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September 2011: The
survey results are in - Soapberry borers are in 42 Texas counties.
The
soapberry borer (Agrilus
prionurus), a native of Mexico, was first reported
in Travis County in 2003.
Recent confirmed reports have documented attacks
of this invasive pest on western soapberry trees in 42
counties in Texas, extending from south Texas to the
Oklahoma border (see map). All soapberry trees larger
than 2 inches DBH are susceptible to attack.
Soapberry trees, the insect’s only known host,
tend to die from the top down in 2 to 3 years.
Signs and symptoms of attack are bark flakes
knocked off by woodpeckers that feed on the larvae,
winding beetle galleries evident on the exposed sapwood,
white larvae up to an inch long beneath the bark,
D-shaped exit holes in the bark, and profuse epicormic
branching along the lower trunk.
Dr.
Donald Grosman (dgrosman@tfs.tamu.edu),
Coordinator of the Forest Pest Management Cooperative in
Lufkin, has been testing several systemic insecticides
for prevention and control of soapberry borer.
One of the most promising is emamectin benzoate
(EB), recently registered by EPA for a variety of
conifer and hardwood pests.
EB has proven effective as both a therapeutic and
preventative treatment, if the infestation is not too
advanced at the time of injection.
There is other good news on the
soapberry borer front.
Although infestations spread rapidly in Texas
from 2008-2010, fewer reports of new infestations are
being reported in 2011. Indeed, most untreated soapberry
trees that Don Grosman has been monitoring as check
trees have yet to be infested and infested trees with
larvae are difficult to find.
Whether this apparent population decline is due
to last year’s cold winter temperatures, this summer’s
heat and drought, or some unrecognized biological
control has yet to be determined.
If
you observe any active infestations of soapberry borer
(western soapberry trees with flaking bark, beetle
galleries and white larvae), or if you have noticed a
similar decline in activity of this invasive pest in
your neck of the woods, please contact Dr. Ron Billings
at
rbillings@tfs.tamu.edu.
We need
to determine if this invasive pest is no longer a threat
to our native soapberry trees.
For more information and photos of soapberry
borer infestations, visit
www.texasinvasives.org.
The Texas Forest Service is attempting to determine
the current distribution of the soapberry borer in
Texas. The soapberry borer, Agrilus prionurus, is an
invasive wood- boring beetle recently introduced from
Mexico that has been attacking and killing western
soapberry trees in various counties of Texas. If you spot dead or dying western soapberry trees,
please fill out
this form and send it to Dr. Ron Billings at
rbillings@tfs.tamu.edu. If possible, attach digital photos of the bark chips,
larval galleries, D-shaped exit holes or other signs of
attack, together with a close-up photo of the tree's
leaves, so he can confirm the identity of the pest. Please follow
this link to see descriptions of how to identify
western soapberry or the damage this flatheaded wood
borer causes. Dr. Ron thanks you for your cooperation.
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