FUNGI 277 



terminated is the chief tree for management in the region, as 

 was the case with the chestnut on the eastern seaboard, the 

 loss is directly to the productive power of the entire forest 

 area. Wood rotting fungi, while they may totally destroy 

 the timber value of the stand, require decades to accompHsh 

 this, and do not attack the trees until fairly well along in Hfe, 

 since they attack the heartwood which is not formed in 

 youth. Their destruction of timber in the virgin forest may 

 be enormous, but in the managed forests, which will follow 

 present day cuttings and can be harvested while still relatively 

 sound, the loss can be kept within reasonable bounds. 



In addition to these two types other less important species 

 cause partial injuries or deformities which at the least result 

 in loss of increment.^ The action of root destroying fungi is a 

 large factor in accounting for losses from wind.^^ 



The influence of fungi is not entirely injurious. They may 

 be beneficial in destroying harmful insects and in accompHsh- 

 ing the rotting of the slash,^ thereby reducing the fire hazard 

 and increasing the humus supply. 



Methods of Control and Prevention. — Tree diseases cannot 

 be controlled by fostering their enemies for practically none 

 such exist. Against most species of fungi direct action is 

 impracticable due to the expense involved. General silvi- 

 cultural measures comprise keeping the stand in thrifty con- 

 dition, the use of thinnings,^^ avoiding the making of wounds 

 on the trees and eliminating infected trees. 



One of the two most destructive tj^es, namely the wood- 

 rotting fungi causing heart rots, can be partially controlled. 

 The control work actually executed in the United States has 

 been conducted principally against the chestnut blight, the 

 white pine blister rust, fungi causing heart-rots, or nursery 

 diseases of coniferous seedhngs. A discussion of the latter 

 may be relegated to the realm of nursery management. 



