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AVRDC International
Cooperators'
Fact Sheet |
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Cucurbit Diseases Powdery Mildew Erysiphe cichoracearum and Sphaerotheca fuligena Found worldwide |
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Damage Symptoms All cucurbits are susceptible to powdery mildew, but watermelon is least affected. Symptoms appear first as pale yellow spots on leaves and stems. Soon thereafter sporulation becomes evident as white powdery masses of conidia are produced over the lesion surface. Lesions frequently are numerous and coalesce to cover the enter leaf surface. Leaves become chlorotic, then turn brown and dry prematurely. |
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Conditions for Development The pathogens are obligate parasites
and can persist on wild cucurbits or crop plants throughout the
year in tropical and subtropical areas. Disease development can
occur over a wide range of temperatures as long as there is sufficient
moisture for spore germination and infection. These conditions
can be provided by high relative humidity or dew formation in
the absence of rainfall. Use resistant cultivars when available. Fungicidal sprays offer good protection for susceptible cultivars. |
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Last updated: 2001. Information from: Vegetable Diseases: A Practical Guide. Lowell L. Black, AVRDC. |
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