Influence of Bentazon on Absorption and Translocation of Sethoxydim in Goosegrass (Eleusine indica)

The absorption and translocation of sethoxydim {2[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} as influenced by bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] were studied in goosegrass [Eleusine indica (L.) Gaertn. ♯3 ELEIN]. The presence of bentazon in the treatment emulsion decreased foliar absorption of 14C applied as 14C-sethoxydim by about half. Significantly less 14C was found in the treated leaf, shoot tissue above the treated leaf, shoot tissue below the treated leaf, and roots of plants treated with a mixture of 14C-sethoxydim and bentazon than with 14C-sethoxydim alone. After 6 h, 3.5% of applied 14C was recovered from plant parts other than the treated leaf in the absence of bentazon, compared to 1.1% of that applied in combination with bentazon. The difference in foliar absorption between the two treatments may account for the antagonistic interaction between these herbicides observed in the field.