Fenclorim (4,6-dichloro-2-phenylpyrimidine) is a pyrimidine herbicide safener that effectively protects rice (Oryza sativa L.) from the phytotoxicity of certain herbicides. It improves rice tolerance to chloroacetanilide herbicides by enhancing the expression of detoxifying glutathione S-transferase (GST). Compared with seed treatment with safener alone, sequential seed treatment with safener and insecticide minimizes the release of fenclorim without causing residue problems in the ecosystem and harvested rice.