中国农业科学 ›› 2018, Vol. 51 ›› Issue (13): 2513-2523.doi: 10.3864/j.issn.0578-1752.2018.13.007

• 植物保护 • 上一篇    下一篇

田间药液用量影响农药单位剂量防治效果的原因分析

顾中言,徐德进,徐广春   

  1. 江苏省农业科学院植物保护研究所,南京 210014
  • 收稿日期:2018-01-15 出版日期:2018-07-01 发布日期:2018-07-01
  • 作者简介:顾中言,Tel:025-84390951;E-mail:guzy@jaas.ac.cn
  • 基金资助:
    国家重点研发计划(2017YFD0200305)、江苏省农业科技自主创新资金(cx(16)1001)

The Cause of Influence of Spray Volume on Control Effect of Pesticide Unit Dose in Rice Fields

GU ZhongYan, XU DeJin, XU GuangChun   

  1. Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014
  • Received:2018-01-15 Online:2018-07-01 Published:2018-07-01

摘要: 【目的】分析药液用量与水稻植株持液量的关系,探索稻田药液用量影响农药单位剂量防治效果的机制,为科学使用农药提供依据。【方法】在喷雾状态下计量水稻单位面积的持液量变化,明确液体在水稻叶片上的流失点和稳定持液量。依照国家标准GB/T 5549-2010测定液体表面张力,利用表面活性溶液的表面张力随表面活性剂浓度变化的规律,测定表面活性剂溶液的临界胶束浓度;用Zisman的方法测定水稻叶片的临界表面张力,分析影响水稻叶片持液量的关键因子。在喷雾塔内模拟用氯虫苯甲酰胺防治稻纵卷叶螟、用吡蚜酮和毒死蜱防治褐飞虱的试验,分析药液用量与雾滴密度的关系及农药单位剂量对防治效果的影响。【结果】随着喷液量的增加,水稻叶片的持液量经历增加、达到最大值后开始流失、随之下降到稳定值并不再随喷液量而变化,与最大值比,稳定值减少持液量约50%。供试水稻的临界表面张力为29.90—31.22 mN·m-1,为低能表面,清水的表面张力为71.8 mN·m-1,大于水稻的临界表面张力,限制了水稻叶片的持液量;助剂TX-10和Silwet-408可使液体的表面张力小于水稻临界表面张力,增加水稻叶片的持液量,当助剂达到临界胶束浓度时,增加持液量的效果最好;喷液量影响雾滴密度,从而影响农药单位剂量的防治效果。雾滴体积中径为200 μm时,药液量150 L·hm-2的雾滴少于10滴/cm2,20、25和30 g 3个有效剂量的氯虫苯甲酰胺对稻纵卷叶螟的防治效果不足60%;药液量450 L·hm-2的雾滴少于40滴/cm2,氯虫苯甲酰胺3个有效剂量对稻纵卷叶螟的防治效果分别为56.92%、62.86%和65.07%;药液量900 L·hm-2的雾滴为82滴/cm2,氯虫苯甲酰胺3个有效剂量对水稻纵卷叶螟的防治效果最好,达到70%以上。减小雾滴体积中径,增加单位体积液体的雾滴数量,可以适量减少喷液量。雾滴体积中径为75 μm、药液量450 L·hm-2时,雾滴为140滴/cm2,氯虫苯甲酰胺防治稻纵卷叶螟的效果与雾滴体积中径为200 μm、药液量900 L·hm-2的防治效果无显著差异。由于水稻冠层的阻挡,叶面喷雾时冠层下的雾滴极少,雾滴体积中径200 μm喷药液量900 L·hm-2和雾滴体积中径75 μm喷药液量450 L·hm-2,冠层下的雾滴不足20滴/cm2,农药对褐飞虱防治效果差。冠层下喷雾,直接将农药喷洒到褐飞虱栖息危害的部位,显著提高了吡蚜酮和毒死蜱单位剂量对褐飞虱的防治效果。【结论】药液用量影响农药在水稻植株上的沉积量和水稻单位面积上的雾滴密度,从而影响农药单位剂量对害虫的防治效果。当稻田药液用量在450 L·hm-2(雾滴体积中径75 μm)或900 L·hm-2(雾滴体积中径200 μm),冠层上下喷雾均匀,能确保药液在水稻最大持液量范围内并使植株表面有足够的雾滴密度,可取得良好的防治效果。

关键词: 农药, 药液用量, 流失点, 持液量, 雾滴密度, 防治效果

Abstract: 【Objective】The objective of this study is to analyze the relationship between the spray volume in rice fields and retention on rice plants, understand the mechanism affecting the control effect of pesticide unit dose, and to provide a basis for the scientific use of pesticides. 【Method】 the liquid retention on unit area of ??rice was measured under spraying conditions, the change of the liquid retention indicated the point of run-off and maximum retention of the liquid on rice leaves. The surface tension of the liquid was measured by the method according to the GB/T 5549-2010, and the critical micelle concentration of the surfactant solution was determined by using the law of the surface tension varying with the concentration of the surfactant. The zisman method was used to measure the critical surface tension of rice leaves. The key factors affecting the leaf capacity of rice leaves were analyzed. By simulating chlorantraniliprole control of rice leaf roller(Cnaphalocrocis medinalis), pymetrozine and chlorpyrifos control of brown planthopper (Nilaparvata lugens) in a spray tower, the relationship between spray volume and droplet density and the effect of pesticide unit dosage on control effect against pests were also investigated. 【Result】 With the increase of the spray volume, the liquid holding capacity of rice leaves increased. After reaching the maximum value, the liquid began to lose and then it decreased to a stable value and no longer changed. The final liquid holding capacity was only 50% of the maximum value. The critical surface tension of the tested rice leaves was 29.90-31.22 mN·m-1, which meant the tested surface was a low-energy surface. The surface tension of clear water was 71.8 mN·m-1, which was greater than the critical surface tension of the tested surface. The surface tension of tested rice leaves limited the liquid holding capacity of the leaves. With the additives TX-10 and Silwet-408, the surface tension of the liquid was less than the critical surface tension of rice, which increased the liquid holding capacity of the rice leaves. When the auxiliary agent reached the critical micelle concentration, TX-10 and Silwet-408 provided the best results. The amount of liquid spray affected the density of spray droplets, thus affecting the control effect of pesticide unit dose. When the droplet volume median diameter was 200 μm, the amount of liquid medicine 150 L·hm-2 was less than 10 drops/cm2. The control effect of three effective doses 20, 25 and 30 g of chlorantraniliprole against C. medinalis was less than 60%. The liquid droplet volume 450 L·hm-2 had less than 40 drops/cm2. The control effect of three effective doses against C. medinalis was 56.92%, 62.86% and 65.07%, respectively. The liquid droplet volume 900 L·hm-2 was 82 drops/cm2, the three effective doses of chlorantraniliprole had the best control effect on C. medinalis, which was over 70%. Reducing the droplet volume median diameter and increasing the amount of droplets of unit volume of liquid could reduce the amount of liquid spray. When the diameter of droplets was 75 μm and the liquid volume was 450 L·hm-2, the droplets were 140 drops/cm2 and the control effect of chlorantraniliprole against C. medinalis had no significant difference with 200 μm droplet diameter and 900 L·hm-2 liquid volume. Because of the barrier of rice canopy, the droplets number under the canopy was very few when spraying on the longitudinal surface of rice. When the droplet volume median diameter was 200 μm and the spray liquid volume was 900 L·hm-2 or the droplet volume median diameter was 75 μm and the spray liquid volume was 450 L·hm-2, the amount of droplets under the canopy were less than 20 drops/cm2, the pesticides had poor control effect on the N. lugens. Under the canopy spray, pesticides were sprayed directly on the infestation sites of the N. lugens, and the control effect of the pymetrozine and chlorpyrifos unit doses on the N. lugens was significantly improved. 【Conclusion】 The amount of liquid used affects the amount of pesticides deposited on rice plants and the density of droplets per unit area of rice, thus affecting the control effect of pesticide unit doses on pests. When the liquid volume was 450 L·hm-2 (droplet diameter 75 μm) or 900 L·hm-2 (droplet diameter 200 μm), the canopy was evenly sprayed up and down in rice fields, which ensured that the liquid retention on rice plant was within the range of the point of run-off and had a sufficient density of droplets, the control effect of pesticide against pests was good.

Key words: pesticide, spraying volume, point of run-off, retention, droplet density, control effect