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Combination of factors led to isolated soybean crop herbicide injury this year.

Tom Bechman 1, Editor, Indiana Prairie Farm

May 29, 2015

2 Min Read

The farmer who contacted us wondered why his soybean stand was 100,000 or fewer in 15-inch rows. He noticed cotyledons rotting and dropping off on some soybeans soon after they emerged from the ground.

Related: Mystery of the rotting soybean cotyledons

Everyone he has talked to said it points toward herbicide injury. He sprayed the field before planting with Sharpen plus Authority. It's the same combination he has used successfully in seasons before this one, and it didn't affect all fields this year.

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Sarah Hanson, Johnson County Extension ag educator, obtained samples of affected seedlings. She elected to contact Shaun Casteel, a Purdue University Extension soybean specialist. She also described the seedlings to him. Her other option would have been to submit the samples directly to the Purdue University Plant and Diagnostic Clinic. They route the samples to the right expert. There is a charge for using their service.

Hanson reports that Conley, like most other advisers and agronomists who have viewed the field, believe insecticide injury was involved. However, like Bill Johnson, Purdue University Extension weed control specialist says, the only cause is hardly ever, if ever, herbicide injury alone.

According to Hanson, Casteel surmises that the seeds were planted a bit deeper than normal. That's judging from the length of the hypocotyl, or stem bringing the cotyledons above ground. Each cotyledon was originally half of the soybean seed.

Temperatures turned cool and it was wet, although not saturated, for several days after planting. He surmises that sitting in the soil, as the cotyledons finally reached toward the surface, they encountered the herbicide. Not growing quickly, they absorbed it and were affected, rather than popping through the soil quickly before absorbing enough herbicide to cause damage.

Related: Why herbicide labels don't always agree with one another

Not all seeds were affected. In fact there was enough stand remaining that the farmer chose not to replant. He also says he will likely continue using Authority in the future. His conclusion is that several things went against these fields, and it may not happen again.

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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