Dessication of Weeds in Some Soybean Fields Recommended

Farmers can’t control the actions of Mother Nature, but sometimes they can trump one of her moves. Soybean producers with heavy weed infestations have just such an opportunity, says a crop specialist with the North Dakota State University Extension Service.

"I’ve seen some weedy soybean fields," says Duane Berglund, extension agronomist at North Dakota State University. "It’s probably a good idea for some soybean producers to desiccate before harvest to prevent weed interference during combing."

The herbicides labeled for desiccation or preharvest weed control in North Dakota: Gramoxone (paraquat), Drexel Defol (sodium chlorate), and Glyphosate. The preharvest spray interval (PHI) is seven days for glyphosate and sodium chlorate and 15 days for Gramoxone.

The rate for application of the glyphosate products for preharvest weed control in soybean is 1 to 2 quarts per acre. Berglund cautions that soybean fields receiving a preharvest treatment with glyposate products should not be used for seed because the herbicides could affect seedling vigor.

The glyphosate products require that the soybean crop be fully mature (all pods free of any green color). The label for Gramoxone Extra says at least 65 percent of the seed pods must display a mature brown color or the seed moisture is 30 percent or less before application can occur.

Berglund says producers should check the herbicide label or consult the NDSU Extension Service’s "2001 North Dakota Weed Control Guide" for further details. The guide is available via the World Wide Web at http://www.ext.nodak.edu/extpubs/plantsci/weeds/w253/w253w.htm .

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