Systemic Distribution of Imidacloprid in Tomato Crop and its Control Effect against Bemisia tabaci with Foliar Spraying or Root Pouring

Systemic distribution of imidacloprid in tomato crop and its control-effect against whiteflies, Bemisia tabaci, were examined with different applications,namely foliar spraying and root pouring,respectively.The results showed that the decline rate of imidacloprid reached 56.1% 2 d after spraying and about 90% 10 d after treatment.However,the residues of imidacloprid in the tomato stem was stable with root pouring method within 2~21 d.The control effect by spraying was better than that by root pouring method in short term (within 7 d) with shorter persistent period.It's found that the control effect by root pouring to whiteflies was kept above 65% from 7 d to 21 d after treated.The result of simulated rain washing foliar experiment showed that the washed ratio always remained about 70%,It indicated that no or little imidacloprid was entered into leaves.Consequently,the effect of foliar spraying to whiteflies Bemisia tabaci was worse than that of root pouring,although the residues of foliar spraying was a little higher than that of root pouring.