How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

Bacterial spot appears as spots that form on leaves, stems, and fruit. Leaf spots first appear as small, angular spots on the undersurface of the leaf. The spots, which are about 0.25 inch in diameter, are initially watersoaked and later turn brown. Elongated raised cankers form on the stems. Fruit spots are circular, brown, and raised with a cracked, roughened, and wartlike surface.

COMMENTS ON THE DISEASE

The bacterium is seedborne and can occur within the seed and/or on the seed surface. The pathogen is disseminated with seed or on transplants. Bacterial spot is a relatively minor disease that is favored by high relative humidity and free moisture on the surface of the plant. Symptoms develop 5 to 15 days after inoculation and develop most rapidly at temperatures of 68°F or above. The bacteria do not survive in soil after the infected plant residue decomposes. Some strains of the bacteria favor pepper, others favor tomato, and others are equally pathogenic on both tomato and pepper.

MANAGEMENT

Use indexed pathogen-negative seed, treated seed, or disease-free transplants. Rotate out of peppers for at least 1 year. Use furrow or drip irrigation instead of overhead irrigation. Treatment with copper spray is seldom justified.

PUBLICATION

UC IPM Pest Management Guidelines: Peppers
UC ANR Publication 3460
Diseases
S. T. Koike, UC Cooperative Extension, Monterey County
R. M. Davis, Plant Pathology, UC Davis
K. V. Subbarao, USDA Research Station, Salinas
Acknowledgment for contributions to Diseases:
B. W. Falk, Plant Pathology, UC Davis

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