Willow rusts are fungal diseases that begin in early summer, but are most noticed in late summer to early fall. Leaves first display yellow spots, which turn dark brown or black by late summer or early fall. Severe infections cause leaves to drop, sometimes resulting in considerable defoliation. The fungus overwinters on dead leaves and infected twigs or on alternate hosts. Alternate hosts for willow rusts include fir, larch, and Ribes species such as currants and gooseberries, depending on the rust species. Rust infections on willows are not typically a serious problem, although growth of young trees may be somewhat slowed by defoliation.
Use Integrated Pest Management (IPM) for successful plant problem management.
Select non-chemical management options as your first choice!
- Rake and destroy all fallen leaves beneath willow trees.
- Avoid overhead watering and splashing water, which contribute to the spread of the disease.
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Apply when conditions favor disease.
- 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.
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.