Herbicide is sprayed on a soybean field in western Brazil on 30 Jan 2011. By Yasuyoshi Chiba / AFP / Getty Images

By Kevin Pieper, USA TODAY
18 April 2012

A much-used herbicide, which for years has helped farmers throughout the United States increase profits, is losing its effectiveness and forcing producers to spend more and use more chemicals to control the weeds that threaten yields.

"I've gone from budgeting $45 an acre just two years ago to spending more than $100 an acre now to control weeds," said Mississippi farmer John McKee, who grows corn, cotton and soybeans on his 3,300-acre farm in the Delta.

The problem is Roundup, a herbicide introduced in the 1970s, and its partner, Roundup Ready crop seeds, genetically modified to withstand Roundup's active ingredient, glyphosate. In 1996, Monsanto introduced Roundup Ready soybean, soon touted as a game changer.

"It was an extremely valuable and useful tool for the past 15 years," said Bob Scott, extension weed scientist with the University of Arkansas.

But now, weeds that Roundup once controlled are becoming resistant to glyphosate, Scott said.

"It's a very, very serious issue here in the Delta," licensed crop consultant Joe Townsend said. "We're knee-deep in it."

As overuse of antibiotics led to resistant bugs or superbugs, the almost exclusive use of glyphosate led to resistant populations of weeds, such as pigweed and ryegrass. Glyphosate-resistant weeds have been identified in Australia, South America, and China, according to the International Survey of Herbicide-Resistant Weeds.

To combat resistant weeds, farmers are turning to older methods of weed control — more chemicals and more tillage, which leads to increased rates of soil erosion. "I used so many chemicals last year, it made me silly," McKee said. "We're going backwards 15 years." […]

Farmers must spend more on herbicides as effectiveness fades



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