Under moist conditions, these blotches enlarge rapidly. A white, fuzzy growth of fungus may also be seen on the undersides of the leaves. Infected plants eventually wither and die. Elongated black cankers develop on the stem and leaf petioles. A whitish mold may cover the infected tissue during moist weather.
Late blight is favored by rainy, foggy periods with cooler temperatures.
For disease control use only disease-free transplants. A fungus causes this rot of ripe tomatoes. Infected fruit first shows small, circular, water-soaked spots. These appear as if the fruit was bruised by pressing with the thumb or a pencil eraser. Small black specks often develop in the center of spots.