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'Super Weeds' Concern for Farmers

By Dan Flynn and Suzanna Schreck

The widespread use of the Roundup weed killer by American Farmers has led to the rapid growth of new super weeds. This is forcing farmers to spray the fields with more toxic herbicides.

Eddie Anderson, a farmer from Tennessee who has used environmentally friendly farming practices recently told the New York Times, "We're back to where we were 20 years ago."  Anderson will plow one-third of his 3,000 acres of soybean fields this spring, which is more than he has in years.

Farm experts worry Roundup resistance and the resulting changes in farming practices--including increased tilling and herbicide use--will lead to higher food prices, less crop production, higher costs for farms, and more erosion and pollution.

Andrew Wargo III, the president of the Arkansas Association of Conservation Districts said, "It is the single largest threat to production agriculture that we have ever seen."

In 2000, the first resistant species was found in a Delaware soybean plant. Since then, the problem has only gotten worse. There are currently 10 Roundup-resistant species affecting millions of acres of soybeans, cotton, and corn.

In the 1990s Monsanto, the makers of Roundup, created its brand of Roundup Ready crops that were genetically modified to tolerate the chemical.  This allowed farmers to spray their crops to kill weeds while leaving their crop unharmed. Roundup Ready crops now make up 90 percent of the soybeans and 70 percent of the cotton and corn grown in the United States.

According to Marion Nestle, professor of Nutrition, Food Studies, and Public Health at New York University, "Roundup is Monsanto's clever way to encourage use of genetically modified (GM) crops. The company bioengineers the crops to resist Roundup. Farmers can dump Roundup on the soil or plants. In theory, only the GM crops will survive and farmers won't have to use a lot of more toxic herbicides. In practice, this won't work if weeds develop Roundup resistance and flourish too. Then farmers have to go back to conventional herbicides to kill the Roundup-resistant weeds."

Farmers have sprayed so much Roundup on their crops that weeds have begun to evolve to survive exposure to it. "What we're talking about here is Darwinian evolution in fast-forward," Mike Owen, a weed scientist at Iowa State University, said. Roundup-resistant weeds are forcing farmers to revert to more expensive techniques.

Eddie Anderson is dealing with a particular species of glyphosate-resistant pest called Palmer amaranth, or pigweed.  Pigweed can grow as much as three inches a day and reach seven feet or more.  Anderson and his neighbors are plowing and mixing in herbicides in an attempt to kill the weeds.  

Some critics of genetically engineered crops say the extra use of herbicides contradicts the claims made by the biotechnology industry that their crops are better for the environment.

"The biotech industry is taking us into a more pesticide-dependent agriculture when they've always promised, and we need to be going in, the opposite direction," said Bill Freese, a science policy analyst for the Center for Food Safety in Washington.

According to Ian Heap, director of the International Survey of Herbicide Resistant Weeds, the estimated total amount of United States farmland affected by Roundup-resistant weeds is 7 million to 10 million acres. This is a relatively small number when you consider that there are 170 million acres of soybeans, corn, and cotton.

In her book Safe Food: The Politics of Food Safety, Nestle says, "From a biochemical standpoint, resistance to Roundup is not difficult to achieve. Its active chemical, glyphosate, inhibits the action of an enzyme that makes three amino acids needed to construct plant proteins. Plants cannot make the protein when the enzyme is blocked. Bacteria, however, are well known to produce a mutant variant of this enzyme that is completely unaffected by glyphosate; they do so through "point" mutations (mutations that alter just one amino acid) or mutations that that cause the enzyme to be produced in such large amounts that glyphosate becomes ineffective. Such mutations could occur in plants as well as in bacteria. The transfer of Roundup resistance to weeks through pollination also is probable, and has already occurred. The idea of widespread resistance to Roundup is not improbable, and it alarms the industry as well as environmentalists."

Monsanto once argued that resistance would not become a major problem. 

Full post as published by Food Safety News on May 10, 2010 (boomark / email).