102 A Blossom Wilt ami Conlvr (^f Apple Trees 



Jan. 9 (1917). Numerous conspicuous pustules were present along 

 the canker and on the infected spurs; the conidia were 

 more or less pulverulent and a considerable number became 

 free on mounting in water. Such conidia were viable for 

 many of them germinated within 48 hours in distilled water 

 at a temperature of 6° to 8° C. 



(h) Inoculation of apple flowers in the Plantation. 



The experiments carried out in the greenhouse furnished definite 

 proof that the fungus is a true parasite under favourable circumstances. 

 It was desirable however that similar experiments should be performed 

 in the plantation in order to obtain evidence that the disease could be 

 induced in a similar manner on trees growing in the open. 



Early in May 1916 inoculations of apple flowers in the plantation 

 were made for comparison with the results obtained under glass. The 

 flowers of the variety Warner's King began to open about May 1 and 

 as this variety was known to be susceptible to the disease it was selected 

 for the experiments. 



As before, the conidia were obtained from cultures, about a week 

 old, growing on steamed potato, but the method adopted in the actual 

 inoculation of the blossoms was slightly modified, in order to avoid any 

 injury to the stigmas that might occur when using the platinum wire 

 in transferring the conidia from the cultures. The steamed potato, 

 with the fungus, was removed from the culture tubes (using sterilised 

 instruments) and placed in sterilised petri dishes; small portions 

 bearing tufts of conidiophores were cut off with flamed scalpels and 

 placed in another sterile petri dish which was taken direct to the 

 plantation. In each case only one flower of each truss was inoculated 

 and the inoculation was made by removing from the dish, on the point 

 of a sterile needle, a particle of potato bearing conidiophores and bring- 

 ing the conidia in direct contact with the stigmatic surfaces, so that the 

 needle itself in no case touched the stigmas. The selected flower of 

 the truss was marked, for identification and comparison with the rest, 

 by a few inches of white cotton tied leosely round the flower. 



Variety Warner's King. 



Results of inoculations : 

 («) May 5. One flower of a truss inoculated on the stigmas. 



,, 11. One style of the inoculated flower brown to the base. 

 ,, 18, The stamens of this flower had collapsed, while those of 



