“ Water may be the most common substance on Earth. But from a physics standpoint, it is pretty unusual. ” — alexander benderskii, page 13
In the News
Widespread use
of herbicides
fosters immunity
Many weeds now resistant
to multiple chemical killers
STORY ONE
Agriculture’s most effective pesticides
are rapidly losing their punch as weeds
evolve resistance to the chemicals. With
no game-changing alternatives in the
pipeline, researchers warn that farmers
could soon see crop yields drop and production prices climb.
“It’s what Chuck Darwin talked
about back in 1850. Organisms evolve in
response to selection pressures in their
environment,” says Micheal Owen, an
extension weed scientist at Iowa State
University in Ames. “In essence, the better
we get at controlling weeds, the more
likely those efforts will select for sur-
vivors that do not respond to controls.”
In the June 8 Journal of Agricultural
and Food Chemistry, Owen and other
researchers describe the rapid rise of
herbicide-resistant weeds and a partic-
ularly threatening trend: an increasing
number of weeds that are simultane-
ously immune to multiple herbicides.
in the United states, the wetland native
water hemp has adapted to herbicides
and is overrunning soy and corn fields.
One price has been the rapid evolution
of weeds resistant to it.
“Today, 98 percent of U.S. soybeans,
88 percent or so of U.S. cotton and more
than 70 percent of U.S. corn come from
cultivars resistant to glyphosate,” Owen
reports. Reliance on these crops — and
an accompanying weed-control strategy
that employs glyphosate to the exclusion of other herbicides — “created the
‘perfect storm’ for weeds to evolve resistance,” O wen and Jerry Green of Pioneer
Hi-Bred International in Newark, Del.,
argue in their new analysis.
But the only thing unique to glyphosate—in terms of breeding weed
resistance — is the extent of its use.
In the same issue of the Journal
of Agricultural and Food Chemistry,
Carol Mallory-Smith of Oregon State
www.sciencenews.org
July 2, 2011 | SCIENCE NEWS | 5
