30 THE SCOTTISH BOTANICAL REVIEW 
this disease was found in England by Professor M. C. Potter, and 
year by year it spread round the originally affected area, and also 
appeared in more distant localities, till centres of infection were 
reported from all over the country. In Ig908 it was scheduled 
under the Destructive Insect and Pest Act as a notifiable disease. 
It is to be hoped that this may be effective in checking its further 
spread in this country. About two years ago this same disease was 
discovered by G. H. Gussow in Newfoundland. In connection 
with the outbreak, Mr. Gussow was sent by the Department of 
Agriculture of Canada to investigate the origin of the disease, and 
assist and advise the Newfoundland Government 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 con- 
jectures as to what would have been the result had this disease 
appeared forty or fifty years ago. Although it bad not actually 
become epidemic, still we have every reason to suppose that in 
time it would have become epidemic 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 
epidemic 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! 
dealing with the liability of the occidental and Japanese larches to 
be attacked by Pesiza Wil/kommii that: ‘ As regards the introduction 
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 advantages as 
regards rate of growth, and is less exacting as regards soil and 
climate. ; 
1“ Peziza Willkommit, R.H., on Laréx occidentalis, Nutt., and Larzx leptolepis, 
Gord.,” published in ‘‘ Notes from the Royal Botanic Garden, Edinburgh, 
No. xxi., August 1909.” 
