Nature, occurrence, and cost of herbicide-resistant green foxtail (Setariaviridis) across Saskatchewan ecoregions

In Saskatchewan, a held survey was conducted in 1996 and a grain elevator s urvey 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 esti mated to have acetyl-CoA carboxylase (ACCase) inhibitor (Group 1)-MR green foxtail. Of the samples received from 30 grain elevators, 83% had Group 1 r esistance. Similar to the held survey, incidence of aryloxyphenoxy propiona te (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 herbic ides to control Group 1-HR green foxtail in broadleaf crops and cross-MR bi otypes in cereal and broadleaf crops increase costs to the grower.