How to Manage Pests
UC Pest Management Guidelines
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.
UC IPM Pest Management Guidelines: Dry