Treating alder and bronze birch borers
Thoroughly spraying foliage (where adults feed)
and bark (whence adults emerge and where they land
to lay eggs) with an insecticide such as permethrin can
provide some control of flatheaded alder borer and
the bronze
birch borer. However, effective products labeled
for trunk treatments are avilable only to licensed
professionals. Well-timed insecticide sprays may
reduce borer attacks, but
do not substitute
insecticide
applications for proper cultural care
or trees are still likely to die. If an application
is planned, beginning the first of April inspect
leaves for adult feeding holes and look for adults
during mid- to late afternoon by examining
foliage and by branch beating. Foliage and wood can
be thoroughly sprayed with a persistent insecticide
when adults are active, usually once about mid-April
and again about 3 to 4 weeks later. Permethrin treatments
are not effective against larvae beneath bark. Do
not apply sprays to heavily damaged trees as they
will die anyway and it may only exacerbate the problem
as borers will emerge and attack nearby
trees.
Soil drenches or injections with imidacloprid may
provide some control if trees are relatively healthy.
Remove adjacent seriously affected trees. |
Look
for borers and feeding holes on bark and foliage to time sprays
|
