40 JOURNAL OF FORESTRY 



tend to favor the continued growth of the mycelium." This last fact 

 may be true for the region Abbott studied, but is certainly not the 

 common condition in the forests of the Northwest. 



Practically all the heart-rotting fungi which attack living trees in 

 the Northwestern region retain their vitality after the tree is cut,-' 

 and if the moisture conditions are favorable the activities of the 

 mycelium will continue as long as sound material is available. If 

 conditions favorable to the production of fruiting bodies are present, 

 then sporophores can be expected to develop on down timber, pro- 

 viding the mycelium within the host has reached that point in its 

 development. These sporophores are capable of distributing millions 

 of spores during one season. BuUer ^ computed from partial counts 

 that on an average of 1,700,000 spores were produced from each pore 

 on the lower surface of Polyporiis squamosus, or a total of more than 

 eleven billion for the entire lower surface, which had an area of 38.75 

 square inches. An average of two million spores a minute is recorded 

 for this fungus during two or more days. This gives an idea of the 

 great number of spores that may be liberated upon a cut-over area 

 where numerous sporophores of the more harmful species of all sizes 

 are developing continuously. 



The factors of shade and moisture as they exist upon a cut-over 

 area greatly influence the production of sporophores appearing upon 

 the slash infected prior to cutting. The drying effects of an open, 

 exposed area having few living trees and little or no brush supplying 

 shade, would, no doubt, retard the sporophore development on both 

 down material and upon the few standing living trees. This has been 

 demonstrated for standing trees in a study of the effect of thinning 

 on the sporophore production on grand fir and hemlock infected with 

 Bchinodoufiiivi tinctorium,^^ previously referred to. But it must also 

 be remembered that with the return of a dense cover of brush and 

 reproduction, the required moisture and shade conditions may be 

 restored and sporophores developed upon the infected slash lying in 

 the shadier and more moist sites. 



Infected cull logs lying in close contact to the ground are unques- 

 tionably better situated for the continuous development of the attack- 

 ing fungus than a similar log not in contact with the ground and sub- 

 ject to rapid drying by a free circulation of air about it. Ground 

 moisture is readily absorbed by wood in contact with the ground, 

 and this serves as a reservoir of moisture to the fungus within the log. 

 Long ^^ found that certain saprophytic fungi were able to attack the 

 brush only when the brush was in close contact with the ground, and 



