"This variety is reported to be virtually indistinguishable from Zadaidai except that the calyx is normal and not large, fleshy, and distinctive. Both Zadaidai and Kabusu are grown primarily as ornamentals in Japan and the fruits are used for decorative purposes and in the preparation of marmalde and vinegar." (Hodgson, 1967, p 492) Dr Bitters says of this cultivar: "In Japan - Kabosu is grown on a small commercial scale - and is used as a condiment - like lemon juice would be here in Calif. - Maybe some orientals would be interested in it. EMN comment: Let's fruit it here in Riverside before putting it into the field at Lindcove. (EM Nauer, 08/1989)
According to Abkenar and Isshiki (2003), 'Kabosu' originated as a spontaneous mutation of standard 'Yuzu' in the Oita Prefecture of Japan. The green-stage fruits have been used as acid citrus for flavoring in cooking and this has resulted in the creation of a small local citrus industry. RAPD markers were able to distinguish 'Kabosu' from various other 'Yuzu'-like fruits but did not provide any further insights into its origins. (RR Krueger, 12/19/2010)
Information on 'Kabosu' from the UC Riverside Citrus Variety Collection.