UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 623 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



July 22, 1918 



CITRUS-FRUIT IMPROVEMENT 

 A STUDY OF BUD VARIATION IN THE 



WASHINGTON NAVEL ORANGE 



By 



A. D. SHAMEL, Physiologist in Charge, L. B. SCOTT, Pomologist, and 



C. S. POMEROY, Assistant Pomologist, Fruit-Improvement Investigations, 



Office of Horticultural and Pomological Investigations 



CONTENTS 



Introduction „ . . 1 



History of the Washington Navel Variety 2 



Variability within the Variety 3 



Occurrence and Frequency of Bud Varia- 

 tions 5 



Objects of the Investigations 7 



Plan of the Investigations ...... 7 



Methods of Keeping Performance 



Records 9 



Descriptions of Some of the Important 



Strains . . 14 



Page 



Individual Fruit Variations ...... 24 



Minor Variations of Fruits 27 



Lessons Taught by These Investigations 27 



Presentation of Data 29 



Comparative Value of the Strains . . . 140 

 The Unintentional Propagation of Unde- 

 sirable Strains 141 



The Isolation of Strains through Bud 



Selection 142 



Top- Working Undesirable Trees ... 144 



Summary 145 



WASHINGTON 

 GOVERNMENT PRINTING OFFICE 



1918 



