PROTECTION 159 



quently utilized for telephone and telegraph poles. 



There are many administrative measures which 

 are practiced on the National Forests, which aim to 

 prevent insect infestation. The prevention and 

 suppression of forest fires, which form infection 

 courts for insects, is probably the most important 

 one. In all timber sales, old dead snags and slash- 

 ing, which are breeding places for insects, are dis- 

 posed of. Through free use and timber sales, in- 

 sect-killed timber is disposed of and the loss due 

 to insects is reduced to a minimum, besides in many 

 cases destroying the young insect broods. 



Tree Diseases. In almost every administrative 

 district there is a Consulting Pathologist, connected 

 with the Bureau of Plant Pathology of the Depart- 

 ment of Agriculture, who has charge of all work 

 dealing with the eradication of tree diseases. 



A tree disease is really any condition that inter- 

 feres with the normal functioning of the tree, be this 

 condition caused by fungi, mistletoe, fumes, smoke, 

 frost, sunscald, drought or excess of water in the 

 soil. Parasitic fungi and mistletoes cause most of 

 the tree diseases. Leaf diseases, by killing a 

 greater part of the foliage, destroy the very organs 

 in which food for the growing tissues is prepared. 



