Bean: White mold (Sclerotinia rot)

Biology

White mold is a fungal disease which may attack stems, leaves, and pods of beans. Water-soaked spots appear on the lower portions of the plant. These spots soon show the white, cottony fungal mats characteristic of the disease. The fungus also forms hard, round, black bodies in the white mats. These variously-sized fungal structures may be internal or external on living or dead diseased tissues. They serve as an overwintering source of fungus for future infections. Diseased plants turn yellow and wilt. Diseased tissues die and turn white to beige in color. White mold development is favored by moist conditions and overfertilization. The fungus has a wide host range, including many vegetables (beans, lettuce, carrot, parsnip, cucumber, tomato, etc.).

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Rotate crops. Do not plant crops in the same location each year. Do not plant susceptible crops where previous infections occurred.
• Space plantings to provide good air circulation.
• Avoid overhead watering. Water early in the day, to allow plants to dry before night.
• Provide proper culture. Avoid overfertilization, which produces large amounts of tender, susceptible growth.
• Remove and destroy infected plants when noticed.
• Remove plant debris from the garden. Destroy or discard (do not compost) diseased materials.
• Do not move infected soil to uninfested areas.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• None recommended.