Diseases and Pests of the Apple and Their Control 217 



spore development is particularly favorable. Only those 

 growers who make two and even three late sprays are able 

 to produce reasonably clean fruit under such conditions. 



Apple-blotch (Phyllosticta solitaria). 



This is essentially a middle western apple disease, being 

 particularly injurious in southern Illinois and Indiana, 

 in the Ozarks, southern Kansas and occasionally in the 

 Missouri River region about St. Joseph. Most susceptible 

 varieties in these states are Missouri Pippin, Northwest 

 Greening and Ben Davis. 



The disease attacks the fruit, leaves and twigs, wintering 

 over in twig cankers. Injury to the fruit is most serious 

 and appears in the form of hard roughened brown spots, 

 irregular in shape and sometimes sunken. Three-cornered 

 cracks in the fruit are characteristic of the disease. 



Bordeaux mixture (3-4-50) is considered most effective 

 against apple-blotch, and lime-sulfur (1-35) in a lesser 

 degree. The latter with the calyx spray and three Bor- 

 deaux sprays at intervals of about three weeks, begin- 

 ning two to three weeks after the petals fall, is recom- 

 mended as an effective program against severe apple- 

 blotch. The first Bordeaux spray is most important. 



Sooty-blotch and fly-speck (Leptothyrium pomi). 



This disease does not penetrate the skin, but detracts 

 greatly from the appearance of the fruit. It appears in 

 two manifestations, the former in large sooty blotches and 

 the latter as minute black spots on the skin of the apple. 

 These diseases are usually controlled by the regular sum- 

 mer fungicides. (See Plate XVI.) 



