Palmer amaranth made a big move into Iowa last year, primarily in conservation habitat, but it will take a concerted effort to keep it from causing problems in row-crop fields this year, said Iowa State University Extension weed scientist Bob Hartlzer.

Farmers will have to step up their scouting efforts to make sure Palmer doesn’t overtake waterhemp as the primary weed concern in their fields, he said.

"Palmer amaranth at this point is not adapted to the state of Iowa," he said. "Trust me, it’s going to adapt and it’s going to be a much bigger issue. Now is the time to be aggressive with it."

Farmers have become accustomed to late-season waterhemp escapes, which generally haven’t caused major yield impacts, Hartzler said. But taking the same approach with Palmer could be dangerous.

"If...