BULLETIN No. 722 ; 
q 
Contribution from the Bureau of Plant industry 
WM. A. TAYLOR, Chief 
Washington, D. C. PROFESSIONAL PAPER October 22, 1918 
A STUDY OF HEART-ROT IN WESTERN HEMLOCK. 
By James R. Werr, Forest Pathologist, and ErNest E. Husert, Scientific Assist- 
ant, Office of Investigations in Forest Pathology. 
CONTENTS. 
Page. Page. 
Introduction. .-.--...- SER gry ese ak 1 | Methods used in presenting data......_.__... 14 
Present status of western hemlock in the Infection. age. 4. aa ae 16 
RO GES Sot BRA ss OPE Se RB Sates SHE aE 2 | Relation of decay to site and to age.._..__._. 18 
Echinodontium tinctorium ..._......-.....-- 3 | Relation of decay to vigor, crown rating, size, 
BhetunsusandatsshOsiseeeseemeae 2 eee 3 and) -VOlUMe@t 2855202 so ee ee 22 
Geographic distribution............2.... 5 | Relation of decay to injury and to sporo- 
The disease caused by Echinodontium NOLES es hae Se Se ie See 24 
tinctorium....:...- AC e tee Rein "lab eee 65 heory.of infection 22" == ee 30 
Outward signs of the disease.._.....__.-- Ole DISCUSSTONIOL TESTS eee ee eee 31 
General characteristics of the rot.....__.- 955 Methods of controls. = Pee eee at 24 
Areas studied and field methods used....--..- led SUMMA Tys. oo ee eee 36 
INTRODUCTION. 
From the fact that the experience and methods of the European 
countries have been worked out and are at present practiced under 
an entirely different set of conditions, forestry in America is con- 
fronted with the necessity of formulating its own fundamentals as 
regards forest organization, working plan, and general silvicultural 
procedure in the virgin forests of the Northwest. Since a large 
number of the basic principles of an ideal forest organization depend 
upon a proper understanding and appreciation of the progress of 
decay in the forest and the general deterioration of the stand and of 
individual trees, the problem is largely one of a pathological nature. 
The need of reliable figures from which an adequate conception of 
the loss to the forest through the death and disease of individual 
trees or stands and through various other causes instrumental in 
reducing the maximum annual increment is self-evident when any 
attempt is made to establish a rotation or cutting age for any one 
species. It is necessary also to concentrate the collection of these 
data upon a single tree species or upon a single type in order to secure 
 63424°—18—Bull. 722—1 
