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High-tech seeds, old-school
herbicides. Roger Smith/Flickr |
In September, the US Department of Agriculture
greenlighted new GMO corn and soybean products engineered to resist two kinds of herbicides, Roundup (glyphosate) and an
older, more toxic one called 2,4-D (which
was one of two ingredients in the powerful defoliant used in the
Vietnam War called Agent Orange). And on Wednesday, the Environmental
Protection Agency
approved of a new 2,4-D formulation called Enlist, which has been designed for use on the novel seeds,
in six corn/soy-heavy states:
Illinois, Indiana, Iowa, Ohio, South Dakota, and Wisconsin.
That means starting in spring 2015, farmers in the Midwestern Corn Belt
will likely be dousing their crops with 2,4-D as well as Roundup, in an
effort to control the plague of weeds that have evolved to resist
Roundup.
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The
authors predict that glyphosate (Roundup)
use will hold steady at high
levels—and
use of other herbicides, like 2,4-D, will soar.:
From Mortensen, at al, "Navigating a
Critical Juncture for Sustainable
Weed Management," BioScience, Jan. 2012 |
So what's the big deal? In this
2012 post, I laid out research by a team led by Pennsylvania State University crop scientist David A. Mortensen (paper abstract
here)
on how the new products are at best a temporary solution to the problem
of "superweeds"—they lead farmers down a path of ever-increasing
reliance on agrichemicals. They argue that chances are "actually quite
high" that Dow's new product will unleash a new generation of weeds
resistant to both herbicides, because when farmers apply 2,4-D to weeds
that are already resistant to Roundup, they'll essentially be selecting
for weeds that can resist both. Their projection of how such double
resistance will affect herbicide use is at the left—a boon for
agrichemical sales, but not so great for the environment.
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