Azalea leaf gall

Description:

Fungal disease affecting many of the wild rhododendrons growing on the mountains. Exobasidium vaccinii causes leaves and flowers to become swollen, curled, waxy and fleshy. The swollen plant tissues or "galls" are made up of abnormal plant tissue. Infected leaf tissue is usually pale green in color during the early stages of the disease; infected flowers are usually pinkish. Later in the season, a white spore layer covers the infected plant parts. Galls eventually turn brown and harden as the season progresses. Lower leaves on plants are usually the most seriously damaged, but under humid conditions and in shaded locations galls may occur at the ends of upper branches.

Habitat:

Great Smoky Mountains National Park, TN