Bacterial spot of tomato and pepper
|Bacterial spot of tomato and pepper|
|Bacterial spot of tomato and pepper on a sweet pepper leaf|
|Species:||Xanthomonas campestris pv. vesicatoria|
|Locations where bacterial spot of tomato and pepper is present (blue)|
|Bacterial leaf spot
Bacterial spot of tomato and pepper is a serious disease because it has a high rate of spread, especially during periods with wind driven rains, because adequate control measures are not available, and because fruit symptoms reduce marketable fruit.
Lesions can occur on leaf parts (leaflets and petiole) and fruit parts (fruit, peduncle, and calyx). Stems are also susceptible but usually the other foliage parts are infected to a greater degree. Positive diagnosis requires testing in a laboratory; however, certain symptoms, especially those on the fruit, are suggestive of bacterial spot.
Distinct leaf spots with or without yellowing occur. Individual leaf spots are not more than 3mm (⅛in) across unless they coalesce with each other, which results in browning of entire leaflets. Spots restricted by leaf veins are sometimes angular while those not restricted by veins may be somewhat round. Leaf spots often are sunken on the upper leaf surface. Leaf spots and fruit spots tend to be aggregated. Fruit spots often begin as dark specks with or without a white halo. As the spots enlarge, they become raised and scab-like. The centers of older spots may be sunken.
In pepper leaves, spots may be similar to those in tomato. However, leaf spots in pepper tend to be lighter in color in the centers of the spots. Also, in some situations, larger spots with definite water-soaking can occur. Fruit spots in pepper are similar to those in tomato except that spots in pepper may appear blistered.
Purchase seed that has been treated with acid or bleach to reduce inoculum on the seed. Do not place transplant beds or greenhouses near functional or abandoned tomato or pepper fields. Purchase only certified disease-free transplants. Resistant varieties of pepper are available. Destroy solanaceous weeds such as ground cherry and nightshade in the vicinity of tomato and pepper plantings.
Spray plants with a tank mix of maneb (pepper or tomato) or mancozeb (tomato only) plus copper prior to the occurrence of this disease. An approved phage (bacterial virus) can be used. Maintain a residue of these materials on plants so that when heavy rains occur, some protection is available. Sprays applied to the plants before rain or irrigation are most beneficial. Avoid working in the fields when plants are wet because this disease will be spread more readily under wet conditions. Use drip irrigation rather than overhead irrigation.
Methyl bromide fumigation can be used to disinfect soil.
- Xanthomonas vesicatoria. European and Mediterranean Plant Protection Organization. p4.
- Kucharek, T. (2000). Bacterial Spot of Tomato and Pepper. Florida Cooperative Extension Service/ Institute of Food and Agricultural Sciences/ University of Florida. p1-2