FOEEST PATHOLOGY IK FOEEST EEGULATION. 33 



interior of the sporophore is vividly rusty red. This rusty color is 

 most characteristic of the fungus and repeats itself very often in the 

 decayed tissues of the host. The sporophores are never formed on 

 the bark of the tree; invariably they appear from the under side of 

 stubs of dead twigs or branches, and commonly the rusty color can 

 be followed through these stubs or knots. As the sporophore is 

 nothing but the fruiting body of the mature fungus plant living in 

 the heartwood of the tree, which alone it is able to attack, every 

 sporophore is a certain sign of far-reaching decay in the tree. The 

 typical rot may be characterized as a stringy brown rot. Wood in 

 this stage of decomposition is brown, with rusty reddish streaks, and 

 becomes distinctly fibrous and stringy. Following the rot away from 

 its maximum of development, we find wood still brown, with rusty 

 streaks, but quite firm. Farther away, the brown color becomes less 

 noticeable, the rusty color disappears, and finally we come to a point 

 where the wood seems to be sound enough to be sent to the mill. A 

 little care exercised in examination, however, will show in this seem- 

 ingly sound wood the presence of small light-brownish spots and dis- 

 colorations, particularly in the summer wood, intermingled with hor- 

 izontal burrows, which at first glance could almost be taken for very 

 shallow insect burrows. The burrows are not easily detected on a 

 cross section. The small brown spots, which give the wood a faintly 

 brown, mottled appearance, cause the entire cross section to be slightly 

 darker than normal and discolored; but they show up very much 

 more clearly in a longitudinal section. A small piece pried out of the 

 end of the log with a hatchet or strong knife gives sufficient informa- 

 tion about the real state of health of the log. This timber at present 

 invariably goes to the mill and without doubt furnishes the lumber 

 that, after being sawed, dries out and by becoming brittle causes the 

 well-known prejudice against this species. It is often characterized 

 by a peculiar sour smell and by a spongy consistency of the wood. 



Cull from decay in white fir, therefore, includes not only typical 

 rot but also this discolored material, which, although not distinctly 

 rotten, is already under the influence of the advance guard of the 

 fungus mycelium and will become completely decayed later on. For 

 this stage of incipient, or, better, latent decay, the writer proposes 

 the term " advance rot," which is used throughout this bulletin. 



DESCRIPTION OF AREAS. 



The three areas chosen for investigation are located on the Crater 

 National Forest, in southwestern Oregon, all of them in the neighbor- 

 hood of the Upper Klamath Lake, a large shallow basin with vast 

 swamps, into which unusually large springs of clear cold water empty 

 themselves. Very few streams of running water come from the 

 98035°— Bull. 275—16 3 



