UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1140 



Washington, D. C. PROFESSIONAL PAPER Match 29, 1923 



THE DETERIORATION OF FELLED WESTERN YELLOW PINE ON 

 INSECT-CONTROL PROJECTS. 1 



By J. S. Boyce, Pathologist, Office of Investigations in Forest Pathologij T 

 Bureau of Plant Industry. 



CONTENTS. 



Page. 



Introduction 1 



Method of collecting data 2 



Kate of deterioration 2 



Paga. 



Causes of deterioration 4 



Conclusions 6 



INTRODUCTION. 



During the past 15 years extensive insect-control measures have 

 become necessary in various localities in the western United States 

 in order to check epidemics of the western pine beetle (Dendroctonus 

 brevicomis Lee.) and the mountain-pine beetle (Dendroctonus mon- 

 ticolae Hopk.) on western yellow pine (Pinus ponder osa Laws.), 

 lodgepole pine (Pinus contorta Loud.), western white pine (Pinus 

 monticola Dough), and sugar pine (Pinus lambertiana Dougl.). 

 Briefly, control consists in felling and barking the infested trees (or 

 burning the bark in the case of Dendroctonus brevicomis) , in order 

 to destroy the overwintering stages of the beetles. The trees usually 

 are limbed well into the top but are not cut into log lengths. 



The attacks of the western pine beetle on western yellow pine have 

 been widespread, and consequently the most extensive control projects 

 have been concentrated on this tree species. At present control work 

 is under way in the yellow-pine regions of British Columbia and 

 central California, while a large project was begun in the spring of 

 1922 in the Klamath Lake region of southern Oregon. 



The southern Oregon-northern California project begun in the 

 spring of 1922 necessitated the felling of about 16,000 merchantable 

 western yellow pines, with an occasional sugar pine, comprising ap- 



1 This study was made in cooperation with the Klamath Forest Protective Association- 

 at Klamath Falls, Oreg. Without the yearly records of the association giving the loca- 

 tion of felled trees, the study would have been impossible. The writer is indebted to 

 J. F. Kimball, secretary-treasurer, and to H. H. Ogle, of the same association, for 

 valuable assistance in obtaining the field data. 



25322—23 I 



