SUPERWEEDS
September 13, 2003
AP
Emily Gersema
WASHINGTON -- Increased findings that weeds are developing resistance to
Roundup, the world's most popular herbicide, have, according to some
scientists urging new planting practices while the product's manufacturer
says the problem is being overblown.
The story cites the U.S. Agriculture Department as estimating that 80
percent of the 73 million acres of soybeans in the United States are Roundup
Ready soybeans, and Roundup Ready cotton accounts for more than 30 percent
of the 12 million acres planted. The corn variety, still new to the market,
covers 11 percent of 70 million acres.
Stephen Powles, an expert on weed resistance at the University of Western
Australia, was quoted as saying, "Farmers are planting too many Roundup
Ready crops," adding that the herbicide is vital for food production systems
in the United States and in many other parts of the world and should weed
resistance become widespread, he said, "I think the problem will become a
crisis."
The story notes that in 2000, University of Delaware scientists reported to
the Weed Science Society of America, which tracks farm chemical resistance,
that in some soybean fields, mare's tail was resisting glyphosate. Since
then, resistant mare's tail has been reported in other states -- Indiana,
Kentucky, Maryland, New Jersey, Ohio, Arkansas, Mississippi and Tennessee.
Far more worrisome are cases in Iowa, Illinois and Missouri, where
glyphosate is becoming ineffective on abundant weeds such as velvet leaf and
water hemp.
Allan Felsot, an environmental toxicologist at Washington State University,
was cited as saying that weeds naturally develop resistance to a pesticide
and dismissed the idea they might be picking up a resistant gene from
Roundup Ready soybeans, corn or cotton, adding, "Any time you have a place
where you're using a strictly singular herbicide, you may end up with some
resistance in some cases."
Mark VanGessel, a weed scientist at the University of Delaware, was cited as
suggesting that farmers rotate their Roundup Ready crops with conventional
varieties, adding, "My gut reaction is that we do need to limit the use of
glyphosate-resistant crops. That doesn't necessarily mean don't develop them
or don't use them altogether, but instead use a planned approach so to not
use the glyphosate-resistant crops year in and year out."
Greg Elmore, a soybean technical manager at Monsanto, was quoted as saying,
"Most of the situations that we're dealing with, we're dealing with very
small acres. We're not talking about a whole county. In some cases, we have
one field only."
On the Net:
Weed Resistance: http://www.farmassist.com/resistance/
Weed Survey: http://www.weedscience.org/in.asp