UNITED STATES DEPARTMENT OF AGRICULTURE 



f^ BULLETIN No. 815 |ffi| 



Contribution from tiie Bureau of Plant Industry 

 \VM. A. TAYLOR, Chief 



S^^'^^U 



Washington, D. C. 



PROFESSIONAL PAPER 



June 1, 1920 



CITRUS-FRUIT IMPROVEMENT: A STUDY OF BUD 

 VARIATION IN THE LISBON LEMON. 



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

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

 Office of Horticultural and Pomological Investigations. 



CONTENTS. 



Importance of the lemon industry 



History of the Lisbon lemon variety . . . . 



Variability wthin the variety 



Objects of the investigations 



Plan of the investigations 



Methods of keeping performance records . 

 Descnptions of the important strains. . . 



Lisbon strain 



Open strain 



■ Dense-Unproductive strain 



Bull strain 



Variegated strain , 



Sporting strain 



PaKC. 



Page. 



Lessons taught by these investigations 11 



Presentation of data 12 



Comparative value of the strains 62 



The unintentional propagation of undesir- 

 able strains G3 



The isolation of strains through bud selection 64 



Top-working undesirable lemon trees 04 



Replacing imdesirable trees in bearing or 



chards 67 



The selection and care of bud wood 68 



Summary 69 



IMPORTANCE OF THE LEMON INDUSTRY. 



In the United States, the lemon (Citrus limonia Osbeck) is grown 

 commercially practically only in California. According to the Thir- 

 teenth Census of the United States there were 957,000 lemon trees of 

 bearing 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 

 in the Thirteenth Census as amounting to 2,770,313 boxes, of which 

 California produced 2,756,221 boxes. 



Additional information concerning the lemon industry of Cal- 

 ifornia will be found in United States Department of Agriculture 

 Bulletin 813, entitled ''Citrus-Fruit Improvement: A Study of Bud 

 Variation in the Eureka Lemon." 



■ 1 This is the fifth in a series of bulletins summarizing the citrus-fruit improvement investigations of the 

 Department of Agriculture. The four former reports, V. S. Dept. Agr. Buls. 623, 624, 697, and 813, 

 presented the results of studies with the Washington Navel orange, the Valencia orange, the Marsh grape, 

 fruit, and the Eureka lemon, respectively. 

 13743.5°— :0— Bull. 815 1 



