15 



DESTRUCTIVENESS. 



The serious nature of apple blotcli became apparent during the past 

 season in southern Missoin-i and northwestern Arkansas, where 50 to 

 90 per cent of the apple crop was destroyed by it in a large number of 

 orchards. During the month of September an examination of a 

 dozen orchards in Benton County, Ark., showed the following esti- 

 mated percentages of the crops affected by this disease: 



Number of trees and percentage of affected fruit. 



These orchards are located at widely separated points in the county, 

 and the table fairly represents the conditions that obtained in un- 

 sprayed orchards throughout that section. Where the injury ran 

 over 75 per cent of the crop no attempt was made to pick and barrel 

 the fruit. It was usuall}^ shaken off and taken to the evaporators. 

 Practically all of the fruit affected with this disease was unfit for bar- 

 reling, but the larger percentage of it made good evaporator stock. 



The season was unusually wet, which may account in part for this 

 serious outbreak. According to the statements of a number of promi- 

 nent apple growers of Arkansas, the disease has been a serious pest 

 in that State for at least four years, but the severity of the outbreak 

 during the past season is probably unusual. 



DESCRIPTION. 



The disease known as blotch first appears on the surface of the appie 

 as a small irregular brown spot, which slowly increases in size until, 

 after several weeks, it reaches one-fourth to one-half inch in diameter. 

 Although the general outline of the spot is circular the margin is 

 broken and fringed, with a radiating appearance, suggesting the name 

 "blotch." (See fig. 2.) Wlien the diseased area reaches about 

 one-eighth to one-fourth inch in diameter several raised points (fruit- 

 ing bodies) appear at and near the center. These points are dark 

 brown at the apex, shading off into a light brown at the base. As 

 the disease advances these bodies become more numerous, and 

 although arranged somewhat in groups they are scattered rather pro- 

 miscuously over the blotch. In some instances these bodies may 

 uplift the sldn of the apple in such a way as to form drab-colored 

 blisters. The diseased area is rather superficial and slightly depressed 

 and the epidermis becomes very hard. 



283 



