150 MANUAL OF TREE DISEASES 



shelves borne on branches arising from a single central stalk. 

 For further details concerning this heartwood-rot, see under 

 oak diseases, page 259. 



White Piped Butt-Rot 



Caused by Polyporus croceus Fries 

 (= P. PUotm Schw.) 



The heartwood of the base of chestnut and oak is often 

 attacked by this white piped-rot. It is also occasionally 

 found in the tops of the trees. The rot extends into the roots 

 and is one of the most destructive wood-rots of the butts of 

 oak in the Ozark Mountains. This disease has been found in 

 chestnut and oak in various localities in eastern and central 

 United States and probably is generally distributed over this 

 area. When chestnut trees have dead limbs in the top, the 

 decay may be found in the upper portion of the trunk. The 

 coppice method of reproduction of the chestnut is responsible 

 for the prevalence of this rot in the base of the trees. 



Symptoms. 



The affected wood is at first brownish and water-soaked. 

 Later white areas appear between the spring- and summer- 

 wood. These areas become larger and the wood between is 

 firm and dark brown. Finally the white areas enlarge and 

 become hollow cavities with white margins. The brown wood 

 between the pockets at this stage is brittle and breaks apart 

 easily into concentric layers. The sporophores of the causal 

 fungus are buff- or orange-colored and are found sometimes on 

 living trees or on fallen trees and old logs. They are soft and 

 watery annual shelf-like bodies, three to six inches across. 



Cause. 



The white piped butt-rot of chestnut and oak is caused by 

 Polyporus croceus or Polyporus PUotw. Infection usually 



