Xanthomonas campestris pv. Vesicatoria

Xanthomonas campestris pv. vesicatoria is a bacterium that causes bacterial leaf spot (BLS) on peppers and tomatoes. It is a gram-negative and rod-shaped. It causes symptoms throughout the above-ground portion of the plant including leaf spots, fruit spots and stem cankers. Since this bacterium cannot live in soil for more than a few weeks and survives as inoculum on plant debris, removal of dead plant material and chemical applications to living plants are considered effective control mechanisms. Classification of the Xanthomonas species that cause bacterial leaf spot is currently in flux. Up until a few years ago, bacterial leaf spot causing Xanthomonads were divided into four groups, A, B, C, and D, based on pathogenicity and physiological characteristics. As of 2004 though, a new classification system was proposed that would change the name of X. campestris pv vesicatoria to X. euvesicatoria (previously group A), and recognized the species X. vesicatoria (group B), X. perforans (group C), and X. gardneri (group D). These changes have yet to be fully recognized, so this article will include information on all groups (A, B, C, and D) of bacterial leaf spot causing Xanthomonads. The principal hosts of BLS causing Xanthomonads are tomatoes and peppers, though other incidental hosts have been recorded, mainly weeds. Group A contains most of the pepper infecting strains, though some strains from groups B and D have also been reported to cause symptoms on pepper plants. Strains from all four groups have been isolated from infected tomato plants. Some strains are able to infect both pepper and tomato plants, while some can only infect one of these plants.