| Leaf blotch is present
throughout the eastern United States. It can affect many types of grapes
but is most often found on leaves of American rootstock cultivars. Leaf
lesions appear after mid-season. Lesion size ranges from 1/25 to 2 inches
(1 to 50 mm). Small lesions have dark margins, and large lesions have light-colored,
zonate rings. Stalked fruiting structures are produced within 3 to 4 days
of the appearance of the lesion, usually on the lower leaf surface. The
fungus may also sporulate on overripe berries. The fungus overwinters in
infected plant debris. |
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