WSU Extension


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

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

None recommended

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