How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS AND SIGNS

Anthracnose of tomatoes is primarily a disease of ripe and overripe fruit. Depressed, circular lesions about 0.5 inch (1.2 cm) in diameter appear on ripe fruit. With age the lesions become tan and dotted with small black specks (microsclerotia). During moist weather, masses of salmon-colored spores may form on the lesion surface. Infection may also occur on stems, leaves, and roots. Root infections (called black dot root rot) become evident when fruit begin to ripen. Root lesions are brown and dotted with microsclerotia. The cortex of infected roots is often completely rotted.

COMMENTS ON THE DISEASE

The fungus is a weak parasite and generally infects ripe or overripe fruit and roots of mature plants. In California, anthracnose on fruit occurs infrequently. Root rot, however, is not uncommon, especially where tomatoes are grown year after year in the same soils. The effect of black dot root rot on yields is not known.

MANAGEMENT

Rotate with nonsolanaceous crops at least every other year. Avoid sprinkler irrigations when fruit begin to ripen. Fungicides are generally not required. Chemical controls for black mold are effective against anthracnose fruit rot.

PUBLICATION

UC IPM Pest Management Guidelines: Tomato
UC ANR Publication 3470
Diseases
R. M. Davis, Plant Pathology, UC Davis
G. Miyao, UC Cooperative Extension, Solano/Yolo counties
K. Subbarao, USDA Agricultural Research Station, Salinas
J. J. Stapleton, UC IPM Program, Kearney Agricultural Center, Parlier
Acknowledgments for contributions to the disease section:
B. W. Falk, Plant Pathology, UC Davis