are flourishing with all of the rain
Gail Ruhl, Sr. Plant Disease Diagnostician, Botany & Plant
Pathology, Purdue University
Anthracnose has been diagnosed on a number of different
shade trees this
year, including sycamore, maple, oak, ash and birch. We also frequently
see anthracnose on walnut and dogwood trees. Dogwood anthracnose
can be quite serious due to the
development of girdling trunk cankers.
Anthracnose requires cool, wet conditions for infection.
growth is most susceptible. Older leaves, drier conditions, and
temperatures usually discourage further disease development.
Symptoms of anthracnose include brown to black leaf
spots, brown to black
blotches, and sometimes (as with sycamore anthracnose) stem cankers
death of entire, young leaves. Anthracnose of shade trees is usually
in the lower or inner canopy of the tree where leaves stay moist
Even though defoliation may occur, long term affects
on tree health are
minimal for vigorous trees. Fungicides are not usually recommended
early anthracnose diseases of shade trees, with the exception of
Dogwood Anthracnose). Spring fertilization following defoliation
will help trees push out a second flush of growth (HO-140,
Fertilizing Woody Plant).
also important to water these trees during periods of drought stress
For more information, refer to BP-9,
Anthracnose of Shade Trees.
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