Rhododendron: Leaf spot

categories: Ornamentals Rhododendron Rhododendron Diseases Shrubs

revision date: 2024-06-05 10:24

Rhododendron fungal leaf spot.
Rhododendron fungal leaf spot
Photo by: R.S. Byther


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

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 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

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.