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Small holes in soybean leaves won't cost you bushelsSmall holes in soybean leaves won't cost you bushels

Do you have soybean leaf holes? Overwintering bean leaf beetles are out looking for food.

Tom Bechman 1

June 3, 2015

2 Min Read

A farmer checking on another problem in his soybean field found a plant here and there with a few round holes in one or more leaves. He wondered what caused it, and he wondered if it was anything to worry about.

Related: Determine Whether Leaf Feeding on Soybeans is a Big Deal or Not

John Obermeyer, Purdue University Extension entomologist, says the answer is pretty straight forward. The holes are most likely due to bean leaf beetle feeding. When overwintering, bean leaf beetles emerge and they look for food.

"It isn't anything to worry about," he says. "I would be surprised if I walked through a soybean field and didn't find a few small holes in leaves here and there."


Several seed treatments supplied on seed control bean leaf beetles. However, the insects have to take a bite of leaf to ingest it, so there will still be some holes.

"Seed treatment insecticides are effective against these beetles, but that doesn't mean anything at harvest," he insists. "There isn't going to be any yield loss from spotty, early feeding anyway."

Obermeyer says soybeans would have to lose half or more of their leaf surface area to feeding by insects at the early stage shortly after emergence before it would be an issue worth worrying about. He hasn't heard reports of any feeding near that level.

"Actually things have been quiet so far this spring," he says. "We just haven't heard about anything out of the usual, or anything in the insect and crop world to get excited about."

The first generation of bean leaf beetles emerging from eggs laid now will show up later in July, he says. Usually they're not a large cause for concern either. If bean leaf beetles are going to be a problem and perhaps threatened yield, it likely wouldn't happen until very late in the season when the second generation emerges.

"Then the issue is whether they feed on pods in significant numbers to cause an economic problem," he says.

For farmers to maximize soybean yields, they need to maximize their management. Often soybean management takes a backseat to corn, but it doesn't have to. Download our free report, Boost Your Soybean Yield, for a one-stop look at ways you can better manage your crop.

About the Author(s)

Tom Bechman 1

Editor, Indiana Prairie Farm

Tom Bechman is an important cog in the Farm Progress machinery. In addition to serving as editor of Indiana Prairie Farmer, Tom is nationally known for his coverage of Midwest agronomy, conservation, no-till farming, farm management, farm safety, high-tech farming and personal property tax relief. His byline appears monthly in many of the 18 state and regional farm magazines published by Farm Progress.

"I consider it my responsibility and opportunity as a farm magazine editor to supply useful information that will help today's farm families survive and thrive," the veteran editor says.

Tom graduated from Whiteland (Ind.) High School, earned his B.S. in animal science and agricultural education from Purdue University in 1975 and an M.S. in dairy nutrition two years later. He first joined the magazine as a field editor in 1981 after four years as a vocational agriculture teacher.

Tom enjoys interacting with farm families, university specialists and industry leaders, gathering and sifting through loads of information available in agriculture today. "Whenever I find a new idea or a new thought that could either improve someone's life or their income, I consider it a personal challenge to discover how to present it in the most useful form, " he says.

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