232 MANUAL OF TREE DISEASES 



of cotton, potato and various field crop plants. The fungus 

 is known to form spores on branches of the mycelium but the 

 manner and place of fruiting and method of infection in the 

 maple is unknown. 



Control. 



Surgical methods are advised when this disease is to be con- 

 trolled (see page 346). Several diseased trees in a group have 

 been observed and the destruction of badly affected individuals 

 is necessary to prevent the fungus spreading to healthy trees 

 near by. 



Common White Wood-Rot 



Caused by Fames igniarius Fries 



Silver and striped maple are more commonly affected by 

 this white wood-rot than the red and sugar maple. Poplar, 

 beech and oak are the most seriously affected of the many 

 species of deciduous trees which are susceptible to this fungus. 

 Beech and maple in mixture in the Adirondack Mountains are 

 often diseased to the extent that the stands will never be worth 

 cutting. Outside the forest, this disease is not so common. 

 The sapwood may be invaded and the tops of the trees or 

 large limbs killed. The sporophores and decay are similar for 

 ail kinds of trees and are described under poplar diseases, 

 page 305. 



Bkown Checked Wood-Rot 



Caused by Polyportis sulphureus Fries 



Maples are at times affected by the sidfur fungus which 

 causes the brown checked wood-rot. Oak, chestnut, walnut, 

 butternut, locust and alder are also frequently affected by 

 the same rot. The wood is reduced to a reddish powdery mass 

 which splits in cubes, separated by sheets of mycelium. The 

 sporophores of the causal fungus are orange and sulfur-yellow 

 in color. They form from branch wounds or directly from the 



