146 PRINCIPLES OF AMERICAN FORESTRY. 



with a very heavy coat of white-lead paint, grafting-wax, 

 or other material that will keep out water and disease. 

 If the wound is very large, or forms a hole in which water 

 is likely to stand, it should be cleaned and pointed as rec- 

 ommended, and then covered with a sheet of zinc, care- 

 fully tacked on, and the joints closed with grafting-wax 

 to keep out water. 



Fungus Diseases are quite common sources of injury 

 to trees of all kinds, including those of our forests. They 

 attack the foliage, trunk, and roots. Occasionally very 

 serious losses occur in timber trees from those that cause 

 the trunks to rot. They are generally most numerous 

 in sections where there is not much of a circulation of 

 air. This subject is too large for a detailed account of 

 any of them here, and only one is referred to, which, al- 

 though not very common, is occasionally quite injurious. 

 It is known as the toadstool root fungus, Agaricus melleus. 

 This fungus lives upon the roots of Pines, Spruces, Firs, 

 etc., and occasionally kills them. At one stage of its 

 growth it lives on the decaying wood of Oaks and similar 

 trees. 



FOREST FIRES. 



Forest Fires are the one great cause of injuries to forests 

 in the United States. All other causes of injury are very 

 slight in comparison to it, and could this one cause be 

 removed it is more than probable that the natural renewal 

 of our timber lands would be sufficient to maintain the 

 timber industries of Minnesota for very many years to 

 come. 



Fires in this country have destroyed large areas of pine 

 log timber before it could be made accessible to market. 

 It is undoubtedly true that more pine timber has been 

 destroyed by fire than the lumbermen have ever cut. 



