Black Rot (fungus - Guignardia bidwellii): Black rot shows up as small, reddish-brown spots on the upper leaf surface. In older lesions the margin is a black line while the inner area of the spot is brown. Small, black dots are also visible in the center of the lesion. Infected fruit shrink until they are dried mummies. The first stage of development on the fruit is small, light-colored lesions with black borders. In advanced stages the fruit is marked with the small, black dots just like the foliage. Young grape foliage is most susceptible to this disease. Disease development is favored by high temperatures and humidity. A rainy period followed by two to three days of foggy weather favors development of this disease. Preventative fungicides along with resistant varieties should be used to control black rot.

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