THE POTATO 129 



is not sure that whole tubers will produce a larger yield 

 than halves. The weight of experience seems to favor 

 planting halves. 



Immature seed. For vitality, high yield and good 

 market qualities, potatoes intended for seed should be har- 

 vested before entirely ripe (by hill selection) ; that is, be- 

 fore the vines have died. Many experiments have shown 

 that immature seed will produce a considerably higher yield 

 than seed allowed to ripen before digging. 



Home-grown seed not always best. Contrary to the 

 rule with most farm crops, seed brought from another 

 region often produces a better crop of potatoes than home- 

 grown seed. Especially is this true when northern grown 

 potatoes are taken farther south. Not only is the yield 

 increased, but the time required for maturing is shortened 

 by securing seed from colder regions. Great care should 

 be taken in importing seed tubers not to introduce new 

 forms of potato diseases. 



5. Potato Enemies 



Potatoes have many enemies, and the number seems to 

 be increasing, owing to diseases being brought in from 

 other countries. 



Scab. Scab is one of the most wide-spread and de- 

 structive of potato diseases. It causes a rough, pitted, 

 scabby condition which may attack the tuber in patches, 

 or extend over the entire surface. Whether scab is caused 

 by a fungous growth or a species of soil bacteria is not 

 certain. It is fortunate, however, that a very simple and 

 effective remedy is known. This consists in treating seed 

 potatoes before planting. 



There are several mixtures used for this purpose; the 

 cheapest and most easily applied is a formalin solution. 



