34 15ULLETIN 1-2-2, U. S. DEPARTMENT OF AGRICULTUEE. 



ill a solution of such forest-regulation problems as are appreciably 

 influenced by the presence of decay in the stand. When once the 

 forester reaches the i:)oint in his calculations upon a proposed sale 

 where he can determine a certain rot percentage as the maximum to be 

 considered in a stand in order to secure the required amount of sound 

 material at a mmimum cost, with this rot percentage as a basis it 

 will be comparatively easy to compute the cutting age of that stand. 



METHODS OF CONTROL. 



The methods of control applicable to such types as are here under 

 discussion can ])e little other than extensive. The foregoing data, 

 owing to the small number of trees included in some of the age classes 

 and to apparently unavoidable errors, are not to be taken as exact 

 in determmmg the cutting age but are given merely as an aid to this 

 determination. Intensive control methods can not be applied to 

 logging operations where extensive logging methods are practiced. 

 Methods such as can be readily incorporated into the usual routine of 

 logging operations and conforming to the practice of the Forest 

 Service are the only ones which can hope to fill the need for forest 

 sanitation among the all-practical lumbermen and foresters. Inten- 

 sive control can be practiced to a limited extent only upon such sales 

 areas as warrant the additional cost. 



The control of wood-destroying fungi is not a matter comparable to 

 the curative treatment of human disease, but is solely dependent for 

 its success upon prevention. With few exceptions there is no help for 

 a stand after it is once attacked by the fungus; hence, if preventive 

 measures are to be effective they must precede the infection, or at 

 least precede the period when the production of spores endangers the 

 remaining healthy trees. There are several methods applicable to the 

 hemlock type, and these can be grouped under two heads, sanitation 

 clauses in timber sales ^ and pathological rotations. Under the 

 first come such suggestions as girdling, killing by burning of infectious 

 cull material and piled brush, thinning, and the direct cutting and 

 burning of infected material. Under the second appear such methods 

 based upon a study of the area in question as would lead to a cutting 

 cycle aiming to secure the maximum amount of sound material with 

 a minimum risk of future infection and at a minimum of cost. Each 

 particular sale area has its individual variations affecting the patho- 

 logical condition of the stand. The species in the mixture and the 

 relative percentage of each, the slope and exposure, the moisture 

 conditions, the cost of logging, the value of the species in the stand 

 (in fact, all the environmental and economic factors) have to be 

 taken into consideration before an attempt can be made to determine 

 a method of control. 



I Meinecko, E. P. Op. cit., p. 62. 1914. 



