FUNGI AFFECTING THE APPLE 



The Apple Scab 



Fusicladium dendriticiim 



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 leayes 

 and green shoots. It first ap- 

 pears upon the leaves in the 

 sliape of smoky greenish siwts, 

 more or less circular in outline. 

 These gradually enlarge, and 

 frequently several of them run 



together, so as to form good 



sized blotiches ; as they grow 

 older their color darkens, finally 

 becoming almost black. The 

 upper surface of the leaf is usu- 

 ally affected. 



Sometimes the fungus de- 

 velops so rapidly on the expand- 

 ing leaves iu 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 



FIG. 11. 



APPLE SCAB SPOTS 

 O'S A LEAF. 



