Petal blight of azaleas is a fungus that causes brown or transparent spots on the flowers. The spots enlarge rapidly until the whole flower softens and becomes slightly slimy. Flowers shrivel prematurely and become brown and papery. They remain fused together on the plant for some weeks.

High humidity and rainy weather favour this disease which spreads rapidly.

Control:
The plants should be sprayed fortnightly with an azalea fungicide from the time the flower buds begin to show colour until bloom is complete.