60 MANUAL OF FRUIT DISEASES 
but also through the cankered area, eventually giving the 
surface a roughened aspect. This is especially noticeable on 
cankers two or three years old. The diseased area may ex- 
tend along the margin at sev- 
eral points, resulting in a 
lobed or somewhat concentric 
appearance. Cankers may 
or may not surround the 
limb; in the latter case the 
margin is marked by a crevice 
beneath which originates a 
callus. 
Affected leaves show spots 
within two months after the 
petals have fallen. The 
lesions are irregular in out- 
line, light-brown to yellowish 
or whitish in color, and meas- 
ure one-sixteenth of an inch, 
or less, in diameter. The 
spots are scattered indiscrim- 
inately over the leaf, occur- 
ring frequently on the veins, 
midrib and petiole. On ac- 
count of their minuteness, 
several lesions may appear 
on a leaf without attracting 
aie attention, and perhaps with- 
Fra. 16. — Apple-blotch cankers. out great injury. In more 
severe cases the diseased leaf 
is more noticeable and such foliage may be dropped prema- 
turely. The leaf-petioles are attacked, in which case the 
leaves, instead of falling, turn brown, die and hang on the 
tree. 
