DISEASES CAUSED BY WOUND FUNGI. 27 



{Betula lutea Miclix. f.), butternut (Juglans cinerea L.), black walnut 

 (Juglans nigra L.), oaks (Quercus spp.), apple (Pyrus malus L.), and 

 hickory ( Hicoria sp.) . In Europe it is everywhere prevalent upon the 

 broadleaf trees, but occurs more commonly on the beech ( Fagus 

 sylvatica L.), oaks (Quercus spp.), and alder (Alnus incana Medic). 



In this country certain species are almost universally affected with 

 the white heart-rot, irrespective of the region where they are found. 

 An excellent instance is the aspen. This tree, which (72, 99) has the 

 widest range of any species of forest tree in Xorth America, is subject 

 to this disease very generally. Fomes igniarius has been found on 

 this host from such extreme points as Maine, western Canada (51), 

 Oregon, Colorado, and southern Xew Mexico. 



In Xew York and Xew England the beech has been found to be 

 the most common host of this fungus. Wherever any considerable 

 amount of beech timber is found, white heart-rot is prevalent. In 

 some sections as many as 90 to 95 per cent of the beech trees of mer- 

 chantable size have been found affected with this disease. Both the 

 butternut and the black walnut are frequently affected. The oaks 

 are quite generally affected, but more especially those belonging to 

 the black oak group. 



A marked difference in susceptibility is occasionally found in certain 

 species of the same genus. Thus it has been reported that the aspen 

 is more seriously affected in western Canada than is the balm of Gilead 

 (51). Among the maples it has been found that the striped maple 

 is quite generally attacked in those localities where the disease is 

 present in the same vicinity upon others of its host species. The 

 silver maple seems to be nearly as susceptible as the striped maple, 

 while the red maple and sugar maple are rather rarely affected. The 

 3'ellow birch is even less frequently attacked than are the red or sugar 

 maples. 



DISTRIBUTION OF FOilES IGNIARIUS. 



The false-tinder fungus ( Fomes igniarius) is known to occur 

 throughout the United States. In general, its distribution may be 

 given as follows: In Xorth America it occurs in Alaska, in various 

 parts of Canada, throughout the United States, and in the Bahamas. 

 In South America it has been collected in Surinam, Brazil, Argentina. 

 and Patagonia. It is prevalent throughout Europe from England to 

 Russia, and from Scandinavia and Finland to Italy and Spain. In 

 Asia it is known from Siberia, Japan, the Philippines, and India. It 

 also occurs in Tasmania, Australia, Java, Xew Zealand, Admiralty 

 Islands, Sierra Leone, and South Africa. 



It will be noted that these localities embrace the four quarters of 

 the world. Because of the lack of knowledge of the mycological 

 flora of many countries, no statement can be made as to the occur- 



149 



