Causal Agent: 

Bacterium (Xanthomonas spp.)

Characteristic Symptoms:
 
Leaf lesions begin as small, brown, water-soaked spots, which turn brown and become necrotic at the center.
   
Under high humidity conditions, numerous lesions may coalesce giving the plant a blighted appearance.
   
Fruit lesions begin as circular green spots, which later enlarge and turn brown with rough and wart-like appearance.
   
Conditions for Disease Development:
 
The pathogen is seed-borne and is capable of overwintering on plant debris in the soil and on volunteer host plants in abandoned fields.
   
Bacteria invade the plant through stomata on the leaf surfaces and through wounds on the leaves and fruit caused by abrasion from sand particles and/or wind.
   
Temperatures between 24-30°C and prolonged periods of high relative humidity favour infection and disease development.
   
The bacteria is spread by windblown rain, overhead irrigation, drainage of infested water, by mechanical means (handling of infected seedlings, on contaminated tools) and by workers (on hands, clothing).
   
Management and Control:
 
Use resistant varieties, if available.
   
Use pathogen-free seeds and seedlings as the disease is difficult to control once introduced in the field.
   
Avoid working in affected areas when leaves are wet to minimize spread. Disinfect tools with10% household bleach (chlorox) after working in infested area.
   
Avoid overhead irrigation. Rain shelters in seedbeds may help reduce rain splash and disease severity.
   
Practice 2-3 years rotation with non-host crops.
   
Apply copper or copper+mancozeb sprays on dry seedlings prior to transplanting and continue at 5 days interval.
   
References:
AVRDC Factsheet. AVRDC Publication 04-572 (2004) at www.avrdc.org; Compendium of Pepper Diseases (2003) by APS; Bacterial Spot of Tomato and Pepper at http://www.apsnet.org/edcenter/intropp/lessons/prokaryotes/Pages/Bacteri...
   

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