Poplar: Bacterial blight
Photo by: C.R. Foss
Biology
Bacterial blight of poplar causes leaf spots, which begin as small, dark, water-soaked spots. Twig dieback and branch or trunk cankers may also occur.
Blighted shoots often turn black and appear scorched or burned as they die back. Infected tissues are less resistant to frost damage. Also, the bacteria often infect through wounds caused by frost injury.
The bacteria are easily spread by rain, insects, and pruning tools. The disease is caused by the same bacterium that causes bacterial blight of lilac, euonymus, willow, and many other woody plants.
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!
- Space trees and prune to provide good air circulation. Humid conditions favor disease development.
- Avoid overhead irrigation.
- Avoid wounding plants.
- Prune out and destroy infected plant parts during dry periods. Make pruning cuts well below infection and sterilize tools between cuts. Do not compost diseased materials.
- Provide proper culture. Healthy plants are more disease-resistant and more tolerant of damage.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply before fall rains and again before budbreak in spring.
- First apply to a small section of the tree and wait a few days to determine if the spray causes any plant damage.
- 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.