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Herbicide-Resistant Weeds Appearing In GM Fields

on Monsanto's GM soybeans
(ENS) -- Reliance on the Monsanto herbicide Roundup to kill weeds in fields of genetically engineered Roundup Ready soybeans has led to increased herbicide use because the weeds have become herbicide resistant, according to a new study.

Dr. Charles Benbrook of the Northwest Science and Environmental Policy Center in Sandpoint, Idaho, says that contrary to the promises of Monsanto that growing its genetically engineered variety of Roundup Ready soybeans would put fewer pesticides into the environment than conventional varieties, farmers are applying more herbicides to Roundup Ready soybean plants to combat weeds.

American Soybean Association president Tony Anderson agrees that the developing resistance of weeds to herbicides such as Roundup is a problem, but says it could be solved more quickly without critics like Dr. Benbrook.

Roundup Ready crops allow farmers to spray a single broad spectrum herbicide active ingredient, glyphosate, over the top of growing soybeans, killing most weeds but leaving the Roundup Ready soybeans largely unharmed.

The report, "Troubled Times Amid Commercial Success for Roundup Ready Soybeans," relies on previously unreleased data from the U.S. Department of Agriculture (USDA) indicating that on average 11.4 percent more herbicides is used on Monsanto's Roundup Ready (RR) soybean crops, than on conventional soybeans. In some cases, 30 percent more herbicides was used.

"More than a dozen soybean herbicides are applied at an average rate of less than .1 pound active ingredient per acre. Roundup, on the other hand, is usually applied on soybeans at about .75 pound per acre in a single spray and most acres are now treated more than once," Benbrook writes.

But Bryan Hurley, spokesman for Monsanto, says the information in Dr. Benbrook's report is not correct. "His report is laden with inaccuracies and biased interpretations of existing data," says Hurley. "He ignores the experince of farmers."

American farmers have planted 60 percent of this year's soybean crop, roughly 40 million acres, with bioengineered Roundup Ready seeds. They would not be selecting these seeds if it was not to their advantage, Hurley says.

Anderson, whose American Soybean Association supports agriculture biotechnology, says Roundup Ready soybeans are good for farmers who are planting them in ever increasing numbers.

"In 1996, when biotech soybean seedstock first became available commercially, U.S. farmers planted only about one million acres of biotech varieties, which represented less than two percent of the total soybean acres planted that year," said Anderson. "In 1997, planted acres of biotech soybeans increased to nearly 10 million acres, or about 14 percent of the total soy acres planted. By 1998, biotech seedstock acres increased to 25 million acres, representing about 34 percent of the total soy planting."

"In 1999, approximately 38 million acres or 53 percent of total U.S. soy acres were planted to biotech seedstock, and last year biotech soybeans were grown on approximately 40 million acres or 55 percent of total U.S. soy acres," said Anderson.

"In 2001, the U.S. Department of Agriculture estimates that soybean farmers will again increase the number of acres they plant of soybean seeds that have been enhanced through modern crop biotechnology," Anderson explained.

But Dr. Benbrook says farmers have eagerly adopted Roundup Ready (RR) soybean technology because it is cheaper than conventional farm methods and simplifies weed management. "Still, Roundup Ready soybean systems are costly in more ways than one and some costs are rising," he writes.

"Intense herbicide price competition, triggered by the commercial success of RR soybeans, has reduced the average cost per acre treated with most of today’s popular herbicides by close to 50 percent since the introduction of RR soybeans. In response farmers are applying more active ingredients at generally higher rates," Dr. Benbrook writes.

"But heightened reliance on herbicides, especially Roundup, has accelerated the shift in weed species in ways that is undermining the efficacy of Roundup and requiring farmers to add new products to their control programs. These trends increase the risk of resistance and will ultimately lead to less reliable and more costly systems," Benbrook maintains.

Troubled Times Amid Commercial Success for Roundup Ready Soybeans
On behalf of the soybean farmers, Anderson agrees that the developing resistance of weeds to herbicide is a problem, but it is a problem that could be solved more quickly if critics had not derailed the approval process for new products.

"Critics of biotechnology cite the potential for herbicide resistance to develop if farmers depend upon only one weed control system," Anderson said today. "Farmers would agree that diverse technologies for weed control are an important part of managing weeds and other pests. Unfortunately, the hysteria caused by environmental activists in the European Union has frozen the regulatory approval for new biotechnology enhanced products that could diversify a farmer’s pest management options."

"One such product, a soybean resistant to glufosinate herbicide, would provide farmers another choice in seed/herbicide management systems, but the EU has not approved this product despite the petition being submitted in 1998," he said.

At Greenpeace headquarters in Amsterdam, genetic engineering campaigner Geert Ritsema says Monsanto has based its claims of herbicide reduction on a comparison between "traditional soybean varieties" and RR crops without explaining that these traditional varieties were a selected number of old generation types, which require high dose rate herbicides."

"This study confirms that genetic engineering of farm crops means more chemicals in our environment," says Ritsema.

But Anderson says that Dr. Benbrook is "so intent on finding something wrong with biotechnology, that he misses the big picture."

"There are always questions about new technology. As farmers growing food for a hungry world, we care very deeply about the safety and quality of our product, and we are committed to finding answers to the questions raised by biotechnology’s critics. But," says Anderson, "this quest for knowledge should not undermine the positive environmental gains we have made using modern biotechnology."

© 2001 Environment News Service and reprinted with permission

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Albion Monitor May 28, 2001 (

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