BUD VARIATION IN THE VALENCIA ORANGE. 119 



It is essential that the rebudded trees be inspected from time to 

 time for the first year or two, in order that they may be cared for 

 intelligently. The growth from the rebuds must be thinned occa- 

 sionally, so that strong, open, and well-arranged tops will be secured. 

 Insect enemies attacking the tender growth of the rebuds must be 

 destroyed. Ten-year-old trees of inferior strains of the Valencia 

 orange rebudded to the Valencia strain by the use of fruit-bearing 

 bud wood usually will begin bearing in two or three years, reaching 

 normal production in about four or five years. 



As a result of these investigations, more than 5,000 undesirable 

 Valencia orange trees in California orchards have been top-worked 

 with buds selected from the most desirable trees in the investigational 

 performance-record plats. The oldest tops grown from such buds 

 are now more than four years old. So far not a single failure has 

 been observed in transmitting the characteristics of the parent trees 

 by means of the selected buds. Several thousand trees of undesir- 

 able strains of the Washington Navel orange and Marsh grapefruit 

 also have been top-worked with selected buds of those varieties in 

 the same manner during the past five years with equal success. 

 This positive evidence as to the possibility of improving undesirable 

 trees by top-working has resulted in the widespread adoption of this 

 practice by California citrus growers. 



SUMMARY. 



Iii proportion to the area of the established Valencia orange 

 orchards in California, the Valencia orange is being planted more 

 extensively in that State than any other variety. It is now the lead- 

 ing summer-bearing orange variety grown in the State. 



The object of these investigations is to discover methods of prac- 

 tice for the conservation and stabilization of the variety. 



The plan of the investigation is a careful, detailed, and intimate 

 study of the individual tree, the results of which are called individual- 

 tree performance records. 



The Valencia trees in these investigations were propagated from 

 the variety originally introduced into California from Florida under 

 the name of Hart (Hart's Tardiff). 



In the performance-record plats considered in these investigations 

 there are trees of 12 important strains and of many minor strains 

 which have originated from bud mutations. 



The frequent occurrence of bud variations in trees of this variety 

 is of definite importance in the consideration of means for the improve- 

 ment of the production of established orchards, the isolation of the 

 best strains, and the control, as far as possible, of bud variation 

 through bud selection based on performance records. 



