Attack of the Superweed

Justin Cariker grabs a 7-foot-tall Palmer pigweed at his farm, bending the wrist-thick stem to reveal how it has overwhelmed the cotton plant beneath it. This is no ordinary weed: Over time it has developed resistance to Monsanto’s best-selling herbicide, Roundup. Hundreds of such “superweeds” are rising defiantly across this corner of the Mississippi Delta. “We’re not winning the battle,” Cariker, owner of Maud Farms in Dundee, Miss., says as he looks at weeds that tower over his infested cotton field like spindly green scarecrows.

Cariker’s superweeds represent a growing problem for Monsanto, whose $11 billion of annual sales are anchored in crops genetically engineered to tolerate Roundup, the world’s best-selling weedkiller. The use of Roundup Ready seeds has transformed farming in the 15 years since their debut, allowing growers to easily dispatch hundreds of types of weeds with a single herbicide while leaving crops unscathed. “When the Roundup system first came out, to a farmer this was the best thing that ever happened,” says Cariker, who used the labor-saving technology to double his planted acreage, to 5,000. “Farmers thought we had died and gone to heaven.”