216 The Commercial Apple Industry 



as the buds begin to burst, and the second when the blos- 

 som buds in the cluster begin to separate. (See Plates 

 XI, XIII.) 



IMPORTANT APPLE DISEASES 



Apple-scab (Venturia pomi). 



The scab is probably the most widely distributed and 

 most destructive apple disease. It thrives in cool moist 

 climates and is particularly injurious in western New 

 York, New England and Michigan. Occasionally it 

 causes heavy losses in cool rainy seasons in Illinois and 

 other middle western regions. The Hood River and 

 Rogue River valleys, Oregon, are the only western apple 

 regions which have suffered materially from scab. The 

 fact that severe scab attacks are intermittent and depend 

 largely on the season is likely to cause growers to become 

 careless and an unexpected scab year very often proves 

 disastrous. (See Plate XVI.) 



The disease is evidenced by brown or grayish spots on 

 fruit and leaves. Badly attacked apples may be dwarfed 

 and very often crack open. The disease is spread by 

 means of spores and lives over the winter on fallen leaves. 



Limes-sulfur 1 to 35, in combination with lead or nico- 

 tine if desired, is effective against scab. Applications 

 should be made (1) in the pink just before the blossoms 

 open; (2) in the calyx; and (3) two to three weeks later. 

 The first two sprays are the most important, since the fun- 

 gus becomes active with the starting of growth in the 

 spring. Late applications of lime-sulfur are sometimes 

 necessary in bad seasons. While a three-spray program 

 usually suffices, it does not always serve in seasons when 



