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Superweeds spreading at warp speed

Linda Wells's picture
Linda Wells
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The near-exponential spread of herbicide-resistant "superweeds" across U.S. farmland is reminding us all that no matter how much the Big 6 pesticide corporations invest in research and development, they can't outsmart Mother Nature.

In just the past two years, the number of fields with glyphosate-resistant weeds has doubled. Farmers reported these particular superweeds on 61.2 million acres in 2012, up from 32.6 million acres in 2010. This, according to a new report by the agrichemical industry consultancy firm, Stratus.  

And these numbers only cover resistance to glyphosate, the active ingredient in Monsanto's RoundUp. They don't account for atrazine resistance or multiple herbicide-resistant strains — both of which have likewise risen dramatically over the last few years, at a dramatically increasing clip.

Total resistant acres increased by 25% in 2011 and another 51% in 2012. Overall, 49% of U.S. farmers reported contending with superweeds last year, up from 34% in 2011. 

Superweed science

Studies mapping the rapid intensification of superweeds have appeared with increasing frequency over the last few years. In 2009 resistant Palmer Amaranth ("pigweed") made headlines as farmers reported resistant strains of the weed growing big enough to "stop a combine in its tracks," forcing some farmers to abandon thousands of acres.

A recent Iowa State study shows that waterhemp, a common weed here in the Midwest, has developed widespread herbicide resistance "at an alarming rate." Over half the weeds tested were resistant to both atrazine and glyphosate. Last year, Penn State weed scientist Dave Mortensen published a widely cited study on superweeds, noting that grappling with glyphosate-resistance cost farmers over $1 billion in 2011. 

The choice

Farmers stand at a crossroads as they decide how to deal with this emerging crisis. Superweeds are the result of a common, heavy-handed approach to weed management driven by GE seed technologies like RoundUp Ready soybeans and corn, both of which are engineered to withstand heavy applications of glyphosate. According to George Naylor, a conventional corn and soy farmer in Iowa: 

"Herbicide-resistant crops may, in the short run, make it easy to weed out weeds, but even the 2012 Herbicide Guide from Iowa State University notes, 'History has proven time and again that herbicide-based weed management will inevitably fail.'"

And here's Mother Jones' Tom Philpott in his coverage of the Stratus study:

"Trouble is, such an escalation in the chemical war on weeds will likely only lead to more prolific, and more super, superweeds, along with a sharp increase in herbicide use."

Both Dow and Monsanto are trying to keep farmers on this pesticide treadmill of ever-stronger chemicals (and ever-stronger weeds) by introducing 2,4-D and dicamba-resistant crops, respectively. My colleague Marcia Ishii-Eiteman calls it "GE's Dirty Little Secret."

In contrast, many farmers are turning to agroecological solutions, like long crop rotations, biological control and good soil management. If the recent, forced delay of Dow's Enlist is any indication, the rising tide of public opinion — including farmers' loss of patience with these failed technologies — may be an indication of a much-needed change in direction for modern farming. 

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