INSECTS, DISEASES, AND INJURIES 161 



often serious on small trees since they may cause complete or 

 nearly complete defoliation. 



All fallen needles should be gathered up and burned. 

 Spraying with a 4-4-50 bordeaux mixture before rain periods 

 will also reduce the infection in the nurseries. 



3. Tree surgery 



In the care of ornamental trees the following points should 

 be remembered; 



1. The wood of a tree is naturally protected by the covering 

 of bark. Any injury to this, or any exposure of the wood, 

 affords an opportunity for the entrance of destructive or- 

 ganisms which may bring about extensive damage, resulting 

 sometimes in the complete loss of the tree. 



2. Early attention to small injuries will render unnecessary 

 expensive treatments in the future. 



3. More harm than good is often caused by allowing in- 

 experienced workmen to do tree-surgery work. 



Whether or not a tree shall be treated surgically will depend 

 on two main factors. In the first place it must be decided 

 whether it is possible to save the tree — a question which can 

 be answered only by one who is thoroughly familiar with the 

 trouble with which it is afflicted. In some cases it will be better 

 to replace the tree rather than to try to save it. Secondly, 

 the expense must be taken into consideration. The amount 

 one is willing to spend on a certain tree will, of course, depend 

 on its value from an esthetic or historical standpoint. All 

 ornamental trees are, however, worth considerable care, for 

 they add greatly to the value of real estate. 



There are a few fundamental principles underlying all 

 tree-repair work. The first essential is that all diseased or 

 dead bark or wood must be removed. In the case of fungous 



