An herbicide; induces light-dependent apoptosis and reduces chlorophyll levels in tobacco leaf discs at 10 µM; eliminates susceptible barley grass but not the paraquat-resistant biotype in field studies at 0.05, 0.1, and 0.2 kg/ha; induces apoptosis, increases intracellular levels of NO, and increases expression of mRNA encoding iNOS in SH-SY5Y cells at 100 µM; toxic to rats (LD50s = 115 and 21 mg/kg for p.o. and i.v. administration, respectively); induces neuronal cell death and seizures, effects that can be inhibited by U-74389G, in rats at 100 nmol/animal, i.c.v.; induces weight loss, lung hemorrhage and edema, and diarrhea in rats at 20 mg/kg