Spike in Armyworm Activity as Summer Picks up Steam

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April
showers have brought forth a lot of things in 2019, some of them more welcome
than others. Among the less desirable, perhaps, was a sharp spike in armyworm
activity in pastures in the northern half of the state.

As
early as May 1, Cooperative Extension Service agents in several counties began
receiving calls from producers as the pest made its annual appearance, chewing
its way through one bermudagrass field in Crawford County. Over the following
two weeks, the pest — alternately referred to as the “true armyworm,” and not
to be confused with the “fall armyworm” — also stirred the ire of growers in
Searcy, Boone, and Randolph counties, among others — all in fescue fields.

Kelly
Loftin, extension entomologist for the University of Arkansas System Division
of Agriculture, said the pest’s appearance isn’t unusual for this time of the
year.

“It’s
pretty typical, to have a spike like that in early May,” Loftin said. “They’re
normally found in pastures, north of the River Valley.”

The
armyworm, which takes several forms throughout the course of its brief life,
primarily inflicts its damage while a caterpillar, spending about two weeks
feeding on grasses before getting back to transforming to a moth.

“It’s
basically an issue of forage loss,” Loftin said. “They infest the field and
reduce yield. It can be quite devastating. In fescue, if the timing’s just
right, the invasion can affect seed production.”

Loftin
said that damage from only one generation of true armyworms is inflicted per
season, unlike the fall armyworm, which can rally multiple generations to
attack a crop simultaneously.

He
said the unusually wet conditions this May have likely not had any effect on
the true armyworm populations in the state one way or another. While Arkansas
doesn’t usually see true armyworms in the sheer numbers that fall armyworms
present, the treatment threshold is two to three caterpillars per square foot
to justify the use of pesticides.

Luckily,
the populations are likely on their way out, Loftin said.

“It’s
mostly passed now, or will be, shortly,” he said.

To
learn about integrated pest management in Arkansas, contact your local
Cooperative Extension Service agent or visit www.uaex.edu. Follow us on Twitter at @UAEX_edu.

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Tammy Teague

Tammy Teague

Mansfield native, with roots in Scott County. Daughter, sister, wife and Christian. Education: 1995 MHS graduate; 1999 Arkansas Tech University Graduate - BA in Journalism. Career: Managing Editor - The Citizen; Copy Writer - Southwest Times Record; 20+ years experience in the news.

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