Movement and Activity of Glyphosate in Purple Nutsedge

Tubers from purple nutsedge ( Cyperus rotundus L.) plants grown in the greenhouse for 2 to 10 weeks did not germinate after foliar applications of 4 kg/ha glyphosate ( N -(phosphonomethyl)glycine). Some tubers from 12- and 24-week-old purple nutsedge plants survived glyphosate application. Translocation of 14 C-glyphosate from treated purple nutsedge leaves to other plant parts increased from 5% of the amount applied at 1 day to 19% at 4 days after application. Specific activity of 14 C in tubers was greater than in leaves of plants 2- to 6-week-old. With increasing plant age, specific activity decreased in both tubers and leaves. As purple nutsedge grew older, total 14 C translocated increased in tubers, and decreased slightly in leaves. Thin layer chromatography showed no evidence of glyphosate metabolism in purple nutsedge.