Bacterial leaf spot is caused by Pseudomonas and Xanthomonas species. Phyton and other copper products are very toxic to bacteria as well as many fungi. However, pesticides are only marginally effective against bacterial diseases unless coupled with sound cultural practices. Since bacteria are spread by water splash, insects, handling and pesticide applications, diseased plants should be promptly isolated from healthy plants and discarded. Adequate space should be provided to allow for quick drying after watering. Discontinue overhead watering when bacterial diseases are evident. Reduce relative humidity and avoid prolonged periods of leaf wetness by the use of fans or a combination of heating and venting. Avoid overhead irrigation to reduce bacterial splash. Copper- based fungicides may help to reduce disease spread, but are only marginally effective when bacterial disease is well established and environmental conditions favorable for disease development. Sanitation and environmental control are important disease management principles.
