Rhododendron: Leaf spot
categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs
last review date: 2025-06-27 11:14
Photo by: R.S. Byther
Biology
Several fungi cause leaf spots on rhododendron. They often infect through wounds.
Infected leaves display dark brown spots which may cover up to half of the leaf surface. These spots may feel bumpy on the surface due to the presence of fungal structures.
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!
- Avoid overhead watering and maintain good air circulation in plantings.
- Prevent injury to reduce likelihood of infection.
- Provide proper culture for plants.
- Prune out and destroy all infected tissues.
- Clean up and destroy any fallen leaves to prevent spread of infection.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Read label for application timing.
- 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
Examples of pesticides that are legal for home use in Washington State are listed below.
The list may not include all products registered for this use.
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.