212 



Brown Rot 

 Caused by Sclcrotinia c'uierea (Bon.) Schroet. 



While very serious on peaches and plums, brown rot does not often 

 become either abundant or severe on apples. Its occurrence in Illinois 

 was noted by Clinton^ in 1902 and by Conel," in 1914. Very little dam- 

 age has ever been attributed to it in our state, though in rainy seasons it 

 may become very severe locally. 



Its known occurrence in Illinois is shown on Map 49, which indicates 

 a greater frequency of occurrence in the southwestern tip of the state, 

 where its abundance is probably encouraged by the moisture present in 

 the valley of the Ohio and the Mississippi. 



The methods useful in controlling brown rot are outlined under 

 peach brown-rot. (See p. 220.) 



Powdery Mildew 

 Caused by Podospliacra Icucotricha (E. & E.) Salm. 



Powdery mildew of apple is not a common disease. It appears as 

 a white, powdery coating on the under surface of the leaves, and occa- 

 sionally upon the leaf stems and on young twigs. 



The damage from this disease consists chiefly in a stunting of the 

 leaves and an early leaf- fall. 



Powdery mildew is apparently of rare occurrence in Illinois. Its 

 distribution, as known at present, is shown on Map 50. 



The usual spray schedule is stifficient, tmder ordinary circumstances, 

 to keep it under control. 



SooTV Blotch 



Caused by Glocodes pomigcna (Schw.) Colby 



This disease is very often found associated with the "fly-speck" 

 disease on apples. It differs in appearance, however, being diltuse and 

 causing a blotchy appearance over a considerable part of the surface of 

 the fruit. The chief injury is a disfiguration of the fruit. 



The distribution of sooty blotch in Illinois is shown on Map .11. It 

 is known to occur, as the map indicates, in 19 counties, 17 of wiiich are 

 situated in the southern half of the state. 



Varieties known to have been .severely affected include especially 

 Ben Davis and Grimes Golden. There is not, however, any apparent 

 distinction between varieties as to susceptibility. The disease appears to 

 develop commonly in damji situations or during moist seasons. 



For control, the usual sjirays in July and August are helpful. In 

 orchards on low ground open pruning of the trees .serves to keep the 

 disease well controlled. 



'Clinton. G. P. .\ppl<< rots in Illinois. III. .\ki-. Kxper. St.i. Bui. 69. 1902. 

 = riiiicl. .1. L. A stiiilv of tln' brown rot funeus In the vicinity ot Champaign 

 and I'rbana. Illinois. I'hyt.ii>:ith, 4: 9J. 1914. 



