Mention the symptoms of downy mildew of grapes?

Answer Posted / swapna

On leaves, young infections are very small, greenish-
yellow, translucent spots that are difficult to see. With
time the lesions enlarge, appearing on the upper leaf
surface as irregular pale-yellow to greenish-yellow spots
up to 1/4 inch or more in diameter. On the underside of the
leaf, the fungus mycelium (the "downy mildew") can be seen
within the border of the lesion as a delicate, dense, white
to grayish, cotton-like growth. Infected tissue gradually
becomes dark brown, irregular, and brittle. Severely
infected leaves eventually turn brown, wither, curl, and
drop. The disease attacks older leaves in late summer and
autumn, producing a mosaic of small, angular, yellow to red-
brown spots on the upper surface. Lesions commonly form
along veins, and the fungus sporulates in these areas on
the lower leaf surface during periods of wet weather and
high humidity.

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