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. 
In 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. 
