The economic impact of the cultivar ‘Gold Nijisseiki’ of Japanese pear (Pyrus pyriforia) is well documented. This cultivar was developed with chronic radiation in a gamma field, Ohmiya, Ibaraki. It is more resistant to black spot disease (caused by Alternaria alternata) than its parent ‘Nijisseiki’. The parent cultivar was susceptible to blackspot disease. The additionalannualincomeby growingthis cultivar is almost US$ 30million accordingto the calculations of a farmers’ group cooperative (Anonymous 2000; E. Amano, pers. commun.). New mutant-cultivars ‘Osa-Nijisseiki’ and ‘Osa-Gold’ with improved disease resistance have been released recently (Table 6). These mutants are also self-compatible and eliminate the need of planting pollinators. In 1997, the over all economic contribution of mutants of rice, pear, soybean and peach in Japan has been estimated at US$ 973.2million (Table 7).