Douglas Fir: Upper stem canker
Photo by: R.S. Byther
Biology
Upper stem cankers are caused by fungi in the soil. Seedling Douglas fir trees are affected, with the tops of infected trees turning yellow. By fall, the tops turn reddish-brown.
Below the discolored portion of the seedling, on the middle or upper stem, a sunken canker can be found. It starts in a bark crevice and expands around the stem, turning red-brown and eventually girdling the tree.
- See also Douglas fir: Stem cankers.
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!
- Do not over-fertilize or irrigate late in the season to prevent susceptible fall growth.
- Space seedlings well apart to discourage spread of disease.
- Do not plant in contaminated soil.
- Remove and destroy infected seedlings.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply from mid-July to bud set in the fall.
- Make applications at intervals listed on the product sheet.
- 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.