UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 360 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



June 17, 1916 



MISTLETOE INJURY TO CONIFERS 

 IN THE NORTHWEST 



By 



JAMES R. WEIR, Forest Pathologist, Office of 

 Investigations in Forest Pathology 



CONTENTS 



Introduction 1 



Genera! Nature of the Mistletoe Injury . 2 



Result of Infection on tlie Branches . . 13 



Uesult of Infection on the Trunk ... 20 

 Relation of Mistletoe Injury to Fungous 



Attack 25 



General Suppression and Fungous Attack 27 



Relation of Mistletoe Injury to Insects . 28 



Influence of Mistletoe Injury on the Seed 



Production of the Host 30 



Host Affinities in Relation to Silvicul- 

 ture 31 



Suggestions for Control 33 



Summary .......<>...• 37 



Literature Cited 39 



WASHINGTON 



GOVERNMENT PRINTING OFFICE 



1916 



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