i66 Bulletin 251. 



larger the number of individuals examined the more likely is he to dis- 

 cover the one producing the maximum yield which will give a valuable 

 new strain. There is no loss in growing the selection-plot aside from the 

 greater amount of time required for the digging so that one should grow a 

 considerable number of plants. 



(3) The planting should be arranged in such a way as to secure a 

 test of the productivity of each tuber. To do this the following method 

 may be recommended. Cut each tuber into four uniform sized pieces 

 making each cut longitudinally so that each piece will contain an equal 

 proportion of the basal end and apical end of the tuber. Plant four hills 

 with each tuber, one piece in a hill. These should be planted consecu- 

 tively in each row beginning at one end, so that starting at that end the 

 first four hills will be from one tuber, the second four hills from another 

 and so on throughout the length of the row. The object in planting this way 

 is so that the four hills can be dug together and the total product weighed to 

 obtain a measure of the productivity of the seed tuber planted. Pro- 

 bably the best way to plant these is to drop the selected tubers one to 

 each four hills and then go over the row and cut each tuber and plant its 

 quota of four hills. The hills in the row should be planted somewhat 

 farther apart than in ordinary planting, probably from 20 to 24 inches. 

 If this is not done a somewhat greater distance than ordinary should be 

 left between each four-hill tuber-unit. The writer would advise that one 

 hill be left unplanted between each four-hill unit. It would doubtless 

 be convenient and desirable to have the plants in rows both ways to 

 facilitate digging. For this selection-plot of potatoes, choose a field of 

 moderately good fertility and as uniform throughout in soil as is possible 

 to obtain. 



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

 exactly the same as you do your ordinary crop. 



How to make tlir selections 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 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 w^hich can be stuck in the ground 

 beside the hills. This field examination while probably important in careful 

 work could ]:)robabl}' be omitted without very great loss, as after all the 

 yield is the primary character. 



Digging the selection-field. — The digging of the field grown for 

 selection purposes requires considerable care, and here hand work is neces- 

 sary. Dig each four-liill unit grown from the same tuber separately. 



