BUD SELECTION AS RELATED TO QUANTITY PRODUCTION 
IN THE WASHINGTON NAVEL ORANGE. 1 
By A. D. Shamel, Physiologist in Charge , C. S. Pomeroy, Pomologist, and R. E. 
Caryl, Assistant Pomologist , Fruit-Improvement Investigations, Office of Horticul¬ 
tural Investigations , United States Department of Agriculture 
INTRODUCTION 
Studies of bud variations in citrus varieties were begun by the senior 
writer at Riverside, Calif., in April, 1909. These investigations have 
been carried on largely in plats located in successful orchards of the 
important California varieties, and detailed reports of these studies 
have already been presented. 2 
In this work individual-tree performance records were kept of the 
production of several hundred trees by recording the number and weight 
of the fruits of each grade and size on each tree for periods of from four 
to eight years. Records were also kept showing the presence of any 
marked variations of the fruit or foliage of these trees. In many trees 
of the standard strains limbs were found on which the fruit or foliage was 
very different from that on the remaining part of the tree, and these differ¬ 
ences usually remained constant from year to year. In many instances 
entire trees were found which possessed similar fruit and foliage charac¬ 
teristics to certain of the limb variations. This condition seemed to 
indicate that the presence of these diverse strains might be due to the 
unintentional use of buds from limb variations in the commercial propa¬ 
gation of the trees in these orchards. 
The results of these investigations have shown that the population of 
the citrus orchards which have been studied is made up of a number of 
diverse strains, some of which are desirable for commercial fruit pro¬ 
duction while others are detrimental or positively worthless. 
PROGENY TESTS OF BUD VARIATIONS 
In order to determine whether or not strains may arise as limb vari¬ 
ations and be perpetuated through budding, propagations were made in 
the spring of 1915 of a number of limb sports which were typical of the 
important established strains, together with propagations of many entire 
tree variations. The buds secured from these sports were inserted in 
1 Accepted for publication August 18, 1923. 
2 Shamel, A. D., Scott, L. B., and Pomeroy, C. S. citrus-fruit improvement: a study of bud vari¬ 
ation IN THE WASHINGTON NAVEL ORANGE. U. S. Dept. Agr. Bui. 623, 146 p., 16 fig., 19 pi. 1918. 
-CITRUS-FRUIT IMPROVEMENT: A STUDY OF BUD VARIATION IN THE VALENCIA ORANGE. 
U, S. Dept. Agr. Bui. 624, 120 p., 9 fig., 14 pi. 1918. 
-CITRUS-FRUIT IMPROVEMENT; A STUDY OF BUD VARIATION IN THE MARSH GRAPE¬ 
FRUIT. U. S. Dept. Agr. Bui. 697, 112 p., 14 fig., n pi. 1918. 
-CITRUS-FRUIT IMPROVEMENT: A STUDY OF BUD VARIATION IN THE EUREKA LEMON. 
U. S. Dept. Agr. Bui. 813, 88 p., 22 fig., 7 pi. 1920. 
-CITRUS-FRUIT IMPROVEMENT: A STUDY OF BUD VARIATION IN THE LISBON LEMON. 
U. S. Dept. Agr. Bui. 815, 70 p., 14 fig., 8 pi. 1920. 
Vol. XXVI, No. 7 
Nov. 17, 1923 
Key No. G-337 
Journal of Agricultural Research, 
Washington, D. C. 
aho 
(3 r 9) 
