The Bug Front Is Mostly Quiet
JACKSON, TENN.
April 17, 2012 – Armyworms in Wheat –
Unlike some areas to our south, there have
been very few calls on armyworms.
Granted, many people included an insecticide
with their fungicide, but the few reports of those
that didn’t indicate that armyworms are not an
issue. I have not found armyworms in the wheat
at the Jackson experiment station. Dr. Angus
Catchot did an excellent podcast about the
treatment threshold for armyworms in Mississippi,
which is essentially the same as ours (link
here). Cereal leaf beetles also appear to be conspicuously
absent, but since first posting this
article, I’ve had a report of one field exceeding
the treatment threshold.
Stink Bugs in Corn – I‘ve had no reports of
stink bugs in Tennessee corn, but some are dangerously
close in NW Mississippi. Stink bugs
feeding on small plants can cause serious injury,
essentially rendering the plant a weed in
the worst cases. Stink bugs, often brown stink
bugs, will feed at the base of plants into the
growing point. This is not commonly a big problem
in Tennessee, but I see a few fields with economic
damage every year. The suggested
treatment threshold is when 10 percent of
plants less than 24 inches tall are infested. It requires
close inspection as they are deceptively
hard to find. Some recommended insecticides
include the synthetic pyrethroids or methyl
parathion. Many people will specifically use
bifenthrin (Brigade, Fanfare or Discipline) as it
tends to have better activity on brown stink bugs
than the other pyrethroids.
Sugarcane Beetles in Corn – I had several reports
of fairly large numbers of beetles being
seen at lights a few weeks back. I also had a report
of someone’s sweet corn patch getting
“hammered”. However, trap catches in our black
light trap have dwindled over the past two
weeks. This may just be the result of cooler
nights.
Reminder – Sugarcane beetles feed underground
by gnawing on the stem. Damaged
plants will often wilt, lay over or outright die.
Problems tend to be more common in Cruiser
treated seed than with Poncho, but no at-planting
treatments are immune from injury. Unfortunately,
rescue treatments only rarely provide
adequate control.
Cutworms in Corn – There were a lot of reports
of high pre-plant populations of cutworms,
but it appears that most folks wisely sprayed a
pyrethroid insecticide at or near planting to
eliminate the risk. Any fields that were not
treated with a pyrethroid within 7-10 days of
planting should be scouted to make sure that
cutworms are not threatening stands. Heck,
you ought to be looking anyway!
Be careful not to confuse bird feeding with cutworm
damage. Birds will sometimes tear off
plant tops while digging for seed, but they also
often leave peck holes in the soil (and the plant
top mostly intact). If cutworms are present, you
will typically find some larvae near freshly cut
plants or their neighbors. This does require a little
digging. Δ
DR. SCOTT STEWART: IPM Extension Specialist,
University of Tennessee
Courtesy of the University of Kentucky
Sugarcane Beetle
Cutworm