244 The Spraying of Plants. 



usually one-sided, sometimes to such an extent that the blossom 

 end and the stem are close together. Isolated spots do not 

 seriously injure the apple, but frequently its market value is 

 thereby considerably reduced. 



The appearance of the disease upon the leaves is similar to 

 that upon the fruit, but the light-colored edge is wanting. The 

 parts attacked are circular or oval, and where several spots have 

 run together the outline is irregular. The first indication of 

 the presence of the fungus on the foliage is the appearance of 



FIG. 38. Fall Pippin apple disfigured by scab. 



small, light green areas which are easily distinguished when the 

 leaf is held up to the light. In a few days the central portions 

 of these areas become raised, causing the leaf to become more 

 or less distorted. The color at the same time changes to a dull 

 brownish-black, which is plainly visible upon the upper side of 

 the leaf. This causes the leaf to curl, the concave or hollow 

 side being underneath ; the edges of the leaf often become 

 brown and torn. (For colored plate of scab, see Cornell Bull. 84.) 

 The scab is undoubtedly the most serious fungous disease 

 with which the apple grower has to contend. Xo other disease 

 annually ruins such a large percentage of the crop. From the 



