Measuring yield loss in soybeans

Frances Gould, Morgan, Johnny W.  |  10/24/2014 1:30:47 AM

Knowing what is causing yield loss in soybeans ranks right up there with how much loss is occurring, according to LSU AgCenter plant pathologist Clayton Hollier, who is conducting a study to determine how to cut those losses. 

He’s trying to get an accurate measurement within plots of how much yield is being affected by the whole disease spectrum, not just any particular disease.

"The reason we took that approach is because in nature you’re not going to have just one disease typically, but several, each contributing to yield loss," he said.

Some of these diseases are so minor it will be hard to measure any yield losses, but others would be very easy to measure.

The benefits of this research will be positive for the growers who want to get the most out of their crops with a good disease management program.

"In disease management, you’re looking for the best field to plant something in. It has the best drainage, easy access and good fertility," Hollier said. "And when you choose a variety, you’re looking for the most resistance against disease."

The problem, Hollier said, is with some of the major diseases. The available varieties do not have high levels of resistance.

"So as we go through the season, scout and make decisions about fungicide use, we make them on what diseases are present in the field and what are the best products that will take care of them," he said.

Unlike insect problems where you deal with thresholds, plant diseases are caused by pathogens that you cannot count. So growers have to determine how much loss occurs and what they can do to prevent most of that loss.

"It’s not just about disease; it’s about the bottom line," Hollier said. "If a fungicide is used, is it going to impact disease development, and will the grower generate more income?

"Well, he’d better. And he’d better get a lot more than he paid out," he added. "We measure yield loss so that we understand how much disease impact we’re actually dealing with." Johnny Morgan

This article was published in the 2014 Louisiana Soybean & Grain Research & Promotion Board Report.

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