Baseline survey of protoporphyrinogen oxidase inhibitor-resistant kochia (<i>Bassia scoparia</i>) in western Canada

Kochia ( Bassia scoparia (L.) A.J. Scott) is a problematic tumbleweed that has been reported resistant to five herbicide sites-of-action. Recently, protoporphyrinogen oxidase (PPO) inhibitor-resistant kochia was documented in Saskatchewan (2021) and North Dakota (2022). However, its frequency and distribution remain unknown. Screening with saflufenacil (50 g ai ha −1 ) revealed PPO inhibitor resistance in two of 14 grower-submitted samples, but not in 882 samples from randomized-stratified surveys of Manitoba (2018), Saskatchewan (2019), and Alberta (2021). To date, PPO inhibitor-resistant kochia has been confirmed in two municipalities in western Canada: the Rural Municipality of Newcombe in Saskatchewan and Forty Mile County in Alberta.