Yellow Nutsedge Control in Soybeans

Abstract

A system for controlling yellow nutsedge(Cyperus esculentusL.) in soybeans [Glycine max(L.) Merr.] which involved preplanting tillage, late planting, herbicides, and cultivation was evaluated in 1969 and 1970. In Illinois on a Drummer silty clay loam,S-ethyl dipropylthiocarbamate (EPTC) andS-ethyl diisobutylthiocarbamate (butylate), incorporated in the soil before planting, gave good and fair control of yellow nutsedge, respectively, but both injured soybeans initially.S-propyl dipropylthiocarbamate (vernolate), also incorporated before planting, controlled yellow nutsedge as well as EPTC did, and resulted in less injury to soybeans. Soybean yields were not reduced by any of the thiocarbamate treatments. Incorporation of 2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide (alachlor) or 2-chloro-N-isopropylacetanilide (propachlor), just before planting, controlled at least 90% of the yellow nutsedge in both years, whereas preemergence applications were only moderately successful and dependent on rainfall. In field microplots, alachlor and vernolate provided only fair control of yellow nutsedge when applied to the soil surface, but they both controlled 95% of the yellow nutsedge when incorporated 7.6 cm. In greenhouse studies on selective control of yellow nutsedge in soybeans, alachlor exhibited a wider margin of safety to soybeans than did vernolate.