Wild oat and green foxtail are the two most abundant weeds and the most economically important herbicide-resistant grass weeds in the northern Great Plains of western Canada. Farmers in this region rarely proactively manage these weed species to prevent or delay the selection for herbicide resistance; they usually increase the adoption of integrated weed management practices only after intergroup herbicide resistance has evolved. The effectiveness of herbicide and nonherbicide practices to proactively or reactively manage herbicide-resistant wild oat and green foxtail are described, based on a decade of field trials, field-scale experiments, and field surveys in western Canada. Nonherbicide weed management practices or nonselective herbicides applied preplant or in crop, integrated with less frequent selective herbicide use in diversified cropping systems, have mitigated the evolution, spread, and economic impact of herbicide-resistant wild oat and green foxtail.

Nomenclature: Green foxtail, Setaria viridis (L.) Beauv. SETVI; wild oat, Avena fatua L. AVEFA.