Greenhouse and field research was conducted to determine the effect of glufosinate, glyphosate, and glyphosate plus additional adjuvant on yellow nutsedge control and tuber production. Glyphosate at 0.84 kg/ha reduced yellow nutsedge dry weight 64%, whereas glufosinate at 0.4 kg/ha reduced dry weight only 22% when averaged over diammonium sulfate (DAS) and spray volume. Furthermore, yellow nutsedge dry weight was reduced 53% in the presence and 34% in the absence of DAS; however, dry weights were similar when spray volumes of glufosinate or glyphosate ranged from 140 to 1038 L/ha. Yellow nutsedge control with glyphosate and glufosinate increased to 88 and 68%, respectively, when the herbicides were injected into the plant. In the field, glufosinate at 0.4 kg/ha and glyphosate at 0.84 kg/ha controlled yellow nutsedge 19 and 53%, respectively. Glyphosate reduced yellow nutsedge tuber density 51%, tuber fresh weight 59%, and tuber sprouting 17% 42 wk after treatment in the field. The addition of nonionic surfactant, methylated seed oil, or crop oil concentrate to glyphosate plus DAS did not increase yellow nutsedge control with glyphosate in the greenhouse or field.
Nomenclature: Crop oil concentrate; diammonium sulfate; dose–response; glufosinate; glyphosate; methylated seed oil; nonionic surfactant; yellow nutsedge, Cyperus esculentus L. #3 CYPES.
Additional index words: Perennial weed, spray volume, tuber production.
Abbreviations: COC, crop oil concentrate; DAS, diammonium sulfate ((NH4)2SO4); GR50, rate causing 50% growth reduction; MSO, methylated seed oil; NIS, nonionic surfactant; WAT, weeks after treatment.