Douglas Fir: Upper stem canker
categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals
revision date: 2023-01-31 12:00
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
Use Integrated Pest Management (IPM) for successful plant problem management.
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: Visit Home and Garden Fact Sheets for more information on using pesticides.
- 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
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.