EE) 
COMBATING THE FUNGOID DISEASES oF 
PLANTS. 
By R. A. Biffen, M.A. 
PRESIDENTIAL ADDRESS. 
Ladies and Gentlemen,— 
The subject I have chosen to address you upon this evening 
is the somewhat technical one of the methods at our disposal 
for protecting our cultivated plants from the attacks of para- 
sitic fungi. I have chosen this branch of mycology in the first 
case because it is one with which I have a certain amount of 
practical experience and also because I think that if an 
economic side is given to our work it is likely to prove of more 
general interest than if we confine ourselves solely to the find. 
ing and describing of rare or new species. My work as a 
botanist concerned for the most part with our cultivated crops . 
continually brings me into contact with the problems of plant 
diseases, and I have gradually become convinced that it is one 
of the duties of the mycologist to obtain, as far as possible, a 
knowledge of the life stories of the commoner parasites and 
methods of checking their spread for the benefit of those who 
would save their crops from their devastating influence. 
It has I know been objected that we have no right to attempt 
to upset the balance of nature by limiting the spread of these 
parasites, but the objection loses weight when one recognises 
that the crops we attempt to save cannot be looked upon as 
natural in the same sense as the wild plants of our flora. They 
are grown under conditions which do not occur in nature, and 
left without man’s fostering care they would soon be extinct 
Under such circumstances the risk of upsetting a very proble- 
matical balance is one which does not appeal much to the 
cultivator. 
The subject is essentially a modern one. Though the exist- 
ence of disease in plants was known from the earliest times the 
facts of parasitism were so imperfectly understood that satisfac- 
tory attempts to prevent epidemic outbreaks of any fungus were 
_ practically impossible. With an increase of our knowledge of 
the relationship of host and parasite the possibilities of the sub- 
ject have become evident, and now, when we come to consider 
the shortness of the period involved, it must be admitted that 
we have at our disposal a fair assortment of methods for com 
