UNITED STATES DEPARTMENT OF AGRICULTURE 



i^ BULLETIN No. 813 4 



•Vl lpC<^ fifc* ^®"'''''"'''*'" from the Bureau of Plant Industry J' 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



s\J^ "^^-ru 



Washington, D.C. 



PROFESSIONAL PAPER 



June 25, 1920 



CITRUS-FRUIT IMPROVEMENT: A STUDY OF BUD 

 VARIATION IN THE EUREKA LEMON/ 



By A. D. Shamel, Physiologist, L. B. Scott, Pomologist, 0. S. Pomeroy, Assistant 

 Pomologist, and C. L. Dyer, Scientific Assistant, Fruit-Improvement Investiga- 

 tions, Office of Horticultural and Pomological Investigations. 



CONTENTS. 



Page. 



Importance of the lemon industry 1 



History of the Eureka variety 3 



Variability withiu the variety 3 



Objects of the investigations 6 



Plan of the investigations 7 



Methods of keeping performance records 8 



Tree numbers , 8 



Picking 9 



Assorting 9 



Recording the data 11 



Descriptions of the important strains 13 



Eureka strain 13 



Small-Open strain 15 



Shade-Tree strain 16 



Dense-Unproductive strain 19 



Pear-Shape strain 20 



Descriptions of the important strains — Contd. 



Dense-Productive strain 21 



Variegated strain 21 



Sporting strain 22 



Lessons taught by these investigations 23 



Presentation of data 25 



Comparative value of the strains 78 



The imintentional propagation of undesirable 



strains 79 



The isolation of strains through bud selection. SO 



Top-working undesirable trees 81 



Replacing undesirable trees m bearing or- 

 chards 84 



The selection and care of bud wood 85 



Summary 87 



IMPORTANCE OF THE LEMON INDUSTRY. 



The lemon {Citrus limonia Osbeck), as grown in the United States, 

 is largely a California product. According to the Thirteenth Census 

 of the United States there were 957,000 lemon trees of bearmg age 

 in the United States in 1910 and 396,000 under bearing age, of which 

 941,293 and 379,676, respectively, were in California. The total 

 production of all States in 1909 was reported as amounting to 

 2,770,313 boxes, of which California produced 2,756,221 boxes. 



1 This is the fourth in a series of bulletins summarizing the citrus fruit-Improvement investigations of the 

 Department of Agriculture. The three former reports, U. S. Dept. Agr. Buls. 623, 624, and 697, presented 

 the results of studies with the Washington Navel orange, the Valencia orange, and the Marsh grapefruit, 

 respectively. A report on bud variations in the Lisbon lemon ^\-ill be found in U. S. Department of Agri- 

 culture Bulletin 815, entitled "Citrus-Fruit Improvement: A Study of Bud Variation in the Lisbon 

 Lemon." 



135336°— 20— BuU. 813 1 



