1911-12.] BOTANICAL SOCIETY OF EDINBURGH 9 



rnent in dealing with it. He found the disease to be far 

 more prevalent in Newfoundland than was supposed, and. 

 needless to say, preventive measures have been put in 

 operation by the Canadian Government to prevent the 

 introduction of this disease to Canada. We can only form 

 conjectures as to what would have been the result had 

 this disease appeared forty or fifty years ago. Although 

 it had not actually become epidemic, still we have every 

 reason to suppose that in time it would have become epi- 

 demic if preventive measures had not been adopted as the 

 result of timely warning. An epidemic of Black Scab 

 would no doubt be much more severe than was the epi- 

 demic caused by Phytophthora infestans. The resting 

 spores of the Black Scab fungus are extremely resisting 

 to drought, and may remain capable of causing infection 

 although kept in a very dry state for years. The disease 

 itself is not influenced by varying seasonal conditions, such 

 as wet and dry seasons. Hence, if it had been allowed to 

 get the upper hand, its virulence would have been very 

 severe. Who knows but that the disease may have been 

 imported from this country to Newfoundland, and who 

 knows what other British dependencies may not have been 

 similarly laid open to the risk of infection ? In any case, 

 it is essential that all the resources of science should be 

 employed to stamp out any new disease directly it appears. 



Owing to the increased and more rapid import and export 

 of plants and plant products (seeds, fruits, tubers, etc.) 

 there is an increased danger of their attendant diseases 

 being spread all over the world. In connection with disease 

 of forest trees, I pointed out in a paper 1 dealing with 

 the liability of the occidental and Japanese larches to be 

 attacked by Peziza Wittkommii that: "As regards the in- 

 troduction of exotics which are intended to be grown as 

 timber -producing trees, certain objects must be kept in 

 view. For example, an exotic is worthy of cultivation in 

 our forests — 



" Firstly, if it is of a species at present unrepresented and 

 capable of producing timber of utility, or if it possesses 



1 "Peziza WiWcommii, R.H.. on Larix occidentalis, Nutt., and Larva 



leptolepis, Gord.,*' published in " Notes from the Royal Botanic Garden, 

 Edinburgh. No. xxi ., August 191 '.'. " 



