Robertson naval orange (CRC 3792)

Citrus sinensis (L.) Osbeck

CRC 3792
PI 539576
VI 364

Source

Received as budwood from Cairns orchard via STG & CCPP, 1978.

Parentage/origins

Originated as a limb sport on an old Washington navel tree.

Rootstocks of accession

Carrizo citrange

Season of ripeness at Riverside

December to January

Description from The Citrus Industry Vol. 1 (1967)

"Fruit virtually indistinguishable from Washington except for medium-large size, slightly lower quality, and earlier maturity, which is usually ten days to two weeks. While maturing about the same time as Thomson, quality is better and fruit is retained much longer on tree. Because fruit is often borne in tight clusters, its shape is sometimes slightly distorted and exhibits flat contact surfaces.

Tree lacking in vigor (more so than Thomson), small (markedly dwarfed on sour orange rootstock), heat-resistant, precocious, and very prolific.

The heat resistance and associated high-yielding behavior of the Robertson navel orange appear to relate to the fact that, although it blossoms at about the same time as other varieties the young fruits develop more rapidly and pass through the fruit-setting phase earlier. The fruits thus escape the severe dropping associated with the heat and dryness normally characteristic of the later fruit-setting period of other varieties (Coit and Hodgson, 1919).

Robertson originated as a limb sport in an old Washington navel tree in an orchard near Redlands, California, where it was found by Roy Robertson in 1925. It was patented (U.S. Plant Patent No. 126) by Armstrong Nurseries of Ontario, California, and introducer to the trade in 1936. Although planted and topworked to some extent, it has not become commercially important in California or Arizona, nor apparently elsewhere. However, because of its small tree size and early and high productivity, it is popular as a dooryard or container-grown patio tree."