POTENTIAL DRIFT AND INJURY OF HERBICIDES SPRAYED IN A WIND TUNNEL

ABSTRACT The possibility of synthetic auxin applications in crops increases the risk of injury to sensitive plants. The aim of this study was to quantify the drift of herbicides sprayed in a wind tunnel and the injury in cotton plants. The experimental design was a completely randomized design with five treatments and four replications. The tested spray solutions were dicamba (0.250 L c.p. ha−1), glyphosate (0.625 L c.p. ha−1), 2,4-D (0.250 L c.p. ha−1), glyphosate + 2,4-D (0.625 L c.p. ha−1 + 0.250 L c.p. ha−1), and glyphosate + dicamba (0.625 L c.p. ha−1 + 0.250 L c.p. ha−1). Drift was quantified in a wind tunnel, collected at distances of 5, 10, and 15 m in relation to the spray tip. Cotton plants were placed in the same wind tunnel and the injury was visually evaluated for at 3, 7, and 15 days after application (DAA). The addition of glyphosate to dicamba and 2,4-D potentiated the drift from 5 m. At 10 and 15 m, dicamba and 2,4-D in isolation had the lowest drift potential. At 5 m, the injury is higher than at other distances regardless of the spray solution. At 10 m, 2,4-D in isolation presented the highest injury when compared to dicamba in isolation at 7 and 15 DAA. At 10 and 15 m, the addition of glyphosate to dicamba enhances the injury in cotton plants and herbicide mixtures do not differ from each other in relation to injury.摘要：在作物中施用合成生长素类药剂的做法，会提升敏感植物遭受药害的风险。本研究旨在量化风洞环境下喷施除草剂的雾滴漂移量及其对棉花植株造成的药害程度。实验采用完全随机设计，设置5个处理组与4次重复。供试喷施药液包括：麦草畏（dicamba，0.250 L商品制剂·公顷⁻¹）、草甘膦（glyphosate，0.625 L商品制剂·公顷⁻¹）、2,4-滴（2,4-D，0.250 L商品制剂·公顷⁻¹）、草甘膦+2,4-滴复配制剂（0.625 L商品制剂·公顷⁻¹ + 0.250 L商品制剂·公顷⁻¹），以及草甘膦+麦草畏复配制剂（0.625 L商品制剂·公顷⁻¹ + 0.250 L商品制剂·公顷⁻¹）。在风洞内于喷施喷头下游5、10、15米处收集雾滴以量化除草剂雾滴漂移量；将棉花植株置于同一风洞内，于施药后3、7、15天（DAA）对其药害程度进行目视评估。结果显示：向麦草畏与2,4-滴中添加草甘膦，会使5米处的雾滴漂移量显著增强；在10米与15米处，单一施用麦草畏或2,4-滴的雾滴漂移潜力最低。无论喷施何种药液，5米处的棉花药害程度均高于其他距离。在施药后7天与15天，10米处单一施用2,4-滴的药害程度高于单一施用麦草畏的处理；在10米与15米处，向麦草畏中添加草甘膦会加重棉花植株的药害，且不同除草剂复配制剂间的药害程度无显著差异。