Shade Tree and Timber Destroyinct Fungi. 



^55 



a 



leader" of the tree when about 5 cm. (2 inches) in diameter had 

 been broken off, possibly by a falling tree, 30 (jr 4() years ago. 

 This leader, as a dead, decorticated object still projected 15 to 

 20 cm. above the j^oiiit where the healing process was going on 

 (Fig. 85). One of the np^^er branches at this point had Ijecome 

 the leader. 



This old fracture of the main trunk years ago very probably pro- 

 vided an opportunity for the entrance of the fungus. Most coni- 

 fers are provided with a cpiantity of free resin in the young branches 

 or shoots, or the growing portion of the trunk. As is well known 

 this resin flows freely from fresh wounds, and often continues for 

 some time from old ones. The presence of this resin and its free 

 exudation from wounds is nature's most effective method of block- 

 ing the way to the entrance of timber destroying fungi in the coni- 



89. — Cross section of red spinicc slLcinng pockets from end mew. 



fers. When the wound is small, or the broken branch or shoot is 

 young, the amount of resin forms an effectual barrier against the 

 entrance of this class of funo-i. Where the wound is laro-er, or the 

 shoot is older, the process of healing over requires many years, and 

 the older portions of the wood do not yield so great an amount of 



« 



free resin. 



The brooken shoot in this example was 5 cm. (2 inches) in diame- 

 ter. Healing began 20 to 30 cm. below the broken end. After 30 



