DECAY IN DOUGLAS FIR, 
Yellow-brown top-rot, true to its name, in Table 7 shows the 
greatest number of infections entering through dead tops, which 
include broken and spike tops. Knots, though with fewer infections, 
were responsible for a greater volume of decay, since such infections 
usually occurred lower down on the bole where there was more 
heart wood for the fungus to work on than was the case when the 
wood destroyer entered through a dead top. The large volume of 
decay the cause of which is recorded as " unknown" resulted from 
an extensive infection which could not be traced to its source. 
Table 
■Injection court of yellow-brown top-rot in Douglas fir. 
Infections. 
Number, 
basis. 
Percentage of total. 
.Wei age 
volume. 
Infection court . 
Number. 
Volume. 
Board 
feet. 
Cubic 
feet. 
Board 
feet. 
Cubic 
feet. 
Knots 
12 
2 
7 
5 
18 
2 
26.1 
4.3 
15.2 
10.9 
39.1 
4.3 
35.8 
8.2 
7.0 
15.4 
17.0 
16.7 
35.7 
6.6 
1.9 
15.0 
23.8 
17.0 
98 
135 
33 
102 
31 
275 
9.6 
10.6 
Falling-tree scars 
.9 
9.7 
4.3 
27.5 
Table 8 shows the infection courts of the unknown decays. Some 
of these were undoubtedly infections of the four common rots, but 
were abnormal or so small that they could not be accurately identified. 
Table 8. — Infection court of unknown rots in Douglas fir . 
Infections. 
Number, 
basis. 
Percentage of total. 
Average volume. 
Infection court. 
Number. 
Volume. 
Board 
feet. 
Cubic 
feet. 
Board 
feet. 
Cubic 
feet. 
Knots 
5 
12 
4 
11 
3 
14.3 
34.3 
11.4 
31.4 
8.6 


10 
s 



Fire scars 
80.0 
20.0 


62.5 
8.8 
20.8 
7.S 
1.8 
Lightning scars 
.8 
Dead tops 
.6 
Roots 
.9 
In Table 9 the data in Tables 4 to 8, inclusive, have been combined. 
Knots were responsible for the greatest number of infections and a 
proportionately greater loss through decay. 
Of all the infection courts fire scars, which were only responsible 
for 4.2 per cent of the total rot volume, are the only factors that can 
be directly controlled. With the increase of efficiency in fire-protec- 
tion methods, injury from fires is being steadily reduced. But the 
other 95.8 per cent of the decay is traceable to sources that can not 
be controlled. Knots, falling trees, lightning, and snov. <>i ice will 
42198—23 2 
