Waterhemp

A University of Idaho Extension weed specialist is investigating the recent discovery in an Elmore County sugar beet field of a weed that had never previously been detected in Idaho and appears to be resistant to the glyphosate herbicide.    

Albert Adjesiwor, who works from the UI Kimberly Research and Extension Center, confirmed in late June that the weed, which covered patches in the sugar beet field, was waterhemp, a member of the pigweed family that causes significant yield reductions in crops.   

The agronomist who notified Adjesiwor of the discovery said the weeds remained healthy even after two applications of glyphosate, which is the active ingredient in Roundup herbicide.

Though waterhemp hadn’t previously been found in Idaho, it’s widespread in the eastern U.S., as well as the South and the Midwest.   

“This is very concerning because glyphosate is the main – and only – herbicide that provides broad-spectrum weed control in sugar beets,” Adjesiwor said. “All our efforts in proactive resistance management would mean nothing if we cannot prevent the introduction of herbicide-resistant weeds from other regions.”