Individual spots are gray with a dark border. Later, the center of the lesion drops out, giving a ragged effect. Downy Mildew Plasmopara viticola , the cause of downy mildew, attacks all green parts of the vine. Initially, lesions are yellowish and oily, and become angular, yellow to reddish brown spots. Infected shoots thicken and curl, then turn brown and die.
Young berries become gray when infected.
Rachis infection can spread into older berries causing a brown rot. All infected parts, except older fruit, are covered with white fungal growth during moist weather. The fungus overwinters primarily in infected leaves on the ground. It may survive as mycelium in buds during mild winters. Pre bloom sprays are necessary for control.