Agronomist studies effects of desiccants on soybean harvest

Kenneth Gautreaux, Gould, Frances I., Blanchard, Tobie M.  |  11/9/2017 8:38:24 PM

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Josh Copes explains how desiccants can serve as a harvest aid on soybeans at the LSU AgCenter Northeast Research Station near St. Joseph. Copes is examining whether a harvest aid can influence soybean quality by increasing shattering of the pods. Photo by Olivia McClure

For some time, soybean farmers have used desiccants to eliminate late-season weeds and aid in drying soybean plants to make harvesting more efficient.

Research by an LSU AgCenter agronomist is questioning the effects of these harvest aids.

Josh Copes, a research agronomist at the AgCenter Northeast Research Station in St. Joseph, has three years of data examining three different desiccant products’ effects on soybeans.

Copes is questioning whether these desiccants affect shattering or reduce soybean seed quality. The impetus for the study occurred when producers applied a desiccant that was followed by a significant rain. Many of the fields experienced widespread yield loss and greatly reduced seed quality.

“Losses can be substantial. It can range from 30 to 60 percent, which means growers are docked pretty significantly,” Copes said.

The three herbicides used in the study were Sharpen, Gramoxone and sodium chlorate. In Copes’ study, the beans were harvested in seven-day intervals with the first harvest seven days after the application and the last harvest 28 days after the application.

Copes found no significant reduction in seed quality or increased shattering from any of the desiccants.

A second question Copes had was whether the desiccants were actually beneficial to producers. Copes applied the desiccants and began harvesting the beans after they reached a 13 percent moisture reading. He also harvested beans at 10 days and 20 days after they reached the 13 percent threshold.

Again, Copes found no significant difference between the test plots that received a desiccant and untreated plots.

“It had me questioning the utility of desiccants, especially in northeast Louisiana,” he said.

Copes said these harvest aids still will have to be applied in the southern part of the state because of pressures such as insects and disease and the prevalence of green bean syndrome.

Copes said that yield losses were not observed, and his plots did not encounter any significant seed shattering. He did have a slight reduction in some seed quality from early harvesting in some cases, and another seed quality issue was environmentally related.

“In terms of using the desiccants and their effect on quality and losses, I have not seen it,” Copes said.

Copes has begun a new research project that will examine the utility of harvest aids for north and south Louisiana.

“This project may offer some insight into geographical differences that may exist between north and south Louisiana,” he said.

Craig Gautreaux

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