Bacterial leaf spot disease produces small, dark irregular spots on tomato and pepper leaves; leaves eventually turn yellow and drop off. This defoliation weakens plants and exposes developing fruits to sunscald. Small, dark, wartlike raised spots with slightly sunken centers may appear on green fruits. Rot organisms are able to enter the fruit at these spots and cause decay. Bacterial spot symptoms are similar to, and often indistinguishable from, bacterial speck.
Very warm, wet weather encourages the development of the disease. The bacteria overwinter in plant residues. This disease is a problem mainly in the East and Midwest.