APPLE DISEASES 



59 



Davis. About the margin of older, sunken spots is sometimes 

 seen a reddish border. On very young apples the points of 

 infection show as small water-soaked areas, and in wet weather 

 there may be a yellowish, gummy exudate. On some varieties 

 at least, like the Ben Davis, the skin ultimately cracks (Fig. 15). 

 The crevices, although usually about one-half of an inch long, 

 may girdle the fruit and extend to the core. Often these 

 cracks intersect, forming a cross (Fig. 15). Within a few days 

 after the blotches become 

 visible, black pimples are 

 developed on the lesions 

 (shown in Fig. 15). These 

 are the fruiting bodies of the 

 pathogene and they may 

 number from three to sev- 

 eral on each diseased area. 

 They are either scattered 

 promiscuously over the 

 lesion, or are arranged 

 around the margin. A large 

 percentage of affected fruit 

 drops prematurely. 



Apple-blotch also affects 

 the fruit spurs, twigs and rapidly growing shoots, showing 

 itself in the form of characteristic cankers (Fig. 16). Larger 

 limbs are not commonly attacked. On the fruit-spurs the 

 cankers are at first purplish or blackish. The center turns 

 brown with age, the margin remaining unchanged in color. 

 The resulting lesion is small and rather inconspicuous, with 

 a crack along the margin. On water sprouts, and on 

 other rapidly growing shoots, the cankers have much the same 

 appearance as just described, but are longer, often measur- 

 ing an inch or more in length, and sometimes girdling the 

 stem. Longitudinal cracks appear not only along the edge 



FIG. 15. Apple-blotch, late stage. 



