Systemic Action of Imidacloprid on Tomato Plant and Its Bio-effect Against Whiteflies Bemisia Tabaci with Foliar Spraying or Root Pouring
|School||Shandong Agricultural University|
|Keywords||imidacloprid spraying root pouring control effects|
In order to study the feasibility of imidacloprid to control important pest insects with piercing and sucking mouthparts with treated the roots of plants, and found suitable formulation and concentration for root pouring,we compared the control effects of three imidacloprid formulations to Aphis gossypii with treating cotton roots and cottonseed dressing, the formulations were emulsifiable solution, wettable powder and water dispersible granule, respectively. We determined the distribution trends of imidacloprid in the plants after treated with root pouring and foliar spraying by residue analysis method, meanwhile, the control effects of two different use modes to whiteflies Bemisia tabaci were determined. Meanwhile, the imidacloprid residues on tomato and cabbage leaves after simulating rain washing were determined. The results showed as follows:1 Determination the different formulations of imidacloprid of the special systemic action through plant root with water culture cotton method, the results showed that emulsifiable solution had the best control effect to aphids in prior period, while in latter period the effect of water dispersible granule was higher, meanwhile, emulsifiable solution could make more serious phytotoxicity, cotton seedlings appeared serious wilt after treated 7d with effective component concentration as 35mg/L. And the worse control effect was wettable powder, but the effects had no difference with another two formulations from 1d to 7d after treated. The effect of water dispersible granule was equally with emulsifiable solution at 7d, and there was no phytotoxicity. The control effects of these three formulations to Aphis gossypii with cottonseed dressing treated were no difference, the effects were over 60% at 10g/L after planted 36 days. The influence of water dispersible granule to emergence rate of cotton seedling was the minimum, and there was no difference with the control group. Therefore, we chose 70% imidacloprid water dispersible granule as the following tested insecticide2 Distribution trends of imidacloprid in tomato crop and bio-effect against whiteflies Bemisia tabaci was examined with different applications, namely foliar spraying and root pouring, respectively. The results showed that the dissiption rate of imidacloprid reached 56.12% after 2d spraying and about 90% after 10d treatment. However, the residue of imidacloprid in the tomato stem was stable with root pouring method within 2-21d. The control effect by spraying was better than root pouring method in short term(within 7d) while with shorter persistent that the control effect by root pouring to whiteflies kept above 65% from 7d to 21d after treated when 126mg/L.3 In order to decide whether systemic effect of imidacloprid is exit on plant leaves, we treated test plants tomato and cabbage by spray method, and then washed them by simulated rainwater. We analyzed results according to the contents of imidacloprid residue on test plant leaves. The results showed that the scour rates of imidacloprid on tomato leaves were about 70%, while on cabbage leaves were about 85%, and imidacloprid on cabbage leaves was more easily washed than on tomato leaves. The scour rate of each plant basically was keeping invariant, which indicated that there were no systemic phenomenon of imidacloprid neither on tomato leaves nor cabbage leaves. This result explained why imidacloprid residue through root pouring was lower than foliar spraying while its effect to whiteflies was higher.