Bean: Gray mold
R.S. Byther
Biology
Gray mold of green beans is a fungal disease. It can affect any aboveground portion of the plant.
Initial infection often occur on old flowers which remain on the plant. After initial infection, gray mold can spread into the adjacent healthy tissues.
Water-soaked lesions appear and quickly become covered with a gray-brown mass of fungus and spores. The disease is strongly favored by cool, moist conditions and can survive on infected plant debris.
Management Options
See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.
Non-chemical Management
Select non-chemical management options as your first choice!
- Rotate crops. Do not plant beans in the same location each year.
- Remove plant debris from the garden. Destroy or discard (do not compost) diseased materials.
- Space plantings to provide good air circulation and reduce humidity.
- Avoid overhead watering, especially during and after the bloom period.
- Irrigate only in the morning, so plants can dry during the day.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Begin application during early bloom stage or when disease first threatens.
- Repeat at weekly intervals or as necessary.
Approved Pesticides
If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.