ORCHARD CARE 155 



nuts quite as seriously as the chestnuts were threat- 

 ened by Endothia, but the time required for the 

 death of a tree is very much longer. Many years 

 elapse before the butternut finally succumbs. Melan- 

 conium is also attacking the Japanese walnut, and 

 at the present writing we do not know what its de- 

 structive range may be in trees of the walnut group. 

 It was described by Mr. Arthur H. Graves, of the 

 United States Department of Agriculture, who be- 

 lieves that it has been with us for at least fifty years. 

 The word "blight" is a convenient term relating 

 to fungous and bacterial microbes. Parasitic blights 

 which are carried from one country to another are 

 particularly disastrous in new surroundings. The 

 reason for that is that any given blight in its natural 

 habitat has survived in competition with hosts which 

 have learned to resist it by processes of selection in 

 evolution, including help given by natural enemies. 

 When a blight finds itself among new surroundings, 

 on the other hand, it meets hosts which have not 

 learned how to protect themselves in any course of 

 long struggle. Excellent examples of this are the 

 hazel blight, Cryptosporella anomala, and the chest- 

 nut blight, Endothia parasitic a. The hazel blight 

 makes little headway among our native hazels and 

 injures very few plants excepting those which have 

 been weakened by age or by accident. When the 

 European or Asiatic hazels are brought to this coun- 

 try, however, they are often attacked so violently that 

 extensive culture of foreign hazels was practically 

 prevented for many years in some localities. We 



