AN ALTERNARIA IN APPLE SPOTS 



introduction 



The twenty-five apples on which this work is based 

 came from Harristown, Illinois, early in July, and therefore 

 were not nearly mature. The spots were in various stages of de- 

 velopment, making it possible to study the probable progress of 

 the disease. Nothing is known of the conditions under which 

 they grew, nor of the time the infection started. 



Descri pt ion 



There is no apple disease which causes a more charac- 

 teristic spot on the fruit than this one. It is striking in its 

 early stages^ due to the decided color change; and in the later 

 ones to the distinct margin as well as the darkened skin and 

 tissue. The fruit is not rotted or softened. The outer skin of 

 the diseased portion is tough like leather, and is difficult to 

 cut through. Only a few millimeters beneath the skin are in- 

 jured. The disease is not destructive to a large part of the 

 fruit, but it is very unsightly, and would decrease salability 

 to a great degree. 



Apple No. 1 (See Table I) was considered to be in the 

 earliest stage of the disease. An idea of its condition may be 

 gotten from Plate II, No. 1. There was no softening of the tissue 

 or change in the size or shape of the fruit. The color was the 

 only indication of any disease. The apple, which was clear green 



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