18H A Blossom Wilt oinJ Canhcr of Aj/ple Trees 



Woioiiin obtained coiiidia of Monilia cinerea on gelatine cultures pre- 

 pared with apple juice or bread broth: these were tried for the apple 

 blossom Monilia but without success. Nor were conidia produced on 

 bread steamed in test tubes or on pieces of apple branches sterilised in 

 the autoclave. The best results were obtained with semi-cylinders of 

 tubers and roots as potato, artichoke {Helianfhus tuberosum), carrot, 

 mangel and parsnip. The last two produced a trace of conidia, the 

 other three developed conidiophores in scattered tufts, and potato, 

 sterilised either by intermittent steaming (20 minutes at 100° C. for 

 each of three successive days) or in the autoclave for 20 minutes at 

 115° C, was generally used as the medium for cultures used in the 

 inoculation of apple flowers. 



{(i) Inoculation of apple flowers in the Greenhouse. 



For this experiment young apple trees about three feet in height 

 were acquired; for convenience they were planted in pots early in the 

 year (1916) and left outside until the* fruit buds showed the first signs 

 of expanding. The pots were then transferred to the greenhouse, with 

 the result that the earliest flowers were fully expanded during the first 

 week in April. 



Conidia for the inoculations were taken from cultures, about seven 

 days old, on steamed potato (in one instance a culture on steamed 

 carrot was used). They were removed from the culture tube and placed 

 on the stigmas of the flower by means of a sterilised platinum needle, 

 which was re-sterilised in the flame of a spirit Jamp after each inoculation. 

 One flower was successfully inoculated by inserting the needle between 

 the stamens and the styles so that the conidia were deposited at the 

 base of the styles, but this method was not generally adopted as usually 

 there was no space between the filaments for the insertion of conidia 

 within the hollow receptacle of the flower.' 



One flower only of each inflorescence was inoculated, and of twenty- 

 four flowers thus treated thirteen not only withered but produced a 

 wilting of the trusses to which they belonged. The results obtained on 

 the four varieties tested were as here shown ; in one column appears 



No. of flowers No. of sucnessful 



Variety inoculated inoculations 



Prince Bismarck 9 7 



Lord Derby 4 2 



Cox's Orange Pippin .5 2 



Worcester Pearmain 6 2 



Totals 24 13 



