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Farmers aren’t the only ones who should be concerned about “superweeds” and the diminishing potency of a popular herbicide

Jonathan Kaplan

Posted May 7, 2010 in Health and the Environment

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Earlier this week, the New York Times reported on an emerging threat facing farmers, rural communities and the environment: The proliferation of “superweeds” that are resistant to the widely used herbicide “Roundup” (also sold generically as glyphosate).

First some background:  In the 1990s, Monsanto genetically engineered corn and soybeans to withstand Roundup (glyphosate) so that farmers could apply Roundup to kill weeds without harming the crop itself.  This turned out to be very popular, and Roundup Ready crops are now grown on millions of acres around the country (90% of soy acres and 70% of corn and cotton, according the Times).  The upside of the herbicide-tolerant crops is reduced tillage, which conserves soil and energy.  A downside is that farmers have to apply more herbicides – 380 million pounds more between 1996 and 2008 than they would have with conventional corn, soy and cotton crops, according to the Organic Center.  

As many scientists and advocates predicted, the repeated and widespread use of glyphosate has resulted in resistance by a growing number of weeds.   This results from accelerated Darwinian evolution, when an anomalous weed that is resistant to the chemical is allowed to flourish while other weeds are killed off.  If this story is sounding familiar, it’s because you’ve heard it before in the context of antibiotics: Over use of these drugs for people and livestock are increasingly rendering them impotent to bacteria.

The superweeds are not the scary part of this story. The big concern here is what happens after Roundup becomes ineffective and growers must resort to more toxic chemicals.  Or if the gene splicers create new crops that are programmed to accommodate more toxic herbicides – which are then applied in vast quantities across millions of acres.

This is not a theoretical concern.  Just this week NRDC released an updated analysis of another widely used herbicide called atrazine, which is now frequently present in drinking water throughout the nation, often at levels of concern. Atrazine persists for weeks after application, resulting in pulses of contaminated runoff that shred aquatic ecosystems and threaten drinking water supplies.   Atrazine is also an endocrine disrupting chemical which means it can throw a wrench into the works of exquisitely delicate biological processes, like fetal development. While no one at NRDC loves the fact that millions of pounds of Roundup are released into the environment every year, I think we can all agree that Roundup is no atrazine.  There’s a huge difference in terms of the risk these chemicals pose.

So the prospect of “Atrazine Ready” corn or soy crops is chilling.  While I haven’t heard anyone propose that particular combination, the Times reports that other high-risk herbicides like 2,4-D are in the pipeline for GMO crops.

Of course if this debate is just about which  synthetic herbicides should be used in massive quantities, then we’re missing the point.  Stay tuned for more about herbicide alternatives and what USDA should be doing to promote them.

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Comments

GMO JournalMay 9 2010 07:18 PM

Given this increasing superweeeds problem (which is only one of the issues associated with GMOs), it was disheartening to learn that the USDA/APHIS' Draft Env. Impact Statement, released in Dec. 2009, approved releasing genetically modified alfalfa into the environment.

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Switchboard is the staff blog of the Natural Resources Defense Council, the nation’s most effective environmental group. For more about our work, including in-depth policy documents, action alerts and ways you can contribute, visit NRDC.org.

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