AN APPLE ORCHARD SURVEY OF WAYNE COUNTY, NEW YORK. 337 



and keeping quality are not so seriously affected as when picked in the 

 stage shown in Fig. 79, but the fungus may make some further growth 

 around the edge of the scar if put in warm storage. 



Fig. 81 shows a Baldwin apple so badly attacked that it has become 

 distorted and cracked. Most cases of cracking of the apple are due 

 to this fungus. 



Fig. 82 shows three sections of apple-leaves. " In Fig. I the leaf is 

 healthy. Observe the regularity of the three upper layers of cells. In 

 Fig. 2, the brown fungus may be seen growing on the upper surface, 

 and at this stage it has 

 destroyed the upper or 

 epidermal cells, although 

 it is probable that the 

 mycelium of the fungus 

 first spreads just under 

 the cuticle, on top of the 

 layer of epidermal cells. 

 Fig. 3 shows the fungus 

 when it is better estab- 

 lished, and it will be seen 

 that all the cells of the 

 leaf are disarranged, the 

 chlorophyll or green 

 grains being few in 

 number, and the leaf has 

 increased in thickness. 



FIG. 81. Baldwin apple showing cracking due to the 

 fungus. 



This, Fig. 3, is a cross-section through one of the blister-like elevations 

 which are shown on the leaf in Fig. 83. It will be seen that the fungus 

 does not enter the deeper tissues of the leaf, although it disorganizes 

 them by its parasitic effects. In Fig. 3, a spore can be seen at A, and 

 two are shown broken off their stem or hyphae at B. In Fig. 2 the spores 

 can be seen in process of formation at the ends of the threads, and at C 

 one of the threads is cut off."* 



Relation of the weather to the scab fungus. Nearly all fungi are fav- 

 ored by wet weather; wheat rust, bean rust, potato blight, etc., are all 

 worse in wet seasons. The wet weather does not create any fungus 



*L. H. Bailey in Cornell Bulletin 84, Jan., 1895. 



