214 



Leaf Spots 



There are numerous leaf spots of apple which are of relatively com- 

 mon occurrence but which usually do very little damage. Among those 

 known to be present in Illinois is one caused by C oniothyrium pyriana 

 (Sacc.) Shel., which has been found in Champaign and Ogle counties, 

 and a second caused by Phoinopsis malt Rob., found in Union county. 



The regular spray schedule is sufficient for their control. 



Pear 



Pear, so far as number of trees indicates, is the third most import- 

 ant fruit crop of Illinois. According to the census reports for 192o 

 there were within the state 54, .58.5 pear trees of bearing age. distributed 

 so as to include 21.3 per cent of the farms of the state. Pear culture is. 

 however, on the decline — a fact which is due in no small degree to the 

 serious efifects of the diseases to which it is subject. The number of 

 bearing trees in 1920 was nearly 11,000 less than in 1010. 



Since 1912 the annual production has varied from 100,000 to 603,000 

 bushels valued at $270,000 to $T35,000. The ten-year average from 1012 

 to 1921, inclusive, was 397,000 bushels, for which an average price of 

 $1.24 is estimated, bringing the annual valuation of the crop up to $473,000 

 for that period. 



The distribution of production, in bushels, according to the 1920 

 census, is indicated on Map 54. In general, production is massed in the 

 southwestern half of the state, and here there appear to be three centers: 

 (1) along the Mississippi north of its junction with the Illinois River. 

 including especially Adams and Hancock counties: (2) in the extreme 

 southwestern part of the state, along the Mississippi including especiallv 

 St. Clair, Randolph, Jackson, Union, and Pulaski comities: and (3) an 

 area of concentration practically confined to Marion county. 



According to the data of the 1920 census the most important coun- 

 ties, mentioned in the order of their rank, are Union, Marion. Pulaski, 

 St. Clair, Jackson, Adams, and Hancock. 



Blight 

 Caused by Bacillus amylovonis (Burr.) Trev. 



This disease is the same as the fire-blight of apple and quince. 



The history of pear blight in Illinois is better known than that of 

 any other disease. From discussions in the Transactions of the Illinois 

 Horticultural Society in 1802 it ajijiears that the disease had by that time 

 become wide-spread, generally recognized, and universally feared. For 

 vears it was the subject of nuich (li,scussion at horticultural meetings 

 within the state, and the fear was often expressed that unless .some means 

 of control were discovered it would shortly wipe out every orchard in 

 the state. 



