Potential herbicide resistance, weather and seed longevity complicate control efforts for Iowa farmers.

Iowa farmers continue their battle in 2025 against the state’s most invasive weed targeting corn and soybean crops.

Waterhemp continues to successfully maneuver around control efforts amid shifting weather and increasing herbicide resistance, proving to be a season-long nemesis for farmers.

Wes Everman, weed science specialist with Iowa State University Extension and Outreach, said this year’s weather challenges have hampered residual herbicide performance, allowing waterhemp to break through more consistently.

“It is coming through a lot,” Everman said. “What it seems like is happening ... they’ll spray and then maybe not get an activated rain after. And so if we don’t get the rain after, that herbicide doesn’t get into the germination zone.”

Wet-dry cycles this year coupled with shallow germination...