Identification Symptoms
- The fungus is an obligate pathogen which can attack all green parts
of the vine.
- Symptoms of this disease are frequently confused with those of
powdery mildew. Infected leaves develop pale yellow-green lesions which
gradually turn brown. Severely infected leaves often drop prematurely.
- Infected petioles, tendrils, and shoots often curl, develop a
shepherd's crook, and eventually turn brown and die.
- Young berries are highly susceptible to infection and are often
covered with white fruiting structures of the fungus. Infected older
berries of white cultivars may turn dull gray-green, whereas those of
black cultivars turn pinkish red.