BUD VARIATION IN THE WASHINGTON NAVEL ORANGE. 145 
no other attention or care than that given the other trees in the 
orchard. 
As a result of these investigations, more than 40,000 undesirable 
citrus trees in California orchards have been top-worked with buds 
selected from the most desirable trees in the investigational perform- 
ance-record plats. The oldest tops grown from these buds are now 
more than 5 years of age. So far, not a single failure has been ob- 
served in transmitting the characteristics of the parent trees by means 
of the selected buds. The large amount of positive evidence as to 
the possibility of improving undesirable trees by top-working them 
with selected buds has resulted in the almost universal adoption of 
this practice by California citrus growers. 
SUMMARY. 
The Washington Navel orange is the most important and most 
extensively growri citrus variety in California. 
It was introduced into the United States from Bahia, Brazil, in 1870, 
by the United States Department of Agriculture. Two trees propa- 
gated from this: introduction were sent to Mrs. L. C. Tibb'ets, at 
Riverside, Cal., in 1873. From this beginning the Washington Navel 
orange industry has been developed, for the most part within the past 
25 years. 
There are great variations in the trees and fruit of this variety in 
California. At least 13 strains possessing very distinct character- 
istics have been discovered up to the present time. 
The objects of these investigations are to determine the comparative 
behavior of the different strains of the Washington Navel orange 
variety, to originate and demonstrate methods for their isolation and 
propagation, to eliminate undesirable trees in established orchards, 
and to conserve, standardize, and stabilize the variety through bud 
selection based on individual-tree performance records. 
The plan of the investigations is to secure reliable information 
regarding individual- tree behavior and fruit characteristics by means 
of systematic performance records. 
Individual-tree performance records include a history of the tree, 
a record of its production, and a description of its fruits and habits of 
growth. 
Bud variations are of frequent occurrence and of great commercial 
importance in this variety. 
Individual fruit variations, such as chimeralike developments and 
other interesting similar phenomena, are found frequently. Many 
minor fruit variations have been discovered, and their relation to more 
important variations is being investigatedo 
14575°— 18— Bull. 623 10 
