FARMERS' METHODS OF PRODUCING PURE SEEDS 291 



desirable tubers for planting are produced, there are some methods 

 which are of help to him in saving tubers. 



Ordinarily the plants grown from tubers of a single plant 

 are alike except for the occasional changes which occur in the 

 inherited characters of the plant itself. Mixture in commercial 

 tubers is one common cause of lack of purity of type. The selec- 

 tion of tubers, therefore, gives the grower an opportunity to im- 

 prove his variety and also insures a constant supply of tubers free 

 from diseases. This freedom from disease is a very important 

 point (Tolaas and Bisby, 1919). 



The first step of the grower is to obtain the best available 

 variety, true to type and free from disease. After obtaining 

 such a variety, one of the following plans may be followed. Both 

 are alike for the first year's work. 



DIAGRAMMATICAL ILLUSTRATION OF TUBER SEED PLOT SELECTION OF THE 



POTATO 



4M year 

 4th year 



Method I 



Etc. 



Method 11 



