Soybean growers look beyond chemicals to fight weeds

As weeds have developed resistance to Roundup herbicide, farmers are looking at non-chemical methods such as cover crops and even hand-weeding to control weeds.

Illinois farmers John Werries and his son Dean started planting cover crops seven years ago to prevent soil erosion on their farm. But in recent years, they’ve discovered that their cereal rye cover crop also helps them control weeds.

The Werries plant soybeans directly into thick stands of cereal rye, which acts as mulch to suppress weeds.

“As all of the cover melts down—and it takes a long time—there is a mat that makes it tough for weeds to grow,” Werries explained. The suppression allowed them to reduce their herbicide use in soybeans this year, and their fields stayed clean through the end of the season.

Herbicide resistant weeds are a major challenge to U.S. corn and soybean farmers. Weeds such as waterhemp, Palmer amaranth or “pigweed,” marestail, giant ragweed and kochia have developed resistance to many herbicides. A recent study by the Weed Science Society of America estimated that if left uncontrolled, weed pressure in soybean fields could drop yields by more than 50% and cost the industry $16 billion a year.

Newer herbicide formulas containing dicamba herbicide have caused drift problems that have damaged millions of acres of farmland, trees, orchards, and gardens.

“We built these big farms on the assumption that you could go across a thousand acres with a boom and kill every weed, and that’s just not working anymore,” said Larry Steckel, a weed scientist at the University of Tennessee.

Steckel says alternative weed-control methods, such as cover crops or hand-weeding, are going to be part of the future.

The number of acres planted with cover crops in the U.S. increased 50% from 2012 to 2017.

Source: DTN/Progressive Farmer

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