It is one of the most destructive diseases of tomato foliage. The fungus can cause disease on tomato, potato, eggplant, petunia, nightshade weeds, horse nettle, and ground cherry. Defoliation of the plant leads to a decreased yield. Symptoms of this disease can be found on the leaves and other green parts of the tomato plant. Small, round, yellowish spots appear on the leaves, usually after the first fruit sets.
Symptoms generally start on the lower leaves first.
The spots later become brown or grayish and may have a yellowish or dark border. Dark specks or dots appear in the center of the spots on susceptible varieties. These are usually fewer or absent on resistant varieties. Heavily infected leaves fall off, normally starting at the bottom of the plant and progressing upward. Fruit infection is rare.