雾滴密度及大小对氯虫苯甲酰胺防治稻纵卷叶螟效果的影响

【目的】分析不同剂量条件下，雾滴密度和雾滴大小对氯虫苯甲酰胺防治稻纵卷叶螟效果的影响，为稻田农药的高效施用提供科学依据。【方法】采用自动行走式喷雾塔模拟田间喷液量，通过添加表面活性剂使不同浓度的氯虫苯甲酰胺药液在水稻叶面上有同等润湿展布能力，利用图像处理方法计算水敏纸上收集到的雾滴密度。【结果】氯虫苯甲酰胺剂量为2.00 mg?m-2，增加雾滴密度能显著提高防治效果。剂量增加到4.00 mg?m-2，雾滴体积中径VMD 200 μm和VMD 75 μm的雾滴密度在分别达到26.06和66.96 个/cm2后，防治效果即可与高密度处理效果相当。VMD 200 μm的雾滴密度为82.09 个/cm2时，剂量从4.00 mg?m-2减少至2.00 mg?m-2，防治效果没有显著降低。VMD 75 μm的雾滴密度为140.06 个/cm2，剂量从4.00 mg?m-2减少至2.50 mg?m-2，防治效果同样没有显著降低。相同喷液量条件下喷施相同浓度的氯虫苯甲酰胺药液，VMD 75 μm的喷头增加了雾滴密度，提高了防治效果。【结论】氯虫苯甲酰胺低用量时，雾滴密度与防治稻纵卷叶螟的效果密切相关。雾滴密度超过一定数量，减少氯虫苯甲酰胺剂量仍可保证对稻纵卷叶螟的防治效果；低容量喷雾时，可通过减小雾滴粒径，增加雾滴密度提高氯虫苯甲酰胺的防治效果。

Effects of Droplet Density and Droplet Size on Control Efficiency of Chlorantraniliprole Against Cnaphalocrocis medinalis (Guenée)

【Objective】 The objective of this study is to analyze the effect of spray droplet density and droplet size on the control efficiency of chlorantraniliprole against Cnaphalocrocis medinalis under the conditions of different doses,and to provide a scientific basis for efficient use of pesticides in rice field.【Method】Volumetric application rate was simulated using an automatic drive spraying tower.The surfactant was added to ensure that the chlorantraniliprole solution at different concentrations could provide equivalent wetting and spreading capacity on the rice leaf.The droplet density collected on the water sensitive paper was measured using the image processing method.【Result】The control efficiency could be improved significantly with the increase of droplet density when the chlorantraniliprole dose was about 2.00 mg·m-2.When the dose was increased to 4.00 mg·m-2 and the droplet density of VMD 200 μm and VMD 75 μm were 26.06 and 66.96 droplets/cm2 respectively,the control efficiency was quite with the higher droplet density treatments.When the droplet density of VMD 200 μm reached 82.09 droplets/cm2,the control efficiency was not reduced with the dose from 4 mg·m-2 to 2 mg·m-2.Likewise,when the droplet density of VMD 75 μm reached 140.06 droplets/cm2,the control efficiency was not reduced with the dose decreased from 4.00 mg·m-2 to 2.50 mg·m-2.Spraying of chlorantraniliprole solution with the same carrier volume and concentration,VMD 75 μm nozzle increased the droplets density and improved the control effects.【Conclusion】 Droplet density was closely related to the control efficiency of chlorantraniliprole against Cnaphalocrocis medinalis when the effective dose was relatively low.When the droplet density reached a certain quantity,the desired effect could still be obtained when the effective dose was decreased.During low spray volume,the control efficiency could be improved by decreasing droplet size which increased droplet density.