New Yorx AaricuttTurAL ExperrmMent Station. 341 
In some instances cankers occur quite uniformly on the south- 
west side of the trees, thus indicating that they had their origin in 
injuries produced by sun scald. The work of the fungus may be 
recognized by the thick rough bark, while the fruiting pustules 
reveal its presence where it is still or has recently been in an 
active condition. 
EXTENT OF INJURY. 
The extent of the injury done to the orchards of the State can 
scarcely be estimated, but it is safe to say that this canker is one 
of the worst diseases with which the orchardist will have to con- 
tend since it attacks the tree directly instead of the foliage and 
fruit as is the case with the majority of our orchard diseases. 
The appearance of the cankers is such that their injurious nature 
may not be apparent to the casual observer until his attention is 
attracted by the shrivelling of the leaves; thus the tree may be 
ruined before it is realized that anything serious is the matter. 
In one instance the loss of a large acreage of orchard was due to 
the attacks of the canker fungus (see page 333) and in a great 
many orchards it has done serious damage. 
TIME AND MANNER OF INFECTION. 
Infection takes place in the spring of the year as is shown by 
the growth that the fungus makes in the bark. The presence of 
the fungus in a newly infected mb is first indicated by a small 
area of discolored bark. ‘This area extends slowly as the fungus 
grows outward in all directions till mid-summer, when a definite 
boundary forms between the dead and living bark, thus showing 
that growth for the season has stopped. ‘This season’s growth had 
stopped by the first of August, and in some instances pycnidia 
containing mature spores were found at that time on bark where 
infection had taken place in the spring. 
Many of the spores remain in the pycnidia till the following 
spring, or longer, when they are given off and disseminated. The 
mycelium is unable to penetrate to the cambium through living 
