Grass Control in Peanut (Arachis hypogaea) with Clethodim and Selected Broadleaf Herbicide Combinations¹

Field studies were conducted to evaluate broadleaf signalgrass and southern crabgrass control and effect on peanut yield of clethodim alone and sequential applications with six broadleaf herbicides. When rated 9 wk after treatment (WAT), broadleaf signalgrass control with clethodim followed by (fb) acifluorfen, imazapic, or 2,4-DB 24 hr later did not differ from clethodim alone. When acifluorfen, acifluorfen plus bentazon, imazethapyr, imazapic, and lactofen were applied in a tank-mix with clethodim, broadleaf signalgrass control was less than 65%. Clethodim alone or clethodim plus 2,4-DB controlled 86 and 73% broadleaf signalgrass, respectively. When acifluorfen, acifluorfen plus bentazon, or imazethapyr was fb clethodim, signalgrass control was less than 72%. Southern crabgrass control was reduced in 2 of 3 yr from clethodim alone when acifluorfen was tank-mixed with clethodim. When other broadleaf herbicides were tank-mixed with clethodim, reduced crabgrass control was noted in only 1 of 3 yr. Where no POST herbicides were used, peanut yield was < 1600 kg/ha, while all plots which received a POST herbicide yielded over 2200 kg/ha.