Growers won’t see immediate results when they apply the new Heligen technology on soybean podworms. But they will see other benefits that could help offset the relatively slow activity of the HearNPV virus.

Among those is a tendency for the podworms to move toward the sunlight, which may make them easier to scout, according to Scott Graham, Extension entomologist and assistant professor with Auburn University.

See, New virus could help with soybean podworms

“From the day of to about three days after application, the larvae will seem pretty normal, and you will not be able to see a lot of difference between an infected larvae or podworm and a healthy podworm,” said Graham, a speaker at the University of Tennessee’s virtual Milan No-Till Field Day.

“One of the odd things about this virus that is neat nonetheless is that when infected the podworms tend to move toward the sunlight,” he said. “When they do that they come up to the top of the soybean canopy which actually makes them a little easier to collect in a sweep net.”

Sometimes when entomologists come into a field five to seven days after application of Heligen to gauge the effectiveness of the spray, they will catch more podworms than they did prior to applying the material.

“They will begin to sweat – you will see very small water beads on their backs, and that is essentially the virus starting to leak out of their bodies,” he said. “The larvae will also start to feed less. You will see a little bit of etching on top of the leaves in the top of the canopy. They will also begin to shrink a little bit.

“Just before they liquify and die they will adhere to the leaf. Once the larvae liquifies, it releases millions of viral particles into the field, which can serve as a source of secondary infections for populations of podworms that were not present at the initial application.”

Next: Keeping the Heligen virus viable in Southern fields