Waterhemp, the weed that won’t go away

COLUMBIA, Mo. –  For a quarter of a century, University of Missouri Extension weed scientist Kevin Bradley has warned farmers about waterhemp and its ability to develop resistance to herbicides.

Bradley will continue his call for diversity in weed management at the 2025 Missouri Crop Management Conference, Dec. 9-10 at the Stoney Creek Hotel in Columbia.

He started sounding the warning bell in the early 2000s, and by 2010 he cautioned that “herbicide-resistant weed populations are evolving rapidly as a natural response to selection pressure imposed by modern agricultural management activities.”

By 2018, a waterhemp population was identified in Missouri that was resistant to 2,4-D, atrazine, chlorimuron, fomesafen, glyphosate and mesotrione.

Bradley continued to write articles with similar but more urgent messaging every year after about the fast-growing weed.

By 2023, he called glyphosate the “silver bullet that wasn’t” as he and weed scientists across the United States and Canada documented growing resistance to it across the past two decades. Use of glyphosate continued to increase, but its effectiveness did not.

One thing that has not changed through the years is waterhemp’s ability to produce enormous amounts of seeds and reduce crop yields.

Bradley will share an update on waterhemp and resistance and will explain future industry offerings for the control of this species as well as integrated weed management tactics, a long-term approach that blends cultural, mechanical and chemical control techniques.

During the conference, he also will give updates on other important developments in the weed world.

Details and registration. For more information, contact Heather Bowden at 573-882-4303 or Nicholshn@missouri.edu.