60 



The Potato 



If the first work of breeding consists of separating out 

 pure lines and if there is very slow progress within these 

 lines, it is obvious that the choice of individuals for 

 planting the first few years is all-important. As large 

 fields as possible should be grown to give opportunity 

 for all of the best plants to appear. 



Number 

 diseased 

 tubers 

 to row 



Fig. 8. Potato yields. Diagrams showing variation in yield of in- 

 dividual rows of potatoes grown on special seed plots in 1909. (Carman 

 No. 1, by R. H. Crosby, Markham, Ont.) 



Until recently, the method of selection has been to 

 choose from the potato bins in the spring the requisite 

 amount of seed, using tubers having the desired size and 

 shape but without knowledge of whether they came from 

 high yielding strains or not. This method of choosing 

 seed from year to year, using merely the best tubers 



