Interaction Between Triflusulfuron and Organophosphate or Carbamate Insecticides in Sugarbeet

Field experiments were conducted in Idaho, Nebraska, and North Dakota to evaluate interactions between postemergence applications of the herbicides triflusulfuron, a nd a premix of desmedipham plus phenmedipham (1:1 ratio) with at-planting applications of the insecticides terbufos, aldicarb, chlorpyrifos or chlorpyrifos applied postemergence in sugarbeet (Beta vulgaris L). In North Dakota, banding terbufos 15G or chlorpyrifos 15G at planting reduced injury from postemergence herbicides as compared to modified in-fur­ row (MIF) insecticide plus postemergence herbicides. Triflusulfu r on gave less sugarbeet injury than triflusulfuron plus desmedipham and phenmedipham when applied to sugarbeet previously treated with insec­ ticide. Terbufos 20CR in combination with postemergence herbicides had greater crop safety than terbufos 15G. In Nebraska, terbufos 15G and chlorpyrifos 15G at-plant­ ing plus triflusulfuron postemergence gave less injury com­ pared to at-planting insecticides plus desmedipham and phenmedipham alone or in combination with triflusulfuron. Chlorpyrifos applied postemergence after herbicide application increased sugarbeet injury compared to chIorpyrifos applied postemergence alone. Triflusulfuron or desmedipham and phenmedipham ap­