318 THE PRINCIPLES OF HANDLING WOODLANDS 



serve to emphasize the necessity of preventing an inva- 

 sion from starting. Careful preventive measures save 

 not only the loss of timber resulting from the work of in- 

 sects, but also the expense of fighting an invasion. 



Protection from Fungous Diseases 

 The protection of trees from attacks of parasitic 

 fungi is of great importance in forestry. The most seri- 

 ous defects in timber are caused by fungi. Every woods- 

 man is familiar with certain external indications of such 

 defects, and is often able to distinguish trees which con- 

 tain so large a proportion of unsound lumber as to render 

 them unprofitable to cut. There is, however, an im- 

 mense amount of hidden defect, resulting directly from 

 fungous attacks. Fungous diseases enormously reduce 

 the value of timber and the profits of lumbering. They 

 contribute directly to the death of trees, sometimes work- 

 ing slowly, as in the case of those which attack the interior 

 of the tree, and sometimes rapidly, as is illustrated by the 

 chestnut-bark disease which may kill the trees within a 

 few years after the first infection. 



Fungous diseases are spread by minute spores which 

 are carried by the wind, and which gain access to trees 

 through wounds. The wood is readily reached through 

 fire scars, broken branches and tops, bruises, borings 

 made by insects, etc. The rapid spread of injurious 

 fungi is illustrated in many mature forests. Southern 

 lumbermen appreciate the damage done by the so-called 

 red rot, which in some localities affects the majority of 



