As the debate over 2,4-d—the widely-used herbicide and Agent Orange ingredient—rattles on in Washington, a larger battle is taking place on American farms over how the fight against superweeds will be fought in the future.
NPR has an interesting piece today about the struggle that farmers, specifically cotton farmers, are facing in their fields against Palmer amaranth, also known as pigweed. Palmer amaranth is one of the hardest-to-beat superweeds: weeds that have developed resistance to glyphosate—an ingredient in Monsanto's Roundup that was used on 91 percent of U.S.-grown cotton in 2007—and that grow up to three inches a day.Finding Alternatives to Agribusiness
As the superweed problem persists, the question remains over how to fight it: Do farmers wait for more chemicals and genetically engineered crops like the ones Dow is pushing for the EPA to approve, or do they try a different approach that doesn't involve such a heavy dependence on chemical herbicides like Roundup, 2,4-d, and whatever would come next?
NPR reports that in Georgia, weed scientist Stanley Culpepper is talking with cotton farmers about an alternative solution to just using more and more chemicals:
You're going to have to spray a lot of different chemicals to overwhelm the enemy, Culpepper tells the farmers. Some will kill your cotton if you aren't careful.
Then, Culpepper puts up a new slide. It's a picture of a field that's covered with a layer of rye, flat on the ground.
This residue works as well as any weedkiller, he tells the cotton growers. Pigweed just despises it. So the system would be: Grow a crop of rye, then roll it flat to keep weeds from growing. But leave some narrow gaps in the rye, and that's where you plant your rows of cotton.
Culpepper is not the only one pushing the use of rye to combat Palmer amaranth. A study involving Arkansas cotton [PDF] that used deep tillage and rye as a cover crop reduced the emergence of Palmer amaranth by 85 percent at the end of the season.
Looking Beyond Superweeds
A separate study [PDF] finds that rye may also benefit subsequent seasons of crops by suppressing pests because rye contains compounds, metabolites called benzoxazinoid hydroxamic acids, that are toxic to a broad spectrum of organisms.
Cover crops have the added benefits of reducing soil erosion and loss of nutrients from leaching and runoff. They also increase soil organic matter and water infiltration, not to mention that they don't contribute yet more chemicals to the environment—or lead to superweeds of their own.