Abstract
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.
Highlights
The application of herbicides is the main method of controlling weeds in agricultural areas and, contributes to the reduction of productivity losses (Heap, 2014; Godinho Júnior et al, 2017)
The experiment was performed in a 20 m long wind tunnel with a 2 m square cross-section, with a 0.9 m diameter double-helix axial fan driven by the power take-off (PTO) of a tractor (Gandolfo et al, 2013)
A significant interaction was observed between the spray solution of herbicides and horizontal distances (Table 2)
Summary
The application of herbicides is the main method of controlling weeds in agricultural areas and, contributes to the reduction of productivity losses (Heap, 2014; Godinho Júnior et al, 2017). With expectations of improving the control of resistant and tolerant weeds to glyphosate, the herbicide dicamba has been studied for commercial use in Brazil. In regions where cotton cultivars tolerant to synthetic auxins were adopted, the use of herbicides such as dicamba and 2,4-D will increase (Mortensen et al, 2012). This shows the need for care in the application of these herbicides (Godinho Júnior et al, 2017) in areas close to sensitive crops (Gandolfo et al, 2012)
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