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How to Manage PestsUC Pest Management Guidelines
CucurbitsAnthracnosePathogen: Colletotrichum lagenarium(Reviewed 11/05, updated 6/08, pesticides updated 5/16) In this Guideline: Symptoms and SignsIn California, anthracnose is unusual on cucurbit crops other than seedless watermelon. It can cause leaf, fruit, and/or stem lesions. Foliage lesions are tan to brown except on watermelon foliage where they are dark brown to black. Fruit may develop brown to black, sunken, water-soaked spots. Tiny, black fruiting structures, called acervuli, form within the lesion. In wet weather, pink or orange spores ooze from these fruiting bodies. Comments on the DiseaseThe fungus overwinters on cucurbit plant residue in the soil, on volunteer cucurbits, or on cucurbit seed. Disease development is favored by warm, wet weather. This disease is rarely seen in the field and more often occurs on transplants raised in the greenhouse. ManagementThere is resistance in some varieties of watermelon and cucumber, but not in seedless watermelon. Control tactics include crop rotation, use of clean seed, and inspection of transplants. Avoid sprinkler irrigation and keep the tops of the beds dry. Fungicides are rarely needed in California but may be required on seedless watermelons at the first sign of disease.
PUBLICATION UC IPM Pest Management Guidelines: Cucurbits Diseases
R. M. Davis, Plant Pathology, UC Davis Acknowledgment for contributions to Diseases:W. D. Gubler, Plant Pathology, UC Davis |