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Say hello to Mr. Grasshopper in soybeansSay hello to Mr. Grasshopper in soybeans

Soybean Watch: The number of insects in this field was small, but they still did what insects do — chew, feed and damage pods.

Tom J. Bechman

October 27, 2023

3 Min Read
A close-up of a grasshoppper on a soybean plant
MEET MR. GRASSHOPPER: This grasshopper and more like it were still feeding right before harvest in the Soybean Watch ’23 field. Overall damage was minimal, but agronomist Steve Gauck noted their presence. Photos by Tom J. Bechman

So, you think your soybean fields were insect-free. Did you look? They might not have been as devoid of insect activity as you think.

“There is a difference between having enough insects to justify treatment and finding a few insects in the field,” says Steve Gauck, a regional manager for Beck’s, sponsor of Soybean Watch ’23. “We scouted the Soybean Watch field several times, and we never found many insects at any one time. However, we found insects on every visit, even right before harvest.

“If you’ve got soybeans, you’ve most likely got insects. Grasshoppers and stinkbugs are most common, and we saw them in most fields this year — especially grasshoppers. If they’re feeding on green leaves, they probably aren’t impacting yield unless they’re present in large numbers. It takes a large amount of defoliation to threaten yields and justify treatment.”

Harvest concerns

Stinkbugs can be a different story, Gauck says. Green stinkbugs are most common in soybean fields, although you may find a few brown marmorated stinkbugs as well. These insects are a concern even as harvest nears because they can feed on pods.

a stinkbug piercing a soybean pod

“A stinkbug has a piercing mouthpart and can sink it into individual beans inside pods,” Gauck explains. “That bean is usually severely damaged. However, that’s not the only reason for concern. Once they penetrate a pod, it’s opened to invasion by other pathogens. That can mean damage to all beans inside the pod. In years with lots of stinkbug activity late, you often hear reports of soybean quality issues.”

Related:More water means bigger beans, higher yields

This was not a year of high stinkbug activity, Gauck acknowledges. Still, he found pods damaged by stinkbug feeding, even in the Soybean Watch ’23 field. This field was not sprayed with fungicide or insecticide.

hands holding a soybean seed with insect damage

“You would expect less insect activity if an insecticide was applied, although it depends on how well the insecticide worked and when it was applied,” Gauck says. “There are people who recommend applying an insecticide as insurance against major insect outbreaks, and then there are people who argue that you should only apply them if an outbreak occurs to practice good stewardship toward the environment and preventing insect resistance.”

Adding insecticide midseason is relatively cheap, he notes. Without a large insect infestation, payoff in terms of more yield may be minimal. It boils down to an individual decision based upon philosophy and risk, Gauck concludes.

Read more about:

Stink Bugs

About the Author(s)

Tom J. Bechman

Editor, Indiana Prairie Farmer, Farm Progress

Tom J. Bechman is editor of Indiana Prairie Farmer. He joined Farm Progress in 1981 as a field editor, first writing stories to help farmers adjust to a difficult harvest after a tough weather year. His goal today is the same — writing stories that help farmers adjust to a changing environment in a profitable manner.

Bechman knows about Indiana agriculture because he grew up on a small dairy farm and worked with young farmers as a vocational agriculture teacher and FFA advisor before joining Farm Progress. He works closely with Purdue University specialists, Indiana Farm Bureau and commodity groups to cover cutting-edge issues affecting farmers. He specializes in writing crop stories with a focus on obtaining the highest and most economical yields possible.

Tom and his wife, Carla, have four children: Allison, Ashley, Daniel and Kayla, plus eight grandchildren. They raise produce for the food pantry and house 4-H animals for the grandkids on their small acreage near Franklin, Ind.

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