WSU Extension

Hortsense

Rose : Rust
(revision date: 3/10/2017)


Biology
Rust usually is first noticed as clumps or pustules of red to orange powder on the lower surfaces of leaves. The upper surface may also show yellow, orange, or brown spots, corresponding to the location of the pustules on the underside. Symptoms may also appear on young stems and green flower parts. Some rose varieties are tolerant of infection, while others drop infected leaves. This fungal disease can be spread by wind or splashing water and is most serious during cool, humid weather.
Management Options

Non-Chemical Management
  • Avoid overhead watering and splashing water onto plants.
  • Pick and destroy infected leaves to prevent spread of disease. Prune and destroy infected stems and flowers.
  • Rake and destroy all fallen leaves.
  • Prune old canes during dormant season to reduce amount of overwintering fungus.
  • Space plantings and prune to provide good air circulation.
  • The PNW Plant Disease Management Handbook contains a list of resistant cultivars.
Select non-chemical management options as your first choice!

Chemical Management

Apply fungicides during the growing season.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • ferti-lome Liquid Systemic Fungicide II R-T-Spray
    Active ingredient: propiconazole  |  EPA reg no: 53883-184-7401
  • This list may not include all products registered for this use.
Images
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Caption: Rust on rose
Photo by: R.S. Byther
Caption: Rust overwintering stage on stems
Photo by: R.S. Byther