THE MODERN POTATO PROBLEM 227 



vegetative portion of the parent plant, namely, the 

 tuber. Therefore, if the daughter plant is to maintain 

 full vigour the parent tuber, or fraction thereof, must 

 possess and maintain this normal vegetative vigour 

 until it is planted. The growing appreciation of the 

 importance of good vigorous seed stock true to name is 

 one of the most promising developments in modern 

 potato culture. Many factors are now known to in- 

 fluence in varying degrees the vitality of seed tubers, 

 as storage conditions, maturity, repeated sprouting, 

 methods of preparation of tubers for planting, physio- 

 logical and virus diseases, climatic conditions, where and 

 when seed is grown, etc. Important researches con- 

 cerning the vitality of seed stock have yielded infor- 

 mation of great value to potato culture, but there is 

 still need of much careful research. 



The practice of seed inspection and certification is 

 contributing greatly toward the improvement of seed 

 stock. The growers of seed potatoes apply to state 

 officials for inspection of their crop. The inspections 

 are made two or three times while the crop is growing 

 and once after harvest. If the crop comes up to certain 

 standards in respect to freedom from diseases and weak 

 plants, as well as true to type, it is certified. The 

 grower pays a small fee for this service and commands a 

 higher price for the certified product. The grower can 

 afford to pay a higher price for he can then grow more 

 and better potatoes. 



If the tubers have begun to sprout before they are 

 planted, as is frequently the case, the character of the 

 sprout growth is a rough index of seed vitality in many 



