Citrus sinensis (L.) Osbeck
Received as seed from an unknown source.
A nucellar seedling selection from Washington navel orange.
Rootstocks of accession
Season of ripeness at Riverside
December to January
Description from The Citrus Industry Vol. 1 (1967)
"Frost Washington is the first, and currently much the most important, nucellar budline of the Washington navel. It was originated by H. B. Frost, the geneticist and breeder, at the University of California Citrus Research Center, Riverside, from a controlled cross made in 1916. It was not released until 1952, however. Since that time its popularity has increased until it is now more widely planted in California, Arizona, and Morocco than any other clonal selection of Washington.
In this connection, mention should be made of the now well-established fact that Frost already has given rise through bud variation to a new and much less desirable clone, characterized by a more acid fruit of later maturity. In comparison to the Frost Washington, the fruit size and navel opening average smaller, the rind texture is coarser, and the flesh is more tender (Soost et al., 1961)."