Snapdragon: Downy mildew
Photo by: R.S. Byther
Biology
Affected plants show stunting and pale yellowish green foliage. Leaves curl in and droop. Leaf undersides may develop a white to purplish fungal growth. The growing point usually dies, and the plant may break off at the base.
Downy mildew is caused by a fungus that is favored by cool, wet conditions and/or high humidity. Spores are produced in abundance on infected tissue. Seed transmission may occur but remains as speculation only.
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!
- Reduce greenhouse humidity by combination of heating, venting, and circulating air.
- Plant in areas with adequate sunlight and air circulation.
- Space plants to foster air flow.
- Remove and destroy infected plants and plant debris.
- Do not overhead irrigate.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- None recommended
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.