EXPERIMENT STATION WORK, LI, 



11 



processes, which open permanent cracks that continue to increase in size from 

 year to year, and to give 

 free access to the many 

 disintegrating processes of 

 nature. The only protec- 

 tion for such a tree is to 

 employ some one who is 

 fully informed on the 

 methods of tree surgery 

 to seal the cavity, and 

 thus prevent further decay 

 or freezing. 



In selecting a species 

 for planting in any par- 

 ticular region it is best 

 not to accept the advice of 

 a journeyman nurseryman, 

 but rather to seek some 

 one who is acquainted 

 with the climatic condi- 

 tions of the region and 

 who knows the degree of 

 hardiness that a species 

 should possess to be grown 

 successfully. 



Other sources of in- 

 jury discussed in the 

 bulletin referred to are 

 horse bites, grazing by 

 wagon wheels, starv- 

 ing of root systems, 

 smoke and gas from 

 factories, overcrowd- 

 ing by improper spac- 

 ing, and girdling by 

 wire labels. Trees can 

 be readily protected 

 from horses and ve- 

 hicles by using some 

 sort of guard. One 

 made of wire netting, 

 as illustrated in figure 

 4, is both neat and 

 effective. There are 

 many good ready- 

 made guards on the j 

 market. 



360 



FIG. 3. Preservation by means of cement filling. 



