INFLUENCE OF APPLICATION VARIABLES ON ANTAGONISM BETWEEN SETHOXYDIM AND BENTAZON

The effects of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexene-1-one} rate, order and timing of sequential herbicide applications, and the addition of oil concentrate on sethoxydim-bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4-3H-one 2,2-dioxide] antagonism were studied on broadleaf signalgrass [Brachiaria platyphylla (Griseb.) Nash.], fall panicum (Panicum dichotomiflorum Michx.) and large crabgrass [Digitaria sanguinalis (L.) Scop.] in field experiments during 1980 and 1981. Tank-mixing bentazon with sethoxydim reduced control of these species compared to applications of sethoxydim alone. Sequential applications of the herbicides prevented the antagonism. Variations in time between and order of sequential applications had no consistent effect on efficacy. Increases in sethoxydim rate reduced the severity of the antagonism in some cases, while the addition of oil concentrate had no effect.