INTERACTIONS OF SETHOXYDIM AND CORN (ZEA-MAYS) POSTEMERGENCE BROADLEAF HERBICIDES ON 3 ANNUAL GRASSES

Greenhouse and laboratory studies were conducted to determine the effe ct of 22 postemergence corn broadleaf herbicide combinations on the ef ficacy of sethoxydim applied to giant foxtail, large crabgrass, and sh attercane. Eighteen combinations caused a reduction in sethoxydim effi cacy on at least one grass species. Dicamba, atrazine plus dicamba, at razine plus bentazon, bromoxynil, primisulfuron, CGA-152005 plus primi sulfuron, MON 12000, and flumetsulam plus clopyralid plus 2,4-D (NAF-7 3) were evaluated further on the efficacy and foliar absorption of set hoxydim applied to giant foxtail, large crabgrass, and shattercane. In timing studies, applying all herbicide combinations at 7 or 3 d befor e sethoxydim application eliminated significant antagonistic interacti ons. However, applying NAF-73, primisulfuron, or CGA-152005 plus primi sulfuron 1 d prior resulted in a reduction in sethoxydim efficacy on a t least one grass species. Dicamba, atrazine plus dicamba, and atrazin e plus bentazon decreased C-13-sethoxydim absorption 9 to 63% across g rass species. Replacing crop oil concentrate (COG) with DASH increased sethoxydim absorption when applied with these herbicides but not to t he full extent of sethoxydim applied alone with DASH. Sethoxydim effic acy was retained or improved with DASH when applied with dicamba, atra zine plus dicamba, atrazine plus bentazon, or bromoxynil. When primisu lfuron, CGA-152005 plus primisuIfuron, MON 12000, or NAF-73 was applie d with C-14-sethoxydim no effect on sethoxydim absorption was observed . DASH was less effective than COC at restoring sethoxydim efficacy wh en applied with these herbicides.