How to Manage Pests

UC Pest Management Guidelines

Tomato

Anthracnose

Pathogen: Colletotrichum coccodes

(Reviewed 12/13, updated 12/13)

In this Guideline:


Symptoms

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). Dark, needle-like spines, called setae, surround the microsclerotia and acervuli, cushion-shaped fruiting bodies that erupt through the plant tissue. During moist weather, masses of salmon-colored sausage-shaped 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 because of its dry weather. 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 irrigation when fruit begin to ripen. Fungicides are generally not required. Fungicides for blackmold are effective against anthracnose fruit rot.

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Tomato
UC ANR Publication 3470

Diseases

R. M. Davis, Plant Pathology, UC Davis
G. Miyao, UC Cooperative Extension, Solano and Yolo counties
K. V. Subbarao, USDA Agricultural Research Station, Salinas, CA
J. J. Stapleton, UC IPM Program and Kearney Agricultural Center, Parlier
B. J. Aegerter, UC Cooperative Extension, San Joaquin County (powdery mildew on field-grown tomatoes)
Acknowledgments for contributions to Diseases:
B. W. Falk, Plant Pathology, UC Davis

Top of page


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2014 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /PMG/r783100811.html revised: September 30, 2014. Contact webmaster.