Methods of Breeding and Improving the Potato Crop. 581 



(4) Manure and cultivate the plot of potatoes grown for selection 

 just the same as you do your ordinary crop. 



How to Make the Selection of Potatoes 



Field Examination. A careful examination of the selection field 

 should be made as the vines begin to mature and while they are yet 



Fig. 2. — Four-hill tuber-nnits of Burpee's Extra Early potato grown side by side 

 from original tubers of about same size. On right, very low yielding progeny; on 

 left, good yielding progeny of well-shaped tubers. 



green. This examination should include observations on diseases and 

 vigor of the tops. If there are any marked differences apparent between 

 the different four-hill units, those with the best appearing, most healthy 

 tops should be marked by small stakes which can be stuck in the ground 

 beside the hills. This field examination, while important in careful work, 

 probably could be omitted without ver}^ great loss, as after all the yield 

 is the primary character. 



