200 Silver-Leaf Duease, IT J 



wise the leaves of another branch somewhat lower. At the same time 

 the end of the main stem was gumming. Silvering spread only slightly 

 during the summer. 



(11) As in (8) but kept as a control. On May 13th no silvering was 

 apparent although the end of the stem was gumming; silvering did not 

 develop later in the year. 



Thus, apart from the control experiment, only three of the other 

 moculationj failed to be followed by silvering. Each of the three inocu- 

 lations carried out under conditions as sterile as possible, resulted in 

 silvering although in one of them it was not the branch nearest the 

 place of inoculation that became affected. In view of the experiments 

 described below in regard to the cutting back of young plum trees 

 without subsequent inoculation and which always remained healthy it 

 is difficult not to connect the development of silver-leaf in the above 

 trees with inoculation by spores of Stereuin furfureum. Tree (No. 1) 

 was cut down to the ground after the autumn of 1914 and the main 

 stem was found to contain extensive discoloured zones of wood down 

 to the base. Another feature of these experiments is the apparent lack 

 of protection afforded by tar after exposure to the weather for two or 

 three months. 



Another series of experiments of the same kind was carried out 

 during the winter of 1914-15. 



The following are the details : 



(1) The main stem of a bush Victoria, 4-5 years old, was cut back 

 on November 20th, 1914, the surface being made smooth with a knife. 

 On April 19th. 1915, a sporophore of Stereuhi purpiiream from a silvered 

 plum tree was suspended over the cut surface and covered with a tube 

 as in the experiments of the previousyear. The fungus was removed a 

 few days later and the tube replaced. 



Silvering did not develop during the following summer. 



(2) As in (I). No silvering. 



(3) Asin(l). No silvering. 



(4) Asin(l). No silvering. 



(5) As in (1), but the cut surface was covered with white paint. 

 No silvering. 



(6) As in (5). 



(7) As in (1), but the cut surface was covered with Stockholm tar. 

 No silvering. 



(8) As in (7), but the cut surface was covered with Stockholm tar. 

 No silvering. 



