Cause hyperplasia and hypertrophy of leaves, flowers and fruit. Important on peach, nectarine, and plum. In humid areas Eastern US and Europe. Life cycle Disease causes fruit and leaf drop, the first symptoms are swelling and distortion downward and inward. Leaves show signs of stress turning reddish and finally gray powdery as fungus sporulates.
Leaves are chlorotic and drop.
Mycelium is dikaryotic and overseasons as ascopores on buds and fallen leaves. Grow intercelluarly no haustoria and cause great cell enlargement. White to grey powdery mildew on both sides of the leaf occurring during dry weather. Whitish mycelium can cover the whole plant and the plant eventually becomes yellow to necrotic. Tiny Cleistothecia begin as white pin points develop into black cleistothecia in older necrotic tissue late in the season.