I9(j A Blossom Wilt and Canker of Apple Trees 



the writer has not yet met with such cases eyen on trees seriously 

 affected with Blossom Wilt. 



Apples of the varieties Warner's Kin<>-, Newton Wonder and Bramley's 

 Seedlinfj were inoculated on August 10 and 1 1 by placing mycelium from 

 a plate culture in wounds made with a sterile scalpel. Unfortunately 

 the apples became attacked by ants and all fell to the ground after a 

 few days; the experiments however continued long enough to show 

 that the fungus rapidly produced a brown rot appearing within four 

 days as a discoloured area 1-5 to 3 cm. in diameter round each point 

 of inoculation. 



The experiments were then continued on apples of the Bramley's 

 Seedling variety, which were brought into the laboratory and inoculated 

 with a strain isolated from a canker. The first inoculations of this 

 series were made on Aug. 17 and the experiments were repeated at 

 intervals throughout September and October. For comparison, other 

 apples were inoculated with Monilia fructuiena, using a strain obtained 

 from a plum, and with a hyaline form of M. cinerea also isolated from 

 a plum. In some cases M. friictigena and the canker strain were placed 

 in wounds made on opposite sides of the same apple, while in others 

 the hyaline strain of M. cinerea and the canker form were grown on 

 the same apple. Under these conditions it was found that each of the 

 three forms produced a rot which extended approximately at the same 

 rate for all, i.e. 2-5 to 3-5 from the point of inoculation in seven days. 

 The canker form of Monilia however seldom produced pustules of 

 conidia; on some of the fruit a few scattered tufts of white barren 

 hyphae developed but on others no pustules were produced. On the 

 other hand the strain of M. fructigena used in these experiments freely 

 produced large yellow pustules more or less in concentric circles. The 

 hyaline form of M. cinerea also developed conidia readily but on smaller 

 grey pustules which were usually fairly numerous. 



The skin of those apples inoculated with the canker Monilia rapidly 

 assumed a dark brown shade over the affected area, which gradually 

 became black. This nigrescence was to be detected towards the centre 

 of the discoloured area about a week after inoculation ; it gradually 

 extended over the surface until the whole was black. The other two 

 strains also produced some blackening particularly in the later experi- 

 ments (i.e. on the more mature fruit) but not so readily. These differ- 

 ences were most striking in those cases where two forms were growing 

 together on the same apple by inoculations at opposite sides. For 

 example, two apples were inoculated on Aug. 17 and two others on 



