14 



EXPERIMENT STATION WORK, LI. 



grafting the wounded part. " This is done by trimming smooth the 

 edges of the girdled part and inserting scions of the same species 

 under the bark in such a way that the wound is bridged over (see 

 fig. 6). These scions, being placed very close together around the 

 stem, become united at the ends with the old trunk and serve to con- 

 duct the elaborated food material down to the lower parts of the tree. 

 During the period of uniting the scions are covered with grafting wax 

 much as is an ordinary graft, and no shoots developing from buds 

 on the scions are permitted to grow. In time, as the tree develops, 

 the wounded part is entirely healed." 



Mr. Taylor calls attention to two forms of tree butchery or improper 

 pruning : " The butchery that is practiced when wires are first strung, 

 and later at intervals to prevent the subsequent 

 growths from coming in contact with the wires," 

 and the butchery by men " who, through igno- 

 rance of the fundamental principles which underlie 

 the operations they would perform, and yet with 

 the best of intentions, have ruined whole avenues 

 of valuable trees by the very process which was 

 intended to prolong the lives of these trees and to 

 add to their beauty and usefulness." Such care- 

 less or ignorant treatment results in many ugly 

 wounds and projecting stubs of dead branches 

 which, if neglected, may lead to the development 

 of large cavities. Tree owners in general should 

 employ only well-recommended persons to prune 

 their trees and to treat existing wounds. The 

 treatment of such wounds has, in recent years, 

 become known as " tree surgery ; " 



FIG. 6. Bridge graft- 

 ing, for the preser- 

 vation of girdled 

 trees. 



Systematic pruning and tree surgery are very closely 

 related. Tree surgery includes the intelligent protection 

 of all mechanical injuries and cavities. Pruning requires 

 a previous intimate knowledge of the habits of growth 

 of trees; surgery, on the other hand, requires, in addi- 

 tion, a knowledge of the best methods for making cavities 

 air-tight and preventing decay. The filling of cavities in trees has not been 

 practiced sufficiently long to warrant making a definite statement as to the per- 

 manent success or failure of the operation ; the work is still in an experimental 

 stage. The caring for cavities in trees must be urged as the only means of 

 preserving affected specimens, and the preservation of many noble specimens 

 has been at least temporarily assured through the efforts of those practicing 

 this kind of work. 



The subject of pruning as well as the protection of wounds and the 

 treatment of hollow trunks is discussed in a previous Farmers' Bul- 

 letin and will not be further considered at this time. The reader 



360 



U. S. Dept. Agr., Farmers' Bui. 181. 



