(370 JOURNAL OF FORESTRY 



and the mistletoe development is favored by the thinning. The logging 

 process, if it does not cause direct mechanical injury to the bark of the 

 standing live trees, is bound to cause an increased number of branch 

 stubs by the breaking of dead and living branches on such trees. An- 

 other factor of importance is the development upon a large number of 

 different host species of a single species of fungus. This is believed to 

 be true so far as investigations have progressed. For instance, Tra- 

 metes pini, one of the most destructive of wood-rotting fungi, is found 

 attacking practically every conifer in this region. Poly poms schzvein- 

 itzii and Foiiies annosiis, two very destructive fungi, are found attacking 

 a number of different hosts. Bchinodontinm tinctorium and Poria 

 zveirii are about the only destructive fungi which are restricted to 

 specific hosts. The former is of economic importance only on the 

 hemlocks (Tsuga) and true firs (Abies), the latter on Thuja. The 

 indiscriminate attack of such a fungus as T. pini upon a large number 

 of hosts emphasizes the possible dangers to susceptible trees by the 

 unchecked production of the sporophores of this fungus. 



Since fungi attacking reserved seed trees weaken the resistance of 

 such trees to the action of wind, the loss by windfall and wind break- 

 age of valuable seed trees before the area has been properly reseeded 

 should be prevented by selecting only such seed trees as are free from 

 all root, butt and trunk rots.^° 



THE PRACTICAL APPLICATION OF PATHOLOGICAL MARKING RULES 



Information for the Marking Officer 



In order to fulfill completely the object of hygienic marking and to 

 secure the greatest returns upon the investments in National Forests, 

 the marking officer should possess a working knowledge of the path- 

 ological conditions which will confront him in the routine of marking. 

 It is not necessary that he become a technical pathologist, but he should 

 become familiar with certain signs or symptoms of the various tree dis- 

 eases and should be able to judge approximately the extent of decay in 

 a tree, once it is determined the tree is attacked and the casual fungus 

 known. ^^ 



The successful application of the pathological marking rules by the 

 marking officer depends upon the following points : 



I. The recognition in the forest of the outward signs and 

 symptoms of the various diseases of standing living trees. 



