BIRCH DISEASES 117 



White Butt-Rot 



Caused by Fames applanatus Fries 



The heartwood of the base of the trunk and the roots of birch 

 is sometimes destroyed by this rot. The decayed wood is 

 marked by numerous sinuous, white-stuffed tunnels which run 

 in the horizontal direction (see Fig. 12, page 109). The sporo- 

 phores of the causal fungus are woody, shelf-like bodies with a 

 brownish, smooth upper surface and a white under surface. 

 This heartwood-rot is more fully described under poplar diseases, 

 on page 310. 



