MSU Extension experts find herbicide-resistant marestail in northeast Montana

From MSU News Service

BOZEMAN — Experts from the Montana State University Extension Service have identified glyphosate-resistant Conyza Canadensis, also known as marestail or horseweed, in northeast Montana. The discovery is concerning given how easily this species can disperse in the wind.

According to Timothy Fine, Extension agent in Richland County, and Fabian Menalled, MSU professor and Extension specialist in cropland weeds, marestail with up to a five-fold increase in resistance to glyphosate, the active ingredient of Roundup and other herbicides, has recently been confirmed in...