UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 722 
Contribution from the Bureau of Plant Industry — 
WM. A. TAYLOR, Chief 
Washington, D. C. PROFESSIONAL PAPER —sOcetober 22, 1918 
A STUDY OF HEART-ROT IN 
: WESTERN HEMLOCK 
2 By ) a . 
JAMES R. WEIR, Forest Pathologist, and ERNEST E. HUBERT 
Scientific Assistant, Office of Investigations in Forest Pathology 
4 
' ; Page Lag Page 
Introduction . . . . . + . + « « - + 1 | Methods Used in Presenting Data. . . 14 — 
| Present Status of Western Hemlock in InfectionAge:s Ys dag ose eee cabs Zoke 
the rades\ cite ees ea « je ic ee 2 Reiation of Decay to Sigteandio Age . 18 
Echinodontium tinctorium. . ... . 3 | Relation of Decay to Vigor, Crown Rat- 
The Fungus and Its Hosts . eset 3 ing, Size, and Volume. . . .. . 22 
Geographic Distribution. .'. . . 5 | Relation of Decay to Injury and to Spore- 
- The Disease Caused by Echinodontium phores'< 5 Soe 5 Fe feet ieee aren 
tinctorium .... sitene s 6 Theory of infection . . . ..-«.«. 30 : 
Outward Signs of the Bibeaker: - - 6, Discussion of Resulig .. +... 31 
General Characteristics of the Rot . 9 | MethodsofControl . . .....e. 34 
Areas Studied and Field Methods Used 11] Summary . 2. 2.2 se 0 ee se 36 
mm 
WASHINGTON Oren 
GOVERNMENT PRINTING OFFICE 
1916 : 
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