American farmers — and by extension consumers — are grappling with a problem a quarter century in the making. In the 1990s, St. Louis chemical company Monsanto developed Roundup Ready crops genetically engineered to tolerate heavy spraying of the company’s blockbuster herbicide Roundup. Today, this crop system defines American agriculture: over 89 percent of all corn, cotton and soybeans grown in the United States are genetically engineered to tolerate glyphosate — the active ingredient in Roundup.
