Pest management research could save producers money

Johnny Morgan, Gould, Frances I., Blanchard, Tobie M.  |  9/12/2018 7:37:10 PM

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Sebe Brown, LSU AgCenter entomologist, inspects corn plants for insect infestations.

New research on pests in soybeans and corn should decrease the amount of money growers spend on pest control.

“After the cold weather we had this winter, we were expecting the numbers of redbanded stink bugs to be lower,” said LSU AgCenter entomologist Jeff Davis.

This should be the case for many of the insects that plague Louisiana crops. Researchers are watching the soybean looper very closely, he said.

In fields across the South, soybean loopers are now showing resistance to some pesticides.

Davis said his colleagues from across the South are sending him soybean loopers, and he is testing them for resistance. He is finding that some loopers have developed resistance levels so high that they will not ingest the pesticide.

The loopers are not a problem during the early part of the growing season but start showing up in high numbers in July, he said.

Research is also continuing on the control of the redbanded stink bug.

“Along with the redbanded stink bug, another pest that we’re looking at is the kudzu bug,” he said. “The kudzu bug is easy to kill, where the redbanded stink bug is a lot harder.”

Anything that kills the redbanded stink bug will also kill a lot of the other insects, he said.

Davis is also evaluating new integrated pest management tactics, which means using a number of different approaches to control insects. He is analyzing new chemicals, better timing schedules for spraying and improved winter cover crop management.

New chemicals coming soon do a good job of taking care of the redbanded stink bug, but they are not quite ready for release yet, Davis said.

Davis is working to find better timing schedules for sprays because when pests are at their highest, the beneficial insects are in the field, too.

When soybeans are in the R2 and R5 stages, the female-to-male ratio of the redbanded stink bugs is high. At this time of the year the females outnumber the males nearly two to one.

“The question is, can we time our sprays to target the females?” said Davis. “The problem is at growth stage R2 there are more beneficial insects in the fields.”

Davis is also studying ways to improve winter cover crop management.

“Cover crops do great things, like hold moisture and put nutrients back in the soil,” Davis said.

As soon as the stink bugs leave wheat fields, they will head for clovers, which may be used as a cover crop. From there they move on to soybeans.

“Actually, we’ve found that clovers are a better host for the redbanded stink bug than soybeans,” Davis said.

AgCenter entomologist Sebe Brown is studying several insect pest problems that need to be controlled in field corn and soybeans.

“In field corn, we are trying to provide the growers with the best information for the most common pests,” he said.

The study is in first year for corn and is showing corn earworms developing resistance to certain organisms in Bt pesticide.

Although Bt products are not performing as well as they have in the past, they will continue to be used, Brown said.

Brown is continuing his research on soybeans and is looking at different types of seed treatments because soybeans tend to be planted early, and slow growth could increase damage from insects.

“The slower the plants grow, the greater the chance of insects causing damage,” Brown said. “With early-planted soybeans, it’s a little like corn. Both are normally planted during suboptimal conditions.”

Brown is evaluating insecticidal control strategies, use rates and application timings against redbanded stink bugs, soybean defoliating caterpillars as well as corn earworm,” Brown said.

Brown said he is now reevaluating some of the older insecticides, which are still labelled for soybeans and examining different rates for effective control.

In another project, researchers are spraying a virus onto the soybean plant to kill loopers. Brown said the study is ongoing, and he hopes to have some results to share soon.

Johnny Morgan

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