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Diseases in Vegetable Seed Crops
- 1. Diseases iinn VVeeggeettaabbllee SSeeeedd CCrrooppss:: IIddeennttiiffiiccaattiioonn,, BBiioollooggyy && MMaannaaggeemmeenntt LLiinnddsseeyy dduu TTooiitt WWaasshhiinnggttoonn SSttaattee UUnniivveerrssiittyy MMoouunntt VVeerrnnoonn RReesseeaarrcchh && EExxtteennssiioonn UUnniitt
- 2. diagnosis of plant problems biotic abiotic physical chemical mechanical pathogenic: 1. fungal 2. bacterial 3. viral 4. nematode insect/mite: 1. feeding habit 2. life “cycle” “macro” organisms
- 3. Effects of diseases of vegetable seed crops • yield loss • infection of harvested seed • reduction in seed germination & vigor • seed transmission of pathogen(s) to new crops
- 4. Classes of seedborne microorganisms 1. Infected seed = primary inoculum source. If seed infection is controlled, the disease is controlled 3. Important crop pathogen, but infected seed = minor source of inoculum 5. Seedborne microorganisms never demonstrated to cause disease 7. Pathogens that infect seed in fields or in storage, and reduce seed quality
- 5. inoculation penetration infection & colonization survival pathogen dissemination life cycle growth & reproduction
- 6. infection seed transmission production crop disease development survival seedborne disease cycle seed crop seed storage & conditioning seed or production crop
- 7. pathogen environment disease host
- 9. Disease management in seed crops • cultural practices • chemical applications, seed treatments • disease resistance
- 10. Disease management in seed crops: Cultural practices • Crop rotation • Elimination of alternative hosts • Destruction of inoculum in the field • Control of insect vectors • Irrigation practices • Planting practices • Ventilation of seed crops • Fertilizer programs • Transplanting • Harvesting • Geographical location
- 11. Disease management in seed crops: Cultural practices Crop rotation • non-host, resistant, or ‘antagonistic’ crops • duration dependent on pathogen host range, foliar vs. soilborne pathogens, longevity of inoculum survival, resistance of cultivar or parent lines cultural practices, etc. • be aware of asymptomatic hosts Elimination of alternative hosts • weeds • volunteers • adjacent crops
- 12. Evaluation of mustard vs. winter wheat cover crops in spinach seed production
- 13. Biomass (g/0.15 m2) of weeds and spinach seed crop on 6/13/03 following incorporation of mustard cover crops 12 10 8 6 4 2 0 Metam sodium B. juncea B. juncea + B. hirta Mustard seedmeal Winter wheat Weeds Spinach crop a b b b b
- 14. % weed control of shepherd’s purse & lambsquarters on 6/13/03, using mustard cover crops prior to spinach seed production 90 80 70 60 50 40 30 20 10 0 Metam sodium B. juncea B. juncea + B. hirta Mustard seedmeal Winter wheat Shepherds purse Lambs-quarters a ab abc bc c z z z z z
- 15. Disease management in seed crops: Cultural practices Destruction of inoculum in the field • remove, or reduce, amount of infected debris or remaining seed after harvest • reduce inoculum of soilborne pathogens • burn stubble/debris • vacuum fields • fumigation (synthetic, biofumigation) • soil solarization • incorporate infested debris into the soil
- 16. Overwintering of spinach leaf spot fungi in western Washington Cladosporium variabile on volunteer spinach Stemphylium botryosum on spinach seed stalk debris
- 17. Survival of Stemphylium botryosum on spinach debris: Surface vs. buried debris
- 18. Disease management in seed crops: Cultural practices Irrigation practices • reduce duration of leaf wetness, splash dispersal, relative humidity • e.g., drip vs. furrow vs. overhead irrigation • economics, practicality? • timing of irrigation
- 19. Incidence of plants on which Xanthomonas campestris pv. carotae was detected in drip vs. overhead-irrigated sections of 4 carrot seed OK OK-drip OL OL-drip OM OM-drip ON ON-drip Aug-03 Jun-03 Apr-03 14 12 10 6 4 2 0 8 16 Incidence (of 20 plants sampled) crops in central Oregon, 2002/03
- 20. Disease management in seed crops: Cultural practices Planting practices • planting date selected to escape inoculum - insect vectored pathogens - pathogens that don’t overwinter in the region • planting date selected for unfavorable conditions for pathogens &/or favorable for crop • row spacing, plant spacing • row orientation Ventilation practices • thinning • canopy management for maximum air circulation
- 21. Brassica seed crop ventilation through row orientation, row spacing, & staking/tying
- 22. Disease management in seed crops: Cultural practices Transplanting & hygiene • avoid mechanical injury during transplanting • avoid dipping transplants in water • mechanical transmission of pathogens by workers: - Septoria apiicola in celery - Xanthomonas campestris pv. campestris in cabbage - tobacco mosaic virus (TMV) transmission on hands of smokers
- 23. Disease management in seed crops: Cultural practices Geographical location • continental level: grow seed crops in environments unfavorable for disease - bean seed in ID & CA to avoid bacterial blights & anthracnose - pea seed ID, WA, CA to avoid Pseudomonas pisi & Ascochyta blight - crucifer seed in WA to avoid blackleg & black rot - sweet corn seed in ID & WA to avoid Fusarium ear rots • local level: avoid frost pockets, areas prone to fogs or dews
- 24. Disease management in seed crops: Chemical applications & seed treatment • organic & biological materials - e.g., sulfurs, coppers, Serenade, AQ10, Contans, … - 2002 Plant Health Progress article by McSpadden Gardener and Fravel - consistency, niche environments? - potential phytotoxicity • natural plant products - oils, plant extracts, compost teas, … - reliability, consistency? • bicarbonate fungicides - powdery mildews
- 25. 2000/01 Brussels sprouts seed crop fungicide trial White mold (Sclerotinia sclerotiorum) du Toit & Derie, 2002. Fungicide & Nematicide Tests 57:V013 a a 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 Control Pristine (BAS516) Elevate Serenade Rovral/Bravo Switch Incidence on 07/01/01 (% infected plants) a c c b b b
- 26. 2002/03 Cabbage fungicide trial White mold (Sclerotinia sclerotiorum) du Toit & Derie, 2004. Fung. & Nem. Tests 59:submitted a ab bc bcd cd cd cd cd cd cd cd d Incidence of plants with white mold (%)
- 27. In vitro efficacy of fungicides against Botrytis aclada, causal agent of neck rot/scape blight of onions 6 days after plating on fungicide-amended agar Colony diameter (mm) aab abc f bc f cd d e e fg ghh h hh hh h h hh hh hh hh hh hh hh hh
- 28. In vitro efficacy of fungicides against Botrytis aclada (7 days after plating on fungicide-amended agar)
- 29. Methods of seed treatment • physical • chemical • biological
- 30. Physical seed treatments • hot water - kill pathogens, not damage seed - Phoma lingam and Xanthomonas campestris pv. campestris on cabbage seed exposed to hot water at 50C for 30 minutes • hot dry air • aerated steam • microwaves • others, e.g., cathode rays, ultrasound
- 31. Chemical seed treatments • chlorine = surface disinfestation e.g., Xanthomonas campestris pv. carotae on carrot seed • fungicides – various products, but few qualify for organic production • insecticide seed treatments for vector control (e.g., Gaucho), but few organic Biological seed treatments • problems with consistency, few available • e.g.- Bacillus subtilis = Kodiak, HiStick N/T - Burkholderia cepacia = Deny
- 32. Efficacy of treatment with chlorine on eradication of seedborne inoculum of spinach leaf spot fungi Duration in Stemphylium Cladosporium NaOCl (% of seed infected/infested) (minutes) % NaOCl 1.2% 0.0 54.75 55.00 10.0 23.25 0.50 20.0 16.75 1.00 30.0 19.00 0.25 40.0 18.25 0.25
- 33. Disease management during harvest, storage & conditioning of seed • adjustment & manipulation of equipment to remove pathogen structures from seed lots (sclerotia, teliospores, etc.) • controlled storage conditions to avoid development of storage molds
- 34. Disease management practices in production crops • cultural practices to minimize impact of seed- or soilborne pathogens • seed treatments to minimize transmission of pathogens • test seed to ensure infection levels lower than inoculum threshold that can cause disease
- 35. Criteria for development/use of inoculum thresholds for seedborne pathogens • suitable seed health assay • incidence of infection on seeds correlated with plant infection • inoculum thresholds established by appropriate statistical analysis, e.g.: - X. campestris pv. campestris of crucifers - X. campestris pv. carotae on carrots in CA - lettuce mosaic virus
- 36. Methods for seed health testing • field inspections • direct visual examination • incubation • grow-out • indicator tests • serological • DNA hybridization Reasons for seed health testing • determine whether infection is below threshold • for quarantine or phytosanitary certification • to determine plant stand/health
- 37. Small-seeded vegetable seed crops grown in semi-arid regions of the PNW Umbelliferous seed crops carrot, coriander, dill, parsley, parsnip, … Cruciferous seed cops radish, daikon, turnip, kale, collard, kohlrabi, Chinese kale, Chinese mustard, … Allium seed crops onion, leek, chives, … Others
- 38. Diseases of small-seeded vegetable seed crops Umbelliferous seed crops • bacterial blights • Alternaria diseases: leaf blight, black rot • powdery mildew • phytoplasmas: aster yellows, BLTVA • viruses: motley dwarf, BCTV, AMV, … • root knot nematode • cavity spot, bacterial soft rot
- 39. Bacterial leaf blight Xanthomonas campestris pv. carotae
- 40. Bacterial blight Xanthomonas campestris pv. carotae
- 41. Alternaria leaf blight Alternaria dauci HHoowwaarrdd ee tt aall.. ((11999944))
- 42. carrot umbel infection by Alternaria dauci
- 43. Cercospora leaf spot Cercospora carotae
- 44. Alternaria lleeaaff bblliigghhtt AAlltteerrnnaarriiaa ddaauuccii CCeerrccoossppoorraa lleeaaff ssppoott CCeerroossppoorraa ccaarroottaaee BBaacctteerriiaall lleeaaff bblliigghhtt XXaanntthhoommoonnaass ccaammppeessttrriiss ppvv.. ccaarroottaaee
- 45. Black rot Alternaria radicina HHoowwaarrdd eett aall.. ((11999944)) SSnnoowwddoonn ((11999922)) SSnnoowwddoonn ((11999922))
- 46. Host range • Xanthomonas campestris pv. carotae carrot • Alternaria dauci carrot, parsley, Umbelliferous weeds • Alternaria radicina carrot, celery, parsley, parsnip, dill • Cercospora carotae carrot, other Daucus species
- 47. Incidence of plants on which X. campestris pv. carotae was detected in 14 carrot seed crops: WA, 2001/02
- 48. Population of X. campestris pv. carotae detected on stock seed & harvested seed of carrot seed crops: WA, 2001/02
- 49. Sampling debris/dust during threshing of seed crops Crop Distance # samples CFU/ft3 1 100’ 10 13.30 150’ 7 33.70 250’ 3 1.80 2 25’ 4 15.00 100’ 12 10.40 150’ 1 0.00 200’ 8 1.00 300’ 1 0.00 800 3 0.00 3 900’ 8 0.00 4 ~ 1 mile 5 0.02
- 50. Management of bacterial blight in carrot seed crops • pathogen-free seed or stecklings • avoid overhead irrigation, where possible • crop rotation • plow or disc infested residues • isolation from carrot root crops, seed crops • copper applications, chlorine?, compost teas?? • hot water seed treatment @ 122oF for 30 min • chlorine seed treatment (surface efficacy)
- 51. Management of Alternaria leaf blight in carrot seed crops • disease-free seed & stecklings • minimum 2-3 year crop rotation • plow or disc infested residues • fungicides - coppers - Bravo, Terranil (chlorothalonil) - Quadris - Rovral (foliar & seed treatment) - applications based on disease severity - new fungicides: Cabrio, Pristine, Folicur, …? • seed treatments - thiram, Rovral, Maxim, hot water, chlorine
- 52. Management of black rot in carrot seed crops • disease-free seed, stecklings • 8+ year crop rotation • plow or disc infested residues • avoid overhead irrigation, where possible • resistance • fungicides - coppers - Rovral 4F (foliar, seed treatment) - new (Maxim, Quadris, Pristine, …) • seed treatments - hot water @ 122oF for 30 min - hot chlorine (0.1-1.0% @ 122oF for 30 min)
- 53. Powdery mildew Erysiphe heraclei
- 54. Powdery mildew in carrot seed crops • no yield loss if infection occurs > mid-June, otherwise seed yield/quality reduced • remove wild/volunteer carrots • isolate crops • pathogen-free stecklings • fungicides: - Kaligreen (potassium bicarbonate) - sulfurs (e.g., Kumulus DF, Microthiol Disperss) - Quadris F - AQ10 biofungicide (incompatible with some fungicides)
- 55. Phytoplasmas Aster yellows & Beet leafhopper-transmitted virescence agent (BLTVA)
- 56. Aster yellows, Beet leafhopper-transmitted virescence agent (BLTVA)
- 57. Phytoplasmas in seed crops • leafhopper transmitted • more prevalent after mild winters • isolate from alternative & weedy hosts (?) Aster yellows/BLTVA: onion, Umbelliferous crops, Cruciferous crops, tomato, lettuce, many weeds, some ornamentals • insecticides for leafhopper control - variable efficacy - timing relative to leafhopper migration
- 58. Beet curly top virus (BCTV) beet leafhopper
- 60. Beet Curly Top Virus (BCTV) in seed crops • beet leafhopper • more prevalent after mild winters • extensive host range - mustards, in perennial or winter annual weeds • insecticides for leafhopper control - variable efficacy - timing relative to leafhopper migration • resistance (?)
- 61. Diseases of small-seeded vegetable seed crops Allium seed crops • gray mold/scape blight/neck rot • black mold • bacterial soft rots • Fusarium basal rot • viruses ?? iris yellow spot virus = IYSV
- 62. Botrytis scape & flower blight B. allii B. squamosa, B. cinerea, B. byssoidea
- 64. 2001/02 survey of onion seed crops in WA Incidence (%) of plants infected with Botrytis allii a Visual symptoms Plants sampled in the fieldb 9/01 11/01 4/02 6/02 7/02 9/01 11/01 4/02 6/02 7/02 Field & irrigation A (spr) 5 5 15 100 100 0 0 0 0 7 B (spr)c 3 0 - - - 0 0 - - - C (furr) 15 3 70 100 100 0 0 0 0 16 D (furr) 8 10 95 100 100 0 0 2 5 10 E (furr) 63 0 70 100 100 0 0 0 2 10 F (furr) 8 3 25 100 100 0 0 1 6 7 G (furr) 18 3 30 95 100 0 0 0 2 4 H (spr)d - - 65 90 100 - - 0 0 17 Mean 19.6 3.2 52.9 97.9 100 0.0 0.0 0.4 2.1 8.7 a 20 or 40 plants sampled randomly per field b 100 plants rated for symptoms of neck/bulb rot, scape/umbel blight c Crop plowed under in 03/02 d Bulb-to-seed crop
- 65. 2001/02 survey of 7 onion seed crops in WA Incidence (%) of seed infected/infested with Botrytis spp.a Stock seed Harvested seed Internalc Externalc Internal B. allii B. allii B.allii B.porri Aspergillus Field & irrigationb A (sprinkler) F,M = 0.00 F,M = 0.75 0.25 0.00 55.25 B (sprinkler) F,M = 0.00 - - - - C (furrow) - - 6.00 0.00 33.75 D (furrow) - - 5.50 0.00 23.00 E (furrow) 1.50 0.75 28.25 0.00 9.00 F (furrow) - - 3.75 0.25 48.75 G (furrow) 3.00 6.75 1.50 0.00 0.75 H (sprinkler) bulb-to- - - 0.00 0.00 27.75 seed Mean 1.13 2.06 6.46 0.04 28.32 a 400 seed/field; F = female parent, M = male parent; - = seed unavailable b sprinkler = overhead irrigation c Internal = 60 sec. rinse in 0.5% NaOCl + triple H2O rinse; External = 60 min. rinse in H2O
- 66. Management of Botrytis in onion seed crops • pathogen-free seed, treated seed • fungicides seed treatment (hot water, Thiram, Rovral, chlorine) foliar sprays (e.g., Rovral, Bravo, Switch) new fungicides (Serenade, Switch, Pristine, Endura, Botran, …) • “healthy” crop • sanitation (volunteers, culls, debris) • rotation & isolation from other Allium crops • well-dried umbels <harvest, artificial drying
- 67. Iris yellow spot virus IYSV
- 68. Iris yellow spot virus (IYSV) in Allium seed crops • onion thrips, not Western flower thrips • not known to be seedborne, nor present in bulbs • can cause significant yield losses (bulb & seed crops) • range from symptomless to striking • host range onion, garlic, leek, chive, iris, Nicotiana benthamiana & N. rustica, Datura stramonium • Brazil, Israel, Holland, US – western states
- 69. Diseases of small-seeded vegetable seed crops Crucifer seed crops in semi-arid PNW • viruses/BLTVA • white rust • powdery mildew • Alternaria leaf/pod spot • white mold • damping-off/seedling blight fungi (Rhizoctonia, Aphanomyces, Pythium) • black leg??
- 70. White rust of radish Albugo candida
- 71. White rust of radish seed crops • light green spots; white, raised blisters • abnormal growth on seed stalk (“staghorn”); seed may not form • seed yield & quality may be reduced severely • select isolated fields • host range radish, rapeseed, mustards (including wild mustard) control wild mustards • resistance (some daikon cultivars) • incorporate debris after harvest • fungicides: seed treatment - captan, thiram at planting – Ridomil Gold
- 72. Root rots/damping off of Crucifer seed crops Aphanomyces, Pythium, Fusarium • blue-black lesions on roots • constricted lesions, sometimes girdling • discolored radial streaks • general root rot, damping-off • plant in well-drained soils, avoid overwatering • > 3 year crop rotation • fungicide treatment: e.g., Quadris in-furrow or banded
- 74. Small-seeded vegetable seed crops grown in the maritime coastal region of the PNW Chenopodiaceous seed crops spinach, table beet, Swiss chard Cruciferous seed crops cabbage, Brussels sprouts, cauliflower, Chinese cabbage, … Others
- 75. Spinach leaf spot fungi: Cladosporium leaf spot Stemphylium leaf spot Anthracnose
- 76. SStteemmpphhyylliiuumm bboottrryyoossuumm CCllaaddoossppoorriiuumm vvaarriiaabbiillee Photo by M.L. Derie
- 77. Pleospora herbarum = sexual stage of S. botryosum
- 78. Seedborne potential of leaf spot fungi Pseudothecia of Pleospora herbarum & conidia of Stemphylium botryosum Conidiophores & conidia of Cladosporium variabile (top right & lower left) & a Cladosporium sp. (top left & lower right)
- 79. Spinach anthracnose: Colletotrichum dematium = C. spinaciae Photo by M.L. Derie
- 80. Spinach anthracnose: Colletotrichum dematium = C. spinaciae http://www.hgic.umd.edu/diagn/veg/anthracnose_fruit.html
- 81. acervuli Spinach anthracnose: Colletotrichum dematium = C. spinaciae setae
- 82. conidia setae Spinach anthracnose: Colletotrichum dematium
- 83. Cladosporium leaf spot, Stemphylium leaf spot, & anthracnose of spinach Cladosporium variable Distinct, develop dark margin Spores in lesions + (abundant in + (in acervuli) moist conditions) Stemphylium botryosum Diffuse, rapidly expanding Seedborne + + + Wind, seed Volunteers, seed Moist, cool Host range > Chenopods? Spinach Spinach Splashing water, seed Dispersal Wind, seed Seed stalk Volunteers, seed debris, seed Overwintering Moist, warm, Wet, cool pollen Favorable conditions + (in moist conditions) Distinct, coalesce Leaf spot symptoms Colletotrichum dematium
- 84. Beet & chard leaf spot fungi: Phoma leaf spot Ramularia leaf spot Cercospora leaf spot
- 85. Phoma leaf spot of beets & chard: Phoma betae Barnett & Hunter, 1972
- 86. Photo by L.J. du Toit Phoma leaf spot of beet/chard: Phoma betae pycnidia holdfasts on water agar
- 87. Photo by D.A. Inglis Ramularia leaf spot of beet & chard: Ramularia betae Barnett & Hunter, 1972
- 88. Cercospora leaf spot of beet/chard: Cercospora beticola Photos at NDSU website: http://www.ext.nodak.edu /extpubs/plantsci/rowcro ps/pp1244w.htm
- 89. Cercospora leaf spot of beet/chard: Cercospora beticola Cercospora conidia http://www.ext.nodak.edu/extpub s/plantsci/rowcrops/pp1244w.htm
- 90. Cercospora leaf spot, Ramularia leaf spot, and Phoma leaf spot of beets/chard Cercospora beticola Circular leaf spots, red-brown margin, older leaves; Crown lesions Minute black dots (stromata) in spots Ramularia betae Light brown leaf spots, angular & larger, older leaves Seedborne + (external) + (?) + Dispersal Splashing water, wind, Wind Splashing water, insects insects Overwinter Weeds, debris Debris Soil, roots, debris, weeds Fav. conditions Warm, moist Cool, moist Cool to warm, moist Host range Beet, chard, Chenopod. Beet, chard Beet, lambsquarter weeds Silvery gray to white in spots Black pycnidia in leaf spots, on crowns Spores in leaf spots Round leaf spots, concentric rings on perimeter, dark margin; Seedling black leg; Crown rot Symptoms Phoma betae
- 91. Crucifer foliar pathogens: Alternaria leaf spot Ring spot Bacterial diseases
- 92. Alternaria leaf/pod spot of crucifers: Alternaria brassicicola & A. brassicae
- 93. Alternaria leaf/pod spot of crucifers Alternaria brassicicola smaller spores in chains, no beak Photo from R.L. Gabrielson Alternaria brassicae larger spores, not in chains, long beak beak conidiophore
- 94. Alternaria leaf/pod spot of crucifers: Alternaria brassicicola & A. brassicae
- 95. Alternaria leaf/pod spot of crucifers: Alternaria brassicicola & A. brassicae chains of conidia of A. brassicicola
- 96. Ring spot of crucifers: Mycosphaerella brassicicola Photos by L.J. du Toit Photo from R.L. Gabrielson
- 97. Ring spot of crucifers: Mycosphaerella brassicicola Photo from R.L. Gabrielson
- 98. sterile spermagonia & “conidia” Ring spot of crucifers: Mycosphaerella brassicicola Drawings from CMI Descriptions of Pathogenic Fungi & Bacteria No. 468 perithecium with asci & ascospores ascus & ascospores
- 99. Black leg of crucifers: (Phoma lingam, sexual stage = Leptosphaeria maculans) asci & ascospores Drawings from CMI Descriptions of Pathogenic Fungi & Bacteria No. 331 conidia ascospores pycnidium with conidia perithecium with asci & ascospores
- 100. Alternaria leaf/pod spot & ring spot of crucifers Alternaria leaf/pod spot Black circular - irregular lesions; necrotic center; black spots on pods & racemes Naked spores Ring spot Circular lesions, definite margin & chlorotic halo, concentric zonation; lowest leaves Symptoms Seedborne + - Dispersal Wind, insects Splashing water, insects Overwinter Debris, biennial seed crops Debris, biennial seed crops Favorable conditions Moist, warm Moist, cool Host range Crucifers, beet Crucifers Black pycnidia &/or perithecia in concentric rings Spores in leaf spots
- 101. Black rot of crucifers: Xanthomonas campestris pv. campestris
- 102. Black rot of crucifers: Xanthomonas campestris pv. campestris
- 103. Black rot of crucifers: Xanthomonas campestris pv. campestris Photos from R.L. Gabrielson
- 104. Xanthomonas leaf spot of crucifers: Xanthomonas campestris pv. armoraciae/raphani
- 105. Peppery leaf spot of crucifers: Pseudomonas syringae pv. maculicola Photos from PetoSeed
- 106. Xanthomonas campestris & Pseudomonas syringae pathogens of crucifers Xanthomonas leaf spot Xanthomonas leaf spot Circular, water-soaked leaf spot, chlorotic halo; dark lesions on petioles - Peppery leaf spot P. s. pv. maculicola Black rot X. c. pv. X. c. pv. raphani X. c. pv. armoraciae campestris Pathogen Symptoms Seedborne + Dispersal Splashing water, seed, insects Overwinter Debris, Crucifer weeds, soil Favorable Cool to warm, Cool, wet conditions extended wet periods Cabbage, broccoli, cauliflower, kale, radish, horseradish Cool to warm, extended wet periods Cabbage, broccoli, cauliflower, kale, radish, tomato, pepper Yellow leaves, wilting, black veins Warm to hot, wet Crucifers (including weeds) Cabbage, broccoli, cauliflower, Br. sprouts, turnip Host range + Circular to angular spots, chlorotic halo Systemic
- 107. Bacterial leaf spot of beet: Pseudomonas syringae pv. aptata Photos at http://www.ext.nodak.edu/extpubs/plantsci/rowcrops/pp1244w.htm
- 108. Pseudomonas leaf spot diseases of spinach & beet P. syringae pv. spinaciae Irregular, water-soaked spots; older lesions dark brown to black, angular; lesions visible from top & bottom of leaf P. syringae pv. aptata Circular to irregular leaf spots, tan center, dark margin; leaf margins; coalesce to ragged appearance Symptoms Seedborne - (?) + Splashing water, machinery Debris? Wet, cool? Spinach, others? Beet, chard, bean, eggplant, lettuce, and pepper Host range Splashing water, insects, machinery Dispersal Overwinter Debris, Favorable Wet, cool conditions
- 109. White mold: Sclerotinia sclerotiorum
- 111. sclerotia Photo by M.L. Derie apothecia Photo by L.J. du Toit
- 114. asci with ascospores ascospores
- 116. Sclerotinia sclerotiorum • extremely broad host range (p. 27 of “2003 PNW Disease Mngmt Hdbk”) • long-lived (sclerotia) • favorable conditions: extended periods of moist conditions high humidity - dense canopy, rain, irrigation, dew cool or warm temperatures
- 117. Wilt diseases: Fusarium oxysporum & Verticillium dahliae
- 118. Wilt diseases: Fusarium osysporum vs. Verticillium F. oxysporum Soilborne + + Seedborne + + Host range Narrow (specific) Broad Survival in soil Long-term Long(er)-term Warm, “dry” Warm, “dry” Favorable conditions for infection/symptoms Verticillium
- 119. Wilt diseases: Fusarium oxysporum Asympto-Forma specialis Symptomatic host matic host Spinach F. oxysporum Beet Spinach f. sp. betae Swiss chard Cabbage (strains 1 & 5) Brussels sprout, cauliflower, collard, kale, mustards, rape, rutabaga, … (strain 1) Flowering stock (strains 3 & 4) F. oxysporum f. sp. conglutinans Radish (formerly strain 2 of F. oxysporum f. sp. conglutinans) F. oxysporum f. sp. raphani Beet Swiss chard F. oxysporum f. sp. spinaciae
- 120. Fusarium wilt of radish: F. oxysporum f. sp. raphani
- 121. Fusarium wilt of radish: F. oxysporum f. sp. raphani
- 122. Fusarium wilt of radish: F. oxysporum f. sp. raphani Photo by D.A. Inglis
- 123. Fusarium wilt of spinach: F. oxysporum f. sp. spinaciae
- 124. Fusarium wilt of spinach: F. oxysporum f. sp. spinaciae
- 125. Verticillium wilt vs. Fusarium wilt of spinach Verticillium wilt Fusarium wilt
- 126. Verticillium wilt vs. Fusarium wilt of spinach Verticillium wilt Fusarium wilt
- 127. Fusarium wilt Verticillium wilt Control
- 128. Systemic infection by Verticillium Non-inoculated control Inoculated with V. dahliae
- 129. Verticillium wilt vs. Fusarium wilt of spinach Verticillium wilt Fusarium wilt
- 130. Verticillium wilt of spinach
- 131. Spinach wilt: Fusarium oxysporum vs. Verticillium dahliae Fusarium wilt Any stage in development General wilting, flaccid, off-green, death Verticillium wilt Only after bolting & initiation of seed set Oldest leaves 1st, initial interveinal chlorosis, then necrosis Symptoms Foliar symptoms Reddening of stem + + External root Black None/Light brown discoloration Vascular discoloration Black Light brown Seedborne/transmitted +/+ +/+ Host range Chenopodiaceae Broad Host resistance + ?
- 132. Verticillium wilt: Verticillium dahliae & V. albo-atrum Crucifer hosts: Susceptible = cauliflower, Brussels sprouts, cabbage Resistant = broccoli, mustards Chenopod. hosts: Spinach, beets, chard Other hosts: Numerous! Dependant on vegetative compatibility group (VCG)
- 133. Virus diseases of Chenopodiaceous & Cruciferous vegetables
- 134. Tools & techniques for diagnosis of virus diseases • symptoms • signs • virus inclusion bodies - light microscopy • virions - electron microscopy • host range studies • vector transmission evaluations • local lesion assays • biochemical/physical tests • immunological assays – ELISA, immunogold labeling, … • molecular (DNA or RNA) assays – PCR
- 135. Virus diseases of Crucifers: Turnip mosaic virus (TuMV)
- 136. Virus diseases of Crucifers: Cauliflower mosaic virus (CaMV)
- 137. Viruses diseases of Crucifers: CaMV vs. TuMV CaMV Mosaic, veinal chlorosis, leaf distortion, premature flowering Several aphids: e.g., green peach aphid, cabbage aphid Vector Transmission Non-persistent Seedborne - Survival Cruciferous weeds Crucifers, lettuce, endive, spinach, zinnia, petunia, … Host range Crucifers only Black necrotic ring spots; mosaic, leaf distortion, necrosis Symptoms TuMV
- 138. Virus diseases of spinach: Cucumber mosaic virus (CMV)
- 139. Virus diseases of spinach: Cucumber mosaic virus (CMV) crown leaves narrow, curled, wrinkled, margins roll in leaves yellow and die stunting symptoms develop faster at high temperatures aphid transmitted overwinters in perennial weeds, builds up in vegetables (especially cucurbits) spread by many aphids
- 140. Virus yellows of beet Host Sheph. Chenop. Virus Name Range Purse capitatum Closterovirus BYV Beet Yellows Virus narrow - + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Luteovirus BWYV Beet Western Yellows Virus wide + - BChV Beet Chlorosis Virus narrow - + BMYV Beet Mild Yellows Virus intermed. + + Table provided by R.T. Lewellen, USDA ARS, Salinas, CA
- 141. Virus diseases of beet & chard: Beet western yellows virus (BWYV)
- 142. Virus diseases of beet & chard: Beet yellows virus (BYV) Photos provided by R.T. Lewellen
- 143. Virus diseases of beet & chard: Beet mosaic virus (BMV) http://www.ipm.ucdavis.edu/PMG/B/D-SB-BMOV-FO.001.html
- 144. Important aphid-borne viruses of beets: BWYV, BYV, BMV BYV BWYV Interveinal yellowing (older leaves first); red-brown spots between veins (bronze cast); thick, leathery, brittle leaves; poor root growth Symptoms Vector BMV Yellow circular spots (young leaves); puckered leaves with mottling; stunting Transmission Semi-persistent Non-persistent Alternative hosts Overwintering seed crops, weed hosts Mainly Chenopodiaceae Persistent Aphids (many) Seedborne - Alternative crop & weed hosts Survival Host range Very broad Moderate
- 145. Virus diseases of beet & chard: Rhizomania Beet necrotic yellow vein virus (BNYVV) & soilborne fungus Polymyxa betae Photos provided by R.T. Lewellen
- 146. Virus diseases of beet & chard: Rhizomania Photos provided by R.T. Lewellen
- 147. Virus diseases of beet & chard: Rhizomania root stunting, proliferation, vascular discoloration upright, yellow leaves, proliferation of leaves distinct veinal yellowing is rare but diagnostic wilting in higher temperatures vectored by the soilborne fungus, Polymyxa betae vector favored by saturated soils spreads in infected soil, on plants vector survives in soils >10 years potential yield loss is high found in sugarbeet fields along Columbia River in 2000 concern re. table beet seed industry in PNW
- 148. Some other viruses of spinach, beet & chard Photos provided by R.T. Lewellen Beet chlorosis virus (BChV) - non-persistent aphid vector -interveinal yellowing Beet curly top virus (BCTV) -beet leafhopper vector -very broad host range - stunting, hairy roots, thickened & rolled leaves
- 149. Monitoring diseases • appearance/development • threshold populations • need for control • effectiveness of actions