226 THE APPLE 



on the yellow or green surface of the fruit, but as they increase in 

 size they become sunken and brown. 



Control measures consist in spraying with a fungicide like 

 Bordeaux mixture or lime-sulphur, generally a weak solution, any 

 time before the last of June. 



Cedar rust and scab. For a discussion of these diseases the 

 reader is referred to diseases affecting leaves, pages 215-217. 



Sooty blotch and fly-speck fungus (Leptothyrium pomi [Mont. 

 & Fr.] Sacc). In ordinary seasons the sooty blotch appears chiefly 

 on apples grown in low, moist situations. The Peck, Rhode Island 

 Greening, and Rome Beauty are conspicuously affected by it. This 



Fig. 102. Sooty blotch. (Courtesy of Michigan Farmer) 



disease causes two kinds of spots — a large sooty spot, apparently 

 made by a fungous mycelium, which spreads over the whole of 

 the discolored area, and a small fly-speck spot, also of fungous 

 origin. Both kinds of spots may occur on the same specimen ; in 

 fact, it is rare to find an apple affected with one that does not 

 show the other also. The fungus of both spots is evidently para- 

 sitic in character, but appears to be quite superficial, occasioning 

 no hardening of the skin or cracking of the apple, as in the case 

 of apple scab, but diminishing the brightness of the skin and the 

 market value of the fruit. From some reports it would seem that 

 the fungus may develop after the apples have been packed in 

 barrels and stored. 



