Purple Nutsedge (Cyperus rotundus) and Yellow Nutsedge (Cyperus esculentus) Control in Glyphosate-Tolerant Soybean (Glycine max)1

Abstract

Field studies were conducted to evaluate the effects of glyphosate and conventional herbicides on purple and yellow nutsedges. Tubers collected from the field were counted and tested for viability via growth chamber or triphenyl tetrazolium chloride test to determine the effect of herbicides on tuber density and viability. With purple nutsedge, herbicide treatments containing glyphosate at 0.84 kg/ha followed by (fb) glyphosate at 0.56 kg/ha reduced viable and total tuber density. Among conventional herbicides, treatments containing metolachlor at 2.2 kg/ha plus sulfentrazone at 0.26 kg/ha plus chlorimuron at 0.05 kg/ha applied preemergence (PRE) and metolachlor at 2.2 kg/ha plus imazaquin at 0.14 kg/ha applied PRE fb bentazon at 0.84 kg/ha applied postemergence (POST) reduced total and viable tuber density compared to the nontreated. Metolachlor at 2.2 kg/ha plus sulfentrazone at 0.26 kg/ha plus chlorimuron at 0.05 kg/ha applied PRE fb bentazon applied POST also reduced viable tuber density of purple nutsedge. With yellow nutsedge, all herbicide treatments reduced total and viable tuber density over the nontreated check.Nomenclature: Tetrazolium red; 2,3,5-triphenyl tetrazolium chloride; purple nutsedge, Cyperus rotundus L. #3 CYPRO; soybean, Glycine max (L.) Merr. ‘Asgrow 4701RR’, ‘Hartz 4998’; yellow nutsedge, Cyperus esculentus L. # CYPES.Additional index word: Perennial weeds.Abbreviations: fb, followed by; POST, postemergence; PRE, preemergence; WAP, weeks after planting.