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Roundup-resistant weeds are cropping up

(Friday, Jan. 10, 2003 -- CropChoice news) -- Philip Brasher, Des Moines Register: Few inventions have altered agriculture recently as much as Roundup weedkiller, but now scientists are concerned that farmers are using the herbicide so heavily it is losing its effectiveness against some of the world's peskiest weeds.

"It's going to happen. It's inevitable," said Bob Hartzler, a weed scientist at Iowa State University.

Known generically as glyphosate, Roundup is powerful yet environmentally benign. It has led to the widespread adoption of soil-saving techniques that reduce land erosion and combat global warming. Even home gardeners are likely to have a version of Roundup in their garage arsenal.

Roundup has been around for nearly 30 years but exploded in popularity in the late 1990s with the development of genetically engineered soybeans, cotton and other crops that are immune to the herbicide. That change means farmers can spray their fields with the relatively cheap weedkiller whenever it's needed with no fear it will harm the crops.

Roundup-immune soybeans now account for 75 percent of all the soybeans planted nationwide and in Iowa. Some 33 million pounds of glyphosate were sprayed on soybean crops alone in 2001, a five-fold increase from 1995, according to the U.S. Department of Agriculture.

Scientists are finding Roundup-resistant weeds in a variety of states, from Iowa to Delaware. Scientists are so concerned that some 200 showed up for a symposium on the issue last month in St. Louis.

Monsanto Co., which invented both Roundup and the Roundup-immune crops, has applied to the Environmental Protection Agency to alter Roundup labels to add special instructions for farmers in areas with resistant weeds.

A rival manufacturer of glyphosate, Syngenta, is advising farmers not to apply the chemical more than twice in every two-year period and not to plant glyphosate-resistant crops in the same field every year.

"The warning signs are already out there," said economist Charles Benbrook, a critic of the biotech industry and a former executive director of the National Academy of Sciences" board on agriculture.

If herbicide-tolerant weeds gain hold, land prices could slip and farmers would be forced to start using additional chemicals, adding to their costs and potentially increasing environmental risks.

No alternatives to Roundup are on the horizon. Industry experts say Roundup has been so effective for so long that there has been no financial incentive for chemical companies to develop a substitute.

Farmers love the bioengineered soybeans because they say Roundup makes it easier and cheaper to control the weeds. Ron Heck of Perry, Ia., says he used to spend $20 to $40 an acre on weed control. Now the cost is down to about $15 an acre, even accounting for the special fee for the seed.

Growers also say the biotech soybeans have allowed them to farm more land and spend more time with their families, or in some cases take a second job.

Monsanto throws in some more incentives: If the biotech crops fail, the company will refund some of the seed cost. And if the herbicide doesn't kill the weeds, farmers can get additional Roundup for free.

Roundup is so effective as a herbicide that many farmers are no longer tilling their fields to control weeds. Less tillage means less erosion and stores carbon in the soil, thereby limiting the production of the greenhouse gases blamed for global warming. No-till soybean acreage increased by 35 percent from 1995 to 2000, according to one study.

Herbicide resistance in weeds is nothing new. It happens regularly with weedkillers, except, until recently, with Roundup.

Some of the first significant reports of Roundup-resistant weeds in the United States surfaced in Delaware. Mare's-tail, or horseweed, that could not be killed by the herbicide was found on several farms in 2000. Scientists said they had to spray the weeds with 10 times the recommended rate of the herbicide to kill the plants.

Scientists in Iowa and Missouri have found fields with types of waterhemp, a prolific Midwestern weed, that are significantly more tolerant of glyphosate than others. More than a quarter of the weeds collected from one Iowa field survived being treated with Roundup.

The scientists say it remains to be seen how quickly the hardier weeds will spread.

"Everybody is in reasonable agreement that the evolution of glyphosate resistance in waterhemp is inevitable," said ISU scientist Mike Owen.

Monsanto, which generates 50 percent of its annual sales from Roundup, says there are two U.S. weeds that are resistant to it - mare's-tail and ryegrass - but company officials say the problem isn't serious. They don't consider waterhemp resistant.

David Heering, who manages the technical side of the Roundup business for Monsanto, said rival companies like Syngenta are trying to discourage farmers from using the glyphosate-resistant, or Roundup Ready, crops because they cut into sales of other herbicides. "As we see increased adoption of Roundup Ready, they are going see lost business," Heering said.

Chemical companies have another reason to discourage use of Roundup Ready crops: Monsanto profits from the special technology fee it charges on every bag of the gene-altered seed. Other companies do not.

Syngenta officials say they are trying to ensure that glyphosate, which they market as Touchdown, remains effective.

In Iowa, farmers typically don't plant soybeans in the same field two years in a row, as some Eastern growers do, so there is less chance of overusing the herbicide. But some farmers are considering growing Roundup Ready corn in addition to Roundup Ready soybeans, and that could increase use of the weedkiller and speed up the spread of resistant weeds, some scientists say.

More about Roundup

Roundup herbicide, introduced by Monsanto Co. in 1974, works by interfering with a key enzyme in plants and preventing then from making essential amino acids. People and animals don't have the enzyme, making the chemical relatively safer than many other pesticides.

POPULARITY: Use of Roundup, known generically as glyphosate, exploded when Monsanto scientists figured out how to make crops immune to it by inserting into them a soil bacterium gene. The bacterium contains an enzyme similar to the one that plants naturally have. The biotech crops accounted for about 75 percent of the soybeans, 50 percent of the cotton and 10 percent of the corn planted by U.S. farmers last year.

FRIENDLY: Roundup also is widely used by homeowners and along roads and railways. Glyphosate is considered so environmentally friendly that it is used to control weeds on the ecologically unique Galapagos Islands.

AWARDS: The Monsanto scientist who first identified the herbicidal activity in glyphosate was awarded the National Medal of Technology in 1987. In 1994, Farm Chemicals magazine called Roundup one of the top 10 products that "changed the face of agriculture."