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How to Manage Pests
UC Pest Management Guidelines
Dry Beans
Bean
Anthracnose
Pathogen: Colletotrichum
lindemuthianum
(Reviewed 8/07,
updated 8/07)
In this Guideline:
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The anthracnose fungus infects leaves, stems, and pods of common
bean plants. The most characteristic symptom of the disease is the black-red
sunken cankers or spots that develop on infected pods. As these spots become
older, the edges develop a black ring with a red outer border and may show a
pink ooze in the center, which contains the spores of the fungus. Similar spots
may develop on seeds. Red-brown spots and streaks also develop on stems,
petioles, and leaves. A characteristic symptom of the disease occurs on the
underside of infected leaves: veins turn brick-red to purple and eventually
black.
Anthracnose develops under cool moist conditions, and thus is rarely
a problem under California conditions. The fungus overwinters in bean debris in
the field or in association with seed. Young beans are infected from spores
carried on seed or spores splashed from debris or nearby infected plants. The
spores are then spread throughout the field by machinery, wind driven rain,
irrigation water, and animals.
Plant certified seed grown in areas unfavorable for anthracnose
(e.g., California or Idaho). Resistant varieties are available, and should be
used if possible. Use furrow rather than sprinkler irrigation because of the importance
of water for disease development. Bean debris in infected fields should be
plowed under immediately after harvest. Because the fungus is primarily a
pathogen of common bean (but also infects lima bean and scarlet runner bean)
crop rotations of 2 to 3 years are effective.
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UC IPM Pest Management Guidelines: Dry
Beans
UC ANR Publication 3446
Diseases
R. M. Davis, Plant Pathology, UC Davis
Acknowledgment for contributions to Abiotic Disorders:
A. E. Hall, Botany and Plant Sciences, UC Riverside
Acknowledgment for contributions to virus sections in Diseases:
R. L. Gilbertson, Plant Pathology, UC Davis
Acknowledgment for co-authorship of Ascochyta Blight:
C. A. Frate, UC Cooperative Extension, Tulare Co.
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