INSECT CONTROL – Early & Late Soybean Pest Management

Soybeans are affected by both early and late-season insect pests.
New pesticide formulations now provide more convenient and effective
products to help manage these challenges.

The three-cornered alfalfa hopper is an early season pest problem in northeast Louisiana.
The three-cornered alfalfa hopper is an early
season pest problem in northeast Louisiana.

Pests are moving targets as anyone in the field can testify. Migration, overwintering species, resistance issues and complex cropping patterns are just a few of the complicating factors.

Pesticide formulations have evolved rapidly over the past few years offering products that are more convenient, more effective and require fewer trips across the field. Meanwhile, the pest spectrum continues to evolve as formulators try to stay one step ahead of it.

“It all depends on the year and the unknown,” says James Clower, independent crop consultant in St. Joseph, La. “We deal with challenges that are localized due to cropping patterns and pests that are migrating in and out.”

In northeast Louisiana early in the growing season, the problems are primarily bean leaf beetle, stinkbugs and three-cornered alfalfa hopper, according to Clower.

“The early foliage feeders can do a lot of damage,” Clower says. “A lot depends on how fast the crop is progressing. Three-cornered alfalfa hoppers are a real concern early on because they cause girdling of the stem at the soil line and interfere with plant growth. Even wind can become a factor because it can snap the plant over at the base.”

Stinkbugs are becoming more problematic, especially the redbanded stinkbug, according to Clower. “They migrate in and out of fields, and they are just downright difficult to control,” he says.

Late-season challenges

“Later in the season once the pods begin developing, we become equally as concerned about pod damage. As the crop progresses toward harvest, you have to worry about foliage damage as well as pod damage. Corn earworm is becoming more difficult to control, and loopers are also a problem.”

As always, scouting frequency largely depends on what pests are prevalent in the area. “A weekly schedule is normal, but if loopers or stinkbugs are present, you better be watching that field twice a week,” Clower says. “Of course, that depends on the spray regimen as well. If you have a good program in place, it’s not as critical from day to day.”

Insecticide resistance is always a concern when considering any spray regimen, and it’s not just a homegrown threat.

“Obviously, there are a lot of crops nearby where growers are trying to control insects that overwinter locally and end up taking a short hop across the road when another crop emerges or becomes more attractive,” he says. “We have vast acreages of corn where corn earworm will naturally move over into soybeans, and those pests have already been subjected to control measures in the previous or adjacent crop.”

Resistance management

International highjackers create additional problems. “We have insects such as loopers that migrate all the way from Central and South America that have been subjected to control programs that may or may not have been as discriminate as what we have in place here. It complicates the dynamics of resistance management.”

That’s where tankmixes and smart rotations come into play, according to Clower.

“It’s important to have different modes of action when you’re constantly battling resistance along with a variety of insects that are already difficult to control,” Clower says. “Last year, I worked with Justice insecticide, which is a pre-mix of the active ingredients bifenthrin and acetamiprid. I was very pleased with the results. We didn’t have extremely high pest pressure, but it was definitely at treatable thresholds, and the product performed better.”

New formulation available

Justice insecticide is a relatively new formulation marketed by Gowan Company that received federal registration in 2012. “It’s a unique liquid oil flowable formulation that allows both active ingredients to remain in their most biologically active form,” says Chad Dyer, Product Manager for Gowan. “We tested various formulations during development, and the liquid oil flowable formulation clearly gave us superior results.”

In Southern states, Justice insecticide is labeled at a use rate of up to 5 oz/A. Soybean looper and armyworm species require the higher labeled rate. The upper end of the labeled rate is also recommended if pest populations are above economic thresholds at time of treatment. Clower used the higher end of the rate to address the range of pests present in the field.

“It worked well,” he says. “The pre-mix is convenient. The two active ingredients in Justice complement each other to take out a wider spectrum of insects with a relatively quick knockdown and a long residual. Bifenthrin is a premier class of pyrethroid that doesn’t break down in sunlight as rapidly as some of the alternatives, and acetamiprid offers the residual.”

While aphids are not yet a problem in Louisiana, field tests in other areas have shown the Justice pre-mix can also handle that potential problem.

“We don’t have any significant problems with aphids in this area at this point,” Clower says, “but nothing surprises me anymore.” Information for this article was provided by Gowan Company.

Information for this article was provided by Gowan Company.

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