Bacterial Spot

Bacterial Spot:
This disease is found mainly in eastern parts of North America where it affects tomatoes and peppers. Small, dark, corky, raised spots with slightly sunken centers appear on green fruits. Rot organisms may enter at the spots and decay the fruit. Infected blossoms drop; small, dark spots form on leaves, which yellow and drop. This defoliation weakens plants and exposes developing fruits to sunscald. Very warm, wet weather encourages the development of the disease. The fungus overwinters in plant residues in the soil.

Prevention And Control:
Use a 3- to 4-year crop rotation. Destroy volunteer tomato and pepper plants and infected fruits. Keep plants well watered and fertilized. Space plants well apart and support vines to ensure good air circulation. To prevent the disease from spreading, avoid overhead watering and working among plants when they are wet. Apply an approved fungicide every 10 to 14 days as long as weather is favorable for disease spread. Organic growers can try using fixed copper-based sprays or aerated compost tea. Purchase only certified disease-free transplants.

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Disease information provided by NationalGardening.com, the online publisher of the National Gardening Association.

Photo courtesy University of Iowa Extension Plant Pathology.