This is one of three rootstocks ('Bitters', 'Carpenter', and 'Furr') originally hybridized at the USDA US Date and Citrus Station in Indio, California, and developed further by the University of California, Riverside. This selection was named in honor of the late Dr Bill Bitters. Produces a small tree, with high yield relative to canopy volume. Young trees on this rootstock showed good tolerance to freezing. Fruit quality of late navels was good and granulation was no worse than fruit on 'Carrizo' or 'C35'. It is tolerant to CTV, moderately tolerant to Phytophthora parasitica, not very tolerant of citrus nematode, and very tolerant of calcareous soil.