MANUAL OF FRUIT DISEASES 



spots may fuse and frequently the leaf is killed. In case of 

 severe infection defoliation may result. On the blossoms the 

 lesions are found chiefly on the pedicels and calyx. The oliva- 

 ceous spots may encircle the slender stalk as a result of which 



it withers and 

 ultimately falls, 

 thus reducing the 



W' s*^J&* , JET Set f frult 



JK Hite^ yJBM Blossoms which 



show even a sin- 

 gle lesion seldom 

 hang to the tree. 

 The petals are 

 never affected. 

 Mature scab spots 

 on the fruit are 

 very similar in 

 size, shape and 

 color to those on 

 the upper leaf- 

 surface, although 

 at first they are 

 smaller and more 

 sharply defined. 

 They are usually 

 most numerous 

 about the blos- 

 som-end (Figs. 2 

 and 3) of the fruit, due to the fact that infection occurs largely 

 in the spring while the young apples still remain in an upright 

 position (Fig. 4). The lesions on the fruit show a whitish, 

 papery margin, often very wide ; this is the undissolved cuticle 

 which has been slightly uplifted by the pathogene advanc- 

 ing at the edge of the lesion (Fig. 2). As the spots grow 



FIG. 1. Apple-scab on leaves ; types of infection on 

 upper (left) and lower (right) surfaces. 



