62 Bacterial Blujht of Pear BlosmniH in South Africa 



or the whole inflorescence was atomised with a suspension of an agar 

 culture in distilled water. 



When either of the first two methods was employed a number of 

 minute water-soaked spots appeared on the receptacle in 24 — 48 hours, 

 or, in the case of a heavy infection the whole receptacle became water- 

 soaked in appearance. 



The infected areas soon began to turn brown and spread until the 

 whole receptacle was involved. The receptacle was finally quite black, 

 the blackening not infrequently spreading into the styles, ovaries and 

 peduncle ; and the slightest movement was sufficient to cause the 

 infected flowers to fall. 



When the inflorescence was atomised, infection was equally prompt, 

 discoloured areas appearing on the sepals, petals, ovary and peduncles. 

 In no case have I been able to infect the leaves or fruit spurs, and I have 

 not observed any such infections in the orchards. 



All inoculations were carried out in the Laboratory under conditions 

 similar to those employed during the preliminary experiment carried 

 out in 1915; a schedule of the inoculations is appended. 



It will be noticed that positive results were obtained in each case 

 when pear and apple blossoms were inoculated, but that attempts to 

 infect cherry, peach and nectarine were all unsuccessful. Up to the 

 present no natural infections on the apple have been found. 



In each experiment an equal number of flowering branches were 

 kept as controls ; and in no case did the disease appear in these. 



