Iowa farmers continue to search for solutions to combat herbicide-resistant weeds, and as the 2025 planting season begins, management decisions regarding preemergent and postemergent herbicides are front and center.

Weed resistance to the current stable of herbicide products continues to increase, making effective management more difficult, said Dalton Webster, agronomic service representative for Syngenta. With fewer effective chemical tools available, growers are rethinking their weed management strategies to maintain yields and profitability.

“We have pretty limited options, especially postemergence, for controlling resistant weeds,” said Webster. “Waterhemp is probably the most important one in Iowa …, and winter annual weeds like marestail …, we’ve got resistance issues with that weed as well.

“And we’re relying on really old chemistry — products that have been around for 20 to 50 years. We’ve got to figure out how to use what we’ve got better before the weeds figure it all...