4 
BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 
The sporophores of the rose-colored Fomes are easily recognized by 
the delicate rose color of the under surface. The pores are small. 
The upper surface is rough, hard, and black. This is illustrated in 
Plate III, Figure 2. The decay caused by this organism is a yellow- 
brown crumbly rot, with mycelium felts much less conspicuous than 
those of the quinine fungus. The incipient decay is indicated by a 
faint brownish color, the outer limit of which is sometimes marked 
by a zone of brownish green discoloration. 
POSITION OF THE DECAYS IN THE TREE. 
The decay caused by the ring-scale fungus and that caused by the 
quinine fungus are not confined to any one portion of the bole but 
commonly extend throughout the tree. 
On the other hand, the decay caused by the velvet-top fungus is a 
typical butt-rot. Of the 70 infections of this decay in 68 trees, each 
separate focus of the rot in a tree being considered an infection, 94.3 
per cent, or all but 4, were in the stump or butt log. The decay 
usually does not extend higher than the first 16-foot log. In 10 trees 
only did the decay go beyond the butt log, and the greatest upward 
extent in any one case was 37.4 feet above ground level. The average 
for all the butt infections was 10.41 feet above the ground. The 
measurements given include the incipient decay. 
The decay caused by the rose-colored Fomes is usually confined to 
the upper portion of the tree in connection with dead tops, and often 
the rot does not extend into the merchantable portion of the infected 
tree. In all, there were 46 infections of this rot, and all but 9 of 
these were in the upper bole. Of those in the upper bole, 18, or 
almost 50 per cent, were in the top beyond the 8-inch diameter limit 
and caused no loss in merchantable volume. 
For the sake of brevity in the remainder of this paper, the decays 
caused by these four fungi will be designated as follows: 
Velvet-top fungus. red-brown butt-rot. 
Ring-scale fungus. conk-rot. 
Quinine fungus. brown trunk-rot. 
Rose-colored Fomes. yellow-brown top-rot. 
When used in tables the designations will be simply butt-rot, conk- 
rot, trunk-rot, and top-rot. 
RELATIVE IMPORTANCE OF THE DECAYS. 
Conk-rot is responsible for by far the greatest amount of cull in 
Douglas fir. In fact, if the species was free from this defect it would 
take its place with the pines as a sound tree. This is brought out in 
Table 2. 
In considering Table 2 it must be remembered that it is not based 
on trees clear cut from a given area. Consequently the figures on 
the percentage of infected trees and volume of decay are not indica¬ 
tive of the actual loss through decay in stands of Douglas fir, but 
they do indicate the relation of the various decays. Under “ unknown 
rots” are placed a number of small infections of decays whose cause 
could not be determined and one infection caused by Gqnoderma 
oreqonense Murr., which resulted in a slight loss. 
Conk-rot stands out as the all-important cause of decay. The 
volume destroyed by this decay in comparison with the others is far 
