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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." | |
