DECAY IN DOUGLAS FIR. 3 
The trees studied were not clear cut from a given area, but average 
trees both sound and decayed were selected to obtain preliminary 
information on which an extensive study of decay in Douglas fir 
could be based. This will be brought out as the discussion proceeds. 
In all 170 trees were felled, bucked up, split open, and studied. 
One of these was only 2 inches in diameter breast high, so it was 
dropped from consideration, leaving 169 trees with a total volume of 
203,920 feet board measure and 33,703.12 cubic feet. 
FUNGI CAUSING DECAY. 
Four species of fungi are responsible for all but an infinitesimal 
portion of the decay in Douglas fir. They are the ring-scale fungus 
[Trametes pini (Thore) Fr.), the velvet-top fungus (Polyporus schwei- 
nitzii Fr.), the quinine fungus (Fornes laricis (Jacq.) Murr.), and the 
rose-colored Fomes (Fornes roseus (Alb. and Schw.) Cke.). The 
decays caused by these four wood-destroying fungi in living trees are 
confined to the heartwood. 
The ring-scale fungus causes decay commonly known as conk-rot 
in this region (ring-scale or red-rot in the pine regions), in which the 
wood is riddled with small white pits or cavities, apparently separated 
by sound wood. This is shown in Plate III, Figure 1. In its incip- 
ient stages, before the appearance of the white pits, the decay appears 
as a pronounced reddish purple or olive-purple discoloration, often 
bounded by a narrow zone of pronounced red color. The sporo- 
phores, or conks, are very common in overmature Douglas fir stands. 
These fruiting bodies issue from the tree through knots and are 
perennial. They vary in size and in shape from bracketlike to hoof 
shaped. The upper side is a dull grayish or brownish black, rough, 
and with concentric furrows parallel to the light-brown margin. The 
under side is a grayish brown or rich brown color with large irregular 
pores. The substance or context of the sporophores is corky or 
punky. Plate IV shows the appearance of the sporophores on a 
living tree. 
The velvet-top fungus causes a red-brown friable rot in the final 
stage. The incipient decay is very difficult to detect. It first becomes 
.noticeable as a faint yellowing or browning of the normal heartwood, 
which still seems to be firm and hard but in reality is seriously weak- 
ened. The sporophores, or conks, of this wood destroyer appear 
either on the infected tree or on the ground near by and are annual. 
They are rather large, with a light-brown upper surface, an olive or 
dirty green under surface, and have a cheesy consistency when young, 
but when old and dry are a dark rusty brown and corky. Sporo- 
phores on the ground have a short thick stalk. Plate V, Figures 1 
and 2, illustrate both sporophores and decay of this fungus. 
The quinine fungus has a large, conspicuous, whitish perennial 
sporophore, not at all common on living trees. The substance of the 
.sporophore is white, soft, and cheesy when young and rather crumbly 
! *and chalky when old and dry, with an exceedingly bitter taste. 
Hence the name. On the older sporophores the upper surface is 
rough and chalky white and brownish in color. The pores are small 
and regular. Plate VI, Figure 1, shows a sporophore. The typical 
decay is a crumbly brown rot easily recognizable by its mycelium 
felts or sheets (i. e., closely woven masses of fungus byphse). This 
characteristic is brought out in Plate VI, Figure 2. The incipient decay 
which appears as a faint brownish discoloration is not easy to recognize. 
