Effects of Seed Coating with Imidacloprid and Thiamethoxam on Maize and Main Pests

To identify the safety of seed coating with neonicotinoids for maize and its effect on main pests,the effects of recommended middle dose,and its 1. 5 times and 2 times doses of 600 g / L imidacloprid FS,70% imidacloprid WS and 30% thiamethoxam FS on maize emergence,growth,yields and main pests were studied. The results showed that they were safe to maize emergence and the germination rate increased by 6. 04% —11. 25%. At 20 days after sowing,70% imidacloprid WS and 30% thiamethoxam FS promoted the growth of maize,with increase of plant height,secondary root number and fresh( dry)weights,and 600 g / L imidacloprid FS promoted root growth but slightly inhibited the aboveground growth.The increasing root-top ratio and better seedling shape were obtained in all treatments. Seed treatments al-leviated the damages of underground pests and aphids,but the damage of Asia corn borer had a serious trend. The yield indicators in all treatments were better than or equivalent to the control,but there were no significant differences among doses. The yield increase ranged from 2. 46% to 20. 48% in treatments,with increase of 19. 04%,20. 41% and 20. 48% in treatment of 600 g / L imidacloprid FS at 1. 5 times doses,70% imidacloprid WS at 2 times doses and 30% thiamethoxam FS at 2 times doses,respectively. These results indicate that seed coating with imidacloprid and thiamethoxam agents is safe for maize growth,but the prevention and control of non-target pests in seed treatment field should be paid more attention in order to obtain better harvest.