Absorption, Translocation, and Toxicity of Glyphosate and Oxyfluorfen in Yellow Nutsedge (Cyperus esculentus)

The potential for yellow nutsedge ( Cyperus esculentus L. var. leptostachyus Boeck. # CYPES) regrowth was reduced by increasing plant age and by glyphosate [ N -(phosphonomethyl)glycine] and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene]. Of the amount of glyphosate transported to underground parts, most was found in the tubers, with immature rhizomes, roots, and tubers having 2 to 3 times higher concentrations than comparable mature tissues. Addition of unlabeled oxyfluorfen as a tank mixture with glyphosate increased absorption and translocation, mainly into leaves and new tubers, of radioactivity from 14 C-glyphosate in 30-day-old plants. In contrast to the younger plants, the addition of oxyfluorfen decreased 14 C-glyphosate detected in 60-day-old plants. The greater effectiveness of glyphosate when applied with oxyfluorfen on yellow nutsedge at the early growth stage has important implications in the field because the tuberization process must be stopped early in the development of the plant for successful control.