The Control Effect On Aphis Gossypii Glover After Cucumber Plant Root Application With Imidacloprid And The Pesticide's Translocation And Distribution In The Plant

In this study, the control efficiency of imidacloprid to Aphis gossypii Glover and its persistence were tested both in the laboratory and greenhouse on cucumber plants treated with seed coating, spray, root drench and furrow drench respectively. Simultaneously the distribution of imidacloprid in the cucumber plants in the treatments of seed coating with 40% imidacloprid FS and root drench with 5% imidacloprid EC were analysed with HPLC. The results were summaried as follows:1. The results in the laboratory experiments showed that the control efficiency of imidacloprid in the seed coating treatment at the dosage of 960g (a. i.) per 100kg seed was still 97.7% 35d after pesticide application. By comparing the control efficiency of imidacloprid (a. i.) at the dosage of 0.25, 0.5 and 1mg per seedling with spray, root drench or furrow drench, it was proved that the control efficiency of imidacloprid in the treatments of root application after 21d were higher than that in the treatment of spray generally.2. The imidacloprid content in cucumber seedling in the treatment of seed coating at the dosage of 960g/100kg seed increased from the day 3 to day 14 after the plant emergence, and then decreased slowly. The residue of imidacloprid was not evenly distributed in cucumber plants, the content of imidacloprid decreased with the order of lower leaf, upper leaf and stem. The distribution of imidacloprid in the cucumber plants was also analysed after the plant root was irrigated with 1mg pesticide per seedling. The results showed that the content of imidacloprid in the lower leaves were higher than those in the upper leaves within 14d after its application, however, this difference disappeared after 14d.3. The control efficiency of imidacloprid against aphid with 4 application methods was tested in the greenhouse. The results showed that: (1) Damage of Aphid in the seedbed was effectively controlled by seed coating with imidacloprid (a. i.) at 960g/100kg. (2)The aphid can also be effectively controlled before the harvest of first fruit by furrow drench with imidacloprid (a. i.) at the dosage of 8g/667m~2 after transplanting. (3) The residue of imidacloprid in the first cucumber fruit was less than 0.05mg/kg when the plants treated with imidacloprid.