On the undersides of young leaves, the spots are small, yellowish green and slightly raised. On older leaves, initially the spots are dark, water soaked and not noticeably raised. Severely spotted leaves turn yellow and drop off. Seedlings infected in the plant bed often lose all their leaves except those at the top of the plant. In the field, plants may lose many of their leaves.
Spots turn brown and appear cracked, roughened, and warty.
In damp weather, various secondary decay-producing organisms enter through these spots and cause the fruit to rot. Contaminated seed is a common source of first infection so seed should be disinfected with bleach. Bacterial spot also overwinters on residue of infected plants and is spread in the field on machinery. Bacteria can overwinter on debris buried more than 12 inches below the surface but are destroyed on the soil surface or if brought to within 12 inches of the surface. Plants infected in the seedbed are the primary source of the disease in the field.