Response of Yellow (Cyperus esculentus) and Purple (Cyperus rotundus) Nutsedge to Metolachlor

Two 1-yr field studies were conducted to evaluate preemergence and preplant incorporated treatments of alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], EPTC (S-ethyl dipropylthiocarbamate), fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone}, and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] for the control of yellow nutsedge (Cyperus esculentus L.). Preemergence applications of metolachlor at 2.24, 3.36, and 4.48 kg/ha gave the best control with no significant differences observed among rates of metolachlor. Depth of herbicide incorporation did not result in any significant increase in control. Preplant incorporation of metolachlor at all rates, or fluridone at 0.56 and 0.84 kg/ha provided seasonal control of yellow nutsedge. Translocation of 14C-metolachlor applied to the root or shoot of yellow nutsedge was primarily acropetal with some limited basipetal movement. Application of 14C-metolachlor to the root or shoot of purple nutsedge (Cyperus rotundus L.) resulted in mostly acropetal translocation with little movement of 14C from the treatment site.