Cotoneaster: Bacterial blight
Photo by: R. Maleike
Biology
Bacterial blight symptoms first appear in the spring (April-May) as brown spots on young stems and leaves, followed by wilted and blackened new growth.
The disease is especially favored by wet conditions. Infection often occurs at injury sites, such as those caused by frost damage or pruning wounds.
The bacterium causing the blight also infects many other hosts, including lilac and maple. Bacteria are easily spread by splashing water and pruning tools.
Bacterial blight may be confused with fire blight.
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!
- Maintain plant health. Healthy plants are better able to resist and tolerate disease.
- Avoid overhead irrigation.
- Space plantings and prune to provide good air circulation and reduce humidity. This can help slow the spread of the disease.
- Avoid injuring plants (especially during wet weather) to reduce chances of infection.
- Prune and destroy infected tissues as soon as they are noticed. Sterilize pruning tools between cuts.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply when leaves drop in fall and during wet spring weather.
- Note: These fungicides can be damaging to plant tissue, so apply only under fast-drying conditions.
- Homeowners should not make foliar applications to trees over 10 ft tall.
- Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.
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.