Post-emergence herbicide which inhibits protoporphyrinogen oxidase. Prepn: P. Plath et al., DE 3603789; eidem, US 5062884 (1987, 1991 both to BASF). Biochemical mode of action: K. Grossman, H. Schiffer, Pestic. Sci. 55, 687 (1999). Field trials in cereals: W. Nuyken et al., Brighton Crop Prot. Conf. - Weeds 1999, 81.