We have experienced a small mushroom type growth on some of our Azalea leaves. The leaves have been removed, but we do not know what has caused it.
Certified GKH Gardening Expert
The problem could have been attributed to azalea gall disease--caused by a fungus and managed by removing and disposing of the infected leaves. The fungus overwinters within the infected plant. In the late spring and early summer, a whitish coating appears on the swollen plant tissue. Spores are produced on the leaves during the spring and summer. The spores are dispersed through the air and rain. This disease is not usually a serious problem unless wet conditions remain for long periods of time.