as necessary. Only effective on immatures. Label permits low-volume application. Foliar-Feeding Mealybugs (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 107 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES neonicotinoid B. azadirachtin (Ornazin 3%EC) C. s-kinoprene (Enstar II) SePRO 12 un Do not exceed 22.5 oz/acre/application. Wellmark 4 7A Apply prebloom. Only effective on immatures. Also labeled for low volume use. A. acetamiprid (TriStar) 70WSP B. dinotefuran (Safari) 20G C. imidacloprid (Marathon 1G) (Marathon II) Cleary 12 4A Apply as a foliar spray. 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 United Phosphorus Valent 12 — 4 4 24 — — 1B Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. 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 MicroGen Whitmire MicroGen FMC 24 1B 12 3 A fogger for greenhouse use only. 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 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. (Marathon 60 WP) D. thiamethoxam (Flagship) 25WG oil4 A. clarified hydrophobic extract of neem oil# (Triact 70) B. horticultural oil5 (Ultra-Fine Oil) organophosphate pyrethroid 1 (SafTSide) (JMS Stylet Oil) A. acephate (Acephate 97UP) B. acephate (Orthene T, T&O Spray) 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. Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. MAJOR INSECT AND MITE PESTS Foliar-Feeding Mealybugs (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 108 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 109 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FUNGUS GNATS (5/10) Scientific Names: 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 TREATMENT THRESHOLDS. 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 (commercial name) A. Bacillus thuringiensis ssp. israelensis# (Gnatrol) A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) insect growth regu- A. azadirachtin lator (Azatin XL) MAJOR INSECT AND MITE PESTS Manufacturer Valent Whitmire MicroGen Webb Wright OHP Mode of R.E.I.1 action2 Comments 4 11 Do not apply with fertilizers or fungicides containing copper or chlorine. Not effective on shore flies. 12 3/— An aerosol. Also effective against adults. 12 3/21B 4 un Also effective against adults. Must contact insect. Repeat applications as necessary. Only effective on larvae. Label permits low-volume application. Fungus Gnats (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 110 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES neonicotinoid organophosphate pyrethroid B. azadirachtin (Ornazin 3%EC) C. cyromazine (Citation 75 WP) SePRO 12 un Do not exceed 22.5 oz/acre/application Syngenta 12 17 D. diflubenzuron (Adept 25WP) E. pyriproxyfen (Distance) F. s-kinoprene (Enstar II) A. acetamiprid (TriStar) 70WSP Chemtura 12 15 Valent 12 7C Wellmark 4 7A Cleary 12 4A Certification training required to use this product. Also effective against shore fly larvae. Apply as spray or drench to top 2 inches of soil. Do not apply more than 2 times per cropping cycle or per 6 months. Apply prebloom. Also labeled for low volume use. Apply as a foliar spray. B. dinotefuran (Safari) 20G C. imidacloprid (Marathon 1G) (Marathon II) Valent 12 4A OHP 12 4A Syngenta 12 4A 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) Whitmire MicroGen Whitmire MicroGen FMC 24 1B 12 3 12 3 OHP 12 3 Bayer 12 3 E. fenpropathrin* (Tame 2.4 EC Spray) F. fluvalinate (Mavrik Aquaflow) Valent 24 3 Wellmark 12 3 G. permethrin (Astro) FMC 12 3 (Marathon 60 WP) D. thiamethoxam (Flagship) 25WG A. acephate (Acephate 97UP) B. acephate (Orthene T, T&O Spray) 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. 1 Restricted entry interval (R.E.I.) 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 MAJOR INSECT AND MITE PESTS Fungus Gnats (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 111 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 112 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES LEAFHOPPERS AND SHARPSHOOTERS (5/10) Scientific Names: Glassy-winged sharpshooter: Homalodisca vitripennis (=H. coagulata) Aster leafhopper: Macrosteles quadrilineatus (=M. fascifrons) Blue-green sharpshooter: Graphocephala atropunctata 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/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 waterconducting 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. 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 MAJOR INSECT AND MITE PESTS Leafhoppers and Sharpshooters (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 113 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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/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 TREATMENT THRESHOLDS. 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 MAJOR INSECT AND MITE PESTS Leafhoppers and Sharpshooters (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 114 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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 (commercial name) R.E.I.1 Whitmire MicroGen Webb Wright 12 3/— 12 3/21B Bayer 12 1A May be applied through sprinkler irrigation systems only. OHP 4 un B. azadirachtin (Ornazin 3%EC) C. s-kinoprene (Enstar II) A. acetamiprid (TriStar 70WSP) B. Imidacloprid (Marathon 1G) (Marathon 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. Wellmark 4 7A Cleary 12 4A OHP 12 4A C. Imidacloprid (Marathon 60 WP) OHP 12 4A A. clarified hydrophobic extract of neem oil# (Triact 70) OHP 4 un 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. 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. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) A. carbaryl* (Sevin SL) insect growth regu- A. azadirachtin lator (Azatin XL) neonicotinoid oil4 Mode of action2 Comments Manufacturer B. horticultural oil5 (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil) organochlorine A. endosulfan* (Endosulfan 3EC) Drexel 48 2A organophosphate A. acephate (Acephate 97UP) United Phosphorus 24 1B B. acephate (Orthene T, T&O Spray) Valent 24 1B C. acephate (PT 1300 Orthene TR) Whitmire MicroGen 24 1B 12 3 pyrethroid A. bifenthrin* FMC (Talstar Professional) MAJOR INSECT AND MITE PESTS An aerosol. 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. Check local water/runoff restrictions. Some varieties of chrysanthemum exhibit phytotoxicity. Do not apply more than 3 lb a.i./ acre/season. 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. Label permits low-volume application. Leafhoppers and Sharpshooters (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 115 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES soap4 1 2 3 4 5 * # B. Cyfluthrin (Decathlon 20 WP) C. Deltamethrin (DeltaGard T&O) D. fenpropathrin* (Tame 2.4 EC) E. Fluvalinate (Mavrik Aquaflow) OHP 12 3 Label permits low-volume application. Aventis 12 3 For outdoor use only. Valent 24 3 Label permits low-volume application. Wellmark 12 3 F. lambda-cyhalothrin* (Scimitar GC) Syngenta 24 3 G. Permethrin (Astro) FMC 12 3 A. potash soap# (M-Pede) Dow Agro Sciences 12 — 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. Restricted entry interval (R.E.I.) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 116 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES LEAFMINERS (5/10) Scientific Names: Serpentine leafminer: Liriomyza trifolii Pea leafminer: Liriomyza huidobrensis 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 TREATMENT 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 (commercial name) insect growth regu- A. azadirachtin lator (Azatin XL) B. azadirachtin (Ornazin 3%EC) insect growth regu- C. cyromazine lator, cont. (Citation 75 WP) MAJOR INSECT AND MITE PESTS Manufacturer OHP R.E.I.1 4 SePRO 12 Syngenta 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. 17 Certification training required to use this product. Also effective against fungus Leafminers (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 117 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES D. novaluron (Pedestal) 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. Label permits low-volume application. Chemtura 12 15 Valent 12 7C Syngenta 12 6 Cleary 12 4A Apply as a foliar spray. Valent 12 4A OHP 12 4A Syngenta 12 4A Valent 24 1B B. acephate (PT 1300) (Orthene TR) A. permethrin (Astro) Whitmire MicroGen 24 1B 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 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. FMC 12 3 pyrrole A. chlorfenapyr (Pylon) OHP 12 13 spinosyn A. spinosad (Conserve SC) Dow Agro Sciences 4 5 E. pyriproxyfen (Distance) macrocyclic lactone A. abamectin (Avid 0.15EC) neonicotinoid A. acetamiprid (TriStar) 70WSP B. dinotefuran (Safari) 20G C. imidacloprid (Marathon 1G) (Marathon II) organophosphate pyrethroid 1 2 3 * (Marathon 60 WP) D. thiamethoxam (Flagship) 25WG A. acephate (Orthene T, T&O Spray3) 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 (R.E.I.) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 118 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES LEAFROLLERS (5/10) Scientific Names: Omnivorous leafroller: Platynota stultana Fruittree leafroller: Archips argyrospila Obliquebanded leafroller: Choristoneura rosaceana Light brown apple moth: Epiphyas postvittana 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 (http://www.ipm.ucdavis.edu/PDF/PUBS/lbam091207.pdf) and the CDFA Web site (http://www.cdfa.ca.gov/phpps/pdep/lbam_main.htm) or a County Agricultural Commissioner. The light MAJOR INSECT AND MITE PESTS Leafrollers (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 119 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES brown apple moth larvae cannot be reliably identified using morphological characters with our current knowledge. Deliver suspect larvae 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 also 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. Class Pesticide (commercial name) MAJOR INSECT AND MITE PESTS Manufacturer R.E.I.1 Mode of action2 Comments Leafrollers (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 120 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES biological A. Bacillus thuringiensis ssp. Kurstaki# (various products) carbamate A. carbaryl* (various) insect growth regu- A. diflubenzuron lator (Adept 25WP) mineral spinosyn 1 2 # * A. cryolite (ProKil Cryolite) 96 (Kryocide) 96WP A. spinosad (Conserve SC) 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 (hours) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 121 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES ROOT MEALYBUGS (5/10) Scientific Name: 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 (commercial name) Mode of action2 Comments Manufacturer R.E.I.1 Whitmire MicroGen Webb Wright 12 3/— 12 3/21B OHP 12 4A United Phosphorus Valent 24 1B 24 1B A. bifenthrin FMC (Talstar Professional) B. cyfluthrin OHP (Decathlon 20 WP) 12 3 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. Label permits low-volume application. 12 3 Label permits low-volume application. C. fenpropathrin* (Tame 2.4 EC Spray) 24 3 Label permits low-volume application. A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) A. imidacloprid (Marathon 1G) (Marathon II) (Marathon 60 WP) A. acephate (Acephate 97UP) B. acephate (Orthene T,T&O Spray) MAJOR INSECT AND MITE PESTS Valent 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. Root Mealybugs (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 122 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES pyrethroid/ neonicotinoid D. fluvalinate (Mavrik Aquaflow) Wellmark 12 3 E. permethrin (Astro) FMC 12 3 A. cyfluthrin/imidacloprid OHP (Discus) 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 (R.E.I.) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 123 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SHORE FLY (5/10) Scientific Name: 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 with hydrated lime. 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 Pesticide (commercial name) R.E.I.1 Whitmire MicroGen Webb Wright 12 3/— 12 3/21B OHP 4 un B. cyromazine (Citation 75 WP) Syngenta 12 17 C. diflubenzuron (Adept 25WP) D. pyriproxyfen (Distance) E. s-kinoprene (Enstar II) A. imidacloprid (Marathon 1G) Chemtura 12 15 Valent 12 7C Wellmark 4 7A OHP 12 4A A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) insect growth regu- A. azadirachtin lator (Azatin XL) botanical neonicotinoid Mode of action2 Comments Manufacturer MAJOR INSECT AND MITE PESTS An aerosol. Also effective against adults. Also effective against adults. 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. 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 Shore Fly (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 124 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES organophosphate pyrethroid 1 2 3 * (Marathon 60 WP) A. acephate (Orthene T, T&O Spray) Valent 24 1B B. acephate Whitmire (PT 1300 Orthene TR) MicroGen 24 1B A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) C. cyfluthrin (Decathlon 20 WP) D. fenpropathrin* (Tame 2.4 EC Spray) E. fluvalinate (Mavrik Aquaflow) Whitmire MicroGen FMC 12 3 12 3 OHP 12 3 Valent 24 3 Wellmark 12 3 F. permethrin (Astro) FMC 12 3 bedding plants intended to be used as food crops. 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. 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. Restricted entry interval (R.E.I.) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 125 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SOFT SCALES (5/10) Scientific Names: Brown soft scale: Coccus hesperidum Hemispherical scale: Saissetia coffeae Black scale: Saissetia oleae Green shield scale: Pulvinaria psidii DESCRIPTION OF THE PESTS 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. Biological 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 neonicotinoid Pesticide (commercial name) A. pyriproxyfen (Distance) B. s-kinoprene (Enstar II) A. acetamiprid (TriStar) 70WSP MAJOR INSECT AND MITE PESTS Manufacturer R.E.I.1 Mode of action2 Comments Valent 12 7C Wellmark 4 3 Cleary 12 4A Do not apply more than 2 times per cropping cycle or per 6 months. Apply prebloom. Also labeled for low volume use. Apply as a foliar spray. Soft Scales (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 126 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES B. imidacloprid (Marathon 1G) (Marathon II) 3 oil (Marathon 60 WP) A. clarified hydrophobic extract of neem oil# (Triact 70) B. horticultural oil4 Ultra-Fine Oil SafTSide JMS Stylet Oil OHP 12 4A OHP 4 un Whitmire MicroGen Brandt JMS Farms 12 — 4 4 — — 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. Use as above for neem oil. Also, do not use with sulfur fungicides; check label for tank mix restrictions. organochlorine A. endosulfan* (Endosulfan 3EC) Drexel 24 2A organophosphate A. acephate (Acephate 97UP) B. acephate (Orthene T, T&O Spray) 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. An aerosol for greenhouse use only. 12 1B Not for greenhouse use. 1 2 Do not apply to 'Bonnaton Deluxe,' 'Fred Shoesmith,' or 'White Knight' chrysanthemums. Check local water/runoff restrictions. Do not apply more than 3 lb a.i./ acre/season. Restricted entry interval (R.E.I.) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 127 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES THREAD-FOOTED (TARSONEMID) MITES Scientific Names: (5/10) Cyclamen mite: Phytonemus pallidus Broad mite: Polyphagotarsonemus latus Bulb scale mite: Stenotarsonemus laticeps 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 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 128 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 (commercial name) macrocyclic lactone A. abamectin (Avid 0.15EC) 3 oil A. clarified hydrophobic extract of neem oil# (Triact 70) B. horticultural oil4 (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil) Manufacturer Syngenta R.E.I.1 12 Mode of action2 Comments 6 Label permits low-volume application. OHP 4 un Whitmire MicroGen Brandt JMS Farms 12 — 4 4 — — organochlorine A. endosulfan* (Endosulfan 3EC) Drexel 48 2A 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. Check local water/runoff restrictions. Some varieties of chrysanthemum exhibit phytotoxicity. Do not apply more than 3 lb a.i./ acre/season. 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 (R.E.I.) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 129 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES THRIPS (5/10) Scientific Names: Western flower thrips: Frankliniella occidentalis Greenhouse thrips: Heliothrips haemorrhoidalis 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 soil-inhabiting 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 Thripobius semileteus. 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 have pore sizes slightly larger than the width of the western flower thrips thorax (145 microns), meaning that some winged adults can MAJOR INSECT AND MITE PESTS Thrips (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 130 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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 treatment 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 biological botanical carbamate Pesticide (commercial name) A. Beauveria bassiana# (BotaniGard 22WP) (BotaniGard ES) Manufacturer Laverlam R.E.I.1 4 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. A. cinnamaldehyde (Cinnacure) Proguard 4 — B. pyrethrin/PBO3 (PT Pyrethrum TR) Whitmire MicroGen 12 3/— C. pyrethrin/rotenone (Pyrellin EC) Webb Wright 12 3/21B A. methiocarb* (Mesurol 75W) Gowan 24 1A OHP 4 un SePRO Chemtura 12 12 un 15 insect growth regu- A. azadirachtin lator (Azatin XL) (Ornazin 3%EC) B. novaluron (Pedestal) MAJOR INSECT AND MITE PESTS 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. Synthetic pyrethroids sometimes 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. Thrips (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 131 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Macrocyclic lactone A. abamectin (Avid 0.15EC) Syngenta 12 6 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. (Marathon 60 WP) Label permits low-volume application. Do not use through any type of irrigation system. oil4 A. clarified hydrophobic extract of neem oil# (Triact 70) OHP 4 un Must contact insect. Repeat applications as necessary. Difficult to get coverage in flowers, best for thrips on foliage. organochlorine A. endosulfan* (Endosulfan 3EC) Drexel 48 2A Check local water/runoff restrictions. Some varieties of chrysanthemum exhibit phytotoxicity. Do not apply more than 3 lb a.i./ acre/season. 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 — 4 5 soap4 spinosyn 1 2 3 4 * # A. spinosad (Conserve SC) 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 (R.E.I.) 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 132 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TWOSPOTTED SPIDER MITES (5/10) Scientific Name: 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 TREATMENT 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 (commercial name) Manufacturer R.E.I.1 Mode of action2 Comments botanical A. cinnamaldehyde (Cinnacure) Proguard 4 — 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. carbamate A. methiocarb* (Mesurol 75W) Gowan 24 1A Apply in 50 gal water. Repeat as necessary up to 4 applications/season. Do not apply with oil or foliar fertilizer. MAJOR INSECT AND MITE PESTS Twospotted Spider Mites (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 133 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES carboximide A. hexythiazox (Hexygon 50DF) Gowan 12 10A No chemigation. Ovicidal/larvicidal action. Use only 1 time per crop or once a year. carboxylic acid A. bifenazate (Floramite) Chemtura 12 un 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. macrocyclic lactone A. abamectin (Avid 0.15EC) Novartis 12 6 Label permits low-volume application. 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 Drexel 12 — 4 4 48 — — 2A 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) organochlorine A. endosulfan* (Endosulfan 3EC) Check local water/runoff restrictions. Some varieties of chrysanthemum exhibit phytotoxicity. Do not apply more than 3 lb a.i./ acre/season. 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. phenoxypyrazole A. fenpyroximate (Akari) SePRO 12 21A 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 Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. pyridazinone A. pyridaben (Sanmite 75WP) BASF 12 21A pyrrole A. chlorfenapyr (Pylon) OHP 12 13 soap3 A. potash soap# (M-Pede) Dow Agro Sciences 12 — 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. 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. Continued on next page . . . MAJOR INSECT AND MITE PESTS Twospotted Spider Mites (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 134 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Treatment, continued Class spinosyn 1 2 3 4 * # Pesticide (commercial name) A. spinosad (Conserve SC) Manufacturer Dow Agro Sciences R.E.I.1 4 Mode of action2 Comments 5 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 (R.E.I.) 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/. 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) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 135 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES WHITEFLIES (5/10) Scientific Names: 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. 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, MAJOR INSECT AND MITE PESTS Whiteflies (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 136 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 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 TREATMENT 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 (commercial name) A. Beauveria bassiana# (BotaniGard 22WP) 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. Manufacturer Laverlam R.E.I.1 4 Laverlam Whitmire MicroGen Webb Wright 4 12 12 3/21B OHP 4 un B. azadirachtin (Ornazin 3%EC) C. diflubenzuron (Adept 25WP) SePRO 12 un Chemtura 12 15 D. novaluron (Pedestal) Chemtura 12 15 Valent 12 7C Wellmark 4 7A Syngenta 12 6 Cleary 12 4A OHP 12 4A B. (BotaniGard ES) A. pyrethrin/PBO3 (PT Pyrethrum TR) B. pyrethrin/rotenone (Pyrellin EC) insect growth regu- A. azadirachtin lator (Azatin XL) botanical E. pyriproxyfen (Distance) F. s-kinoprene (Enstar II) macrocyclic lactone A. abamectin (Avid 0.15EC) neonicotinoid A. acetamiprid (TriStar 70WSP) B. imidacloprid (Marathon 1G) (Marathon II) (Marathon 60 WP) MAJOR INSECT AND MITE PESTS 12 12 Must contact insect. Repeat applications as necessary. Label permits low-volume application. Do not exceed 22.5 oz/acre/application. Whitefly suppression. May damage poinsettias if used over labeled rate. Also effective on fungus gnat larvae and lepidopteran larvae. 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. Apply prebloom. Also labeled for low volume use. 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. As above. Apply only as a drench. Whiteflies (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 137 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES oil4 A. clarified hydrophobic extract of neem oil# (Triact 70) OHP 4 un B. horticultural oil5 (Ultra-Fine Oil) (SafTSide) (JMS Stylet Oil) A. endosulfan* (Endosulfan 3EC) Whitmire MicroGen Brandt JMS Farms Drexel 12 — 4 4 48 — — 2A A. acephate (Acephate 97UP) United Phosphorus Valent 24 1B 24 1B C. acephate (PT 1300 Orthene TR) D. malathion (various) A. bifenthrin (Attain TR) B. bifenthrin* (Talstar Professional) C. cyfluthrin (Decathlon 20WP) D. fenpropathrin* (Tame 2.4EC) E. fluvalinate (Mavrik Aquaflow) 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. 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. pyridazinone A. pyridaben (Sanmite 75WP) BASF 12 21A pyridine A. pymetrozine (Endeavor) Syngenta 12 9B 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. soap4 A. potash soap# (M-Pede) Dow Agro Sciences 12 — 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. organochlorine organophosphate B. acephate (Orthene T, T&O Spray) pyrethroid 1 2 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. Check local water/runoff restrictions. Some varieties of chrysanthemum exhibit phytotoxicity. Do not apply more than 3 lb a.i./ acre/season. Restricted entry interval (R.E.I.) 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 MAJOR INSECT AND MITE PESTS Whiteflies (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 138 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES 3 4 5 * # 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 pesticide. Permit required for purchase or use. Acceptable for use on organically grown ornamentals. MAJOR INSECT AND MITE PESTS Whiteflies (5/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 139 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES OTHER INVERTEBRATES Mollusks SNAILS AND SLUGS (4/13) Scientific Names: Brown garden snail: Cornu aspersum (formerly Helix aspersa) Amber Snail: Succinea sp. Gray garden slug: Deroceras reticulatum (formerly Agriolimax meticulatus) Banded slug: Lehmannia poirieri Greenhouse slug: Milax gagates DESCRIPTION OF THE PESTS Both snails and slugs are members of the mollusk phylum and are similar in structure and biology, except slugs lack the snail's external spiral shell. Slugs and snails constantly secrete mucus, which later dries to form the silvery "slime trail" that indicates the presence of these pests. Adult brown garden snails lay about 80 spherical, pearly white eggs at a time into a hole in the topsoil. The eggs are initially white, but turn brown as they develop. They may be mistaken for slow-release fertilizer. Eggs may be laid up to six times a year. Brown garden snails mature in about two years, whereas slugs reach maturity in about a year. Snails and slugs are most active at night and on cloudy or foggy days. On sunny days, they hide in places that are out of the heat and sun. Often the only clues to their presence are their silvery trails and plant damage. In mild winter areas, such as southern California and coastal locations, young snails and slugs are active throughout the year. During cold weather, snails and slugs hibernate in the topsoil. During hot, dry periods, snails seal themselves off with a parchment-like membrane and often attach themselves to tree trunks, fences, or walls. DAMAGE Snails and slugs feed on a variety of living plants as well as on decaying plant matter and algae. On plants, they chew irregular holes with smooth edges in leaves and can clip succulent plant parts. They can also chew fruit, flowers, and young plant bark. Because they prefer succulent foliage, they are primarily pests of seedlings, herbaceous plants, and ripening fruits such as strawberries, lettuce, artichokes, and tomatoes, that are close to the ground. However, they will also feed on foliage and fruit of some trees. SAMPLING MOLLUSKS Snails and slugs can be trapped under boards positioned throughout the nursery. Traps can be made from 12" x 15" boards (or any other convenient size) that are raised off the ground by 1-inch runners. The runners make it easy for the pests to crawl underneath. After counting, scrape off snails and slugs daily and destroy them. Amber snails are more difficult to detect as they tend to live on the surface of the planting medium. Look for these snails on pot surfaces and where wet (planting medium) and dry areas (container) meet, generally around the inner lip or head space of the container. OTHER INVERTEBRATES (4/13) Mollusks Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 140 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES MANAGEMENT A good snail and slug management program relies on a combination of methods. • If possible, eliminate all places where snails or slugs can hide during the day. Boards, stones, debris, weedy areas around tree trunks, leafy branches growing close to the ground, and dense ground covers such as ivy are ideal sheltering spots. There will be shelters that are not possible to eliminate; e.g., low ledges on fences, the undersides of wooden decks, and water meter boxes. Reducing hiding places allows fewer snails and slugs to survive. The survivors will congregate in the remaining shelters, where they can more easily be located and controlled. • Switching from sprinkler to drip irrigation will reduce humidity and moist surfaces, making the habitat less favorable for these pests. • If possible, do not use wooden benches as these stay moist for longer periods of time, tend to be good sites for algae to grow, and allow snails and slugs to hide between the bench and the container. Cultural Control Handpicking Handpicking can be very effective if done thoroughly on a regular basis. Snails and slugs can be trapped under boards positioned throughout the nursery and destroyed as described above. Crushing is the most common method of destruction. Do not use salt to destroy snails and slugs; it will increase soil salinity. Copper barriers Several types of barriers will keep snails and slugs out of planting beds. The easiest to maintain are those made with copper flashing and screens. Vertical copper screens can be erected around planting beds. The screen should be 6 inches tall and buried several inches below the soil to prevent slugs from crawling beneath the soil. Copper screens can also 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 netting (for example, Snail-Barr) can be wrapped around planting boxes and bench legs to repel snails for several months or longer, depending on the integrity of the copper strips. Copper barriers are thought to be effective through the reaction between the copper and the slime that snails and slugs secrete, causing a flow of electricity. Bordeaux mixture Instead of copper bands, Bordeaux mixture (a copper sulfate and hydrated lime mixture) can be brushed or sprayed on trunks or bench legs to repel snails. One treatment should last about a year. Adding a commercial spreader may increase the persistence of Bordeaux mixture through two seasons. Biological Control Snails and slugs have many natural enemies, including ground beetles, pathogens, snakes, toads, turtles, and birds, but they are rarely effective enough to provide satisfactory control in the nursery. In California, a predaceous snail, the decollate snail (Rumina decollata), is available for use in Fresno, Imperial, Kern, Los Angeles, Madera, Orange, Riverside, Santa Barbara, San Bernardino, San Diego, Ventura, and Tulare county. However, its release for snail control in commercial nurseries is not recommended since all plants must be snail-free (including beneficial and pestiferous species) prior to shipping. Additionally, it feeds only on small snails, not full-sized ones. Because of the potential impact of the decollate snail on certain endangered mollusk species, it cannot be released outside of the above mentioned counties. Decollate snails may feed on seedlings, small plants, and flowers. When shipping, all decollate snails must be removed. Chemical Control Commercial snail and slug baits can be effective when used properly in conjunction with a cultural management program. (Note: Baits will kill decollate snails if they are present.). The active ingredient of most baits is either metaldehyde, iron phosphate, or ferric sodium EDTA. Growers have reported that under high rainfall or high humidity conditions, iron phosphate appears to be more effective. Placement of the bait in a commercial bait trap reduces hazards to non-target animals such as dogs and can protect baits from moisture, but may also reduce their effectiveness and attractiveness to snails and slugs and is not recommended for commercial nurseries. Bait should be scattered throughout the beds and near areas where snails hide to be most effective. The timing of any baiting is critical; baiting is less effective during very hot, very dry, or cold times of the year, because snails and slugs are less active during these periods. As snails and slugs are more likely to travel when soil is moist, it may be beneficial to irrigate before applying the bait to promote snail activity. OTHER INVERTEBRATES (4/13) Mollusks Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 141 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Methiocarb (Mesurol) is a sprayable molluscicide. It is a “Danger” labeled pesticide and can only be used two times per crop per year. This product is very effective and fast acting, but due to its high toxicity and label restrictions should only be used as a “rescue” treatment. Common name (trade name) Amount per acre R.E.I.‡ (hours) P.H.I.‡ (days) A. BORDEAUX MIXTURE# 0.5:0.5:100 1 lb See label See label MODE OF ACTION GROUP NUMBER1: Multi-site contact (M1) COMMENTS: Apply as a dilute spray only. Do not use with antagonistic microorganisms. Check with your certifier to determine which copper products are organically acceptable if you are mixing your own formulation. For information on making a Bordeaux mixture see UC IPM Pest Note: Bordeaux Mixture. B. METALDEHYDE (Durham 3.5, 7.5) Label rates 12 0 COMMENTS: The bait has minimal impact on other organisms in the field. Reapply as bait is consumed; minimum re-treatment interval is 21 days and a maximum of 6 treatments per season is allowed. Monitor to determine where the product should be broadcast. 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. Should only be used as a rescue treatment. D. IRON PHOSPHATE# (Sluggo) 24–44 lb COMMENTS: Reapply as bait is consumed or at least every 2 weeks. 0 0 E. SODIUM FERRIC EDTA (Ferroxx) 5–20 lb 0 0 COMMENTS: For terrestrial uses. Do not apply directly to water or to areas where surface water is present or to intertidal areas below the mean high water mark. Do not contaminate water when disposing of equipment wash water or rinse water. Apply near pots rather than broadcasting the material. May cause damage to succulent leaves. ‡ Restricted entry interval (R.E.I.) 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 a1B 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 organically grown produce. Permit required from county agricultural commissioner for purchase or use. 1 # * OTHER INVERTEBRATES (4/13) Mollusks Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 142 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Nematodes (3/09) DESCRIPTION OF THE PESTS Nematodes are tiny (usually microscopic), unsegmented roundworms. Depending on the type of nematodes, they feed on roots, bulbs, stems, leaves, or seeds. Root knot nematodes (Meloidogyne spp.) are the most prevalent nematodes attacking floricultural crops. However, there are numerous other nematodes, both ectoparasitic (feed externally on plants) and endoparasitic (enter plants to feed and reproduce) that can attack floricultural crops. Because growing media used in containers is usually pasteurized, soil-dwelling nematodes are primarily a problem in field soils. Root Knot Nematodes. Root knot nematodes occur throughout California and most of the United States (http://plpnemweb.ucdavis.edu/nemaplex/Taxadata/G076.htm). Root knot nematodes can enter roots only as second-stage larvae. The nematodes become immobile soon after entering roots and spend most of their active life cycle in galls on roots. After several weeks, females develop inside the galls and deposit up to 400 eggs in a protective gelatinous mass. Under favorable conditions (temperature, host crop) larvae hatch from eggs to repeat the cycle, or eggs can remain infective in the soil as a source of inoculum for the next crop or growing season. Root knot nematodes are most commonly pests of plants grown in warm, sandy, irrigated soils. The particular Meloidogyne species that is active can depend on seasonal temperature and cropping history. At least some Meloidogyne species also show host preferences, so cropping history can influence the species of root knot nematodes present. To tentatively diagnose an infestation, dig the plants up after they have grown for about 4 to 6 weeks in soil above 65°F (19°C). 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 root knot nematode infection, send roots and/or soil to a laboratory. Foliar Nematodes. Foliar nematodes, also called bud and leaf nematodes, prefer moderate temperatures and moist or humid conditions (http://plpnemweb.ucdavis.edu/Nemaplex/Taxadata/G011.htm). Aphelenchoides fragariae and A. ritzemabosi are the leaf-infesting nematodes that attack ornamental plants in California. Strawberries, ferns, tropical foliage plants, and vegetatively propagated ornamentals are important hosts of A. fragariae. Foliar nematode damage in California occurs mostly in certain greenhouses and along coastal areas where ornamental hosts and strawberries are grown. Foliar nematodes are tiny, only 0.02 to 0.04 inch (0.5-1 mm) long, and must be sent to a diagnostic laboratory to confirm infestation. Foliar nematodes infest new plants by swimming up stems and along the surface of moist plant tissue. After entering leaves through stomata, females lay their eggs in intracellular leaf spaces. 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 on 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 allow them to resume activity. Growers can make an initial diagnosis by tearing symptomatic tissue into small pieces and placing 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. DAMAGE Root knot nematodes. Root knot nematodes cause galls or swellings on roots of many broadleaf plants. Severely infected roots may subsequently be attacked by a variety of decay- or disease-causing organisms, including crown gall and root rot fungi. Aboveground symptoms are usually nonspecific, reflecting a poorly functioning root system and may include yellowing, stunted growth, and early wilting. Many weeds and nonfloral crops host root knot nematodes. Some infected plants, especially annual grasses, may exhibit no galls. 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 OTHER INVERTEBRATES Nematodes (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 143 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES the roots. Also, a thumbnail can be pressed into a bacterial gall easily, but not into a root knot gall. To provide positive identification, collect galled roots and surrounding soil and send the material to a diagnostic laboratory. Foliar nematodes. Foliar nematode damage can be confused with damage caused by bacteria, fungi, viruses, nutrient deficiencies, or chemical injuries. Nematodes may interact with certain fungi or bacteria to cause severe foliar blight. General damage symptoms appear as vein-limited blotches and lesions on leaves. If young leaves or shoots are infested, they may remain undersized, become bushy or distorted, and produce little or no marketable foliage or flowers. Damage usually appears beginning in spring (or winter in coastal areas) and becomes most severe by summer. 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 main veins. Because monocots have parallel veins, discoloring on them looks like streaks. Damaged foliage may become brittle or shrivel and then drop. SAMPLING NEMATODES The best time to sample nematodes for a coming crop is at or around harvest of the current crop, when plants with damage symptoms are available for testing. Nematodes are usually concentrated near or in plant roots. Unless your laboratory recommends other procedures, the following general 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 quart 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 part of the field and send them for 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 material reaches the laboratory. Laboratories report the genus of the nematodes that were found, the number of nematodes per unit of soil (usually per pint or liter), and the extraction efficiency. It is important to know the laboratory's method (and the method's efficiency) for extracting nematodes from soil. Certain methods are not adequate for detecting the presence of certain genera of nematodes; or certain tests 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 will tolerate heat without damage, cuttings can be disinfected by dipping them in hot water at 122°F (50°C) for 5 minutes or at 111°F (44°C) for 30 minutes. Foliar nematodes infesting Easter lilies may be controlled by dipping bulblets in 125°F (52°C) water for 10 minutes before planting. However, treatment at the same temperature for 20 minutes resulted in severe damage to the crop. Thus, to avoid damage to plant material, it is critical that both temperature and exposure time are accurately controlled. Employ good sanitation practices 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. Avoid crowding plants and using overhead irrigation to reduce the risk that foliar nematodes will spread throughout the crop by traveling in a water film on plant surfaces. MANAGEMENT OF ROOT KNOT AND OTHER SOIL-DWELLING NEMATODES Sanitation, crop rotation, employing good cultural practices, and pasteurizing media are the most important strategies for preventing and managing most soil-dwelling nematodes. Soil amendments and biological controls may sometimes suppress nematode populations. OTHER INVERTEBRATES Nematodes (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 144 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Manage foliar nematodes according to the guidelines in the above section. Sanitation and Cultural Practices. Avoid introducing nematode-infested plants into growing areas. Use only good-quality stock from a reliable supplier and, if available, from participants in the California Certification Nursery program to minimize the risk of introducing nematodes with the planting stock. Use growing media known to be free of nematodes or pasteurize growing media before planting. Remove infested plant 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 soil is treated first, do not plant susceptible crops in field soils where nematodes have previously been a problem. For example, do not replant the same plant genera into the old site; rotate crops by replanting with species or varieties 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 population levels of nematodes. Heat Pasteurization. Pasteurizing media with heat, such as steam, can control nematodes and other pests 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. 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 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 pesticides in combination with solarization can provide better control than using any single method. Correct use of the "double-tent" solarization technique can completely eradicate plant-parasitic nematodes, pathogens, and weed seeds from containerized growth media (Nursery Inspection Procedures Manual, NIPM Item 7; http://www.cdfa.ca.gov/phpps/pe/nipm.htm). 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. U.C. Plant Protection Qtr. 8(1 & 2): 7-9 (www.uckac.edu/ppq). Hot Water Dips. Hot water dips can control 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 control depend on the nematode species and crop variety. Exceeding temperature or exposure time can damage plants, but insufficient temperatures or exposure time may not kill nematodes. Cool plants immediately afterward with clean, cold water, then dry thoroughly in warm air or sunshine. Store material afterwards under cool, low-humidity conditions until plants are used. OTHER INVERTEBRATES Nematodes (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 145 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Amendments and Biological Control. Although amendments and biological control agents reduce plant parasitic nematodes in certain situations, 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 controls 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: inorganics, animal-based, plantbased, 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. Animal-based amendments include chitin-containing crab shells and shrimp shells that apparently stimulate populations of soil-dwelling fungi that feed on chitin. Because chitin is a component of nematodes' egg shells, these chitin-feeding fungi also feed on these egg shells. Incorporating animal manure, organic fertilizers, crop residue, and compost increases the organic matter content of soil. This improves water and nutrient availability to plants, reduces plant stress, and can encourage greater numbers of nematode predators and parasites. However, organic amendments sometimes contain contaminants such as weed seeds, and their effectiveness is largely limited to the depth of material incorporation. Barley, marigold, perennial rye, certain legumes such as clover and vetch, and other plants with bioactive properties are grown as cover crops, trap crops, or crop rotations 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, suppress nematode growth, stimulate premature egg hatch, or disrupt the attraction between nematodes seeking to mate. However, crops suppressive to one species of nematode often host other nematode species. Rotating certain marigold cultivars with crops such as lilies grown for bulb production has been somewhat successful in controlling 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, as phytotoxicity to lilies and other crops is often observed when they are grown in rotation after incorporating marigolds into the soil. Some new biological pesticides (mycopesticides) contain nematode-killing microorganisms. These beneficial microorganisms include certain Burkholderia and Pseudomonas species bacteria and natural by-products of Myrothecium species fungi. At least one mycopesticide, Myrothecium verrucaria (Ditera), is registered for nematode control in California. 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; improper application is not effective and may be hazardous. Postplant nematicides for use in soil around established plants may be available, but it is generally more effective to employ other controls and preventive measures before planting. Herbicide (commercial name) Amount to Use R.E.I.+ (hours) When choosing a pesticide, consider information relating to environmental impact. PREPLANT A. 1,3-DICHLOROPROPENE*/CHLOROPICRIN* (InLine) Label rates 7 days 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. Fumigants such as 1,3-dichloropropene are a source 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. OTHER INVERTEBRATES Nematodes (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 146 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) Amount/Acre R.E.I.+ (hours) B. 1,3-DICHLOROPROPENE* (Telone EC) Label rates 7 days 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. Fumigants such as 1,3-dichloropropene are a source 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. C. CHLOROPICRIN* 300–500 lb 48 COMMENTS: If treated area is covered with a plastic tarpaulin immediately after application, dosage may be reduced. D. METAM SODIUM* (Vapam, Sectagon) 50–75 gal 48 COMMENTS: Contact your farm advisor for advice on the most effective application method for a particular situation. Fumigants, such as metam sodium and 1,3-dichloropropene are a prime source of volatile organic compounds (VOCs), which are a major air quality issue. Fumigate only as a last resort when other management strategies have not been successful or are not available. E. ETHOPROP* (Mocap) 15G 2.1 lb/1000 row feet (12–15 inches wide) 72 (Mocap) EC 5.3 fl oz/1000 row feet (12–15 inches wide) 72 COMMENTS: Apply just before planting. Mix into the top 2–4 inches of soil right after application. Do not allow the granules or spray to contact the seed. Make only one application per crop. F. 1,3-DICHLOROPROPENE* (Telone II) Label rates 7 days COMMENTS: Do not disturb the soil for at least 7 days after application. Fumigants such as 1,3-dichloropropene are a source 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. + Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. * Permit required from county agricultural commissioner for purchase or use. OTHER INVERTEBRATES Nematodes (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 147 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES WEEDS General information (Section reviewed 3/09) Managing weeds in ornamental plant production, whether in the field or in the greenhouse, in containers or in field soil, can be difficult but is essential to successful production. Weeds not only compete for plant nutrients and sunlight with the crop but are also unsightly. In addition, ornamental plants infested with certain noxious weeds cannot be sold because of quarantine requirements. Because of the high value of ornamental crops and the limited number of herbicides available, growers often resort to hand-weeding, which is becoming increasingly expensive. 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 production or established shrub areas greatly reduces excessively wet areas, thus reducing the germination and growth of weeds. WEED CLASSIFICATIONS (3/09) Weeds can be 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 flowering and setting seed. Summer annuals germinate in spring, grow through summer, and flower and set seed. 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 (e.g., bermudagrass, creeping wood sorrel, and nutsedge) are perennials; they live for 2 years or more. TABLE 1. Common Weeds in Floriculture and Ornamental Nurseries. COMMON NAME SCIENTIFIC NAME WINTER ANNUALS Bittercress Cardamine sp. Bluegrass, annual Poa annua Burclover, California Medicago polymorpha Chickweed, common Stellaria media Cudweeds Gnaphalium spp. Filarees Erodium spp. Goosefoot, nettleleaf Chenopodium murale Groundsel, common Senecio vulgaris Lettuce, prickly Lactuca serriola Mallow, little (cheeseweed) Malva parviflora Mustard, wild Brassica sp. Nettle, stinging Urtica dioica Pearlwort Sagina sp. Radish, wild Raphanus raphanistrum Rocket, London Sisymbrium irio Shepherd's-purse Capsella bursa-pastoris Sowthistle, annual Sonchus oleraceus Spurry, corn Spergula arvensis Willowherbs Epilobium spp. SUMMER ANNUALS Barnyardgrass Echinochloa crus-galli Buttercup, yellow Ranunculus sp. Crabgrasses Digitaria spp. Fleabane, hairy Conyza sp. Henbit Lamium amplexicaule (Continued next page) WEEDS: GENERAL INFORMATION Weed Classifications (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 148 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TABLE 1. Common Weeds in Floriculture and Ornamental Nurseries. COMMON NAME SCIENTIFIC NAME SUMMER ANNUALS, continued 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 sp. Pigweed, tumble Amaranthus albus Puncturevine Tribulus terrestris Purslane, common Portulaca oleracea Sprangletops Leptochloa spp. Spurge, prostrate or spotted Euphorbia (=Chamaesyce ) maculata 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 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, and prostrate and spotted spurge. Sometimes pearlwort, liverwort, annual bluegrass, or willowherb are a problem. 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, and • Greenhouse-grown crops. WEEDS: GENERAL INFORMATION Weed Classifications (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 149 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GENERAL METHODS OF WEED MANAGEMENT (3/09) Whether ornamentals are grown in containers, fields, or greenhouses, there are some control practices common to all methods of production that can reduce the impact of weeds on the crop. 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 soil, manure, uncomposted yard waste, 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. 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 an herbicide after weed emergence so that the soil will not be disturbed by cultivation before planting. Each time cultivation occurs, new weed seeds are brought close to the soil surface and they germinate. This method reduces the soil seed bank so fewer weed seeds will be present to germinate when the crop is planted. After planting, herbicides can be used before weed emergence or the field can be cultivated between rows again after new weeds germinate. 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. 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 (see Table 2). An annual cover crop can be established and allowed to senesce naturally or be killed back by exposure to frost. TABLE 2. Potential Cover Crops for Field-Grown Ornamentals. DESIRABLE INTERMEDIATE WINTER ANNUALS beans, bell or fava clover, rose or crimson bromegrass, blando fescue, zorro pea, Austrian winter field brome, California rye, cereal oat (forage) vetch, hairy or purple SUMMER ANNUALS beans, dry sorghum sudangrass sudangrass/sorghum hybrids PERENNIALS perennial ryegrass/hard fescue orchardgrass, berber LESS DESIRABLE ryegrass, annual mustard, wild or black bermudagrass, clover, strawberry or white 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 operations 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. 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 by flaming than grasses are, and young weeds are better controlled than older ones. Because of the cost of fuel, the time required to pass over the beds, and potential injury and fire hazard, flaming is not a widely used method of weed control for field grown flowers or nurseries. WEEDS: GENERAL INFORMATION General Methods of Weed Management (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 150 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL 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. Bark (various kinds), composted yard waste, and other organic material can be used to help suppress annual weeds by covering the soil surface and preventing weed seed germination and establishment. Fine organic mulch (finished yard waste) may require only 2 to 3 inches of material to totally eliminate light and suppress 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 soil structure, drainage, 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 or landscape fabrics) made of polypropylene or polyester can also be used as mulches but because of cost they should only be used with perennial shrubs or trees or in 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 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, ultraviolet (UV)-protected polyethylene 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 field bindweed, yellow and purple nutsedge, and clovers. 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 Publication 21377 and UC IPM Pest Notes: Soil Solarization for Gardens and Landscapes, UC ANR Publication 74145, for more details on soil solarization. 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 herbicides than new seedlings. Chemical Control. Herbicides are used in many ornamental production areas as an economical option to control weeds. By using herbicides before the weed emerges, 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. A preplant herbicide is applied before planting. These herbicides are used before the desirable plants are present because they control both germinating seedlings and established plants. Preemergent herbicides kill weeds at the seed germination stage. These herbicides are applied before weeds emerge. The third type of herbicide, the postemergent herbicide, is applied after the weed has emerged. Preemergent and postemergent herbicides may be applied before or after the crop is planted depending on the crop and the herbicide selected. The section on "Susceptibility of Weeds to Herbicide Control" outlines the susceptibility of weeds to different herbicides. Preplant herbicides. Herbicides that are applied before planting the crop may be fumigants, nonselective postemergent materials, or selective preemergent products. The fumigant herbicides, such as metam sodium or K-Pam, are often applied as an injection to cultivated soil. They are generally covered with a polyethylene tarp to seal in moisture and keep gas from escaping immediately. Dazomet (Basamid) is a powder that is incorporated into the soil. These materials must be applied by licensed applicators. Nonselective postemergent herbicides are applied to young weeds before planting. For example, glyphosate is applied to perennial weeds generally when they are growing vigorously and are beginning to flower to obtain the best control. Other nonselective herbicides include diquat (Reward), pelargonic acid (Scythe), plant oil-based herbicides, and crop oil. A selective preemergent herbicide can be applied and incorporated mechanically into soil before direct seeding or transplanting. Preemergent herbicides. Preemergent herbicides comprise the largest number of herbicides, because the weed seedling stage is the easiest part of the plant cycle to interrupt, and these herbicides are generally safest for the crop. Examples of these herbicides are oryzalin (Surflan), napropamide (Devrinol), oxadiazon (Ronstar), WEEDS: GENERAL INFORMATION General Methods of Weed Management (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 151 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES trifluralin (Treflan), pendimethalin (Pre-M, Pendulum), prodiamine (Endurance, Barricade), oxyfluorfen (Goal), isoxaben (Gallery), and flumioxazin (Broadstar or Sureguard). There are a number of preemergent herbicides sold as combinations such as Snapshot (oryzalin/isoxaben), Rout (oxyfluorfen/oryzalin), OH2 (oxyfluorfen/pendimethalin), and others. Apply preemergent herbicides to the soil after hand-weeding or cultivating to remove emerged weeds. Follow the application with an irrigation or rain to settle the soil. Some preemergent herbicides can also be mechanically incorporated. However, read the label to know if doing so will affect the chemical barrier. For example, oxadiazon and oxyfluorfen are taken up by the seedling as it emerges; disturbing the chemical may create some gaps where a seedling can avoid growing through the herbicide. These two materials depend on a barrier of herbicide on the soil surface to be effective. A second hand weeding 7 to 10 days after an herbicide application may be needed to ensure elimination of previously germinated seedlings. Preemergent herbicides must be applied before the weed seeds germinate. Because of the varied germination periods of the weed species and the selectivity of the herbicides, it is usually necessary to use different herbicides at different times of the year 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 fall- and winter-germinating 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. Also, herbicides may not control weeds for as long as stated on the label because of frequent irrigation. Postemergent herbicides. Postemergent herbicides are applied after weeds have emerged. They often are very selective and control only a narrow range of weed species. Examples of selective postemergent herbicides include sethoxydim (Vantage), fluazifop-p-butyl (Fusilade), and clethodim (Envoy). Sethoxydim and fluazifop-p-butyl control most annual grasses, except annual bluegrass and fine fescue. Clethodim will control annual bluegrass as well as other grasses. Products containing the phenoxy group of herbicides, such as 2,4-D, will selectively control broadleaf weeds in monocots but will injure a broadleaf crop. There are no selective postemergent herbicides that can be used over a wide spectrum of ornamental species for broadleaf weed control. Nonselective herbicides are those containing glyphosate (Roundup Pro, Touchdown, etc.), diquat (Reward), pelargonic acid (Scythe), glufosinate (Finale), and plant oils such as euginol. Nonselective herbicides can be used around the field to keep weeds from seeding but must be kept away from the crop. Apply postemergent herbicides when weeds are in the seedling stage, which is the stage when they are the most susceptible and require the least amount of herbicide for effective control. Most postemergent herbicides need an addition of an adjuvant (surfactant or nonphytotoxic oil) for maximum control. Glyphosate may not need an additional surfactant depending on the formulation, but fluazifop-p-butyl and clethodim need a nonionic surfactant and sethoxydim needs an oil additive for best results. Check the herbicide label for information about which type of surfactant to use and the rate. In some field-grown flowers, shrubs, or trees, control of grasses with the postemergent herbicides sethoxydim, fluazifo-p-butyl, or clethodim can be very effective. Since sethoxydim or fluazifop-p-butyl will not control annual bluegrass, the field may not look good aesthetically, but annual bluegrass does not compete heavily with the crop. Most broadleaf ornamentals tolerate these herbicides. There are no broad-spectrum broadleaf herbicides that are safe to use on a wide variety of ornamentals. By using preemergent or postemergent herbicides or, where possible, mulches instead of hand-weeding or cultivation, the root system of desirable plants is not disturbed. Roots are not cut off with a hoe or plants pulled accidentally, and because new weed seeds are not brought to the soil surface, as would be with cultivation, fewer weeds will germinate to start a new weed crop. Equipment for Application of Herbicides. Choice of application equipment depends on the product formulation and the location and size of areas to be treated. In greenhouses or small farm operations, a backpack hand-pump sprayer may be effective. In field nurseries, a small pull-behind or tractor unit may be more desirable. In large nurseries, over-the-top sprayers to cover full beds may be best. To get the most uniform distribution of preemergent liquid herbicides (either wettable powder (WP), water dispersable granules (WDG) or other liquid formulations), use flat fan nozzles evenly spaced on a boom. If spraying foliage with a postemergent herbicide, hollow or solid cone nozzles can be used. WEEDS: GENERAL INFORMATION General Methods of Weed Management (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 152 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Most 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 preemergent herbicide applications is highly dependent on the concentration applied to the soil, make applications as uniformly as possible. When applying to containerized 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 product would be more effective. Dry materials (granules) are applied by common types of spreaders. The distribution of granules by the droptype applicator is probably the most accurate, although the side-throw-type of spreader is easier to use. In large container operations, applicators such as a Gandy spreader may be a worthwhile investment. Granule size and weight differs among herbicides. Also, size of granule may not be uniform within a single formulation, making uniform distribution from one herbicide to another is difficult with the same spreader. As with liquid formulations, calibration of the equipment is essential for proper application. In contrast to liquid applications, granules can cause severe wear to the application equipment, so the equipment will need to be calibrated more frequently. WEEDS: GENERAL INFORMATION General Methods of Weed Management (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 153 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SUSCEPTIBILITY OF WEEDS TO HERBICIDE CONTROL (3/09) PREEMERGENCE POSTEMERGENCE DCP FLM ISX MET NAP ORY OXA OXY PEN PRO TRI CLE DIQ FLU GLU GLY PEL SET ANNUAL WEEDS Barnyardgrass Bittercress, lesser-seeded Bluegrass, annual Burclover, California Chickweed, common Crabgrasses Cudweeds Filarees Fleabane Goosefoot, nettleleaf Groundsel, common Henbit Horseweed Junglerice Lambsquarters 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 C — N C C C C P C C C C C C C C C C P — C P P P C C P P P N P N C C P N C — N C C C C P C C C C C N C C C N N — C N N N N C N N N N P N C C P N C C C C C C N P C C C N C N C C C N C P N C C C C N C C C C P C C C P C N — C N P N C C N N N N P N C C P N P — C N C P C C N N N N N N C P N N N C P N N N P P N N N N N N C C N N C — C P C C C C C C C N N N C C N N N C C N C P P C N N N N N N C C N N P C C N N C C C C C C N N N C C N N N C P N P N P P N N N N N N C C N N C — N C C C C P C C C C P C C C P C C C C P C C C C C C C N P N C C P N N — C N C P P C N N N N N N C C N N P C C N P P P C P P P N N N P P N N P — C N P N C C N N N N P N C C P N P C C C P P C C P P P N P N C C P N P C C C N N C C N N N N P N C C P N P C C C N N C C N N N N P N C C P N P — C P C C N P C C C N N N C C N N C — C C C C C C C C C N P N C C P N C C C C C C C C C C C N C N C C C N N — C N N N C C N N N N C N C C C N P — C N C N C C N N N N N N C C N N N C C P P N C C N N N N P N C C P N P C C P C N C C N N N N P N C C P N C — N C C C P N C C C N N N C C N N P — C N N C C C C C C N C N C C C N P — C C C C N P C C C N P N C C P N N C P N N P P C N N N N P N C C P N N — N N N N N N N N N N N N P C N N Continued on next page . . . WEEDS: GENERAL INFORMATION Susceptibility of Weeds to Herbicide Control (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 154 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES PREEMERGENCE POSTEMERGENCE DCP FLM ISX MET NAP ORY OXA OXY PEN PRO TRI CLE DIQ FLU GLU GLY PEL SET 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) Woodsorrel, creeping (seedling) MISCELLANEOUS Liverwort C = control N — N N N N N N N N N C N P P C N P C — N C C C P N C C C C C C C C C C N — N N N N P N N N N N N N P P N N N — N N N P C C P P C N C N C C P N N — N N N N N N N N N N N N P C N N N — N N N N N N N N N C N P P C N P P — N C C C N N P C C C C C C C C C N P N P P N N N N N N N N N N P N N N N N P N N N N N N N N N N N P N N N — N N N N N N N N N N N N P C N N C — C N N C C C C C C N C N C C C N — C — — — — P P — — — P = partial control N = no control DCP = DCPA (Dacthal) OXA = oxadiazon (Ronstar) ISX OXY = oxyfluorfen (Goal) = isoxaben (Gallery) FLM = flumioxazin (Broadstar/Sureguard) PEN = pendimethalin (Pre-M, Pendulum) MET = metolachlor (Pennant) PRO = prodiamine (Endurance, Barricade) NAP = napropamide (Devrinol) TRI = trifluralin (Treflan) ORY = oryzalin (Surflan) WEEDS: GENERAL INFORMATION Susceptibility of Weeds to Herbicide Control (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 155 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Container Nurseries WEEDS IN CONTAINER NURSERIES (3/09) 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 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 soil mixes are usually weed-free at planting, weed seeds can be blown in from other areas or may be brought in with the liner (transplant). Frequently, preemergent herbicides are applied to the potting mix surface in gallon or larger containers to prevent establishment of these weed seeds. Mulches may also be applied after canning or after weeding. After container plants are established, preemergent 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; plants growing in, between, or near pots; potting mix (if it is stored uncovered where weed seed can blow in); irrigation water; vehicles; equipment; movement of soil; birds; and windborne seeds. Transplants produced in the nursery or purchased from others should be free of weeds and weed seed. Move gallon-size plants into larger, weed-free containers. Use of preemergent herbicides in and between the containers can reduce contamination or reinfestation but care must be taken that herbicides are not carried in water runoff. Nursery Site Selection and Preparation. When selecting a new nursery site, choose one that is free of perennial weeds and away or upwind from sources of windborne weed seed. Some of the weed species that have easily wind-dispersed seed are sowthistle, common groundsel, horseweed, hairy fleabane, cudweed, and willowherb. 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 gravel, concrete, or a geotextile (landscape fabric) 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, steam sterilize, or solarize any seed-contaminated soil mix. Check the soil mix periodically for weed seeds by placing soil mix samples 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 imbibe water and begin to germinate. If the mix is too dry, too wet, or if there are large soil clods, fumigation will not be uniform. Fumigation is most successful when the soil is placed on a concrete pad or in a container and the steam or fumigant is introduced at several locations in the mix. WEEDS Weeds in Container Nurseries (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 156 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES There are two main methods to fumigate a soil mix: • Steam fumigation. The steam is usually mixed with air and injected into a loose soil mix to heat the mix to at least 140oF (46oC) 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 140oF. A major problem of steam fumigation is that equipment, such as a boiler blower, is required. • Chemical fumigation. Vapam (metam sodium*), K-Pam (metam potassium*), or Basamid (dazomet) fumigation is sometimes used as a preplant treatment in potting mixes. Basamid is a dry formulation that must be mixed into the potting mix before wetting the pile. The pile is then covered for about 2 weeks as the Basamid 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. Vapam and K-Pam 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 the crop is planted. Fumigants such as metam sodium or metam potassium are a source 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 discussion of soil solarization in "General Methods of Weed Management" at the beginning of the weed section.) Monitoring Container Nurseries. Common weeds in container production nurseries are listed in Table 3. 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 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. TABLE 3. 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 strategy to take. Use the Grower's Weed Identification Handbook, UC ANR Publication 4030, Weeds of California, UC ANR Publication 3488, and the UC IPM Weed Photo Gallery, (http://www.ipm.ucdavis.edu/PMG/weeds_common.html), to help identify weeds. University of California Cooperative Extension farm advisors or county agricultural commissioners, botanic gardens, or arboretum personnel can also help with weed identification. Once the weed is identified, the herbicide susceptibility tables will help to determine the best herbicide or combinations of herbicides to supplement a weed management program and provide optimum control of the weed species present. Herbicides. Preemergent herbicides are used extensively in container-grown ornamentals, usually in conjunction with hand weeding, 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 that the right herbicide is selected. WEEDS Weeds in Container Nurseries (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 157 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Because they are selective, the 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: • Plant size. The smaller the plant the greater the sensitivity to herbicides, and therefore, the greater the likelihood of it being injured. • Degree of plant establishment. Newly-planted plants are more sensitive, because generally they have smaller root systems than established 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 and on different soil fractions. The more clay and organic matter content, the greater the binding and usually the less leaching. • Rate of plant growth. Actively growing plants often are more sensitive to injury from certain herbicides than dormant 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 in question. • Temperature. Temperature affects rates of chemical reactions in plants. Higher temperatures can greatly increase the speed of chemical reaction, which results in greater injury to plants as well as to weeds. Higher temperatures may also increase herbicide absorption through leaves and roots. • Tank mixing of products. Mixing wetting agents or another product that has wetting agents in it with an herbicide that has postemergent activity can greatly increase the activity and perhaps crop injury and affect selectivity. • 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 output. • 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. Herbicide runoff can be a serious problem in some situations, so observe the following precautions to reduce runoff from occurring: (1) use herbicides with water solubility of less than 3.5 ppm; (2) spot treat; (3) use low-volume applications; (4) 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 potential. WEEDS Weeds in Container Nurseries (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 158 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES SPECIAL WEED PROBLEMS FOR CONTAINER NURSERIES (3/09) BITTERCRESS (hairy bittercress, lesser-seeded bittercress, popweed) is a small winter annual but will germinate almost any time in container-grown ornamental production areas. It grows upright when the seed stalk starts to form and is easy to handweed, 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. Because it is easily missed with weeding, bittercress is almost always present if an herbicide is not used. Herbicides that are effective against bittercress are those that contain oxadiazon, oxyfluorfen, or isoxaben. 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 if moving 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 is tolerant to many preemergent herbicides. This weed germinates anytime during the year in container-grown nurseries, whereas in the field it usually germinates in fall and early winter. It grows in an upright manner and has a vigorous root system that makes it difficult to hand-weed. Preemergent herbicides suppress the rooting, making the weed easier to pull. Also, because the seedling is smaller after the use of a preemergent herbicide, competition with the desirable plant is not very significant. Remove this weed before it flowers, however, because its seeds are easily spread by wind. Preemergent herbicide combinations containing oxyfluorfen or isoxaben 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 10 feet or more 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 roots as possible, and to control germinating seeds with mulch or preemergent herbicides such as pendimethalin, oryzalin, oxadiazon, oxyfluorfen, or isoxaben. 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. Herbicide combinations containing 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 from dense colonies in ornamental containers resulting in crop damage and reduced marketability. Preemergent herbicides containing flumioxazin, oxyfluorfen, or oxyfluorfen in combination with napropamide, oryzalin, oxadiazon, or pendimethalin provide good control of this weed. These products may not be used on every ornamental species so check the label carefully before application. At this time there are no selective postemergent 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 preemergent application of oryzalin, pendimethalin, or isoxaben will give control. SPURGE. Prostrate or spotted, and creeping 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 preemergent herbicides isoxaben, pendimethalin, oryzalin, oxadiazon, and oxyfluorfen 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. Preemergent herbicides that have been effective in controlling germinating seeds include oxadiazon and oxyfluorfen. WEEDS Special Weed Problems for Container Nurseries (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 159 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TREATMENT FOR CONTAINER NURSERIES Herbicide (commercial name) (6/10) R.E.I.+ (hours) When choosing a pesticide, consider information relating to environmental impact. Note: Not all ornamentals will tolerate each herbicide. Check the label for species selectivity. PREEMERGENT HERBICIDES A. ORYZALIN (Surflan, etc.) 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: A relatively broad-spectrum preemergent herbicide that does not need mechanical incorporation. Controls annual grasses and many broadleaf weeds and can be used safely around many woody and herbaceous 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 pines, Taxus, arborvitae, and junipers are more tolerant. Stems of Monterey pines may exhibit some swelling. Oryzalin is a strong root inhibitor. Most broadleaf ornamentals are very tolerant to oryzalin if the herbicide is not in the root zone. Often used in combination with other herbicides to widen weed spectrum controlled. Even when applied at rates of 4 lb(4.4 kg/ha) a.i./acre, sometimes weeds in the Asteracae (common groundsel, sowthistle, prickly lettuce, fleabane), mustard (bittercress), and legume (burclover) families are not completely controlled. For most labeled weeds, control usually is effective for 2–3 months. Can control spotted spurge and oxalis from seed for about 4 months. Re-treatments have been required for full-season (1-year) control. Re-treat at about 3- to 4-month intervals and supplement with some hand-weeding for best control of most weeds. B. TRIFLURALIN (Treflan, etc.) 12 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, or covered with a mulch, very soon after application. Inhibits root growth. Often mixed with other herbicides (isoxaben or benefin) to widen weed spectrum controlled. C. PRODIAMINE (Barricade, Endurance) 12 MODE OF ACTION: Unknown. COMMENTS: Stable on the soil surface. Does not provide as long weed control as oryzalin at the maximum label rates for both. Has been less effective for spurge and groundsel suppression than some other dinitroaniline herbicides. Inhibits root growth. Low water solubility and does not move deeply in the soil. D. PENDIMETHALIN (Pendulum, etc.) 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: Gives excellent grass control and controls many broadleaf weeds. Weed spectrum controlled is similar to that of oryzalin. Often combined with an additional herbicide material to widen spectrum of weeds controlled. Controls oxalis and spotted spurge. Available as a water dispersible granule and a newer formulation (AquaCap) has no odor and less persistent orange color. Both are safe over the top of many nursery plants. Though it is a root inhibitor, it is less injurious to roots than oryzalin or prodiamine. E. NAPROPAMIDE (Devrinol) 12 WSSA MODE OF ACTION GROUP NUMBER1: 15 COMMENTS: Works best if mechanically incorporated or followed by rainfall or a sprinkler irrigation of 0.5 inch within 7 days after application. 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 nightshade and aster families, spurge, and oxalis. It is an excellent grass herbicide and can suppress common groundsel. Generally less efficacious but often safer than the combination herbicides, it is useful in the herbaceous market. 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. WEEDS Treatment for Container Nurseries (6/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 160 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) R.E.I.+ (hours) F. OXADIAZON (Ronstar) 12 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: A broad-spectrum preemergent herbicide that is moved off the foliage and into the soil by a sprinkler irrigation following application. Oxadiazon is a shoot-girdling herbicide. Used during the growing season from spring until fall. Granular oxadiazon is safe on most woody plants. The wettable powder formulation is generally not used in nursery stock. In containers, granular oxadiazon plus napropamide is a good combination, with a broad range of safety in woody plants. Oxadiazon plus napropamide often has an improved margin of safety over Rout or OHII, especially in young, actively growing plants. 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 pearlwort, chickweed, and horseweed. Re-treatments are required at about 3- to 4-month intervals to maintain control throughout the season. 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, however, 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. G. OXYFLUORFEN (Goal XL) 24 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: For use around conifers in container production. An excellent place for oxyfluorfen sprays is in dormant or hardened conifers where groundsel, malva, purslane, or mustards are found. Controls these weeds in a few days and provides residual broadleaf control. Oxyfluorfen cannot be safely sprayed over most deciduous plants and is registered for use only around conifers. Safest to the conifers when applied as granules. Weak on horseweed, common chickweed, and grasses. Oxyfluorfen acts by girdling the young stem of seedlings; thus in soil, oxyfluorfen is most effective with frequent irrigation. If treated soil is cultivated, weed control is reduced. H. ISOXABEN (Gallery) 12 WSSA MODE OF ACTION GROUP NUMBER1: 21 COMMENTS: Excellent material for broadleaf weed control. The major weakness is poor annual grass control. Therefore, it is often mixed with oryzalin or trifluralin. Isoxaben stunts seedlings by inhibiting cell wall formation in dividing cells. Some broadleaf weed species can be controlled for up to 18 months with the labeled usage rates. It is safe to a wide range of woody ornamentals. Isoxaben does not effectively control mallow or willowherb and related species. Disadvantages associated with using isoxaben are the cost and potential crop injury. Susceptible nursery crops are lilac, Euonymus alatus compacta, mints, legumes, snapdragon, mustards, and members of the figwort family. Some herbaceous ornamentals such as Veronica and Digitalis may be killed by postplant, preemergent applications of isoxaben. I. FLUMIOXAZIN Broadstar (granular), Sureguard (sprayable) 12 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: Avoid contact with young plants or foliage. Wash foliage as soon as possible after application. Can cause stem dieback or leaf burn on sensitive plants. Has some postemergent activity. Provides good liverwort control. Helps provide preemergent control of annual grasses, chickweed, horseweed, hairy fleabane, and other annual broadleaves. Test on a small number of plants before using widely. PREEMERGENT 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 a.i. on any label when tank mixing products that contain the same a.i. A. ORYZALIN/OXYFLUORFEN (Rout) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 3/14 COMMENTS: One of the standards in the container industry. 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. WEEDS Treatment for Container Nurseries (6/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 161 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) R.E.I.+ (hours) B. OXYFLUORFEN/PENDIMETHALIN (OH II) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 14/3 COMMENTS: One of the standards in the container industry. Provides excellent broad-spectrum control of annual broadleaf and grassy weeds. Should be watered-in immediately after application. Residual control is 3–4 months. C. ISOXABEN/TRIFLURALIN (Snapshot TG) WSSA MODE OF ACTION GROUP NUMBERS1: 21/3 COMMENTS: Gives broad-spectrum control of annual broadleaf and grass weeds. 12 D. OXYFLUORFEN/OXADIAZON (Regal O-O) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 14/14 COMMENTS: Gives broad-spectrum of control. Plants with leaf bases that hold granules can be injured, but formulation is such that most of the material falls through the canopy to the soil surface. E. OXADIAZON/PRODIAMINE (Regalstar II) 12 WSSA MODE OF ACTION GROUP NUMBERS1: 14/Unknown. COMMENTS: Gives broad-spectrum grass and broadleaf control. Injury may occur if material is applied to wet foliage. Formulation is similar to Regal O-O. F. DIMETHENAMID-P/PENDIMETHALINE (Freehand) 1.75G 24 WSSA MODE OF ACTION GROUP NUMBERS1: 15/3 COMMENTS: Controls many common nursery weeds such as eclipta, spurges, willowherbs, and oxalis. Can be applied very soon after potting. Provides preemergence control or suppression of yellow nutsedge. G. ISOXABEN/OXYFLUORFEN/TRIFLURALIN (Showcase) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 21/14/3 COMMENTS: Similar to Snapshot but broader-spectrum control of annual broadleaf and grass weeds. Do not apply to newly transplanted ornamentals. Do not apply Showcase to wet foliage or plants where the whorls or leaves can catch granules. Longer residual. POSTEMERGENT HERBICIDES Nonselective A. GLYPHOSATE (Roundup Pro) 4 WSSA MODE OF ACTION GROUP NUMBER1: 9 COMMENTS: Labeled for use around container-grown ornamentals. A systemic herbicide that translocates to the roots and growing point of plant 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 preemergent herbicide. Often takes 7 or more days after application for complete control. Avoid drift. B. PELARGONIC ACID (Scythe) 12 WSSA MODE OF ACTION GROUP NUMBER1: 27 COMMENTS: Labeled for use around container-grown ornamentals. Works by contact activity only (does not move in plant) and affects only green tissue. Kills annual weeds (good control of young annuals weeds), but only burns off the tops of perennials. Must be applied at high rates in high volumes of water. Very rapid (minutes in high sunlight) activity. Growers have experimented with this product as a semiselective herbicide. In some cases lower effective rates of this herbicide might be applied over crops with only minor injury, while completely eliminating susceptible annual weeds in the container. In some cases, the product has been directed towards susceptible annual weeds in the container if the crop plant has a leafless, woody base, or the plant is shielded from the spray. WEEDS Treatment for Container Nurseries (6/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 162 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) R.E.I.+ (hours) C. PARAQUAT* (Gramoxone Inteon) 24 WSSA MODE OF ACTION GROUP NUMBER1: 22 COMMENTS: Can be used around the perimeters of nursery. Controls young annual weeds; contact activity only; affects only green tissue. D. DIQUAT (Reward) 24 WSSA MODE OF ACTION GROUP NUMBER1: 22 COMMENTS: Labeled for use around container-grown ornamentals. Kills annuals weeds, but only burns off the tops of perennials. Control of young annual weeds; contact activity only; affects only green tissue. Good for weed control in winter. Selective (broadleaves) A. OXYFLUORFEN (Goal) 24 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: Registered for use around conifers only. Postemergent 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. FLUAZIFOP-P-BUTYL (Fusilade II, Ornamec) see comments WSSA MODE OF ACTION GROUP NUMBER1: 1 COMMENTS: 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 products; consult the label carefully. Combines very well with oxyfluorfen as long as the stage of growth of the ornamental plants is tolerant to oxyfluorfen. Requires a surfactant. Restricted entry interval for Fusilade is 12 hours; for Ornamec it is 4 hours. B. CLETHODIM (Envoy) 24 WSSA MODE OF ACTION GROUP NUMBER1: 1 COMMENTS: Controls most annual grasses, including annual bluegrass. Safe to use over most ornamentals except at flowering stage (see label). * Permit required from country 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 (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. 1 + WEEDS Treatment for Container Nurseries (6/10) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 163 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Field-Grown Trees, Shrubs, and Flowers (3/09) GENERAL INFORMATION ON FIELD-GROWN TREES AND SHRUBS Field-grown trees and shrubs are generally grown in rows to facilitate planting, weeding by hand or mechanical cultivation, and cultural operations such as pruning or grafting. Most weed control in established plantings is accomplished by cultivation or with preemergent herbicides, but perennial weeds need to be controlled before the ornamental crop is planted. Crop Rotation. In some cropping systems a field is fumigated before planting. During the growing season, cultivation, herbicides, or other weed growth suppression 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 (wheat, oats, or barley) and harvested the following spring. Herbicides can be used in the cereal crop that will reduce weed problems in the next tree cycle. Solarization. Soil solarization is a valuable tool to clean up a site before a fall planting (see "Solarization" under "General Methods of Weed Management"). 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 spring. Mow the cover crop and work it into the soil before it seeds to reduce competition with the crop. Mulches. To reduce weeds in the row, field-planted cuttings can be planted into a paper mulch. After planting, mulches (organic or geotextile) can be placed along the sides of newly planted stock. Organic mulch must be deep enough to shade out all weed seedlings as they germinate. The geotextile materials must be placed so no light gets to the soil around the plant or weeds will grow around the base of the plant. SPECIAL WEED PROBLEMS FOR FIELD-GROWN TREES AND SHRUBS (3/09) LITTLE MALLOW (Cheeseweed). Cheeseweed is a winter annual or biennial plant that forms hard seeds, which can remain dormant for long periods of time. It generally germinates in fall after rainfall or an irrigation but may germinate any time during winter and spring. The seed is not controlled with methyl bromide but most preemergent herbicides, especially oxyfluorfen and oxadiazon, are 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 very effective in controlling this weed. Repeat applications of glyphosate (before five-leaf stage when new tubers are formed) will reduce populations over time. If the area is left fallow, halosulfuron can be used and then the crop can be planted the next season. Most preemergent herbicides do not control nutsedge, but metolachlor (Pennant) will suppress the sprouting of the tubers. Soil solarization will reduce yellow nutsedge but will not eradicate it. BURCLOVER. Burclover is a winter annual that can be a problem if herbicides are not used. Though it is relatively low growing, it is difficult to keep off of the trees and shrubs. Most preemergent herbicides other than those in the dinitroaniline family (e.g., oryzalin, prodiamine, trifluralin) will control burclover. WEEDS Field-Grown Trees and Shrubs (3/09) and Special Weed Problems for Field-Grown Trees and Shrubs (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 164 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TREATMENT FOR FIELD-GROWN TREES AND SHRUBS (3/09) Herbicide (commercial name) R.E.I.+ (hours) When choosing a pesticide, consider information relating to environmental impact. PREEMERGENT HERBICIDES A. ORYZALIN (Surflan) 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: A relatively broad-spectrum preemergent herbicide that does not need mechanical incorporation. Controls germinating seeds of annual grasses and many broadleaf weeds and can be used safely around many woody ornamentals. Leaches into the soil with rainfall or irrigation. Can cause girdling of certain ornamentals at the soil line: young hemlocks are particularly susceptible to root inhibition and girdling from oryzalin. Seedlings of Douglas fir and true firs (Abies spp.) up to about 3 years of age are also affected, but pines, Taxus, arborvitae, and junipers are more tolerant. Stems of Monterey pines may exhibit some swelling. Often used in combination with other herbicides to widen weed spectrum controlled. Even at rates of 4 lb a.i./acre (4.4 kg/ha), it sometimes has not completely controlled weeds in the Asteraceae (common groundsel, sowthistle, prickly lettuce, fleabane), mustard (bittercress), and legume families. Control is usually for 1–2 months. For full-season control (1 year), re-treat in about 4 months. Re-treatment at about 3- to 4-month intervals, supplemented with some hand-weeding, has given control of most weeds. B. TRIFLURALIN (Treflan, and others) 12 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: Can be applied as a preplant incorporated, or postplant directed and incorporated treatment. 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, or covered with a mulch, very soon after application. Often mixed with other herbicides (isoxaben, benefin) to widen weed spectrum controlled. C. PRODIAMINE (Endurance, Barricade) 12 MODE OF ACTION: Unknown. COMMENTS: Prodiamine is a dinitroaniline that is stable on the soil surface. It will not provide as long weed control as oryzalin at the maximum label rates. Because of its low water solubility, it does not leach. It is a strong root inhibitor like oryzalin. D. PENDIMETHALIN (Pendulum, etc.) 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: Labeled for use in field-grown ornamentals. In most cases, pendimethalin will probably not control a broad enough spectrum of weeds to rely on it as a "stand alone" product. It should be applied in some combination with an additional material. Controls oxalis and spotted spurge. Available as a WDG and an encapsulated formulation, which has no odor and less orange staining. E. NAPROPAMIDE (Devrinol) 12 WSSA MODE OF ACTION GROUP NUMBER1: 15 COMMENTS: Preemergent herbicide that works best if mechanically incorporated or followed by rainfall or a sprinkler irrigation of 0.5 inch within 7 days after application. 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 nightshade and aster families, spurge, and oxalis. An excellent grass herbicide and can suppress common groundsel. Generally less efficacious but often safer than the combination herbicides, it is useful in the herbaceous market. Unless applied before rooted liners become established, injury is rare. If placed in the container around the newly planted liner before irrigation can settle 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. WEEDS Treatment for Field-Grown Trees and Shrubs (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 165 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) R.E.I.+ (hours) F. METOLACHLOR (Pennant) 24 WSSA MODE OF ACTION GROUP NUMBER1: 15 COMMENTS: Controls yellow nutsedge as well as most annual grasses. To be effective, must be incorporated into the soil where nutsedge germinates and grows through the treated area. Granules of metolachlor are safe at all stages of growth. With pines and certain deciduous plants, over-the-top sprays of metolachlor should be on dormant stock, before budbreak. Metolachlor EC distorts plants. Metolachlor has been effectively combined with simazine, oxyfluorfen, or isoxaben for broad-spectrum weed control. One of the more soluble herbicides (solubility 490 ppm) so care must be taken that it does not move with irrigation or rainwater. Oryzalin and metolachlor combinations form an orange sludge in the tank so they should be applied in separate operations. If they must be tank-mixed, reduce this incompatibility by increasing spray volume to 80 GPA and by adding a "mix-aid" type of product. G. OXADIAZON (Ronstar) 12 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: A broad-spectrum preemergent herbicide that is moved off the foliage and into the soil by an irrigation following application. Used during the growing season from spring until fall. Granular oxadiazon has broad safety in woody plants. The wettable powder formulation should not be applied over young growth. It can be applied as a directed spray to the base of the trees or shrubs. Has a relatively long residual, 12–16 weeks. Does not control chickweed and horseweed. Re-treatments are required at approximately 3- to 4-month intervals to maintain control throughout the season. Fall and spring applications of oxadiazon have been very effective. Oxadiazon does not leach readily in the soil, and thus injury has not resulted on many species evaluated in tests. Injury may occur, however if oxadiazon is applied to wet foliage, is not washed from the foliage, or the granules collect in the leaf bases or crowns. If treated soil is cultivated, weed control effectiveness is reduced. H. OXYFLUORFEN (Goal) 24 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: For use around conifer or selected deciduous trees grown in the field. Oxyfluorfen sprays are effective in dormant or hardened conifers where groundsel, malva, purslane, or mustards are a problem. Oxyfluorfen will control these young plants in a few days as well as provide residual broadleaf control. Oxyfluorfen cannot be safely sprayed over most deciduous plants and is registered for use only around conifers. Safest to the conifers when applied as granules. Weak on horseweed, common chickweed, and grasses. Insoil, oxyfluorfen is effective with frequent irrigation. If treated soil is cultivated, weed control is reduced. I. ISOXABEN (Gallery) 12 WSSA MODE OF ACTION GROUP NUMBER1: 21 COMMENTS: Excellent for broadleaf weed control. Does not control annual grasses, therefore often it is mixed with oryzalin or other grass herbicides. Some broadleaf weed species can be controlled for up to 18 months with the labeled usage rates. Because of this long residual, the application schedule may need to be altered to accommodate this longer weed control period. Safe to a wide range of woody ornamentals. Isoxaben does not effectively control primrose, mallow, sida, and related species. Susceptible nursery crops are lilac, Euonymus alatus compacta, the mints, legumes, mustards, and members of the figwort family. Does not control willowherbs. J. DICHLOBENIL (Casoron) 12 WSSA MODE OF ACTION GROUP NUMBER1: 20 COMMENTS: Labeled for use in either established or young nursery plants. A dormant season application of dichlobenil can control many seed-propagated perennial broadleaf weeds and provide residual control through early summer. The drawbacks include the limited number of ornamental species over which it may safely be used; consult the label very carefully. It can be mechanically incorporated in the top 2–3 inches to effectively control many established perennial as well as annual weeds. Good for Equisetum and mugwort control. WEEDS Treatment for Field-Grown Trees and Shrubs (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 166 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) R.E.I.+ (hours) PREEMERGENT 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 a.i. on any label when tank mixing products that contain the same a.i.) A. ORYZALIN/OXYFLUORFEN (Rout) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 3/14 COMMENTS: Provides excellent broad-spectrum control of annual broadleaf and grass weeds. Can apply after a cultivation to reduce subsequent germination. Water in after application. Residual control about 3 months. B. OXYFLUORFEN/PENDIMETHALIN (OH II) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 14/3 COMMENTS: One of the standards in the industry. Provides excellent broad-spectrum control of annual broadleaf and grassy weeds. Should be watered in immediately after application. Slightly less root pruning than the oryzalin/oxyfluorfen formulation (Rout). Residual control about 3 months. C. ISOXABEN/TRIFLURALIN (Snapshot) 2.5 TG 12 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. D. OXYFLUORFEN/OXADIAZON (Regal O-O) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 14/14 COMMENTS: Gives broad-spectrum control of grasses and broadleaf weeds. Soil should be thoroughly settled after cultivation and rainfall/irrigation because the product forms a surface barrier that controls seedlings as they germinate and grow through the herbicides. Cultivation after treatment destroys the control. E. ISOXABEN/OXYFLUORFEN/TRIFLURALIN (Showcase) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 21/14/3 COMMENTS: Similar to Snapshot but broader-spectrum control of annual broadleaf and grass weeds. Do not apply to newly transplanted ornamentals. Do not apply Showcase to wet foliage or plants where the whorls or leaves can catch granules. Longer residual. POSTEMERGENT HERBICIDES Selective (broadleaves) A OXYFLUORFEN (Goal) 24 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: See label for tree crops for which this material is registered. Postemergent applications control certain annual broadleaf weeds. Effective only on certain young seedling weeds, especially malva; 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 are tolerant after about 5 weeks of new growth. Hemlocks, Taxus, arborvitae, junipers, Monterey pine, white pine, and Douglas fir are exceptions in that the new growth is normally not affected by oxyfluorfen. Dormant applications do not cause injury. Selective (grasses) B FLUAZIFOP-P-BUTYL (Fusilade II, Ornamec) see comments WSSA MODE OF ACTION GROUP NUMBER1: 1 COMMENTS: 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. Combines very well with oxyfluorfen as long as the stage of growth of the ornamental plants is tolerant of oxyfluorfen. Restricted entry interval for Fusilade is 12 hours and 4 hours for Ornamec. WEEDS Treatment for Field-Grown Trees and Shrubs (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 167 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) R.E.I.+ (hours) C. CLETHODIM (Envoy) 24 WSSA MODE OF ACTION GROUP NUMBER1: 1 COMMENTS: Controls most annual and perennial grasses but not broadleaves. Effective on annual bluegrass. D. SETHOXYDIM (Poast) 12 WSSA MODE OF ACTION GROUP NUMBER1: 1 COMMENTS: Controls most annual grasses, except annual bluegrass. Safe to use over most ornamentals except at flowering stage (see label). Nonselective A. GLYPHOSATE (Roundup Pro, Touchdown) see comments WSSA MODE OF ACTION GROUP NUMBER1: 9 COMMENTS: A systemic herbicide that translocates to the roots and growing point of the plant and kills the entire plant. Effective on both annual and perennial weeds. Avoid applications where spray or drift may contact leaves of ornamentals or there may be a residual effect that might not be evident until the next season: strapped shaped leaves, stunted growth, sometimes dead shoot tips. Activity is increased in low water volumes. Greater activity is obtained at 20 gal solution/acre, for example, than at 50 gal/acre. Use alone or combined with a preemergent herbicide. Use a shielded sprayer to reduce chance of drift. Do not use in over-the-top applications. Restricted entry interval for Roundup Pro is 4 hours and 12 hours for Touchdown. B. GLUFOSINATE (Finale) 12 WSSA MODE OF ACTION GROUP NUMBER1: 10 COMMENTS: Contact herbicide with a limited amount of systemic activity; kills annual weeds but only burns off the tops of perennials. Can be widely used in field-grown ornamentals. C. PELARGONIC ACID (Scythe) 12 WSSA MODE OF ACTION GROUP NUMBER1: 27 COMMENTS: Labeled for use in field-grown ornamentals. Controls young annual weeds with 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 tops of perennials. Very fast acting (minutes). D. PARAQUAT* (Gramoxone Inteon) 12 WSSA MODE OF ACTION GROUP NUMBER1: 22 COMMENTS: For use in field-grown ornamental trees. Kills annual weeds but only burns tops off perennials. Controls young annual weeds with contact activity only and affects only green tissue. * Permit required from country 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 (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. 1 + WEEDS Treatment for Field-Grown Trees and Shrubs (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 168 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES FIELD-GROWN FLOWERS (3/09) Most weeds are controlled in field-grown flower crops with cultivation, hand-hoeing, and preplant fumigation. Crops are planted in rows to make cultivation easier, and there is less crop damage from the cultivators. The crops may be direct seeded but are often transplanted as plugs or bulbs. 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 hand weeding 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 wheat, oats, or barley in winter and sudangrass or corn 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 yard waste) applied at 1.5 to 2 inches in depth 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 4 inches or more 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 (tubers, rhizomes, or bulbs). Soil Solarization. Solarization is an effective method of controlling 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, ultraviolet (UV)-protected polyethylene 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, yellow and purple nutsedge, and sweet clover. In areas where radiation and temperatures are marginal for solarization, purslane is not controlled well. Flaming. Shielded propane burners are effective in controlling 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 it controls grasses. HERBICIDES Most crops have one or more selective preemergent herbicides available for use. See Table 4 for selective herbicides that are registered on different flower crops. Postemergent herbicides can be used on a few flower crops. Most grass weeds can be controlled selectively with postemergent herbicides but broadleaf weeds cannot. Control weeds when they are small and before they flower and set seed. If a few weeds remain, rogue them out by hand weeding. Herbicides can be used before the crop is planted. The broad-spectrum fumigants metam sodium* (Vapam), metam potassium* (K-Pam), and dazomet (Basamid) can be used on prepared beds to control weeds and other 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. Another method of using herbicides 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 postemergent 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 2 or more times before planting the crop to reduce the seed populations in the soil. Preemergent 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 0.5 inch irrigation after application. See specific comments on the herbicides in the Treatment Table. WEEDS Field-Grown Flowers (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 169 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Postemergent herbicides (fluazifop-p-butyl, sethoxydim) are available to control most grasses in broadleaf 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, it will require more herbicide and some weeds may not be controlled. Broadleaf weed herbicides are generally not safe enough to use over flower crops. Even some selective grass herbicides may injure the crop if treated during flowering stage. 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, to keep the soil from eroding, reduce dust, and to maintain organic matter in the soil. * Permit required from county agricultural commissioner. WEEDS Field-Grown Flowers (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 170 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TREATMENT FOR FIELD-GROWN FLOWERS Herbicide (commercial name) (3/09) R.E.I.+ (hours) When choosing a pesticide, consider information relating to environmental impact. PREEMERGENT HERBICIDES A. ORYZALIN (Surflan) 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: A relatively broad-spectrum preemergent herbicide that does not need mechanical incorporation. Controls annual grasses and many broadleaf weeds and can be used safely on some crops after transplanting. Leaches slightly into the soil with rainfall or irrigation. A strong root inhibitor. Many broadleaf ornamentals are very 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 Asteracae (common groundsel, sowthistle, prickly lettuce, fleabane), mustard (bittercress), and legume (burclover) families are not completely controlled. For most labeled weeds, control usually is effective for 2–3 months. Oryzalin can control spotted spurge and oxalis from seed for about 4 months. Tolerance is marginal on some crops; thus, use low rates until familiar with the herbicide and crop combination. B. TRIFLURALIN (Treflan, and others) 12 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. C. PRODIAMINE (Endurance, Barricade) 12 MODE OF ACTION: Unknown. COMMENTS: Prodiamine is stable on the soil surface. Does not provide weed control for as long as oryzalin at the maximum label rates for both. It also has been less effective for spurge and groundsel suppression than some other dinitroaniline herbicides. Inhibits root growth. D. PENDIMETHALIN (Pendulum, etc.) 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: Gives excellent grass control and will control many broadleaf weeds. Controls a broad-spectrum of grass and broadleaf weeds that is similar what oryzalin controls. Is often combined with an additional herbicide material to widen spectrum of weeds controlled. Though it is a root inhibitor, it is less injurious to roots than oryzalin or prodiamine. E. NAPROPAMIDE (Devrinol) 12 WSSA MODE OF ACTION GROUP NUMBER1: 15 COMMENTS: Works best if mechanically incorporated or followed by rainfall or a sprinkler irrigation of 0.5 inch within 7 days after application. The first irrigation seems to be critical for maximum activity. 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. F. OXADIAZON (Ronstar) 12 WSSA MODE OF ACTION GROUP NUMBER1: 14 COMMENTS: A broad-spectrum preemergent 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. Is weak on all of the chickweed family and on certain broadleaves including pearlwort, chickweed, and horseweed. Has a relatively long residual, 12–16 weeks, but if cultivated control will be lost. 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, however, if applied to wet foliage, if it is not washed from the foliage, or if the granules can collect in leaf bases or crowns. WEEDS Treatment for Field-grown Flowers (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 171 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) G. R.E.I.+ (hours) ISOXABEN (Gallery) 12 WSSA MODE OF ACTION GROUP NUMBER1: 21 COMMENTS: Excellent material for broadleaf weed control. Major weakness is annual grass control. Therefore, it is often mixed with oryzalin or trifluralin. Isoxaben stunts seedlings by inhibiting cell wall formation in dividing cells. Some broadleaf weed species can be controlled for up to 18 months with the labeled usage rates. Isoxaben does not effectively control mallow and related species. Disadvantages are the cost and potential crop injury. Some herbaceous ornamentals such as snapdragon, Veronica, and Digitalis may be killed by postplant, preemergent applications of isoxaben. PREEMERGENT 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 a.i. on any label when tank mixing products that contain the same a.i. A. ORYZALIN/OXYFLUORFEN (Rout) 24 WSSA MODE OF ACTION GROUP NUMBERS1: 3/14 COMMENTS: A product with 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. POSTEMERGENT HERBICIDES Nonselective A. GLYPHOSATE (Roundup Pro, Touchdown) see comments 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 preemergent herbicide. Often takes 7 or more days after application for complete control. Avoid drift. Restricted entry interval for Roundup Pro is 4 hours and 12 hours for Touchdown. B. PELARGONIC ACID (Scythe) 12 WSSA MODE OF ACTION GROUP NUMBER1: 27 COMMENTS: Labeled for use as a preplant treatment. 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 tops of perennials. Does not move in plant. Very rapid (minutes in high sunlight) activity. C. PARAQUAT* (Gramoxone Inteon) 12 WSSA MODE OF ACTION GROUP NUMBER1: 22 COMMENTS: Can be used as a preplant treatment or around the perimeters of a nursery. Controls young annual weeds with contact activity only; affects only green tissue. D. DIQUAT (Reward) 24 WSSA MODE OF ACTION GROUP NUMBER1: 22 COMMENTS: Labeled for use as a preplant treatment. Kills annuals weeds, but only burns off the tops of perennials. Controls young annual weeds with contact activity only; affects only green tissue. Selective (grasses) A. SETHOXYDIM (Poast) 12 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. WEEDS Treatment for Field-grown Flowers (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 172 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Herbicide (commercial name) R.E.I.+ (hours) B. FLUAZIFOP-P-BUTYL (Fusilade II, Ornamec) see comments WSSA MODE OF ACTION GROUP NUMBER1: 1 COMMENTS: 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. Restricted entry interval for Fusilade is 12 hours and 4 hours for Ornamec. C. CLETHODIM (Envoy) 4 WSSA MODE OF ACTION GROUP NUMBER1: 1 COMMENTS: Controls most annual grasses, including annual bluegrass. Safe to use over most ornamentals. * 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 (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. 1 + WEEDS Treatment for Field-grown Flowers (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 173 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES Greenhouses GREENHOUSE-GROWN CROPS (Inside greenhouses) (3/09) It is difficult to control weeds in greenhouses because greenhouse-grown plants are generally sensitive to herbicides and weeds are often hard to reach and there are no registered preemergent herbicides. Only a few weed species commonly present problems in greenhouses, and they are all closely associated with high moisture and nutrients; they also spread rapidly if they are allowed to become established. The most common weeds in and around greenhouses include annual bluegrass, lesser-seeded bittercress, creeping woodsorrel, pearlwort, common chickweed, moss, and liverwort. Others that may be present include cudweed, sowthistle, willowherb, fireweed, cheeseweed, and prostrate and spotted spurge. Controlling these weeds inside the greenhouse will also help reduce the reservoir of insects and diseases that are often associated with weeds. Liverwort and Mosses. Liverwort and mosses can be found in many greenhouses where plants are highly irrigated. Their presence is exacerbated when there is high nitrogen in the upper soil surface, such as by top-dressing. These types of plants reproduce vegetatively and by spores and are easily spread throughout a greenhouse. They can compete with the crop for water and nutrients and also create a barrier on the potting media surface that restricts water movement into the container resulting in 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 impact of liverwort and mosses. 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 creeping woodsorrel (oxalis) and bittercress. 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. Irrigate with water that is free of weed seeds or fungal spores. If using raised or self-contained beds, sterilize soil before planting by either steaming or solarizing. These methods are described in GENERAL METHODS OF WEED MANAGEMENT (solarization) and in CONTAINER NURSERIES (steaming). Herbicides. There are no preemergent herbicides currently available for use in greenhouses. Many of these herbicides are quite volatile at greenhouse temperatures and can move and/or accumulate in greenhouses to toxic levels for crop plants. Even though some herbicides may be labeled for use in a crop, it must specifically indicate to be used in greenhouses to be legal and safe. On the greenhouse floor and under the benches, a postemergent herbicide treatment can be used to reduce weed populations and to keep the weeds from flowering and seeding. Try to have good drainage and level the gravel or soil under the benches to reduce water collecting in low areas. Wet areas increase the chance of mosses and liverwort infestation. Air movement at the floor level will help dry off the floor and will also reduce the chance of infestations of weeds that favor 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 seed bank in the soil. WEEDS Greenhouse-grown Crops (Inside Greenhouses) (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 174 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TREATMENT (Inside greenhouses) Herbicide (commercial name) (3/09) Amount to Use R.E.I.+ (hours) When choosing a pesticide, consider information relating to environmental impact. POSTEMERGENT HERBICIDES A. DIQUAT (Reward) Spot application: 1–2 pt plus 8–16 oz nonionic surfactant/100 24 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 Broadcast application: 3 qt when weeds 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) Spot application: 0.66–1.33 oz product/1 gal water 4 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) 12 WSSA MODE OF ACTION GROUP NUMBER1: 27 COMMENTS: Apply to young weeds under benches, along walkways, or along the edge of greenhouses. Apply in a ventilated area. 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 (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. + WEEDS Treatment (Inside Greenhouses) (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 175 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES GREENHOUSE-GROWN CROPS (Outside greenhouses) (3/09) 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 insect and disease pests that may live and reproduce on weeds will move into the greenhouse. If insects such as aphids, thrips, leafhoppers, whiteflies, or lygus bugs 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 mowing or cultivation where feasible and with herbicides. Care must be used when applying an herbicide so that it does not get in the greenhouse by drift or runoff. Preemergent herbicides can be used if the soil slopes away from the greenhouse so no water or soil 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 (such as oxyfluorfen) should not be used around the outside of a greenhouse. WEEDS Greenhouse-grown Crops (Outside Greenhouses) (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 176 UC IPM Pest Management Guidelines - FLORICULTURE AND ORNAMENTAL NURSERIES TREATMENT (Outside greenhouses) Herbicide (commercial name) (3/09) Amount/Acre R.E.I.+ (hours) When choosing a pesticide, consider information relating to environmental impact. PREEMERGENT HERBICIDES A. ORYZALIN 2–4 lb a.i. (Surflan) 2–4 qt 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: Apply to weeds or combine with a postemergent herbicide if young weeds are present. May be combined with other preemergent herbicides to control grass and some broadleaf weeds. B. PRODIAMINE (Endurance, Barricade) 0.65–1.495 lb 12 MODE OF ACTION: Unknown. COMMENTS: Apply as a preemergent treatment. May be combined with a postemergent herbicide if young weeds are present. May be combined with other preemergent herbicides to control grasses and some broadleaf weeds. C. PENDIMETHALIN (Pendulum) 3.3 EC or 60% WDG 2–3.96 lb a.i. 24 WSSA MODE OF ACTION GROUP NUMBER1: 3 COMMENTS: Apply as a preemergent treatment. May be combined with a postemergent herbicide if young weeds are present. May be combined with other preemergent herbicides to control grasses and some broadleaf weeds. E. ISOXABEN (Gallery) 0.9975 lb 12 WSSA MODE OF ACTION GROUP NUMBER1: 21 COMMENTS: Apply preemergent or combine with a postemergent herbicide if young weeds are established. May be combined with other preemergent herbicides to control additional broadleaf weeds. POSTEMERGENT HERBICIDES A. GLYPHOSATE (Roundup Pro, Touchdown) Annuals: 2 qt–1 gal/100gal water see comments 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 good enough to maintain active growth of the weeds. Maximum application rates are up to 2 gal/100 gal water for Roundup Pro and up to 5 qt/100 gal for Touchdown. Restricted entry interval for Roundup Pro is 4 hours and 12 hours for Touchdown. B. GLUFOSINATE (Finale) Spot application: 1.5 fl oz/1 gal water 12 Broadcast application: 3 qt when weeds 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. DIQUAT (Reward) 1–2 pt plus 16–32 oz nonionic 24 surfactant/100 gal water WSSA MODE OF ACTION GROUP NUMBER1: 22 COMMENTS: Apply 15–40 gal/acre or enough to wet young weeds. Apply to young weeds for improved control. 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 (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Weeds Treatment (Outside Greenhouses) (3/09) Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 177 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 (cancer-related 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 Linda Marie Manton, Affirmative Action Contact, University of California, Davis, Agriculture and Natural Resources, One Shields Avenue, Davis, California, 95616, (530) 752-0495. Precautions for Using Pesticides Illustrated version at http://www.ipm.ucdavis.edu/PMG/selectnewpest.floriculture.html 178