Reduce seed bank, layer herbicides and adopt alternative tactics to manage waterhemp’s resilience in Iowa crop fields.

Reducing waterhemp seed populations is critical to managing what has become one of the most challenging weeds infesting Iowa crop fields.

Effective strategies, such as layered residual herbicide management, crop rotation, harvest weed seed control and providing competition with cover crops, can significantly limit waterhemp’s ability to establish in fields, said Bob Hartzler, a retired Iowa State University Extension weed management specialist.

Hartzler shared tools and tactics for managing waterhemp, which has become one of the most troublesome weeds for farmers in recent decades, at an Iowa State University Crop Advantage Series event in Ankeny in January.

“(Years ago) you didn’t know what waterhemp was, even though it was out in your landscape … because it wasn’t a problem of agronomic fields,” Hartzler said. “But then something happened … in the 1990s, waterhemp just took over.”

Waterhemp’s prolonged emergence pattern, high seed production and resistance to common...