PURPOSE:To provide a herbicidal composition containing a specific compound and bialaphos as active components, exhibiting excellent synergetic effect for the control of wide variety of weeds such as barnyard grass, Johonson grass, etc., at a low rate of application compared with the separate use of each component and giving no phytotoxicity to crops. CONSTITUTION:The objective composition contains, as active components, (A) 2-(4-chloro-2-fluoro-5-propargyloxyphenyl)-5, 6, 7, 8-tetrahydro-1H-1, 2, 4- triazolo-(1, 2-a)-pyridazine-1, 3-2H-dione of formula I having herbicidal activity and (B) bialaphos of formula II {=2-amino-4[(hydroxy)(methyl) phosphionyl]butyryl-alanylanine or its salt e.g. sodium salt} known as a herbi cide. The amount of bialaphos is 0.1-70pts.wt. per 1pt.wt, of the compound of formula I. The active components are mixed with a carrier or adjuvant and used in the form of wettable powder, emulsifiable concentrate, etc.
