Rapid increase in glyphosate resistance and confirmation of dicamba-resistant kochia (<i>Bassia scoparia</i>) in Manitoba
Charles M. Geddes, Mattea M. Pittman, Robert H. Gulden, Tammy Jones, Julia Y. Leeson, Shaun M. Sharpe, Scott W. Shirriff, Hugh J. Beckie
Abstract
Increased adoption of crops with stacked traits conferring glyphosate and dicamba resistance, and recent confirmation of kochia [Bassia scoparia (L.) A.J. Scott] biotypes resistant to these herbicides in Alberta and Saskatchewan, warrant surveillance of herbicide-resistant kochia in Manitoba. A randomized–stratified survey of 315 sites in Manitoba was conducted in the fall of 2018. Overall, 58% of the kochia populations tested were glyphosate-resistant, while 1% were dicamba-resistant. This survey documents rapid increase in glyphosate-resistant kochia over a five-year time frame, and also confirms the first cases of kochia in Manitoba with dicamba resistance alone and in combination with glyphosate resistance.