Early Spring May Yield Extra Generation Of Crop-Eating Insects
LONOKE, ARK.
Arkansas farmers need to budget now for
one, and possibly two extra insecticide applications
this growing season, as the early
spring is expected to provide more time for a
crop pests to create an extra generation.
“This is one of the earliest springs we’ve seen
in a long time,” said Gus Lorenz, extension entomologist
for the University of Arkansas System
Division of Agriculture. “The warmer-than
normal-temperatures have allowed insects to
get an early start
this year. They’re
developing at a
f a s t e r - t h a n -
normal rate.”
Insects are expected
to have an
extra generation
this growing season.
Insects that
may produce
three generations
during a growing
season “may have
a fourth and part
of a fifth,” he said.
“That may not
sound that bad
on the surface,
but with every
new generation,
they build up bigger
numbers.”
One such pest
is the tarnished
plant bug, which
Lorenz called the
No. 1 pest of cotton.
“They’re at huge
numbers, much
higher than what
we usually see at
this time of year,”
he said. “Based on our observations, we feel
there is a much worse situation that’s brewing
for the future.”
The higher numbers will mean more spraying.
“Generally, speaking a tarnished bug application
will be $8-12 an acre,” Lorenz said. “What
this means is increased costs to growers and a
more expensive crop.
“It’s nothing we can’t handle. Our growers can
manage, but it’s a matter of being able to budget
another insect application or two to get a handle
on the problem and growers should be prepared
for that eventuality,” he said. The
downside to extra applications is the loss of
beneficial insects that can keep the pests in
check.
More sprays early in the season “causes secondary
insects like aphids, mites, and even bollworms
to become worse,” Lorenz said.
HOST PLANTS
The warm temperatures have accelerated
growth of host plants, providing a feast for the
early insects. The warmth also accelerated
growth of winter wheat, a crop that unfortunately
is serving as a host plant for armyworms
(See earlier story: http://bit.ly/HdEbqz ) that
arrived in Arkansas a full month earlier than
normal, Lorenz said.
Lorenz predicted that “if that wheat field is
next to a corn field or a rice field that’s emerging,
the armyworms will leave the wheat and go
across the turnrow or the highway and go into
that seedling crop and eat it right down to the
ground, past the growing point. Growers will
lose their stand.”
Scouting fields for armyworm activity is of primary
importance – and not just in the lower
canopy of wheat, but also in the dirt.
“It’s extremely important where rice, or other
small grains like corn and milo are growing that
you monitor that and be prepared for the armyworms
to go across the road,” Lorenz said. “I’ve
seen them crossing the road so thick, the road
would get slick from people driving and crushing
them. They don’t call them armyworms for
nothing.”
Armyworms are also masters of the disappearing
act.
Lorenz told of one producer with a damaged
wheat crop who thought the worms were gone.
“I told him to lift up the dead grass on the
ground and tell me what you see. He lifted it up
ad said, ‘they’re everywhere!’” Lorenz said.
“Armyworms are like the vampires of the insect
world. They don’t like the sunshine,”
Lorenz said. The worms will often seek shelter
under rocks or clods of dirt. “Fifty or 60 can
cram underneath a dirt clod” the size of a halfdollar.
Chuck Wilson, director of the Rice Research
and Extension Center in Stuttgart, said
pyrethroids were the product of choice and
warned producers to spray as late in the day as
possible.
“Pyrethroids break down in sunlight, so late in
the day spraying will help maintain activity
when the armyworms come out at night.”
Growers should consult the MP-144 “Insecticide
Recommendations for Arkansas,” or their
county agent. Δ
Tarnished plant
bugs fill a sweep
net. The plant bugs
were appearing
in high numbers
much earlier than
usual in April 2012.
U of Arkansas System
Division of Agriculture
photo by Gus Lorenz