The Weed Science Society of America (WSSA) reports scientists have confirmed the first case of waterhemp with six-way resistance. A waterhemp population in Randolph County, Mo., was treated with eight herbicides, and only dicamba and glufosinate provided accepted control. Of that studied weed population, 16% of the plants contained genes stacked for six-way herbicide resistance (2,4-D, atrazine, chlorimuron, fomesafen, glyphosate and mesotrione.)
The study is featured in the journal Weed Science, and its research was conducted from 2015 to 2017. Randolph County is located in central Missouri.
The researchers say six-way resistant weeds will demand a diversified approach including cultural, mechanical and biological control methods.