New YorK AGRICULTURAL EXPERIMENT STATION. 305 
wounds usually occurred on large limbs near the trunk, from 
which they extended up and down. The dying bark of the 
canker spots was first of a dirty brown color, later becoming 
rough, charred and punctured by “grayish ochre” colored 
stromata of the fungus. It is thought that the mycelium ad- 
vances mere rapidly in the wood than in the bark because 
limbs “ examined at points several feet away from the can- 
kered spot” had “brown and discolored” heart-wood. A 
branch dies by the time or before it is girdled. It is consid- 
ered a wound parasite, which gains entrance through dead 
stubs, pruning wounds, etc. 
H. H. Whetzel*® attributes a common form of apple-tree 
canker to the fire-blight Bacillus. Blight canker is said to 
have occurred very commonly in the upper Hudson River Val- 
ley and other parts of New York State, on trees 8-15 years 
old. About 95 per ct. of such trees were more or less affected 
on their limbs and trunks by this canker, and many of them 
were dead or dying. Crotch-cankers were found on numerous 
young and old trees, but it was thought that young trees were 
more often killed than older ones. 
The beginnings of these cankers were more readily noticed 
on young, smooth-barked trees, as discolored, sunken areas 
with slightly raised or blistered margins, and sometimes ex- 
uding a sticky fluid largely composed of bacteria, but fungi 
were found present only some time after the death of the 
bark. The dead bark soon turned brown and later dropped 
off. Wet, cloudy weather is said to favor the spread or exten- 
sion of cankered regions and sunlight to check them. Most 
cankers were limited to but one season’s growth, though some 
were said to be perennial in their progress. 
It is suggested that the large-cankers at the bases of young 
trees and the disease on the crowns of King may also be due 
to the canker Bacillus. Collar-rot and crotch-cankers were 
thought to be the most destructive types of injury. 
* Til. Agr]. Expt. Sta. Bul. 70. 1902. 
*'The blight canker of apple trees. Cornell Univ. Agrl. Expt. Sta. Bul. 
236. 1906. 
