Cedar Leaf Blight Description:
Cedar leaf blight is a fungal disease affects western red cedar (Thuja plicata). Severely infected leaves drop in fall.
Hosts:
Cedar leaf blight primarily affects young saplings. While it occurs in the western U.S. and Canada, it has also been found on northern white cedars in the eastern United States.
Western red cedars are the most common host plants, especially ‘Atrovirens’ and ‘Excelsa’ cultivars.
Biology & Symptoms:
The fungus infects one-year-old foliage with symptoms first appearing in late spring. While this blight is typically a problem for young cedars, it can infect lower branches on older trees and cedars of any size.
Individual leaves will have bleached spots that develop brown or black areas where spores are being produced. After spores are released, these areas dry out leaving pits in the damaged leaves. Leaves killed by the fungus turn light tan or gray, sometimes described as being “scorched.” Often, these infected leaves will drop from the plant in the fall.
Cedar leaf blight can look like normal color changes in fall. However, seasonal color changes affect entire trees, not on scattered branches throughout the tree.
Management:
Controlling this disease requires keeping the leaves as dry as possible. Some steps to achieve this include:
- Avoiding overhead watering
- Spacing plants far apart
- Pruning to improve air circulation
Additional control options include the application of fungicides during spring and early summer. Repeated applications may be needed. Consult a tree service professional about the products registered for this use. Resistant cultivars are available as well.
See More Articles
Anthracnose Disease Of Deciduous Trees
