LIFE HISTORY OF THE FUNGUS. 13 



Moderately affected. — Oldenburg, Benoni, Arkansas. Bradford. In- 

 gram, Collins. Minkler. Kambo, and Golden Russet. 



Slightly or not at all affected. — Grimes. Winesap, Jonathan, York 

 Imperial, and Red Reese. 



In addition to those mentioned in the above list the Avriters have 

 observed the blotch in various sections on the following varieties: 

 Sherman. Shannon. Arkansas Pippin, Bough. Baldwin. White Pear- 

 main. Yellow Newtown, Smokehouse, and Northern Spy; also on the 

 wild crab apple (Pints corona ria) in Pennsylvania. 



CAUSE OF THE DISEASE. 



The apple-blotch disease is caused by a fungus belonging to the 

 genus Phyllosticta. Clinton," in 1902. after having submitted speci- 

 mens of this fungus to both Ellis and Peck, concluded that it was 

 a new species. However, in 1907 Sheldon a identified it^as Phyllos- 

 ticta solitaria E. & E.. which was described in 1895 6 on leaves of 

 the wild crab apple (Pirns coronaria L.). Sheldon did not examine 

 the type specimens, but found that the spores of the apple-blotch 

 fungus, on the wild crab as well as on the common apple, agreed with 

 Ellis and Everhart's description. 



Through the kindness of Dr. W. A. Murrill, assistant director of 

 the Xew York Botanical Gardens, the writers were able to examine 

 the type collection of Phyllosticta solitaria, and found that the 

 spores were practically identical with those of the apple-blotch 

 fungus (PL III, fig. 5) and that the spots on the leaves were of the 

 same character as those described above on the leaves of the common 

 apple. 



LIFE HISTORY OF THE FUNGUS. 



In 1906. when the writers first began to study the apple-blotch dis- 

 ease, very little was known of the fungus causing it. It was supposed 

 that this fungus lived over winter in the fruits mummified by the 

 disease and that these mummies furnished the source of infection 

 for the new crop. An examination of a large number of such dis- 

 eased fruits revealed so few spores that they could not be considered 

 an important source of infection. The fungus evidently does live 

 over winter in the mummied fruits and in the spring makes an abor- 

 tive attempt to produce either perithecia or pyenidia. but as yet no 

 ascospores and but few pyenospores have been obtained from this 

 source. It was necessary, therefore, to look elsewhere for the source 

 of spring infection. 



" Loe. cit. 



b Ellis and Everhart, Proceedings of Academy of Natural Sciences of Phila- 

 delphia, 1895, p. 430. 



144 



