喷雾和灌根施药后吡虫啉在番茄植株中的分布及其对烟粉虱的防效
Systemic Distribution of Imidacloprid in Tomato Crop and its Control Effect against Bemisia tabaci with Foliar Spraying or Root Pouring
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摘要: 以番茄为供试植物,采用喷雾和灌根两种施药方法,测定了吡虫啉在植株内的分布动向及其对烟粉虱Bemisia tabaci的防效。结果表明,喷雾后第2 d,吡虫啉消解率为56.1％,第10 d接近90％;灌根后第2~21 d茎内持留量基本处于稳定状态。施药方法不同,吡虫啉对烟粉虱的防效不同。喷雾法施药对烟粉虱的短期防效好于灌根法(7 d以内),但"持效期"较短,喷雾施药 7 d 后,其防效大幅下降;而灌根施药后第7~21 d内,吡虫啉对烟粉虱的防效一直保持在65％以上,在此期间可有效控制烟粉虱的危害。模拟雨水冲刷试验结果表明,药剂在叶面的冲刷率始终在70%左右,表明吡虫啉叶面喷雾后没有或仅有很少一部分进入叶片内部,因此,喷雾叶片在吡虫啉持留量略高于灌根的条件下,对烟粉虱的防效却不如灌根的好。Abstract: 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.
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