Effects of adjuvants and formulations on efficacy, absorption, and translocation of glyphosate in purple nutsedge (Cyperus rotundus L.)

Adjuvants, Sylgard 301, Citowett, Tendal, Latron CS-7, Attract, and Besmore CT 671 at 0.025 percent (V/V) were applied in combination with glyphosate (isopropylamine salt) for purple nutsedge control under simulated rain fall at 1, 2 and 3 hours after application and no rain. At low rate of glyphosate, 0.75 kg ae/ha, all adjuvants did not increase glyphosate activity under simulated rainfall or no rain conditions. At high rate of glyphosate 1.5 kg ae/ha under no rain condition all adjuvants did not incresae glyphosate activity for purple nutsedge control, but at 3 hours of simulated rainfall all adjuvants except Latron CS-7 increased glyphosate activity. Furthermore, Tendal and Attract increased glyphosate activity more than other adjuvants. However all adjuvants did not reduce plant dry weight, dry weight of regrowth of increased percent of plant reduction. For formulation study, at low rate of glyphosate trimethylsulfonium salt increased activity more than isopropylamine salt under simulated rainfall at 2 hours after application and no rain condition. However, both salts increased glyphosate glyphosate activity more than monoammonium and sodium salts. Under simulated rainfall at 2 hours after application, isopropylamine and trimethylsulfornium salts increased percent of plant reduction more than other adjuvants. At high rate of glyphosate under no rain condition, isopropylamine and trimethylsulfonium salts increased glyphosate activity more than monoammonium and sodium salts. But when high rate of glyphosate was applied under simulated rain fall at 2 hours after application, formulations did not effect on glyphosate activity at 7 to 14 days after application. But at 21 days after application isopropylamine and trimethylsulfonium salts increased the activity of glyphosate more than monoammonium and sodium salts. However, all formulations of glyphosate did not significantly different in reduction of plant dry weight, regrowth dry weight and increase percent reduction of purple nutsedge plants.