WSU Extension programs and employment are available to all without discrimination. Evidence of noncompliance may be reported through your local Extension office.
Cedar: Leaf blight
categories: Cedar Conifers Ornamentals
revision date: 2024-06-05 10:24
Photo by: R.S. Byther
Biology
Leaf blight is a fungal disease. The symptoms typically appear first in late spring as bleached spots followed by brown or black cushion-like fungal fruiting bodies. Infected foliage may be anywhere on the plant. Individual leaves are killed by the fungus and turn a light tan to gray color. As the fruiting bodies drop out of the leaves, deep pits are left in the dead tissue. The infected tissues often have a “scorched” appearance. Infected leaves often drop in the fall. Western red cedar (Thuja plicata) is most commonly infected, particularly the cultivars ‘Atrovirens’ and ‘Excelsa’. A similar disease attacks junipers.
Management Options
Use Integrated Pest Management (IPM) for successful plant problem management.
Non-chemical Management
Select non-chemical management options as your first choice!
- Avoid overhead watering. Leaf blight is favored by moist foliage conditions.
- Plant resistant cultivars.
- Space plants and prune to allow good air circulation.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Apply in spring and early summer.
- Use Monterey Liqui-Cop Fungicidal Garden Spray on Eastern red cedar only.
- 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.
Additional Image
Photo by: R.S. Byther
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.