DECAY IX DOUGLAS FIR. 15 
Furthermore, observation shows that they indicate extensive decay in 
the tree. Only one tree studied had sporophores of this rot, and the 
decay volume in cubic feet was 31 per cent and in board feet 74 per 
cent of the gross volume of the tree. But the total loss caused by 
this decay was trifling. (See Table 2.) 
YELLOW-BROWN TOP-ROT. 
Yellow-brown top-rot also is rather hard to judge. Swollen knots 
do not accompany the decay. Sporophores are not uncommon, 
particularly with the more extensive infections. In the trees studied, 
seven infections, which resulted in 42 per cent of the cubic-foot 
volume and 41 per cent of the board-foot volume of yellow-brown 
top-rot, had developed sporophores. However, the sporophores are 
commonly so high up in the trees that they are easily overlooked 
and. in fact, are often completely hidden by the branches. Broken 
or spike tops commonly indicate infection (see Table 7). The 
aggregate loss caused by this decay is small. 
INDICATIONS OF DECAY IN FELLED TIM BE":. 
The estimate of the extent of defect in logs or felled timber is 
much easier than in standing trees. The red-brown butt-rot is 
revealed in the butt cut. and its upward extent can be more closely 
approximated. Knots can be tested carefully for signs of rot, and if 
the timber has been bucked the ends of the logs can be examined for 
typical decay or the discolorations caused by incipient decay. How- 
ever, if the logs have been exposed to the weather for several months 
these discolorations fade and can not be seen. 
It is not at all difficult to judge quite accurately the extent of 
conk-rot in felled Douglas fir by chopping into the knots to reveal 
the brown corky context of the abortive sporophore. 
EXTENT OF INCIPIENT DECAY. 
A knowledge of the vertical extent of incipient decay, which is the 
term used to designate the early stages of rot, beyond the typical 
decay or well-advanced rot is of practical value. In some infections 
the incipient decay may end with the typical decay and in other 
cases extend many feet beyond it. The horizontal or radial extent- 
normally amounts to only a few inches. Incipient decay, which is 
usually indicated by a discoloration of infected wood, in some cases 
pronounced and in others so faint as to be practically invisible, is 
not always easy to detect. Affected wood in a casual examination 
seems to be firm and strong. Consequently, it is the rule rather 
than the exception in the lumber trade to include incipient decay 
with sound lumber. 
Wood is weakened by incipient decay, the degree depending on 
the stage of the rot and also on the species of fungus at work. T 
on Douglas fir with incipient decay of conk-rot showed that the 
wood was apparently not weakened, but pieces with incipient decay 
of red-brown butt-rot and brown trunk-rot. to which general type of 
decay yellow-brown top-rot also belongs, were much reduced in 
strength. Furthermore, if infected material is merely air dried, the 
hyphse may remain dormant, ready to continue to decay the \ 
again if suitable conditions arise. Hence, wood with incipient d< 
