A U.S. government program designed to convert farmland to wildlife habitat has triggered the spread of a fast-growing weed that threatens to strangle crops in America’s rural heartland. The weed is difficult to kill and, if left unchecked, destroys as much as 91 percent of corn on infested land, according to the U.S. Department of Agriculture (USDA). The weed is spreading across Iowa, which accounts for nearly a fifth of U.S. corn production and, in 2016, exported more than $1 billion of corn and soy.
The federal Conservation Reserve Program pays farmers to remove land from production to improve water quality, prevent soil erosion and protect endangered species. The destructive weed, named Palmer amaranth, has spread through seed sold to farmers in the conservation program, according to Iowa’s top weeds scientist, Bob Hartzler, an Iowa State Univeristy agronomy professor. “We are very confident that some of these seed mixes were contaminated,” Hartzler said.
Hartzler said one seller was Allendan Seed Company, the state’s largest producer of local grass and wildflower seeds for conservation land. Allendan said it was “possible that pigweed seed … was present in some mixes.”
Palmer amaranth is a type of pigweed. Allendan did not confirm it had found the seed in any of its supplies. It said outside labs that the firm hires to test seed quality had been unable to distinguish Palmer amaranath from other pigweeds. The company said it started using a new DNA test in February to check its seed for Palmer amaranth.
Palmer amaranth first arrived in Iowa in 2013 but exploded across the state last year, spreading from 5 to 48 of the state’s 99 counties, according to Iowa State University. In at least 35 of those counties, the weed was found on land in the conservation program. Many farmers joined the conservation program in the past year as prices for their crops tanked amid a global grains glut. The weed can be killed, but the cost of clearing it would be another hit to the cash-strapped farming community in the United States, the world’s top corn supplier.
In another state, Minnesota, authorities are also investigating whether the conservation program inadvertently introduced the weed to that state.
The Natural Resources Conservation Service (NRCS) and the Farm Service Agency (FSA), both part of USDA, denied responsibility for the infestation because they do not supply or test the seed that farmers use to turn cropland into a refuge for wildlife. Landowners are responsible for finding their own seed.
However, the NRCS is considering giving financial assistance to Iowa farmers to help control the weed and is working with the farming community and other government agencies to control it.
Palmer amaranth, which is native to the southwestern United States, grows up to 2 inches (5 cm) a day and can reach a height of 10 feet. It produces up to 500,000 seeds, which travel easily on the wind, in manure or stuck to farm equipment and vehicles.
Iowa farmers currently spend between $35 to $40 per acre on herbicides. Iowa State University research shows if Palmer amaranth is firmly established, costs could increase by up to 50 percent, Hartzler said.
