PAPERS ON BIOLOGY AND AGRICULTURE 89 



DISEASES OF FRUITS 



Among Apple diseases, the development of Bitter Eot 

 in epidemic form for the first time in nearly 20 years was 

 the outstanding feature of the season. The epidemic 

 ranged throughout the southern third of the state and the 

 area of infestation was limited northward, with the ex- 

 ception of Macoupin county, by a line running east and 

 west along the northern boundary of Clay county. The 

 Black Eot disease, first found June 4 in Jackson county, 

 was less prevalent than usual. Blister Canker was found 

 in its usual abundance in Ben Davis orchards, and Blotch, 

 our most serious apple disease, was found to be extend- 

 ing its range northward in commercial orchards. Apple 

 rust occurred in its usual range in southern Illinois and 

 along the Mississippi river to the Wisconsin border. 

 Heavy infections of Fire Blight were reported on Jona- 

 than, Transparent, Benoni, "Wine Sap, and King David. 

 Powdery Mildew, which requires a relatively dry season 

 for its development, was seen once only. Scab appeared 

 in greater amounts in western Illinois than in the south 

 and central parts of the state. 



Among the diseases of the Pear, Blight was as usual 

 the most important. Brown Eot was seen only in Pike 

 county and Leaf Blight only in Marion, Johnson and 

 Pulaski counties. Scab was serious on both fruit and 

 leaves in Champaign county. An unusual feature was 

 the abundant development of Sooty Mold on pear leaves 

 in southeastern Illinois following the attack of sucking 

 insects. 



On the Quince, Fire Blight appeared in its usual sever- 

 ity throughout the southern two-thirds of the state. Leaf 

 Blight was equally severe but was limited to the southern 

 half of the state. 



Peach diseases were more severe than usual. The 

 bacterial Shot Hole was abundant as far north as Bureau 

 county and Brown Eot as far north as Champaign county. 

 Leaf curl was the cause of severe defoliation through 

 central Illinois in early spring, while Scab, rampant from 

 spray failures, injured a considerable part of the crop in 

 the south. 



