New GM crops could make superweeds even stronger

Dow Chemical appears to be on the verge of winning regulatory approval for corn that is genetically engineered to be immune to 2,4-D, allowing farmers to spray the chemical to kill weeds without harming the corn stalks.  Approval may come in time to allow planting next year.

That would be a welcome development for corn farmers who are coping with runaway weeds that can no longer be controlled by Roundup, the herbicide of choice for the last decade, The New York Times reports.

But some consumer and environmental groups oppose approval of the corn, saying it will lead to a huge increase in the use of 2,4-D, which they say may cause cancer, hormone disruption and other health problems.  The Environmental Protection Agency continues to say that there is not enough evidence to call 2,4-D a human carcinogen, according to The Times.

More than 140 advocacy groups participated in a letter writing campaign calling on U.S. Agriculture Secretary Tom Vilsack to reject Dow's regulatory application for the herbicide and herbicide-resistant crops, submitting more than 365,000 missives during the public comment period that ended last week, the Huffington Post blog noted.

With this focus on herbicides and herbicide-resistant crops, one aspect of this issue has largely been overlooked, according to Wired Science. What about this startling evolution of the superweed?

Wired Science reporter Brandon Keim writes that as agriculture companies genetically engineer a new generation of plants to withstand heavy doses of multiple, extra-toxic weed-killing chemicals, more superweeds may follow:

It’s a more intensive version of the same approach that made the resistant superweeds such a problem — and some scientists think it will fuel the evolution of the worst superweeds yet.

These weeds may go a step further than merely being able to survive one or two or three specific weedkillers. The intense chemical pressure could cause them to evolve resistance that would apply to entire classes of chemicals.

“The kind of resistance we’ll select for with these kinds of crops will be different from what we’ve seen in the past,” said agro-ecologist Bruce Maxwell of Montana State University. “They’ll select a kind of resistance that’s more metabolism-based, and likely resistant to everything.”

What might new herbicide regimes create? Click here to read the explanation from Wired Science.