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Perhaps you have noticed your
Live Oaks dropping new leaves this spring. The moist conditions of
the past winter and early spring, in conjunction with seasonably cool
temperatures, has allowed a number of fungal diseases to develop on the
leaves of many of our shade trees. One of these more prevalent
this year is Oak Anthracnose. This disease infects the foliage of
nearly all Oak species. It is most prevalent in our Live Oaks this
year. Although it can cause problems, generally this disease is
not a serious threat to the long-term health of the tree.
The spores of the fungus infect young supple
leaves just emerging in the spring. After a period of rapid
infection, the leaves begin to fall. Symptoms are evident on a
portion of the leaf and are expressed by the margin of the new leaf
turning brown or becoming necrotic. This area of browning is
usually along one of the leaf margins, causing the leaf to become curled
and fall to the ground. Not all infected leaves fall. In
fact, many will remain on the tree throughout the season causing the
overall appearance of the tree to look a bit odd. Trees in areas
of little air movement and those with thick, dense foliage are most
readily infected. The lower, inside canopy usually exhibits the
most intense symptoms, as these leaves dry more slowly.
Temperatures consistently over 80-85 degrees
Fahrenheit cause the infection cycle to cease. Fortunately, the
portions of the canopy that drop leaves, will produce new leaves.
Single year infections rarely cause much damage to the tree. If
the disease repeats next season and infects a larger portion of the
tree, preventative fungicide applications may be needed. Foliar
sprays, which reduce the incidence of the disease, should begin when the
new leaves appear in March. It usually requires 2-3 applications
at 21-30 day intervals to adequately manage this disease. If
evidence of the disease is observed in late spring or early summer,
foliar sprays are normally not recommended. Your arborist may
however, recommend deep root fertilization in order to encourage the
production of new leaves and improve the overall health and vigor of the
tree.
Of course, if you have any further questions
regarding Oak Anthracnose, Live Oaks, or trees in general, we are here
for you. |
