way and hoping that each year the number of co-operators will be increased, and 

 consequently make the survey more extensive. 



Most of the advantages to be derived from a well-organised plant disease 

 survey would be familiar to you, but I am going to rapidly review them, so that 

 later they may suggest to you points for discussion. 



1. The rendering of assistance of fundamental importance to plant patholo- 

 gists in their investigation work by: 



(a) placing at their disposal information demonstrating the problems re- 

 quiring the greatest attention, and 



(b) supplying such information as prevalence, geographical distribution and 

 severity, and so placing the chosen problem on a broad basis from which 

 to build up lines of research. 



2. An annual report by itself has considerable use, but its full value cannot 

 be realised until it has become one of a series, recording year by year the fluct- 

 uations in amount and destructivenesse of any disease in accordance with changes 

 of temperature, soil, moisture, etc., so adding to our scant knowledge of environ- 

 ment in relation to disease infestation and the possibility of being able to predict 

 an epidemic through knowledge of the weather conditions found to be most 

 favourable to an outbreak, together with the experience of former years as to 

 the time of year when such an infestation may be expected. 



Careful accumulation of data on epidemics would also lead to a better un- 

 derstanding of the conditions infkiencing the development, spread and control of 

 such outbreaks. 



3. It gives everyone the benefit of the experience of others on the resistance 

 or susceptibility of certain varieties. 



4. It disseminates results derived from various methods of control. 



5. A record of the appearance of new diseases or the possible introduction 

 of others from other countries is of extreme importance. 



6. An organised survey would be a means of collecting information about 

 any disease requiring immediate attention. 



7. Last, but one of the most important, the education of the public to the 

 importance of plant disease investigation by the published account of losses sus- 

 tained from various diseases, and thereby assisting the plant pathologist to get 

 recognition of his work. 



The record of the presence of a disease is as important as the amount of ma- 

 terial damage incurred. Positive figures are always extraordinarily difficult to 

 ■obtain, but this does not matter so much j)rovided that figures or terms are used 

 which are comparable and always represent a similar standard. That is. "severe" 

 or "20Y<r reduction of yield" in Alberta should be exactly comparable to "severe" 

 or "207c reduction of yield" in New Brunswick. It will take several years to 

 determine which will be the best method of estimating losses and recording data, 

 but this year the survey would have to be planned in such a way as would permit 

 of the results being compared with the same data gathered by the United States 



