DISEASES OF CULTIVATED PLANTS 461 



This fungus is very characteristic in its appearance on the apple. 

 It is frequently called by fruit-growers the pink fungus, from the 

 color of the spots as the fungus matures. 



If we examine an apple affected by this disease in its more ad- 

 vanced stage, we notice one or more pink spots which are usually 

 more or less circular and sunken. Around the fungus and in the 

 edge of the sunken portion, the skin is brown. If we examine these 

 spots at an earlier stage, we will usually find a circular white patch 

 of mould, or still earlier, perhaps a ring of mould about a darker 

 scab spot. 



The first change in the appearance of the apples, is that the 

 skin or epidermis turns brown around the spots. This gradually ex- 

 tends out in all directions so that the various spots merge into each 

 other, covering large areas, or the entire surface of the apple. As the 

 spots increase in size, they also sink. The sinking may be due not 

 only to the dissolving of the solid parts of the apple by the fungus, 

 but also to the evaporation of water through the spots. Not only 

 does the skin of the apple in the edge of the sunken spot turn brown, 

 but the flesh beneath is similarly colored, and is bitter to the taste. 

 (N. Y. [Ithaca] E. S. B. 207.) 



Apple Rust. Apple rust is a widely distributed disease, and 

 in some sections is quite injurious. It is of common occurrence in 

 New Hampshire and, while not one of the most serious apple troubles, 

 it often does considerable damage. It sometimes attacks the fruit, 

 but its effects are usually confined to the foliage. Here it causes yel- 

 lowish spots, which usually become somewhat elevated in the center 

 and in which are produced numerous spores. The spots usually ap- 

 pear on the leaves in June. The spores from the leaves are borne by 

 the wind and attack the twigs of cedar trees, causing morbid growths 

 or swellings, the so-called cedar apples. The fungus passes the win- 

 ter in the tissue of the cedar apple and in the spring produces an 

 abundance of spores in the gelatinous outgrowths of these galls. These 

 spores, when borne back to the apple foliage, produce the rust again, 

 and thus the fungus passes from one host back to the other. 



Numerous efforts to control the disease by spraying have been 

 without success. Since the cedar apples harbor the fungus through 

 the winter the method of control is obviously to destroy them, or, 

 when practicable, the cedar trees themselves. (N. H. E. S. B. 144.) 



Sooty Blotch and Fly Speck. The sooty blotch and the fly 

 speck of the apple were formerly thought to be caused by two 

 different fungi, but the recent work of Floyd indicates that both are 

 due to the fungus indicated above. The names given these two ef- 

 fects characterize their appearance. The former produces blotches 

 y& to y% inch in diameter on the fruit and the latter numerous 

 minute specks. They give the apple a sooty appearance that de- 

 preciates its market value. The fungus growth is entirely on the 

 surface of the fruit, and hence the disease is especially dependent 

 upon moist weather for development. 



