REPORT OF THE SOCIETY 59 



SOME POTATO PROBLEMS 



P. R. Cowan, Division of Botany, C. E. F., Ottawa 



Little does the average man realize the vastness of the potato industry 

 in Canada, where potato culture is still in its infancy. From statistics 

 for the years 1914-16 we find the value of the potato crops ranks high in 

 the Dominion. In 1914 Canada produced some 853^ millions of bushels 

 of potatoes which valued at 49 cents per bushel gave a return of $41,598,000; 

 whereas in 1915 the estimated crop of Canada was only 62M millions 

 which valued at 57 cents per bushel gave a return of $35,964,000. Those 

 amongst us who have had anything to do with the buying of potatoes this 

 year know that the price is away above the average price, which for 

 the last five years averages at 49 cents per bushel. So bearing this deficit 

 in production in mind I intend to put before you some of the problems that 

 have influenced this. 



The chief cause of the deficit I think may be largely laid to the door 

 of disease, so as time will not permit more I shall only deal with this cause 

 this afternoon. 



Susceptibility to Disease. 



At the present time very little is known about resistance of varieties 

 to disease. I think one of the greatest reasons for lack of knowledge is due 

 to the over-whelming numbers of varieties we have grown in North America. 

 As a rough estimate I would say that there are at least 2,000 varieties 

 known in Canada and the States. We have at the present time one or two 

 varieties that are resistant to one or two diseases but more or less 

 susceptible to others. As a rule the earlier varieties are subject to 

 Late Blight, and the later one more resistant to Late Blight. Resis- 

 tance to disease is usually associated with stiff upright woody stems, small 

 firm hairy leaves and dense foliage. Again, a potato that is resistant to 

 disease in one locality may not be resistant in another locality. I cannot 

 give you actual data for this statement, but in the course of discussion 

 with Mr. Davis, Assistant Horticulturist at Ottawa, we came to the con- 

 clusion that notes taken on varieties in N. B., did not show the same results 

 as at Ottawa, although the seed was originally from the same source. This 

 is further borne out by experiments in England with Canker resistant 

 varieties. Change of locality and climate seem to alter the resistant quality 

 of varieties. 



