Learn / Ask The Landscape Professional
I have small fleshy white things growing on the outside of my azalea bush branches. Is this a fungus? What shall I do? April B., Groton
Answer
Actually, what you are seeing is called an
"Azalea Leaf Gall" which is caused by a fungus,
Exobasidium vaccinii. "Azalea leaf gall" is quite
common and first shows up in early spring
on new azalea growth and causes the leaves
to become distorted and thickened. It is not
well understood how the fungus penetrates
the growing tissue of azaleas and causes the
abnormal growths, but it is likely due to the
interaction of hormones and other chemicals.
The fungus has a layer of cells called the
"hymenium" which contains spore-bearing cells;
as the spores get scattered in the wind, the
fungus spreads. The azalea leaf gall growths
start out as light green and can change to pink,
white and then brown before they harden and
fall off the plant. Sometimes they can also
develop a black coating. Most often galls will show up on
the lower leaves of azaleas, but if the weather
is humid, you may see them on the upper branches
as well. You generally see Azalea Leaf Gall more
in the spring or early summer if the weather has
been cool and moist.
The good news is that although Azalea Leaf Gall looks
awful, it doesn't generally damage the
azalea and can be easily removed. When you first spot
it, carefully prune off the affected branches,
bag them and put them in the trash to be taken to the
incinerator. As you are pruning, disinfect your
pruners with rubbing alcohol so the infection is not
spread to other parts of the azalea. After you
prune the gall out, it's a good idea to add a fresh
layer of mulch under the azalea to bury the spores
so they don't re-infect the plant. Most often azalea
leaf gall doesn't become an annual problem,
but be vigilant and prune them out if you see them.
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About Linda Lillie
Linda K. Lillie is the President of Sprigs & Twigs, Inc, the premier
landscape design and maintenance, tree care, lawn care, stonework, and carpentry
service provider in southeastern Connecticut since 1997. She is a graduate of
Connecticut College in Botany, a Connecticut Master Gardener and a national
award winning landscape designer for her landscape design and landscape installation work.
