4 BULLETIN 624, IT. S. DEPARTMENT OF AGRICULTURE. 



vi duals of the variety in one or more constant and recognizable 

 characteristics and which are capable of perpetuation through vege- 

 tative propagation. Within the various strains there are variations 

 in the amount and commercial quality of the fruits produced by the 

 individual trees. The variability of individual-tree production in 

 the orchard as regards quantity, commercial quality, time of ripening, 

 and other characteristics is of the highest importance to growers of 

 fruit varieties. 



The variability of the trees and fruits within the variety is of 

 fundamental significance from the standpoint of the grower and in 

 any study of the conservation and stabilization of the variety as a 

 whole. 



The Valencia strains are distinguished by differences in habits of 

 growth, time of ripening fruits, quantity and quality of crops, and 

 other definite and marked characteristics. The trees of certain 

 strains were found to have upright habits of growth, while those of 

 other strains are drooping or spreading. The trees of some of the 

 strains produce, as a rule, full crops of the best-grade fruit, while 

 those of other strains produce light crops of low-grade fruit. The 

 trees of at least one of the strains produce early-ripening crops, 

 while those of other strains produce later ripening fruits. The leaves 

 of the trees of some of the strains are large, broad, and bluntly 

 rounded in shape, while trees of other strains have small, narrow, and 

 sharply pointed leaves. 



In many cases, fruits of two or more of the different strains have 

 been found on the same tree grown from a single bad and therefore 

 upon the same individual stock. Such instances have shown the 

 fallacy of the theory that the different strains are variations due to 

 climatic or soil conditions or the influence of different stock. Later, it 

 was found that the different strains occurring in a single tree could be 

 isolated through bud selection in propagation, thus proving that the 

 differences observed were true inherent cases of bud variation. 



The mixture of strains in the Valencia orchards under observation 

 was found to be so marked and frequent as to warrant careful inves- 

 tigations of their relative value. The results of these investigations, 

 which have covered more than four years, together with suggestions for 

 the isolation of the best strains of this variety through bud selection 

 and for the stabilization of the variety through the propagation of 

 only the most desirable strains, are set iorth in the following pages. 



OCCURRENCE AND FREQUENCY OF BUD VARIATIONS. 



A casual observation of the Valencia orange trees selected for 

 these investigations will reveal little of the startling condition of bud 

 variability existing in the trees and their fruits. Several Valencia 

 orange growers, with many years of experience in the culture of this 



