INFLUENCE OF DROPLET SIZE ON SPRAY DEPOSITION AND WEED CONTROL USING GLYPHOSATE

ABSTRACT Droplet size is one of the most important factors that affect spray deposition and weed control through the use of herbicides. The aim of this study was to evaluate the influence of the droplet size on the spray deposition and control of Euphorbia heterophylla and Urochloa ruziziensis by using glyphosate. The treatments included spraying glyphosate with fine, medium, coarse, very coarse, and ultra-coarse droplet sizes to determine the deposition, uniformity of distribution, visual control, and dry weight reduction (DWR). The treatments were compared with the values of the dose required to achieve 50% DWR or 50% visual control (C50) at 7, 14, 21, and 28 days after herbicide application. Fine and medium droplet sizes afforded high deposition values and low distribution uniformities in E. heterophylla . Fine and medium droplet sizes yielded the lowest C50 on visual control and DWR in E. heterophylla, respectively. The droplet size did not affect the spray deposition on U. ruziziensis plants; however, the larger droplets had less uniformity of distribution. In U. ruziziensis plants, spraying glyphosate with coarse and medium droplet sizes yielded the lowest values of C50 to visual control and DWR, respectively.

摘要：雾滴粒径是影响除草剂喷施沉积效果与杂草防除效果的关键因素之一。本研究以草甘膦为供试药剂，旨在评估雾滴粒径对飞扬草（Euphorbia heterophylla）与鲁兹臂形草（Urochloa ruziziensis）的喷施沉积效果及防除效果的影响。试验设置细雾滴、中雾滴、粗雾滴、极粗雾滴及超粗雾滴五种喷施处理，以测定药剂沉积量、分布均匀性、目测防效与干重损失率（DWR）。以药后7、14、21、28天时，达到50%干重损失率或50%目测防效所需的药剂剂量（C50）作为评价指标，对各处理的试验结果进行对比分析。在飞扬草上，细雾滴与中雾滴可实现较高的沉积量，但分布均匀性较差；针对飞扬草，细雾滴与中雾滴分别使目测防效C50与干重损失率C50达到最低值。雾滴粒径对鲁兹臂形草的药剂沉积量无显著影响，但雾滴粒径越大，分布均匀性越差；针对鲁兹臂形草，采用粗雾滴与中雾滴喷施草甘膦时，分别使目测防效C50与干重损失率C50达到最低值。