SOME OF Oi'R MOST CO.M.MO.N AJTIJ-; DISKASKS 



861) 



stand out prominently, giving a blistered appearance to the canker, 

 whence the name. A satisfactory control method is unknown. 



SOOTY BLOTCH 



This disease, which is caused by the fungus Lejttofli //riiuii 

 is so named because of the appearance of the spots on the fruit. 

 The blotches are rather irregular in outline, sooty in aspect, and 



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f 



m 



I 



FIG. 244. SOOTY BLOTCH 



superficial in nature. The blotched appearance is due to the 

 presence of the fungus, the vegetative parts of which grow on the 

 surface of the skin of the apple. These vegetative parts are com- 

 posed of a network of radiating olive-brown threads. Apparently 

 no spores are produced to be scattered throughout the summer as, 

 for example, in the case of the apple scab fungus. 



Another form of the trouble is found in what is known as " fly 



