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.

[5] 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.

When symptoms on the fruit do occur, they start as pale-green, water-soaked areas and eventually become raised, brown, and rough.

[3][4][5] Bacterial colonization of intracellular spaces induces the macroscopically visible symptoms including water-soaked lesions on the leaves that later become necrotic.

[1][2][6] Though these spots start out at about .24 inches in diameter, they increase in size and number, eventually causing the leaves to drop off.

BLS can also affect the stems of plants, leading to elongated, raised, light-brown cankers, less than .25 inch long.

[5] The bacterium can also be found in association with wheat roots and some weed species which are both considered sources of inoculum as well as diseased tomato and pepper plants.

Overcrowding in propagation facilities also increases the likelihood of spreading this disease when an infected plant comes into physical contact with its neighbors.

Bacterial spot of pepper and tomato can spread extremely quickly with infected plants showing symptoms 3–5 days after exposure to the pathogen.

However, the bacteria developed resistant strains and widespread antibiotic application is no longer an effective method of control.

While there has been some research made into finding resistant varieties of host plants, success has been limited due to the variation in the pathogen Xanthomonas campestris pv.

vesicatoria does not survive well in decayed plant material therefore removal of debris and crop rotation are two good methods for preventing the spread of this bacterium.

[9] Finally, there is some research being done into the foliar application of bacteriophages (viruses that infect bacteria) to control the disease but this approach has been met with some resistance and is not currently a widely used method.