UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1163 
Wastagton, D. C. 
July 2!, 1923 
A STUDY OF DECAY IN DOUGLAS FIR IN THE PACIFIC NORTHWEST. 
By J. S. BoycEj Pathologist, Office of Investigations in F hology, Bureau 
of Plant Industry. 
CONTENTS. 
Page. 
Importance of decay in Douglas fir 1 
I of collecting data 2 
Fungi causing decay 3 
Position of the decays in the tree 4 
Relative importance of the decays 4 
Mechanical injuries 5 
Page. 
Entrance of the decays 7 
Indications of decay in living trees 10 
Extent of incipient decav 
Summary 16 
Outlook 17 
Literature cite ] ig 
IMPORTANCE OF DECAY IN DOUGLAS FIR. 
Douglas fir is the most important timber tree in the Pacific North- 
west, covering, as it does, the greater part of the foothills and lower 
slopes of the Cascade Mountains and the Coast Range in practically 
pure stands of great density. The stand of this species in Oregon and 
Washington is estimated at 505 billion feet (6\ p. 23), * or nearly one- 
fourth of the remaining merchantable timber in the United States. 
The loss through decay in Douglas fir in this region is very high.. 
While some overmature stands are relatively sound a loss of 20 per 
cent in such stands is not uncommon. In certain cases the cull figure 
may reach 50 per cent or more, so high that in timber on difficult 
ground it becomes impossible to log at a profit. It is only in young 
stands of second growth that Douglas fir is uniformly sound. Plato 
I shows defective trees left uncut after logging in an overmature- 
stand. In this instance about 25.000 feet board measure per a 
was left standing. Where clear cutting is practiced numerous logs 
and entire trees remain on the ground after logging, absolutely worth- 
less on account of decay. This is illustrated in Plate II. Practically 
all the large pieces were left because of rot. 
Recognizing the importance of this question, foresters and lumber- 
men in the Douglas fir region have repeatedly felt the need for es 
information on decay in Douglas fir. This bulletin presents obser- 
vations by the writer and the results of a preliminary 
iThe serial numbers (italic) in par 1 of this bul 
2 This study was made in the siimi 
writer is indebte I for supervisi 
Lth the For- 
to Forest : ; ... ;. K 
a ore detailed study of di 
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