Dr. John F. Baniecki
WVU Extension Service
Plant Pathology and Entomology Specialist
August 2000

The abnormal swellings which are commonly found on Azalea and Rhododendron are caused by species of the fungus Exobasidium.

The leaves of the host plant become thickened or fleshy and turn a pale green color, or at times, may become whitish or pinkish. There may at times develop a rosette of fleshy leaves at the tip of the branch. On Rhododendron maximum and other species, the flower parts, especially the petals, become thickened and the whole bloom becomes a hard, fleshy gall which is covered with a whitish, powdery coating commonly called "bloom." These galls are often called "pinkster apples" and are eaten by those familiar with their qualities.