WSU Extension

Hortsense

Rhododendron : Rust
(revision date: 4/23/2014)


Use Integrated Pest Management (IPM) for successful plant problem management.

Biology
Yellowish spots on the upper leaf surface and dark brown or purple spot on the lower leaf surface can indicate the presence of a rust infection. Later, the underside develops blisters which break open to reveal characteristic yellow to orange or reddish spores. Rusts can also affect azaleas. The disease overwinters on the host plant.
Management Options

Non-Chemical Management
  • Prune and destroy infected leaves.
  • Clean up and destroy any diseased leaves that have fallen to the ground.
Select non-chemical management options as your first choice!

Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

None recommended

Images
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Caption: Rhododendron rust
Photo by: R.S. Byther