Question: My question is regarding an azalea. We have
over 50 azaleas on the grounds and nobody I ask has ever
seen this. Iwas hoping to be able to send a picture, because
it is hard to describe. It seems to be a leaf fungus. It
engulfs the leaf with a thick, green to white , succulent
feeling substance. It does have the little green worms living
in the cavities, they are very common up here this time
of year, but it isn't the worm that is eating the leaf.
After it takes over the entire leaf, it has the appearance
of the original leaf but is approximately 1/4 inch thick.
ANSWER: It looks like a common disease problem on azaleas
and rhododendron - leaf gall caused by Exobasidium sp.
Prevention and treatment options:
Typically this problem rarely requires chemical control.
Picking off and destroying galls is the best prevention
and management method. Should more drastic measure be needed,
chemicals such as cooper fungicides and mancozeb, can be
used as a preventative spray according to labeled instructions.
Pick off the affected foliage and destroy (don't just throw
on ground). Degree of symptoms vary year to year based on
weather conditions in spring as young leaves are expanding.
Fungicides would have to start as leaf shoots develop and
expand until weather conditions turn hotter/drier.
Kevin Ong, PhD
Assistant Professor & Extension Plant Pathologist
Texas Cooperative Extension
Texas A&M University - Dallas REC
17360 Coit Road
Dallas, TX 75252