Nature, Occurrence, and Cost of Herbicide-Resistant Green Foxtail (Setaria viridis) Across Saskatchewan Ecoregions

Abstract

In Saskatchewan, a field survey was conducted in 1996 and a grain elevator survey in 1997 to determine the nature and occurrence of herbicide-resistant (HR) biotypes of green foxtail (Setaria viridis). Based on results of the field survey, one in every 20 fields (1 million ha) in Saskatchewan is estimated to have acetyl-CoA carboxylase (ACCase) inhibitor (Group 1)-HR green foxtail. Of the samples received from 30 grain elevators, 83% had Group 1 resistance. Similar to the field survey, incidence of aryloxyphenoxy propionate (AOPP) resistance was much higher than cyclohexanedione (CHD) resistance. Both surveys indicated relatively low incidence of dinitroaniline (Group 3) resistance or cross-resistance (Groups 1 and 3). Most alternative herbicides to control Group 1-HR green foxtail in broadleaf crops and cross-HR biotypes in cereal and broadleaf crops increase costs to the grower.