Glyphosate-resistant downy brome (<i>Bromus tectorum</i>) control using alternative herbicides applied postemergence

Abstract Downy brome is a troublesome facultative winter-annual grass weed that invades agricultural and nonagricultural lands in western North America can cause substantial crop yield losses particularly no-till winter wheat. Glyphosate-resistant (GR) downy was identified southern Alberta 2021, representing the first confirmation of GR Canada. This study designed to evaluate alternative herbicides herbicide mixtures applied postemergence (POST) for control glyphosate-susceptible (GS) populations at seedling stage under controlled environment. The did not exhibit cross-resistance other POST. Quizalofop alone or combination with imazamox, imazamox + bentazon, imazamox/imazethapyr, glufosinate mixed either clethodim tiafenacil resulted ≥80% visible control, plant mortality, reduction biomass both GS 21 d after treatment. Diligent stewardship these remaining options warranted since resistance inhibit acetyl-CoA carboxylase acetolactate synthase have been reported neighboring states.