Effect of Cucumber Seed Coating with Imidacloprid against Aphis gossypii and the Pesticide's Distribution in the Plant

Control efficacy of cucumber seed coating with 40% imidacloprid FS against Aphis gossypii Glover was tested. The results showed that 35 d after treating the seed with imidacloprid (a.i) by 240 g, 480 g and 960 g per 100 kg seed,the decline rates of A.gossypii were still 89.2%,92.0% and 97.7%,respectively. Simultaneously the distribution of imidacloprid in the cucumber plant was tested by HPLC. The results revealed that the content of imidacloprid in cucumber plant kept increasing from 3 to 14 d after the plant emergence,and then decreased slowly. The content of imidacloprid in the lower leaf was the highest,in the top leaf was moderate and in the stem was the lowest.