BUD VARIATION IN THE WASHINGTON NAVEL OEANGE. 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 grown 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. Tibbets, 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 co mm ercial 

 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 investigated. 

 14575°— 18— Bull. 623 10 



