

Like a dentist he removes all de- 

 cayed matter from a cavity 



THE science of tree surgery is but 

 twenty years old. Yet it has already 

 become of inestimable value. It is 

 saving thousands of shade trees and fruit 

 trees each year. All trees, and sweet- 

 sapped trees especially, are liable to fungus 

 disease. The fungus is a parasite by 

 nature and sends 

 little, thread-like 

 tentacles into the 

 woody tissue. 

 These travel 

 from cell to cell, 

 disintegrating 

 the internal 

 structure of the 

 tree. The result 

 is what we call 

 "rot." When 

 fungus starts in a 

 tree it never 

 stops unless ar- 

 rested by human 

 skill. The tree 

 surgeon alone 

 can destroy the 

 disease. 



The accom- 

 panying illustra- 

 tions show how 

 useful tree sur- 

 gery can be. In 

 one of the illus- 

 trations is shown 

 steel cables 

 strung between 



the upper a sick tree on the way to 



branches so that filling reaches almost to 



Operating Upon Trees 



When trees get sick or are dam- 

 aged they need the tree surgeon 



the weakened trunk would not be unduly 

 strained under the action of the wind. 

 This was a comparatively easy task, but 

 real tree surgery is not simple. It is a diffi- 

 cult and exacting art. Some trees require a 

 combination of bolts and lock-nuts, rein- 

 forcing rods and cross-bolts with lock-nutr; 

 above the crotch. Others need a combina- 

 tion of bolts and criss-cross bolts with lock 

 nuts, tortion rods and chains, and still 

 others call for iron straps, tortion rods, 

 iron backbone and ribs in addition to 

 chains and la*g-hooks higher up. 



Another illustration shows large cement 

 fillings built up in separate block sections to 

 allow swaying of the tree. In a very short 

 time, the edges of the cut "heal" to the 

 cement. That is, the soft living tissue 

 solidifies upon the cement, making a tight 

 joint which is waterproof. Often the bark 

 at the sides of the patch gradually grows to- 

 gether closing 



health. The cement 

 the heart of the tree 



over the cement. 

 Young trees are 

 not so difficult to 

 doctor. One of 

 their chief ene- 

 mies is the bore 

 worm. The tree 

 surgeon, upon 

 discovering a 

 worm hole in the 

 tree drills into it 

 with a stiff wire, 

 kills the worm 

 and fills up the 

 hole with tar. 



But tree sur- 

 gery is not merely 

 a matter of filling 

 cavities. Unless 

 the work is scien- 

 tifically accurate 

 and mechanical- 

 ly perfect, it fails. 

 Since decay de- 

 stroys the struc- 

 tural strength of 

 the tree, this 

 strength must be 

 restored by me- 

 chanical means. 



346 



