UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 799 
Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 
Washington, D. C. 
PROFESSIONAL PAPER 
November 10, 1919 
y k 
A STUDY OF THE ROTS OF WESTERN WHITE PINE. 
By James R. Weir, Forest Pathologist, and Ernest E. Hubert, Scientific As- 
sistant, Office of Investigations in Forest Pathology, Bureau of Plant 
Industry, Missoula, Mont. 
CONTENTS. 
Page. 
Losses due to fungi 
Local pathology of western white pine- 
Field studies of the rots in western 
white pine 
Relation between rot and various fac- 
tors 
Age 
Size 
Page. 
Relation between rot and various fac- 
tors — Continued. 
Infection age 11 
Injuries , 13 
Sporophores 15 
Discussion of results 19 
Methods of control 22 
Summary _ 23 
LOSSES DUE TO FUNGI. 
The estimated stand of western white pine (Pinus monticola) in 
British Columbia, Oregon, Washington, Idaho, and Montana is about 
23,685 million feet B. M., valued at approximately $102,875,000. 
The average loss due to the activities of fungi in western white pine 
for the entire white-pine belt, based on data from logging operations 
in northern Idaho, is 1,658 million feet B. M. 1 This figure, 
on a basis of the above given valuation, shows a loss of $7,201,250 
from this cause alone. These figures, taken as an average condition 
throughout the merchantable range of the species, indicate the loss 
from decay to be enormous. The limited area occupied by 
merchantable white pine, the adaptability of its wood to a wide 
range of uses, and the ease with which it is worked so establish its 
value as a timber tree that it becomes imperative to investigate any 
cause of financial loss in the species, the amount of this loss, the 
1 Based on the recorded data, which give 6.9 as the average rot percentage for the 
entire area upon which the data were collected. The actual loss due to rot would no 
doubt be greater if figured on a basis of cull percentage or actual volume discarded, 
according to scalers' practice. 
128265°— 19— Bull. 799 1 
