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Bacterial leaf spot is a common disease of peppers and tomatoes that occurs throughout the world and favors high humidity and warm weather conditions. Contaminated seeds and infected plant debris from previous seasons are common sources of infection. The bacteria enters plant tissues through stomates and hydathodes or through injured tissues. Symptoms will appear within a week if conditions are permissible. After bacterial leaf spot is introduced to the field, the bacteria can spread from plant-to-plant through splashing water, contaminated tools, and workers on the field.

The initial symptoms include the formation of water-soaked spots on foliage, which become dark with time. Lower leaves tend to suffer the most and fall from plants when infestations are high. Affected leaves might exhibit chlorosis, while the spots themselves are sometimes encircled with yellow halos. Small elongated, brown-black spots may develop on petioles and along the stems. As the disease progresses, the spots cover more of the foliage surface which eventually collides and creates large necrotic areas. The symptoms on the fruit manifest as small, brown irregular shaped scabs.