The University of Arkansas Cooperative Extension Service is warning beef cattle producers and dairy producers that fall armyworms could become an economic threat over the next several weeks.
Kelly Loftin, an entomologist, said fall armyworms haven’t been too active so far this year, but with recent rains and grass greening up, their numbers could increase dramatically.
Fall armyworms can quickly devastate a pasture and other crops if left untreated.
Jefferson County agent Don Plunkett said armyworms have begun showing up in cotton fields.
“It’s the end of the season, and farmers want to quit spending money, so this is not a good development,” he said.
Loftin said he’s hearing reports of armyworms in pastures in several counties, including Faulkner, Logan and White.
“They prefer green vegetation. A dairy producer in Van Buren County had to treat for fall armyworms recently, while another producer in the county with less grass had no problem,” Loftin said. “They could show up anywhere in the state where there’s grass.”
Fall armyworms showed up in Arkansas about July 15 of last year, but reports this year didn’t trickle in until about Aug. 1. Loftin figures the dry summer is the main factor.
Until recently, there hasn’t been much for the pest to dine on.
Loftin warned that if producers are seeing armyworms now, they’ll likely see a second generation in about 30 days.
He said the treatment level is three or more armyworms per square foot.
Sevin and Tracer are the pesticides of choice. Both are labeled for use in pastures, but Loftin said producers should read the labels for information about grazing withdrawal.
With Sevin, producers can’t graze cattle on treated pastures for two weeks, but with Tracer, producers only need to wait for pastures to dry after treatment to reintroduce cattle.
“Last year, producers were having trouble getting Tracer if they weren’t near to row crop areas,” he said. “Hopefully, it’s a little more accessible this year.
“The bottom line is that if you have grass growing, be sure to scout regularly from now through the end of September,” he said. “Pay attention to the areas with plush growth. Dust the sprayer off, and be ready to treat when the insect reaches treatment level.”
Producers can’t afford to be surprised by a serious outbreak, he said. “Cattle producers want to keep every blade of grass that they can. It’s a critical commodity.”
For more information and updates, contact a county Extension agent or go to go to www.uaex.edu  and select Agriculture, Newsletters and Pest Management News. The Cooperative Extension Service is part of the U of A Division of Agriculture.