Q. I have a lovely white azalea that has always been healthy
and that flowered profusely every spring. It did not have as many
flowers this spring, and I have noticed something wrong with the
leaves. They appear yellow and curled; some have pale green
swellings on them, but it looks white on others. Can you tell me
what this is and how to get rid of it?
leaf and flower gall is caused by a fungus, Exobasidium vaccinii.
Young leaves become swollen and fleshy, with a pale green color.
These become white when they begin to form spores. Once the
spores are released, the galls become hard and brown. The spores
produced will not cause new infection until next spring when
your azalea begins to put on new growth. New growth is more
susceptible to infection than older growth that has hardened
off. Wet, humid weather creates a favorable environment for this
disease to develop.
White Azalea in full blossom
and destroying the galls before they turn white is one of the
primary controls for this disease. Send them out with the trash
or burn them, rather than attempting to compost them. This
removes the spores that would overwinter on twigs and buds to
cause infection the following spring. I imagine most of the
galls on your azalea have already turned white; pruning the
galls off may not be enough to protect it next spring. As new
growth starts next spring, make repeated applications of
mancozeb (Dithane) to protect it. Applications can cease once
the leaves have reached their full size. Be sure to read and
follow label directions as to application rate and intervals
Lawn surface roots