Azalea: Ovulinia petal blight
categories: Azalea Azalea Diseases Ornamentals Shrubs
last review date: 2026-02-13 10:58
Photo by: R.C. Linderman
Biology
Ovulinia petal blight affects the flowers only (not leaves or shoots) of azaleas and rhododendrons.
Infected flowers first display small, water-soaked spots which enlarge quickly. The petals quickly become slimy and turn brown, sometimes within two or three days after fully opening.
The infected blossoms remain on the plant and later provide a source of infection for next year’s flowers. Flowers on lower branches are affected first.
The disease overwinters in dead flower material or top layers of mulch, and is favored by high humidity.
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!
- Remove and destroy all infected flowers from plants and from the ground.
- Remove top inch of soil or mulch from beneath infected plants and replace it with clean material.
- Avoid overhead watering.
- Space plantings and prune to provide good air circulation in and around plants.
Chemical Management
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Apply protective fungicide just before budbreak and then at recommended intervals during bloom period.
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.