FUNGI AFFECTING THE APPLE 



The Apple Scab 



Fusicladium dendriticum 



There is, probably, no fungous disease of fruits so 

 familiar to the general public as the apple scab, or, as it 

 is sometimes called, the black spot. This is due to a 

 fungus which produces the well- 

 known scabby spots upon the 

 fruit, and also attacks the leaves 

 and green shoots. It first ap- 

 pears upon the leaves in the 

 shape of smoky greenish spots, 

 more or less circular in outline. 

 These gradually enlarge, and 

 frequently several of them run 

 together, so as to form good 

 sized blotches; as they grow 

 older their color darkens, finally 

 becoming almost black. The 

 upper surface of the leaf is usu- 

 ally affected. 



FIG. 11. APPLE SCAB SPOTS Sometimes the fungus de- 

 ON A LEAF. velops so rapidly on the expand- 



ing leaves in early spring as to blight them, dwarfing 

 and killing the younger foliage. An instance of this, 

 observed by Professor L. H. Bailey, is illustrated in 



27 



