PRUNING BEARING-ORANGE TREES 377 



moved; dead interior branches, which have given up the struggle for 

 the light, should also be removed. It is an appalling undertaking to 

 get into the inside of an old orange tree and saw off and drag out the 

 dead wood but, as already stated, the conviction is growing that this 

 should be done. Of the growing shoots there is a reasonable amount 

 of thinning to be done. The clipping back of ambitious shoots multi- 

 plies laterals. There should be a good cover of leaves, but the crowd- 

 ing of leaves on leaves excludes light and air and weakens the tree by 

 lessening the vigor of leaf action. Dead twigs which appear among 

 good bearing shoots should always be removed. 



The gourmand shoots <or suckers should be repressed, unless, by 

 clipping, one can be turned into a branch where a branch is needed. 

 The importance of resolutely removing sucker growths even from trees 

 in w r hich the wood may have become hardened is being recognized as 

 a fixed policy in pruning. Good trees have been diverted from bearing 

 fruit of good type to that which is in all respects inferior, by allowing 

 supremacy to sucker-growths. Growth of new fruit wood from old 

 is desirable, but suckers from stem or main branches, showing the 

 marks of wild growth should be extirpated.* 



PRUNING FROZEN TREES 



The widespread freezing of citrus trees which occurred in January, 

 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. 

 V'ery few trees were seriously frozen, though very many lost good 

 fruiting wood, even with the temperature lower than has been experi- 

 enced for sixty years, and the crop being gathered in 1914 demonstrates 

 the quick recovery of the trees. Policies in the pruning of frozen trees 

 and in treatment of rare injuries like bark-splitting, are being carefully 

 studied through field studies and actual tests, by the citrus experts of 

 the California Experiment Station, and popular instruction will appear 

 in due time through that channel, even though the occasion for the use 

 of it may not recur for half a century. 



DISEASES OF THE ORANGE 



The orange is thus far subject to few diseases in California. The 

 most grievous is the so-called gum disease, which is analogous to the 

 gumming of other trees and will be discussed in the chapter treating 

 of tree diseases. Cracking of the fruit is a trouble which has never been 

 fully explained. 



There are several serious insect enemies of the orange, which will be 

 discussed in the chapter on that subject. The "black smut," which 

 makes leaves and fruit unsightly in some parts of the State, is a fungoid 

 growth upon the exudations of insects, and can be prevented by remov- 

 ing its cause. 



*Detailed discussions of the subject are given in the Pacific Rural Press, January 17 

 and March 14, 1914. 



