College of Arkansas System Division of Agriculture entomologists are searching for an emergency exemption to permit for the usage of Intrepid to assist management armyworms that threaten the state’s 1.24 million acres of rice.
“This is the biggest outbreak of fall armyworm situation that I’ve ever seen in my career,” Gus Lorenz, extension entomologist for the Division of Agriculture, mentioned Wednesday. “They’re in pastures, rice, soybeans, grain sorghum. It’s epic.”
Lorenz mentioned the Part 18 request to allow use of Intrepid must be submitted to the Arkansas State Plant Board by Friday.
Intrepid is a development regulator that’s accredited to be used in nearly each different row crop however is not labeled to be used in rice.
“This armyworm thing started about three to four weeks ago,” he mentioned. “It’s continued to build from that time. It’s from the Bootheel of Missouri down to Louisiana.”
Eaten to the bottom
Lorenz mentioned he acquired a name from a producer in “south Arkansas, that they’d eaten his bermudagrass pasture to the ground. It was a 30- to 40-acre pasture. And he wasn’t even calling about the pasture. He was calling about his rice crop. He said his rice was being eaten to the ground.”
“Fall armyworm is a particularly voracious caterpillar,” mentioned Jarrod Hardke, extension rice agronomist for the Division of Agriculture. “They tend to shock us as a result of adults lay very massive egg plenty however the earliest instar larvae eat little or no. It’s not till they become old and begin to unfold out that they eat a lot of the meals of their life cycle.
“This is why we go from zero to TREAT seemingly overnight,” Hardke mentioned.
Why a Part 18?
Extension entomologist Nick Bateman examines a rice subject in Jefferson County on July 21, 2021 for fall armyworms. (U of A System Kurt Beaty)
Usually, armyworms may be managed effectively utilizing pyrethroids, however Lorenz mentioned “when this outbreak first started, we got reports out of Texas and Louisiana that they weren’t getting control. We’re getting failures.”
Lorenz mentioned he and colleagues ran some fast assessments, spraying this yr’s armyworms with pyrethroids “and we got 48% control.”
In cattle-heavy elements of the state producers use one other insect development regulator known as Dimilin to handle armyworms, however in row crop nation, “they just don’t carry it. It’s just not available,” Lorenz mentioned.
Fellow extension entomologist Nick Bateman mentioned, “another problem with using Dimilin is the pre-harvest interval. The pre-harvest interval on Dimilin is 80 days which will lead to major harvest issues.”
“We’re limited on the options in control for rice,” he mentioned. “It’s not just a problem of row rice. We are also seeing them in flooded rice, all through the field. They are eating rice all the way down to the waterline.”
Lorenz mentioned rice growers in California sought and acquired a Part 18 exemptions during the last three years. “We felt like that was our best option.”
Arkansas farmers who managed to replant after the floods and heavy rain in June have younger, tender crops which are extremely enticing to armyworms.
“Those crops are extremely susceptible to damage from armyworms,” Lorenz mentioned.
“My concern is that if we get another generation of them, the next wave could be unbelievable,” he mentioned.
The primary era of armyworms matured into moths in Texas and Louisiana and flew northward. Now that they’re in Arkansas, “We’re making our own generation, which is what makes it so dangerous,” Lorenz mentioned.
There’s additionally an opportunity that, relying on the atmosphere, “the population could collapse,” he mentioned. “There are some natural controls out there. When you get a big buildup a lot of things can happen. There are a lot of naturally occurring pathogens that can help control them.”
Some brokers in southwest Arkansas discovered armyworms that had fallen sufferer to a naturally occurring virus. Lorenz is hoping that virus could present another choice for management sooner or later.
Arkansas is the nation’s main rice producer.
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