CHAPTER VII 

 HEART-ROT CAUSED BY OTHER FUNGI 



Polijporns ScJiwcinifzii, Poria mpararia, Pnlypnnift ftn]phi<n'n#, Trametes 

 Pini. 



Heart-rot caused by Polyponis Schweinitzii, Fr. Next to 

 Fomes annosus this fungus is the most frequent cause of 

 heart-rot. Though in many respects resembling the two 

 following diseases, this rot may easily be distinguished from 

 that caused by the Fomes by the rotted wood being very 

 dry, light, and friable, and not spongy or fibrous. It has 

 marked cleavage surfaces which are at right angles to each 

 other, so that the wood breaks up easily into more or less 

 cubical blocks, and, owing to shrinkage, the cracks often 

 open before the tree is felled and the interstices become 

 filled with white mycelium which frequently becomes 

 embedded in resin and assumes a chalky consistency. When 

 the rot is far advanced the wood is usually light or dark 

 brown and reeks strongly of turpentine. 



The fungus enters by the roots and grows up the stem, 

 and is in the vast majority of cases confined to the heart- 

 wood. But dead trees are occasionally found in which all 

 the wood up to 20 ft. or more from the ground is rotted. 



The disease is reported as fairly common on the Con- 

 tinent, especially on Scots pine, Weymquth pine, and 

 larch. There are frequent notices of it in the United States 

 of America on Wey mouth pine, balsam fir, white and red 

 spruce, and arbor vitae, and in New England it is con- 

 sidered one of the most destructive diseases (Schrenk, 1900). 

 In Scotland, Murray (1916) reports it as occurring on 

 Douglas, spruce, and Scots pine. My own observations 

 have been made in the south of England % where I have 

 found it on Sdots pine, cluster pine, and larch, chiefly in 

 Sussex. Surrey, Berkshire, and Devonshire, but I have no 



