ABSTRACT
The influence of a mineral oil on the antagonistic effect of bentazon [(3-(1-methylethyl)-(1H)-2,l,3-benzothiadiazin-4(3H)-one 2,2-dioxide)] on the phytotoxicity of the graminicides sethoxydim {(2-[ 1 -(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1 -one)}, cycloxydim {(2-[1-(ethoxyimino)butyl]-3-hydroxy-5-(3-thiamyl)-2-cyclohexen-1-one)}, and clethodim {((E,E)-± -2-[1-[[3-chloro-2-propenyl)oxy]imino]propyl]-5-[2-ethyl-thio)propyl]-3-hydroxy-2-cyclohexen-1-one)} was examined on pot-grown barley (Hordeum vulgare L. cv.Igri). The results were analyzed using a parallel-line assay technique.
It was found that bentazon significantly reduced the activity of all three cyclohexadiones. Addition of a mineral oil adjuvant significantly increased the herbicidal effect of the graminicides whether bentazon was added or not. While the mineral oil reduced the severity of the antagonistic effect of bentazon on sethoxydim increasingly with increasing concentration of the adjuvant, no reduction in antagonism was found on cycloxydim and clethodim. Applying the parallel-line assay technique, it was possible to determine that the reduced antagonistic effect of bentazon on sethoxydim phytotoxicity, when adding the mineral oil, was caused by a reduced interaction between the two herbicides, and not merely the result of the increased phytotoxicity of the graminicide.
