Weedkiller-resistant ragweed is one consequence of using chemical weedkillers.

RODALE NEWS, EMMAUS, PA—Chemical weedkillers may seem cheap. Roundup weed killer, a common chemical used in conventional agriculture and by homeowners, sometimes costs less than a gallon of milk. But we're starting to pay the price in other ways, as pesticide-resistant superweeds develop and spread throughout the country, potentially causing lower yields on farms and affecting food prices. After years of use all over the country, about 10 species of weeds—including the allergy-inducing ragweed plant—are starting to outsmart us and have developed ways to survive the sprayings. Aside from their impact on agriculture, could these superweeds also make their way into people's yards and the parks they love to visit? "Yes, and they already have," explains Jeff Moyer, chair of the United States Department of Agriculture's National Organic Standards Board and farm manager at the nonprofit Rodale Institute, an organic research farm in Pennsylvania. "Weed seeds travel by many ways," he explains: "wild birds' and animals' digestive systems, wind, flooding, field and harvest equipment, crop seed that is improperly cleaned, bird seed put in feeders, mulch hay, composted plants and manure, improperly sterilized potting media, and so on."

THE DETAILS: Dubbed "the single largest threat to production agriculture that we have ever seen" by a conservation expert quoted in a recent New York Times article on the subject, the rise of superweeds created by chemical agriculture has experts concerned that this will spur the use of more toxic pesticides, leading to an increase in land and water pollution and human illness, and a lowering of crop yields. The seeming convenience of chemical farming has caught up with us, and now the agrichemicals are actually making farmers' jobs harder, more dangerous, and less profitable. "More and more farmers are being instructed to mix herbicide strategies to reduce the possibility of resistance from building up to any one herbicide," explains Moyer. "This adds to the costs of production and reduces profit potential."