UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 1053 



&M? 



<mTl> 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



jiC^ve. 



Washington, D. C. 



PROFESSIONAL PAPER 



May, 1922 



STUDIES OF CERTAIN FUNGI OF ECONOMIC IMPORTANCE 

 IN THE DECAY OF BUILDING TIMBERS, WITH SPECIAL 

 REFERENCE TO THE FACTORS WHICH FAVOR THEIR 

 DEVELOPMENT AND DISSEMINATION. 



By Walter H. Snell, 1 Forest Pathologist, Office of Investigations in Forest 



Pathology. 



CONTENTS. 



Page. 



Introduction 1 



Basidiospores 4 



Sources of basidiospore ma- 

 terial 4 



Methods used in the basidio- 

 spore studies 5 



Germination of the basidio- 

 spores 5 



Retention of the viability of 

 the basidiospores 11 



Observations on the casting of 



the basidiospores 14 



Observations on the dissemina- 

 tion of the basidiospores of 



Trametes serialis 1G 



Mycelium 19 



Preparation of cultures 19 



Macroscopic appearance of cul- 

 tures grown at room tem- 

 perature 19 



Microscopic characters of the 



mycelia on malt agar 22 



Page. 



Mycelium — Continued. 



Differentiation of the cultures 



upon agar 24 



Effect of temperature on the 



growth of the mycelium 2,~> 



Secondary spores 2K 



Intramural dissemination of 



fungi causing decay 2<i 



Review of the literature of 



secondary spore formation 27 



Occurrence of the secondary spores 



in cultures of the fungi studied__ 30 

 (termination studies of the second- 

 ary spores 32 



Experiments upon the dissemination 



of the oidia of Lenzites sepiaria 30 



Occurrence in buildings of the 

 secondary spores of the fungi 



studied :;s 



Summary gs 



Literature cited 42 



INTRODUCTION. 



There is no means of estimating the total annual loss occasioned 

 by fungi which attack timbers in buildings, but from the evidence at 

 hand it is certain that this loss is very large. This is particularly hue 

 in textile mills, paper mills, and canning factories, in which high 



•The writer wishes to acknowledge his indebtedness in connection willi these studios 



Prof. L. it. Jones, Of the department of plant pathology of the University of Wis 



conBin, for hln Interest, encouragement, and criticisms; to Mr. C. .r. Humphrey, <>f the 



Office oi Investigatioiui In Forest Pathology, Bureau of Plant Industry, Madison, Wis., 

 under whoso Immediate direction this work was undertaken, tor general supervision, 

 facilities, and criticisms; and to Mr. i<\ .i. Bexle, engineer and special inspector tor the 

 Associated Factory Mutual Eire Insurance Companies of Boston, Mass., tor courtesies 

 tendered in connection with m j 1 1 Investigations and for the loan of photograph 

 82278—22 1 



