ngin - Norfolk Genetic Information Network
15 January 2003

Widely Used Crop Herbicide Is Losing Weed Resistance
New York Times

The world's most widely grown genetically engineered crops - soybeans, cotton and corn developed to be impervious to a popular herbicide - are facing a new challenge to their continued long-term use. The herbicide, known as Roundup, is beginning to lose its effectiveness in controlling weeds.

In the last few years, weeds resistant to the herbicide have emerged in Delaware, Maryland, California, western Tennessee and at the edges of the Corn Belt in Ohio and Indiana.

The problem, crop scientists say, is the very success of the genetically engineered crops, particularly the soybeans, which now account for more than three-quarters of all soybeans grown in the United States. Farmers like the genetically engineered crops, which are sold under the brand name Roundup Ready, because they can spray Roundup herbicide directly over those fields, killing the weeds while leaving the crops intact.

But the popularity of the crops has caused the use of the Roundup herbicide to skyrocket, setting up "survival of the fittest" conditions in which the rare weeds that survive the herbicide can flourish. Eventually, experts say, farmers will need to reduce their applications on the genetically engineered soybeans and other crops to preserve the long-term usefulness.  The resistant weeds could also be a problem for the Monsanto Company, which developed both Roundup and the Roundup Ready crops. Roundup is Monsanto's biggest product, accounting for about 40 percent of its estimated 2002 revenue of $4.6 billion, according to Bear, Stearns. The Roundup Ready crops, the linchpin of Monsanto's agricultural biotechnology business, had revenue of roughly $470 million last year, Bear, Stearns said.

Referring to Roundup herbicide by its generic name, Mark J. VanGessel, an associate professor of crop science at the University of Delaware, said, "With the advent of Roundup Ready crops, all we're using is glyphosate."

"Long term," he said, "what's going to have to happen is getting away from the continuous use of Roundup Ready crops."

The resistance is currently found only in a few types of weeds, crop scientists say, and farmers can easily use other herbicides to kill those weeds.

But some scientists are concerned that the resistance could spread, rendering Roundup herbicide less useful. That would be a problem for farmers because glyphosate is by far the most popular weed-killing chemical in the world. It is considered relatively benign in environmental terms and safe enough for use in home gardens, and it helps farmers control weeds without the tilling that can contribute to soil erosion.

Weed specialists say it might be hard to find good replacements, in part because the very success of Roundup has cut profits from other herbicides, causing farm chemical companies to reduce investments in developing new ones.

"There aren't a lot of new herbicides coming down the road that will bail us out," said Christy Sprague, a weed specialist at the University of Illinois.  Monsanto executives say that the resistance is not a significant problem. "The reality is, and the facts are that, one, resistance to glyphosate is rare and, two, where it has occurred around the world it is very manageable," said Kerry Preete, vice president for United States markets. Company officials said they expected use of the crops and of glyphosate to continue increasing.

Still, at its annual meeting next month, the Weed Science Society of America is to discuss if Roundup is being overused and will perhaps recommend restraint, said Ian Heap, chairman of the society's committee on herbicide-resistant plants.

And competitors of Monsanto have seen an opportunity to push their own products as alternatives to Monsanto's. Syngenta is widely advertising its recommendations that farmers limit the use of Roundup and not grow Roundup Ready corn if they are also growing Roundup Ready soy. "If it works on one thing, it might not work on the other," one ad reads, picturing a meal with ketchup slathered on a hot dog and French fries - and also on the apple pie.

Besides soybeans, about 65 percent of the cotton and 10 percent of the corn grown in the United States contains the Roundup Ready gene, according to Monsanto. Roundup Ready canola, an oilseed crop, is widely grown in Canada. Monsanto is also developing Roundup Ready wheat, alfalfa and grass for use largely on golf courses.

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