as of 2009, hppd inhibitors had 3 fundamental chemical frameworks: pyrazolones: pyrazolate (sanbird, introduced sankyo, 1980); pyrazoxyfen (paicer, introduced ishihara, 1985); benzofenap (yukawide, introduced mitsubishi chemical corp , rhône-poulenc agro, 1987, of 2009 sold bayer cropscience taipan); pyrasulfotole (huskie , infinity, introduced bayer cropscience, 2007); , topramezone (clio , impact, introduced basf, 2006) triketones: sulcotrione (mikado, introduced zeneca, 1990 , of 2009 sold bayer cropscience)); mesotrione (callisto , lumax, introduced zeneca, 2002 , of 2009 sold syngenta); benzobicyclon (showace, introduced sds biotech , sandoz crop protection (now syngenta), 2001); tembotrione (laudis introduced bayer cropscience, 2007) diketonitriles: isoxaflutole (aka ift) (balance , merlin, introduced rhône-poulenc agro, 1996 , of 2009 sold bayer cropscience) ^ cite error: named reference almsick invoked never defined (see page). ^ george w. ware , david m. whitacre. introduction