New York Agricultueal Experiment Station. 349 



as they occur on the hosts under consideration. Those on apple 

 and Japanese plum trees are the only ones where the average 

 length is noticeably greater than the rest in the list. Cultures of 

 Sphaeropsis from either apple or Japanese plum trees when inocu- 

 lated into apple, pear, or quince fruits produce black rot and as is 

 shown in Table II these cultures grow interchangeably on at least 

 four species of trees. In each instance the fruiting bodies result- 

 ing from the cross inoculations have the same characters as those 

 that occur on the trees naturally. 



Since cultures oi'Sphaeropses from the different hosts produce 

 black rot of fruit, one apparently as readily as another, it was to 

 be expected that the different cultures would make similar growths 

 when cross inoculations were made in the trees. Accordingly, 

 apple, pear, plum, cherry, and quince nursery trees were planted 

 in a plat on the Station grounds for inoculation experiments. 



Dilution plate cultures were made of the Sphaeropses from the 

 different hosts and after spores formed, transfers were made to 

 sterilized bean stems in test tubes. The inoculations were made 

 by making a small incision in the bark with a flamed knife and 

 inserting some of the pure cultures of the fungus from the test 

 tubes bet^^'een the bark and wood; then the wounds were covered 

 with grafting wax. The work was done the last of May and first 

 of June. 



Table II gives the plan of the experiment together with the 

 results; and shows: (1) Kind and number of trees inoculated 

 and number of inoculations made in each tree; (2) source of cul- 

 tures with which inoculations were made; (3) growth of fungus 

 where inoculated. 



