During the 1993/94 growing season, it was carried out a field experiment at the Agronomic Experimental Station of Federal University of Rio Grande do Sul, in Eldorado do Sul, RS, Brazil, in order to evaluate the possibility of using reduced rates of the herbicides haloxyfop-methyl and sethoxydim for Alexandergrass [Brachiaria plafitaginea (Link) Hitchc.] control in soybeans. Haloxyfop-methyl was tested at 120, 90, 60, and 30+30 g/ha, where as sethoxydim was at rates, of 220, 165, 110, and 55+55 g/ha. Herbicide spraying occurred 15 days after soybean sowing; at this time Alexandergrass plants ranged from one leaf to one tiller. Herbicide treatments using reduced rates in sequential applications had the second spraying accomplished 11 days after the first one. It was obtained Alexandergrass control around 95% for all the treatments, with small but not significant variations among them. Soybean seed yield was equivalent for the hoeing check, haloxyfop-methvl at 90 and 60 g/ha and sethoxydim at 220, 110, and 55+55 g/ha. The additional treatments were equivalents among them, but all surpassed the weeded check, which produced the lowest yield. These results evidence the possibility of using reduced herbicides rates, which may reach yield levels as high as those attained with full rates.
Chemical control; haloxyfopmethyl; sethoxydim; Brachiaria plantaginea; Glycine max