THE POTATO 



121 



reach the tubers and cause the rot. The fungus once 

 having gained entrance to the tubers, may or may not 

 vegetate rapidly. Its presence, however, is soon m^ade 

 evident by a browning of the flesh underlying the skin, 

 and by more or less extensive discoloration and de- 

 pression of the latter." When such affected tubers 

 are planted, the disease is very likely to develop in the 

 plants from them. 



The Early i^light appears early in summer in 

 the shape of small brown, brittle spots, scattered over 

 the leaf. Careful inspection shows that their upper 

 surfaces are more or less roughened by darker areas 

 rising above the dead gray tissue. The spots grad- 

 ually enlarge, and finally run together to form large 

 brown patches, the intermediate tissues becoming 

 yellow or sickly green in color. . The entire plant 

 finally withers, and dies long before the proper period, 

 the tubers being small — generally less than half full 

 size. But the tubers do not rot and are of fair quality. 

 This fungus has proven difficult to study in the field, 



a 



