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ON A NEW CANKER-DISEASE OF PRUNUS YEDOENSIS, etc. 
early spring the red crusts composed of masses of ascospores are sometimes 
seen on the stromata. 
c. Development of the Canker. 
The canker appears first as a more or less discolored area about the point 
of infection, which takes place most frequently through cracks and wounds 
on the bark, or where a branch or twig has been pruned, or killed from some 
cause, as winter injur} - . It is also not seldom that the fungus gets a start 
from the wound which is given by an insect such as Sesia hector Bltl. or a 
crack in the crotch of the branches. Judging from my observations, the 
disease may also arise through the injured buds. The affected area of the 
branch soon becomes sunken, making the boundary between the dead and 
living tissues very marked. Gum pockets are often formed at this point. 
The gummy exudation pushing through the tissue of the bark appears on its 
surface as a copious gum flow. The bark of such a diseased portion gradual- 
ly dries up and at last produces numerous pustules which are the beginning 
of the stromata. Callus soon pushes out from the edge of the canker, but it 
is very soon attacked by the fungus and produces a large new canker sur- 
rounding the previous one, requiring for its formation just one year. One 
can see, therefore, at times on a large tree cankers as large as five or six feet 
long, having three or four concentric ridges. Such injuries are gradually ex- 
tended, often girdling the branches and even the trunks of the tree. The 
gummosis is also constantly associated with these cankers, being especially 
conspicuous on Prunns Mume. 
d. Age and Parts of the Hosts affected. 
According to my observations, the disease attacks the large trees more 
frequently than the smaller ones. This is evidently caused by the facts that 
the larger trees have a much greater chance of getting wounded by insects 
and other causes than the young trees, that the healing power of the former 
is not so strong as in the latter, and that moreover the younger it is, the 
