MAPLE DISEASES 233 



bark in late summer. The sapwood and bark are often invaded 

 and destroyed, causing the tops of the trees or large limbs to 

 die. The symptoms of the brown checked wood-rot are simi- 

 lar for all kinds of trees and are described under oak diseases, 

 page 247. 



White Strand Wood-Rot 



Caused by Polyporus squamosus Fj-ies 



Many kinds of deciduous trees are reported as seriously 

 damaged by this white rot in Europe. Those specially men- 

 tioned are maple, oak, elm, walnut, basswood, willow, ash, 

 birch, horse-chestnut and beech. In the United States, no 

 authentic information is available on this wood-rot, except 

 that the fungus is found in some cases growing from wounds 

 in living trees. 



Symptoms. 



The heartwood and sometimes the sapwood of the trees are 

 decayed. Trees in which the rot has affected the conduction 

 tissue of the sapwood show marked decline and are often 

 killed. The wood is characteristically rotted. It is almost 

 white and marked with pure white narrow strands of mycelium 

 running in the radial, tangential and longitudinal directions, 

 causing the wood to be split into small cubes. In general this 

 character is similar to the rot produced by Polyporus borealis 

 in the wood of conifers (see page 185). 



The annual fruiting-bodies are easily recognized. They 

 are soft and watery and almost circular with a short stout stem 

 at one side attaching them to the tree. The top is slightly 

 convex and is covered with overlapping brown scales, while 

 the under surface is white and honeycombed. 



Caiise. 



The white strand wood-rot of maples is caused by the 

 fimgus Polyporus squamosiis; so named because of the scales 



