New York Agricultural Experiment Station. 347 



fruit. The decay progresses rapidly in the ripe fruit; in some 

 instances the greater portion of the surface became brown, and 

 mature spores of the fungus were formed in six days. 



In the spring of 1899 a Sphaeropsis was found on dead and 

 dying Japanese plum trees at Kiverhead, IST. Y. Cultures were 

 made of the fungus, and apple, pear, and quince fruits were 

 inoculated. Black rot was again produced in the inoculated fruit 

 while the check fruits remained sound. 



These results led to an investigation of the local distribution of 

 the genus Sphaeropsis, when it was found to be widely distributed ; 

 as the list of host plants given in Tables I and II will show. 

 Cultures were made of the Sphaeropses from each host and apple, 

 pear, and quince fruits were inoculated with cultures from each so 

 far as the supply of fruit would permit. Three fruits at least, and 

 in a majority of instances six, were inoculated with cultures from 

 each host. Black rot was readily produced in the fruits, there 

 being apparently no difference in the effect of the Sphaeropses as 

 obtained from the different hosts. The inoculated fruits as well 

 as the cheeks were kept in closed glass pars, as before. 



During the progress of the work it was noticed that in most 

 cases there was but little difference in the average size of the 

 spores as they occurred on the different hosts. It was also found 

 that when apple, pear, or quince fruits were inoculated with 

 cultures of Sphaeropsis from these hosts the resulting spores were 

 larger and of the size of those found on fruits attacked by black 

 rot. The series of spore measurements given in the table below 

 was made to show the relation of the average size of the spores 

 to the host on which they are grown. Since spores of Sphaeropsis 

 as they occur on any host vary greatly in size, even in the same 

 pycnidium, an average of fifty measurements was taken in each 

 instance. 



Table I gives: (1) A list of hosts from which cultures of 

 Sphaeropsis were made; (2) average length of 50 spores as they 

 occur on the hosts; (3) average length of 50 spores as they occur 



