Armyworms Active In Corn And Wheat
PRINCETON, KY.
Armyworm larvae have
been reported feeding in
corn. Although armyworm
can damage wheat,
that very rarely occurs and
when it does is usually
much later in the season.
Certainly this entire season
is much earlier than normal
because of the warm January – March temperatures.
Nonetheless, the general sequence
of events is likely to remain the same.
Captures of armyworm moths in the UK-IPM
pheromone baited traps have not been very
large. Captures did begin very early this year
and the first several weeks appeared to be
greater than the rolling 5-year average. However,
recent counts have dropped below the 5-
year average. At this point I don’t expect an
unusually large population for 2012. That
means that one should probably concentrate
their scouting efforts on those situations that
are at greatest risk.
Of special interest will be “NON- B.t.” containing
corn products (food grade, white, specialty,
etc.) fields that were planted into a
cover crop, especially a grass cover, or into
new ground (fallowed, pasture etc.) where
grasses might predominate. If armyworm eggs
and larvae were already in these grass covers,
killing the cover will serve to move these insects
over to the newly emerging corn. So, if
this is your situation it may pay you to scout
your corn, even if the cover / weeds have already
been killed back (Figure 1).
Since most of the field corn products we grow
in Kentucky are genetically modified to contain
one to several “B.t.” expressing genes, you may
in fact get some control of armyworm with
these. Of course corn rootworm “B.t.s” will not
have any effect. I would expect the Viptera
“B.t.s” to be quite active and those products
that claim control of corn earworm and fall
armyworm to have some activity.
In corn, chemical control should be considered
if 2 or more larvae are found on 25-30
percent of the plants.
Armyworm is not very difficult to control in
Corn, providing of course, one gets decent coverage.
If insecticidal control is required, see
ENT-16 Insecticide Recommendations for Corn
or ENT-47 Insecticide Recommendations for
Small Grains. These publications are available
at your County Extension Office or On Line at:
http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html. Δ
DR. DOUG JOHNSON: Extension Entomologist,
University of Kentucky
Figure 1. Armyworms collected in a western Kentucky white
corn field 4/16/2012.