Soybean South


Early Bug Bashers

Entomologists in the Mid-South and Southeast are investigating the efficacy
and other benefits of soybean insecticide seed treatments.

By Carroll Smith

Every good plan has a beginning, a middle and an end. For soybean producers in the Mid-South, incorporating an insecticide seed treatment into their production strategy is the beginning of a successful season, according to Mid-South entomologists who have been gathering data on these products for several years.

Initially, in Arkansas, the Extension and research work with CruiserMaxx and Gaucho began because of issues surrounding ground pests such as rootworms, wireworms and grape colaspis, especially in the Grand Prairie region.

“At that time, we began looking at Cruiser and saw that it was providing good insect control,” says University of Arkansas Extension entomologist Gus Lorenz. “As our studies continued, we began to notice that there also was an obvious vigor improvement where we used insecticide seed treatments.”

To test this observation further, members of the Arkansas group expanded their tests and found that over a wide range of soil types, they were beginning to see a trend for increased vigor and yields associated with these seed treatments.

“The increased vigor ultimately resulted in a yield increase in the majority of our trials,” Lorenz says. “After sharing the data with my colleagues, we’ve been able to amass a data set of more than 100 replicated trials over the past four or five years throughout the Mid-South. And of those trials, about 80 percent of the time we see a net return on yield of about three bushels per acre.”

The Arkansas entomologist says the seed treatments are efficacious on below ground pests as well as above ground pests such as thrips, bean leaf beetle and three-cornered alfalfa hoppers.

“This combination of control turns into a very positive yield response from the seed treatment,” he adds.

The seed treatment protection lasts about three weeks, depending on the environmental factors that have an impact on residual and the insect pests that are present. From that point on, Lorenz urges producers to begin scouting their beans on a regular basis because the seed treatments have very little to no impact on early season infestations of fall armyworm, garden webworm or early season corn earworms.

Lesser cornstalk borer plagues Southeast
In the Southeast, University of Georgia (UGA) Extension entomologist Phillip Roberts says the soybean planting window in Georgia is different from that of the Mid-South, and seed treatments are not routinely used.

“We really haven’t adopted the early season production system,” Roberts says. “We typically plant soybeans in May, June and even July, so we don’t have the early season insect pests like they encounter in the Mid-South. The most common seedling pest we do encounter is the lesser cornstalk borer, especially in our later planting.”

Although this particular pest currently is not on the soybean seed treatment labels, the Georgia entomologist says that UGA has been looking at the insecticide seed treatments for a couple of years to see if they have enough activity to help control the lesser cornstalk borer – an unpredictable, dry weather pest.

“We do have insecticide seed treatment trials out there this year and will be harvesting them in the coming months,” Roberts says. “Because our production system is different from the Mid-South, the verdict is still out for us. However, when the results of our trials come in, we should have a better understanding of whether they have a place in Georgia soybean production systems and when and if we need to use them.”

Insecticide Seed Treatments

• At this time, the only two insecticide seed treatments labeled for use in soybeans are CruiserMaxx and Gaucho.

• Arkansas entomologists initially began looking at soybean insecticide seed treatments to see how well they control ground pests such as rootworms, wireworms and grape colaspis.

• Arkansas entomologists also noticed a trend for increased vigor and yields associated with the seed treatments.

• University of Georgia entomologists are testing seed treatments to see if they help control the lesser cornstalk borer.