Answer: Azalea leaf gall, a fungal disease, causes swollen, green masses on leaves. As it ages, the mass turns white and then hard and brown. You did the right thing in removing the galls, to keep the fungal spores from spreading to other parts of the plants. Some azaleas are less susceptible to leaf galls, and some seem to have them almost every year. Prune to improve air circulation around and within the plant, and remove any galls that you find each spring.
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