182 A Blossom Wilt and Canker of Apple Trees 



available it seemed probable that M. fructigena and M. cinerea of the 

 Continent were present on our own fruit trees. When it was found that 

 cultural methods were a great aid not only in distinguishing M. fructigena 

 from the grey Monilias, but could also be employed for the recognition 

 of certain forms among the latter, efforts were made to obtain strains 

 of the Brown Rot fungi from the Continent. 



To the time of writing I have only succeeded in obtaining specimens 

 from Holland, Dr H. M. Quanjer of the Instituut voor Phytopathologie, 

 Wageningen, having on several occasions kindly forwarded mummified 

 fruit. The fungus usually present on such material was a yellow one, in 

 cultures indistinguishable from the yellow form of England, and there 

 can be no doubt that this is Monilia fructigena Pers. One strain from 

 these specimens was obtained from a mummified pear received in March 

 1916. Conidia were fairly numerous and on the average measured 

 19-5 X 9-5/x, dimensions which are greater than the average size of 

 conidia from grey Monilias in winter ; these conidia failed to germinate 

 when placed on agar so evidently they had not survived the winter. 

 Particles of a pustule were teased out in sterilised water and placed on 

 a prune agar plate ; these grew out but were impure. More successful 

 results were obtained by cleansing a portion of the skin with cotton- 

 wool soaked with 94 % alcohol, then, raising a portion of this sterile 

 skin with a scalpel, particles of the pulp were removed and placed on 

 an agar plate. The resulting culture was apparently pure ; sub-cultures 

 on potato yielded conidia and the isolation of some of these afforded 

 pure sporelings. Sub-cultures from the sporelings were then grown for 

 comparison with other strains of M. fructigena and no appreciable 

 difference has been detected either in the mode of growth or coloration ; 

 on potato the average size of the conidia was 2f-0 x 12-5/x. 



One batch of fruit from Dr Quanjer received early in January 1917 

 included plums bearing grey Monilia pustules with viable conidia and 

 a strain was isolated from each of two of the plums. Conidia, taken 

 from the plums as received, and later obtained from potato cultures, 

 were measured and their dimensions found to be as follows: 



Average of 100 conidia in each case 



From mummied plums From potato culture 

 Grey MnniJin from Holland, Strain 1 ll-.') x S^a 16-.'j x 12-.'>/it 



„ 2 ll-O X 7m 16-0 X 120m 



It will be seen that these figures approximate closely to those obtained, 

 under corresponding conditions, from strains found on plums grown in 



