BULLETIN 191: THE RED ROT OF CONIFERS 



BY F, H. ABBOTT! 



SUMMARY 



The so called red rot of conifers is caused by the fungus 

 Trametes Pini, which is primarily a parasite, assuming more or 

 less the characters of a saprophyte when the tree falls. The fungus 

 commonly attacks five species of conifers: tamarack, pine, hemlock, 

 spruce and balsam. Its ravages are greatest in unthinned stands, 

 especially pure stands of white pine. 



Infection occurs mainly through broken branches which ex- 

 pose the heart-wood. Root infection is doubtful. Sporophores are 

 the principal means of spreading the disease. They form on all 

 host species but vary in form from an incrustation on the spruce 

 and balsam to a bracket or hoof on pine and tamarack. They exist 

 on both standing and falling trees. The mycelium spreads more 

 rapidly up and down the trunk than across it. The damage to 

 the wood is wrought by the solution of its lignin content by the 

 enzym of the fungus. This damage appears to cease when the tree 

 falls. 



Laboratory cultures of the fungus from various sources ex- 

 hibited uniformity. Spores were not produced in the cultures, at 

 least up to six months. Successful cultures may be made on 

 sterile wood. 



Prevention is best effected by proper thinnings, removing dis- 

 eased trees and destroying fruiting bodies. 



The weight, breaking and crushing strengths of the woods 

 were decreased approximately in proportion to the permeation of 

 the wood by the fungus. 



The red rot of conifers damages Vermont timber owners an- 

 nually to the extent of about a quarter of a million dollars. The 

 diseased wood is used in the manufacture of boxes, tubs, wooden 

 pails, etc. 



1 The writer expresses his appreciation of the assistance he has received from 

 Arthur S. Graves of Yale University, B. A. Chandler of the Vermont Forestry De- 

 partment and from the Station Forester and Plant Pathologist in assembling the 

 data and in preparing this paper. The collection of references was facilitated 

 through the assistance of Perley Spaulding of the United States Department 

 of Agriculture. Valuable specimens were contributed and field observations made 

 by Mr. Chandler. The collection of the data regarding losses in the mills and woods 

 was accomplished only through the cordial cooperation of landowners, millowners 

 and operators. C. G. Hedgecock of the United States Department of Agriculture 

 also assisted in the identification of sporophores and diseased wood. 



