Control Effects of Seed Dressing with Imidacloprid and Thiamethoxam on Wheat Aphids and Its Safety to Wheat

The control effects of 70% imidacloprid WS and 70% thiamethoxam ZF as seed dressing(SD) agents on wheat aphids during wheat seedling and heading stages,and their effects on the emergence,effective tillers per plant,1 000-grain weight,and yield of wheat were investigated for evaluating the control effects of the two insecticides as SD agents and their safety.The results of two years showed that by SD with 1.4-2.0 g/kg of imidacloprid and 1.0-4.0 g/kg of thiamethoxam,both pesticides had good control effects on wheat aphids during the whole occurrence period,with 96.02%-100% before wheat heading,93.12%-100% at flowering stage,and84.19%-98.31% at filling stage,respectively.SD with 1.4 g/kg of imidacloprid and 1.0-2.0 g/kg of thiamethoxam had no negative effects on the time and rate of wheat seed emergence,but the germination time of wheat seed was delayed 0.5-1d with thiamethoxam at 4.0 g/kg,which had no effect on the emergence rate.By SD with imidacloprid at 1.4 g/kg and thiamethoxam at2.0 g/kg,the effective tillers of wheat increased most,by 55.38% and 34.58%,respectively.The1 000-grain weight of wheat increased noticeably by SD with imidacloprid at 1.4 g/kg,significantly higher than that with thiamethoxam at 1.0-4.0 g/kg.Meanwhile,the increase of wheat yield by SD with imidacloprid at 1.4 g/kg was significantly higher than that with thiamethoxam at 4.0 g/kg,slightly higher than thiamethoxam at 1.0-2.0 g/kg.The field trial results suggest that SD with imidacloprid at 1.4-2.0 g/kg and thiamethoxam 1.0-2.0 g/kg could achieve good control effects on wheat aphids during the whole growing season,showing safe to wheat,and has a significant yield-increasing.