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New virus could help with soybean podworms

Insect susceptible to new product, Heligen, a specific, naturally occurring virus.

The insect Helicoverpa armigera goes by several names. In corn, it’s known as the corn earworm; in cotton, the cotton bollworm; and, in soybeans, the soybean podworm. It’s also a close relative of the tobacco budworm.

By whatever name it’s called, the insect is susceptible to a new product called Heligen, a highly specific, naturally occurring virus called HearNPV or Helicoverpa armigera Nuclear Polyhedrosis Virus.

“One of the important things to remember about this virus is that it is highly specific, and it will only control one pest, the corn earworm, bollworm or podworm,” said Scott Graham, Extension entomologist with Auburn University, a speaker at the University of Tennessee Milan Field Day, which was held online this summer.

“For this talk since we’re talking about soybeans so we’ll call them podworms,” said Graham, one of the speakers on the No-Till Soybean portion of the field day. (Heligen is active on tobacco budworms, typically a pest in cotton, which is also a member of the heliothine complex.)

Because it is so specific it is safe on beneficial arthropods and insects. Neither is it harmful to honeybees, which is a growing concern among fruit and nut tree producers in several regions of the United States.

“But with that it is also safe on other pests,” he said. “So, if you have soybean loopers in the field, stinkbugs or similar insects, it will have no activity on those types of pests. It will only control podworms.”

AgBiTech

The virus is produced by AgBiTech, a company that was originally based in Australia and relocated to the United States in the early to mid-2000s. They’re now in the Dallas-Ft. Worth area where they produce and package the virus.

The product is a Group 31 insecticide and is a midgut peritropic membrane disruptor, Graham said. Essentially, the virus infects these worms, ruptures their midgut, and the virus begins to leak and kill the podworms.

The treatment threshold for Heligen is much lower than for synthetic chemistry, he said. “We’re using a threshold of two to five small worms per 25 sweeps. Ideally, we want to use this product when the population is one-fourth inch in length. We can go to one-half inch, but when you start getting closer to three-fourths of an inch you will want to use synthetic chemistry.

“These worms will continue feeding until they die,” he said. “In the first three to five days after infection, they will continue feeding. As they get larger, they will eat more so they do more damage. It’s important we control these worms before they get into the fourth, fifth and sixth instar because the fifth and sixth instar is when they do 80 percent of their feeding.”

The labeled use rate in soybeans is from 1.28 to 1.6 ounces per acre, he said. At the low rate, 1 gallon of the virus will treat 100 acres, which will cost growers from $5.50 to $6.88 an acre for the virus.

“It’s an economical option for us,” he said. “Keep that in mind when you’re comparing it with a lot of synthetic chemistry. We’re putting out a product that doesn’t cost as much, so we can’t have the same expectations of this virus as we do those chemistries.”

The labeled use rate in soybeans is from 1.28 to 1.6 ounces per acre, he said. At the low rate, 1 gallon of the virus will treat 100 acres, which will cost growers from $5.50 to $6.88 an acre for the virus.

“It’s an economical option for us,” he said. “Keep that in mind when you’re comparing it with a lot of synthetic chemistry. We’re putting out a product that doesn’t cost as much, so we can’t have the same expectations of this virus as we do those chemistries.”

Next: Soybean podworms may “get a lift” from new virus

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