100 



SHADE TREES. 



Xone of these rusts are considered serious and treatments arc 

 seldom given. The blister rust of the white pine, however, 

 which attacks the steins is most dangerous and demands most 

 vigorous treatment. (See page 103.) 



2. DISEASES OF THE STEMS. 



The diseases of the stems may be arbitrarily grouped into 

 (a) bark diseases, (b) heart rots, (c) sap rots, and (d) twig 

 diseases. 



Fig. 37. Chestnut Bark Disease. Forest tree nearly dead. 

 Note characteristic sprouts and dwarfed leaves on sur- 

 viving branches. (Photo by Perley Spaulding.) 



