by Dan Charles, The Salt at NPR Food (10/15/14)
Government regulators have approved a new generation of genetically engineered corn and soybeans. They're the latest weapon in an arms race between farmers and weeds, and the government's green light is provoking angry opposition from environmentalists.
The actual decision, at first glance, seems narrow and technical. The Environmental Protection Agency has announced it had "registered" a new weedkiller formula that contains two older herbicides: glyphosate (better known as Roundup) and 2, 4-D.
Versions of these weedkillers have been around for decades. But farmers in six Midwestern states will be allowed to use the new formula, called Enlist Duo, on their corn and soybeans. And that counts as big news.

Farmers will now be able to plant new types of corn and soybeans that have been genetically engineered by the biotech company Dow Agrosciences to tolerate doses of those two weedkillers. (The beauty of herbicide-resistant crops is that they make the herbicides exquisitely selective: They kill the weeds but not the crop.) So farmers can spray either glyphosate or 2, 4-D (or both) to wipe out weeds without harming their corn or soybeans.