Protoporphyrinogen IX oxidase inhibitor; pre-emergence herbicide for use in rice and other food crops. Prepn: R. Boesch, DE 2227012; idem, US 3818026 (1972, 1974 both to Rhone-Poulenc). Properties and field trials: R. Dickmann et al., Brighton Crop Prot. Conf. - Weeds 1997, 51; G. Tracchi et al., ibid. 885.