The most significant insect event in the past week was the
reports of plant bug tolerance to all labeled or recommended insecticides in
the Tennessee Valley of North Alabama. Several of our most experienced
consultants are reporting that all classes of chemistry are suppressing plant
bugs but their presence and damage behind applications are still above
threshold levels. This has required repeated sprays and now tank mixtures with
two recommended insecticides. Under these conditions, input costs for cotton
insects, particularly plant bugs, make cotton an unattractive crop option going
into the 2015 season. Some areas of the mid-south have been dealing with this
problem for several years. At this point, the Alabama situation appears to be
confined to the Tennessee Valley area.
It has been my experience that once plant bugs get embedded
in rank cotton in July, they have always been difficult to control, requiring
multiple applications. So now, we have insecticide tolerance in addition to a
coverage issue. Looking ahead I see a larger role for the IGR Diamond during
the early bloom period in future years.
Now to a quick oversight of other insect problems on cotton
and other crops; stink bugs, primarily brown, are requiring controls in some
cotton fields. However, overall they are not as heavy and widespread as
expected. Aphids are showing back up in some fields requiring controls. Spider
mites are present in many fields. It seems like we get more calls about mite
control following weeks of high temperature and dry conditions.
In soybeans we are beginning to see loopers as far north as
Montgomery in older beans. So far they are only at about a third of a threshold
level. Scouts are reporting an occasional corn earworm and velvetbean
caterpillar in the soybean mix. The same holds true for peanuts.
Fall armyworms (grass strain) are on about every crop except
cotton now. Hay, grasses, peanuts, soybeans are all experiencing the need for
repeated applications for FAW. We could safely say that FAW’s have about worn
out their welcome, even though they are easy to control. It seems like their
preferred row crop is soybeans planted in wheat stubble. Some fields are now on
their third infestation and replanting has been required due to near 100%
defoliation.
In many ways, 2014 has been like “old times” to Extension
entomologists with numerous phone calls about when to treat and what chemical
to choose. We don’t feel like step-children to the weed resistance and disease
issues this season.
Scouting crops is the first step in all insect management
and control programs.
Ron Smith