22 BULLETIN" 275, IT. S. DEPARTMENT OF AGRICULTURE. 



both impossible and undesirable to eliminate these species altogether." 

 He specifically names white fir and incense cedar. Their aggressive- 

 ness makes it impossible to eliminate them, even if this were desirable. 

 But more than one species, not so many years ago considered inferior, 

 has now come into its own. The history of the lumber markets of 

 Europe and our own country shows conclusively that with closer 

 utilization necessitated by the growing scarcity of timber, the value 

 of lower grades, as well as of so-called inferior species, is advancing 

 more rapidly than that of upper grades or more valuable species. In 

 the case of incense cedar this evolution may be watched at the present 

 time. Up to a very short time ago incense cedar was "almost a drug 

 on the market;" now even very short logs when sound are utilized for 

 pencil wood and priced accordingly. 



Concentration of study on the inferior species, therefore, promises 

 the most immediately applicable results. 



METHODS OF INVESTIGATION. 



CHOICE OF SPECIES AND SITE. 



Forestry is not interested primarily in the morphology and life 

 history of a given heartwood-destroying fungus. Such studies, though 

 indispensable and of the highest value, belong to an altogether differ- 

 ent realm of science. The forester thinks in terms of trees, not of 

 fungi; he concentrates on timber species to be protected or utilized, 

 not on parasitic organisms, however interesting they may be from a 

 mycological point of view. If forest pathology is ever to be of any 

 value to practical forestry, all work and all conclusions must be 

 focused on the tree, the species, as a producer of timber values and as 

 a member of the forest community. 



The fact that the same species may be subject to serious loss from 

 several fungi and that the same fungus often works differently in 

 different host trees complicates the difficulties naturally connected 

 with all work for which a basis first had to be constructed. Partly 

 for this reason, the writer first worked on incense cedar, which, so far 

 as known, has only one heartwood parasite, Polyporus amarus. The 

 studies described in the following pages were concentrated on white 

 fir, because its management presents, perhaps, the most embarrassing 

 problem of to-day on the Pacific coast and because, in by far the greater 

 number of cases, serious loss is caused by one fungus only, EcMnodon- 

 tium tinctorium. 



After deciding upon the species to be investigated, the choice of 

 the sites for the study becomes the main question. One single type 

 will probably yield interesting clues, but the result can not with impu- 

 nity be applied to all sites and types within the range of the species. 

 It is clear that studies within what might be termed the merchantable 

 range of the species must be most important from a practical point of 

 view. But inside of the merchantable range the species is subject to 



