228 



NOTE ON DR J. SMOLAK'S PAPER "A CONTRI- 

 BUTION TO OUR KNOWLEDGE OF SILVER- 

 LEAF DISEASE." 



(Annals of Applied Biology, July, 1915.) 



In reading Dr Srnolak's interesting paper I gather that he does 

 not fully understand my views on Silver-leaf disease. As his presentation 

 of my views may lead to misunderstanding, I wish to take this oppor- 

 tunity of correcting any misapprehension that may arise. 



On page 154 of his paper the following statement occurs : " According 

 to the investigations of..... Brooks the basidiomycete Stereum pur-> 

 pureum is the cause of Silver-leaf disease as was shown by successful 

 inoculation experiments/' the investigations referred to being those 

 described in the Journal of Agricultural Science for June. 1913. This 

 statement does not agree with my own deductions from these investiga- 

 tions which were expressed in that paper in the following words: 



"In a previous paper (Journal of Agricultural Science, 1911) 



I pointed out it would be rash to say that Stereum pur- 



pureum was the only cause of Silver-leaf. Recent investigations 

 have strengthened this view, for specimens of silvered foliage have 

 been seen which I am unable to attribute to the action of Stereum 

 purpureum" (page 288). 



"....silvering of foliage is a widespread phenomenon which is 

 probably induced by various means, the chief one of which in 

 the fruit-growing districts of this country being the fungus Stereum 

 purpureum " (page 288). 



"It has been shown that Silver-leaf is a pathological condition 

 of widespread distribution, the chief cause of the malady in the 

 fruit plantations of this country being the fungus Stereum pur- 

 pureum Examples of silvered foliage have, however, come 



under observation which, in my opinion, cannot be attributed to 

 the action of Stereum purpureum. It is unlikely that the silvering 

 of the leaves of seedling Plums and of such a plant as the White 



