By Ryan Adams
Bacterial spot is caused by four species of Xanthomonas and occurs worldwide wherever tomatoes are grown. Bacterial spot causes leaf and fruit spots, which leads to defoliation, sun-scalded fruit, and yield loss. Due to diversity within the bacterial spot pathogens, the disease can occur at different temperatures and is a threat to tomato production worldwide. Disease development is favored by temperatures of 75 to 86 ℉ and high precipitation. In North Carolina, it is more prevalent in seasons with high precipitation and less prevalent during dry years.
The disease is caused by four species of Xanthomonas (X. euvesicatoria, X. gardneri, X. perforans, and X. vesicatoria). In North Carolina, X. perforans is the predominant species associated with bacterial spot on tomato and X. euvesicatoria is the predominant species associated with the disease on pepper. All four bacteria are strictly aerobic, gram-negative rods with a long whip-like flagellum (tail) that allows them to move in water, which allows them to invade wet plant tissue and cause infection. For more information on Bacterial Spot including signs, symptoms and disease management,
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Bacterial spot symptoms on field tomatoes caused by Xanthomonas perforans.
Fruit lesions of bacterial spot caused by Xanthomonas perforans.