Disease Management of Cucurbits

Transcription

1 Disease Management of Cucurbits Bacterial spot (bacterial leaf spot) Powdery mildew Anthracnose Sclerotinia blight on fruit Mohammad University of Illinois Bacterial spot (bacterial leaf spot) The causal pathogen is Xanthomonas cucurbitae Bacterial spot is an emerging, highly important disease of pumpkin and squash in Illinois and other states in the Midwest Bacterial Spot of Pumpkin Bacterial spot (bacterial leaf spot) Bacterial spot on jack-o-lantern pumpkin Bacterial spot (bacterial leaf spot) 1

2 Bacterial spot on processing pumpkin Bacterial spot on squash fruit Collapse of pumpkin fruit infected with Xanthomonas cucurbitae Colonization of bacterial-infected fruit by other organisms Surveys NW: 2010 surveyed: 12 with disease: 8 (67%) - Infect. fruit: 54% 50 Fields NW NE NE: surveyed: 12 disease: 11 (92%) - Infect. fruit: 39% SW: surveyed: 12 with disease: 9 (75%) - Infect. fruit: 15% SW SE SE: surveyed: 14 disease: 12 (86%) - Infect. fruit: 28% 2

3 02/12/13 Bacterial Spot of Pumpkins in Illinois (2010) No. fields surveyed: 50 Fields with infected fruit: 40 (80%) Overall infected fruits: 34% Fields with > 90% infected fruit: 3 (6%) Fields with > 80% infected fruit: 4 (8%) Fields with > 50% infected fruit: 9 (18%) NW: surveyed: 22 disease: 18 (82%) - Infect. fruit: 33% SW: surveyed: 13 disease: 10 (77%) - Infect. fruit: 7% Fields: 54 JOK 11 Proc. NW SW NE SE NE: surveyed: 14 disease: 14 (100%) - Infect. fruit: 21% SE: surveyed: 16 disease: 15 (94%) - Infect. fruit: 32% Bacterial Spot of Pumpkins in Illinois (2011) No. fields surveyed: 65 Fields with infected fruit: 57/65 (88%) JOL fields with infected fruit: 48/54 (89%) Proc. P. fields with infected fruit: 9/11 (82%) Overall infected fruit: 24% Infected fruits in JOL pumpkin field: 24% Infected fruits in Proc. pumpkin field: 24% Bacterial Spot of Pumpkins in Midwest (2011) State surveyed: IA, IN, KS, MO, NB, OH, WI No. fields surveyed (all JOL): 46 Fields with infected fruit: 38/46 (83%) Overall infected fruit: 30% Bacterial Spot of Pumpkins in the Midwest, 2012 State Fields surveyed (no) Fields with infected fruit [# (% )] Infected pumpkins (%) Illinois (88%) 34 Iowa 8 4 (50%) 8 Indiana 7 7 (100%) 62 Kansas 5 5 (100%) 30 Missouri 6 3 (50%) 14 Nebraska 5 5 (100%) 54 Ohio 9 9 (100%) 32 Wisconsin 6 5 (83%) 18 Bacterial Spot 3

4 Bacterial spot on pumpkins, Austria ( Europe) Culture of Xanthomonas cucurbitae Survival of Xanthomonas cucurbitae Survival of Xanthomonas cucurbitae In an experiment, we kept leaf and fruit infected with Xanthomonas cucurbitae on soil surface and buried in the ground We processed the samples every 3 months So far, we have been able to re-isolate Xanthomonas cucurbitae from the samples Survival of Xanthomonas cucurbitae We processed the samples every 3 months So far, we have been able to re-isolate Xanthomonas cucurbitae from the samples Survival of Xanthomonas cucurbitae Conclusion: Xanthomonas cucurbitae survives in infected leaves and fruit in commercial fields for at least 12 months For management of the disease, two-year crop rotation with noncucurbit crops is needed 4

5 Host-Range of Xanthomonas cucurbitae We have tested Xanthomonas cucurbitae on cucurbits, other crops grown in Illinois, and weeds in cucurbit fields So far, Xanthomonas cucurbitae was proved pathogenic on species of the Cucurbitaceae family only Xanthomonas cucurbitae on cantaloupe in greenhouse Tomato Eggplant Pepper Mustard Host-Range of Xanthomonas cucurbitae Conclusion: Host-range of Xanthomonas cucurbitae is likely limited to species in the Cucurbitaceae family Xanthomonas cucurbitae on other crops Seed-Borne Aspect of Xanthomonas cucurbitae Most of Xanthomonas species are seed-borne Although Xanthomonas cucurbitae has been reported as a seed-borne pathogen, seed-borne aspect of this bacterium has not been well-documented We have been trying to determine seedborne importance of X. cucurbitae Collecting seeds from infected fruits 5

6 Seed-Borne Importance of X. cucurbitae _ Conclusion: Xanthomonas cucurbitae is associated with pumpkin seed We have not determined the exact location of X. cucurbitae in seed yet Moving X. cucurbitae from seed to seedling has not been documented yet More studies are needed to document seed-borne importance of X. cucurbitae Management of Bacterial Spot No cucurbit cultivar resistant to Xanthomonas cucurbitae has been determined yet Pathogen-free seed should be planted Two-year crop rotation with non cucurbit crops is necessary Some compounds (coppers and others) reduced disease severity (See Handout) More research is underway Powdery mildew Powdery mildew is caused by two fungal pathogen Powdery mildew occurs in cucurbit fields in Illinois every year Powdery mildew reduces yield and quality Powdery mildew on vines Management of Cucurbit Powdery Mildew Resistant cultivar: available Fungicides: very effective fungicides are available (See Handout) Powdery mildew on leaves 6

7 Anthracnose Anthracnose is caused by the fungus Colletotrichum orbiculare Is a common disease of cucumber, muskmelon, and watermelon Has become frequently occurring disease on pumpkin and squash Anthracnose of cucurbits Anthracnose of pumpkin Management of Cucurbit Anthracnose _ Grow resistant cultivars, as available Plant certified, pathogen-free seed Crop rotation with non-cucurbits, 3 years Control weeds and volunteer cucurbits Do not work in wet condition in the field Apply fungicide (e.g., chlorothalonil, strobilurin) Sclerotinia blight on fruit Caused by the fungus Sclerotinia sclerotiorum Is a fruit disease 7

8 Management Sclerotinia Blight _ Limited information is available on Sclerotinia blight on cucurbits Crop rotation with non-cucurbits, 3 years Deep plowing after harvest Moisture management (low moisture) Fungicide application: Topsin-M, Flint, and Fontelis are expected to be effective Research Money (Acknowledgements) North Central IPM SARE Program IL Department of Agriculture, Specialty Crops Chemical companies Fungicide Name Commercial Fontelis 1.67SC (DuPont) Common FRAC Code penthiopyrad 7 Crop Target Diseases Bulb Gray mold, PM, vegetables Purple blotch Alternaria, Gray Brassicas mold, PM, Sclerotinia rot Alternaria, Gray mold, Gummy stem Cucurbits blight, PM, Sclerotinia rot Fruiting Alternaria, Early vegetables blight, Gray mold, (tomato, PM, Septoria leaf pepper, ) spot, Target spot Fungicide Name FRAC Crop Target Diseases Code Commercial Common Fontelis 1.67SC (DuPont) penthiopyrad 7 Alternaria, Cercospora, Early Leafy blight, Gray mold, vegetables PM, Rust, Septoria leaf spot, Sclerotinia rot Alternaria, angular leaf spot, anthracnose, Legume Ascochyta blight, vegetables Cercospora, Gray mold, PM, Rust, Septoria blotch, Sclerotinia rot Fungicide Name FRAC Commercial Common Code Crop Target Diseases Fontelis Alternaria, Root Cercospora, Gray 1.67SC penthiopyrad 7 vegetables mold, PM, (DuPont) (Beet,.) Southern blight, Rust, White mold Quash 50WDG (Valent) Torino 10SC (Gowan) metconazole 3 Tuber & corm Black dot, Brown vegetables spot, Early blight, (artichoke, Gray mold, ginger, Powdery mildew, potato, White mold.) cyflufenamid U6 Cucurbits Powdery mildew Fungicide Name FRAC Target Crop Code Diseases Commercial Common Kumulus 80DF (Arysta LifeSci.) sulfur M Presidio 4SC (Valent) fluopicolide 43 Artichokes Leaf spot Asparagus Rust Cucumber, Powdery melon, squash mildew (MP) Carrot PM Onion & garlic PM Eggplant PM Lettuce PM, Rust Mint PM Beets PM Brassicas Downy mildew, Phytophthora Root & tuber Pythium crops diseases 8

9 Fungicide Name FRAC Target Crop Commercial Common Code Diseases Zampro SC (BASF) ametoctradin + dimethomorph Brassicas Down mildew Bulb veg (Onion, Down mildew garlic, ) Down mildew, Phytophthora capsici Cucurbits Fruiting veg (eggplant, pepper, tomato) Late blight, Phytophthora capsici Questions/ Comments 9