The diseases caused by bacteria, viruses, and nematodes can be severe, reduce tomato yield and quality, and generally are more difficult to control than those caused by fungi. Management of these diseases is most effective with the integrated use of practices such as crop rotation, resistant varieties, sanitation, and disease exclusion. The intent of this fact sheet is to aid tomato growers in the identification of diseases caused by bacteria, viruses, and nematodes, and to provide guidelines for their management.
Bacteria are microscopic, single-celled organisms.
Bacteria multiply rapidly by simple cell division and absorb nutrients from their immediate environment. Bacterial spot - Small, dark brown leaf spots. Spots on wet leaves will have a greasy appearance. This disease is most important in the eastern half of Oklahoma where rainfall and humidity levels are moderate to high. Bacterial spot reduces tomato yield and quality by defoliation and spotting of fruit.