Downy mildew—Pseudoperonospora cubensis
Downy mildew attacks all cucurbits, although cucumber is the most commonly infected. It appears first
as small, pale green to yellow, angular spots delimited by leaf veins that give the foliage a mottled
appearance. Eventually the spots coalesce and the leaf will turn brown. During moist weather, the lower
surface of the leaf may be covered with a white to purple growth. Older leaves become infected first.
Identification
SolutionsSpores of the downy mildew fungus are carried by air currents or by rain-splash or sprinklers. A wet
leaf surface is required for infection. Avoid using overhead sprinklers. Spacing plants to reduce canopy
density and humidity will reduce spread. Some varieties of cucumber, melons, and watermelons may show
resistance. |
Downy
mildew on cantaloupe leaf
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