roundup

Bob Hartzler / Iowa State University

New herbicide-resistant corn and soybeans are a step closer to reaching farm fields in the U.S. They would help farmers control weeds that are no longer killed by the popular herbicide, Roundup.

Roundup resistant crops dominate corn, soybean and cotton production in the U.S. But the list of weeds that have evolved to withstand Roundup is growing, and as a result, farmers are using more chemicals to keep up.

Abbie Fentress Swanson/Harvest Public Media

Eleven miles northeast of Centralia, Mo., five U.S. Geological Survey scientists don waders and bright reflective life jackets to wade into Goodwater Creek. Plenty of fish live in the stream’s murky slow-moving waters, along with snakes, crayfish, mussels and snapping turtles. On this overcast morning, the team collects water samples and checks submerged cages of fathead minnows for eggs.

roundup resistance
Bob Hartzler / Iowa State University

Farmers and weeds are in a constant competition.

But with Monsanto’s introduction of Roundup herbicide and genetically engineered Roundup Ready crops in the mid-1990s, farmers gained a clear edge. The seeds, which were able to tolerate the herbicide, were adopted quickly. By 2011, more than 90 percent of soybeans and cotton, and more than 70 percent of corn were planted with Roundup Ready seeds.