JOraALOFAGRKlTIIALlSEARCe 



Vol. XII 



Washington, D. C, January 14, 191 8 



No. 



PURE CULTURES OF WOOD-ROTTING FUNGI ON 

 ARTIFICIAL MEDIA 



By W. H. Long, Forest Pathologist, and R. M. Harsch, Assistant in Forest Pathology, 

 Bureau of Plant Industry, United States Department of Agriculture ' 



INTRODUCTION 



The study of wood-rotting fungi by means of cultures on artificial media 

 has been very meager in the past compared to the almost universal use of 

 cultural methods by bacteriologists and workers with strictly parasitic 

 fungi. A critical study of the existing literature on cultures of wood- 

 rotting fungi develops the fact that much of this work was either not done 

 under proper control conditions where the purity of the organism under 

 investigation was guaranteed or the media used by many of the workers 

 consisted of pieces of wood, bread, dung decoctions, etc., and not artificial 

 media of such a character that others could reproduce the media, growth 

 conditions, etc., and thus repeat and verify the experiments. 



Brefeld (i-sY, Falck (5-7), Humphrey and Fleming (8), Lyman (11), 

 Rumbold (12), and Zeller (75, 14) are some of the workers who have made 

 cultural studies of a number of hymenomycetous fungi on a rather exten- 

 sive scale. However, the line of investigation followed by most of them 

 has been more along the lines of polymorphism in spore forms, enzymic 

 action, the rot caused by each fungus, and the prevention or control of 

 these fungi in the rotting of structural timber rather than a critical study 

 of their cultural characters on artificial media. Probably the most seri- 

 ous drawback to investigators in working with wood-rotting fungi, espe- 

 cially the Polyporaceae, has been the fact that it was not possible under 

 conditions used by them to obtain with any degree of certainty the sporo- 

 phores of the various fungi on artificial media. 



This paper deals with two lines of investigation of fungous activity 

 when grown in pure cultures : (i) A method by which various wood- rotting 

 fungi can be differentiated from each other by their cultural characters 

 alone when grown upon artificial media; and (2) a method by which the 



1 The writers are under obligations to Dr. E. A. Burt for assistance in identifying the various species 

 of the Thelephoraceae, and to Dr. W. A. Murrill for identifying the more di£5cult species of the Polyporaceae 

 discussed in this paper. 



2 Reference is made by number (italic) to " Literature cited," pp. 81-82. 



Journal of Agriculture Research, 



Washington, D. C. 



Ip 



(33) 



Vol. XII. No. 2 

 Jan. 14, 1918 

 Key No. G — 132 



