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Monsanto's Roundup Spawning Superweeds
Roundup-resistant weeds are cropping up. The
herbicide is so popular that it may not be as effective as it was
initially.
By PHILIP BRASHER
Des Moines Register Washington Bureau 01/10/2003
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Washington, D.C. - 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.
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