AN UNDESCRIBED TIMBER DECAY 

 OF HEMLOCK 



Erdman West 



For several years, dead hemlock timber in the vicinity of State 

 College, Pennsylvania, has been destroyed by a peculiar rot which 

 seems to be quite constantly associated with sporophores of the 

 fungus Polyporus tsugae (Murrill) Overholts. An investigation 

 of the problem was undertaken at the suggestion of Dr. L. O. 

 Overholts and a preliminary report of the situation prepared but 

 not published. Soon after assuming his duties in New Jersey, 

 the writer noticed a group of hemlocks along the Raritan River 

 near New Brunswick, N. J. An excursion to these showed a 

 large number of them dead or dying from the effects of the root 

 rot fungus Polyporus schweinitzii. Some of the trees bore sporo- 

 phores of the sap rot Polyporus ahietinus, but most of the trees 

 that had died recently, bore sporophores of Polyporus tsugae, 

 sometimes in great abundance. Further investigation showed 

 present in these standing trunks the same rot that had been 

 studied in stumps and prostrate trunks of hemlock near State 

 College. This abundant material has made further observations 

 possible. 



Polyporus tsugae (Murrill) Overholts has been reported on 

 pine and hemlock for a number of years but the decay caused by 

 it has never been described. The sporophore was first described 

 by Dr. W. A. Murrill under the present specific name. He 

 placed it in the section Fomiteae under the name Ganoderma 

 tsugae along with several other species of Ganoderma. It is, 

 however, an annual plant and the entire genus as limited by Dr. 

 Murrill more properly belongs in the section Polyporeae instead 

 of Fomiteae. This point will be given further consideration 

 later. The species has also been referred to the genus Polyporus 

 by another writer. The species is very closely related to Poly- 

 porus lucidus and P. curtisii. 



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