l94 A Blossom Wilt and Canker of Apjjle Trees 



Nov. 28. The spur bore several Monilia pustules with chains of 

 conidia; the latter were not pulverulent and evidently 

 immature. 

 Jan. 10 (1917). Numerous conspicuous pustules present along 

 the whole length of the spur: conidia more or less 

 pulverulent (a large number becoming free on mounting 

 particles of the pustules in water). 



Although the conidia were obtained when the 

 temperature of the air was below 0° C. many of them 

 germinated within 48 hours, in a drop of water kept 

 at 6° to 8° C. 

 (/) May 5. One flower inoculated of an unbranched spur 2 cm. in 

 length. 

 ,, 16. Flower discoloured to the base of the pedicel. 

 ,, 18. Leaves at the base of the truss drooping. 

 June 2. Bark on the branch cracking immediately above and 

 below the insertion of the spur; a slightly depressed 

 area extended one-quarter round the branch. 

 ., 26. . Canker now extended half round the branch. 

 Oct. 19. The canker had not extended any further round the 

 branch; it was however quite well defined but at this 

 date bore no Monilia pustules. 

 Dec. 1. Immature pustules (conidia not pulverulent) present 



along the whole length of the spur and on the canker. 

 Jan. 10 (1917). Pustules more conspicuous: conidia more or less 

 pulverulent ; many germinated in distilled water within 

 48 hours at 6° to 8^ C. 

 A flower on each of three other trusses was also inoculated ; the 

 three flowers died but became detached about May 20 and the disease 

 did not extend into the axis of the inflorescence. The inoculation of 

 three flowers on May 10 and five on May 11 did not produce any wilting 

 of the trusses and it may be that in these cases the flowers were too old 

 for successful infection, although at the time of inoculation the stigmas 

 appeared receptive and showed no discoloration. These results corre- 

 spond to those obtained in the greenhouse where, as already shown, the 

 inoculations were most successful on those flowers which had recently 

 expanded. 



Tt will be observed that in every case where inoculation with the 

 fungus was followed by the death of the truss, Monilia pustules appeared 

 on the cankers and dead spurs during the succeeding winter. Usually 



