CALIFORNIA ORANGE VARIETIES 383 



nating their own sides and carrying light toward the center of the 

 tree also. Thus one can get a much greater surface of adequately 

 lighted bearing wood. Prof. C. S. Paine of Redlands aims to secure 

 the same result by operating upon the interior of the tree in this 

 way : 



By cutting out from the top of the tree several larger branches at their 

 junction with the trunk of other branches, there is left an open space in 

 the tree top which may be likened to an inverted cone or a deep basin. In 

 old trees the topmost limbs lose vital force sooner than limbs issuing 

 nearer the ground; thus, the loss to the tree of such limbs is of less mo- 

 ment than elsewhere. After opening the top growth renewal took place 

 on the exposed parts of the trunks and limbs around the basin and new 

 growth issues not alone from the new bark, but also from the under sides 

 of the twigs and branches of the limbs below, which become fruit bearers. 



Both these methods of opening from the sides and from the top 

 are more rational and less heroic than cutting back the tree to 

 stubs and renewing the whole top. In fact it is believed that such 

 loss can be avoided by systematic pruning which will induce the 

 tree to keep continually renewing itself while fruit-bearing. 



PRUNING FROZEN TREES 



The widespread freezing of citrus trees which occurred in Jan- 

 uary, 1913, demonstrated that the orange tree is hardier against a 

 drop of the mercury to 12 or 15 degrees Fahr. than any Calif ornian 

 supposed. Very few trees were seriously frozen, though very many 

 lost good fruiting wood, even with the temperature lower than has 

 been experienced for sixty years, and the crop gathered in 1914 

 demonstrated the quick recovery of the trees. Policies in the 

 pruning of frozen trees and in treatment of rare injuries like bark- 

 splitting, were carefully studied through field studies and actual 

 tests, by the citrus experts of the California Experiment Station, 

 and it was shown that pruning should not be undertaken for several 

 months or until the tree demonstrated useless parts to be removed. 



DISEASES OF THE ORANGE 



Citrus fruit trees are subject to many insect pests and diseases, 

 and though we may not have the worst the world knows we have 

 enough to keep many experts continually busy investigating and 

 prescribing for them. The California Experiment Station at 

 Berkeley has made many publications on these subjects and is 

 always ready to identify suspected specimens and to give detailed 

 information. The subject is too wide and varied to be discussed 

 in this connection. 



VARIETIES OF THE ORANGE 



Though many varieties of the orange have been introduced in 

 California, but few are largely grown. During the last twenty 

 years there has been a pervading disposition to concentrate upon 



