SPRAYING EXPERIMENTS. 



51 



Fig. 2. Winesap and Red June apples showing apple scab. 



Let it be said at the start that "cedar apples, " which are seen 

 so commonly on cedar trees in spring, have no relation whatever 

 to apple scab but do have a very close relation to the rust on 

 apple leaves. Many fungi have two or more stages of growth. 

 One stage of apple scab occurs on the foliage, fruit and twigs of 

 apple trees during summer and the other on the dead apple leaves 

 in winter and spring. Fig. 1 indicates something of the appear- 

 ance of scab on the leaves in summer and fig. 2 shows how scabby 

 fruits look. At first the scab shows as a brownish discoloration 

 in spots on the underside of the leaves, on the flower or fruit 

 stems, and on the young fruits. Later the upper surface of the 

 leaves shows the disease, appearing as if swollen in spots (see 

 fig. 1). The affected fruits often present many small, grayish- 

 brown spots of scab and usually a few large patches of a similar 

 color. The larger scabs often crack open (see fig. 2). If the 

 fruits are badly affected while quite small, they frequently drop 

 before they have grown appreciably. Infection takes place in 



