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 

 attention, and perhaps with- 

 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. 



FIG. 16. Apple-blotch cankers. 



