THE POTATO 313 



The Seed. — The potato thrives in a relatively cold climate and loses 

 vigor when grown during midsummer in warm latitudes. The best seed is 

 obtained from our northernmost states, grown in midsummer, or from more 

 southern states when grown in the cool months of autumn. As a rule, the 

 northern seed is preferred, partly because it is in abundant supply. 



Successful growers prefer potatoes of marketable size for planting. 

 The tubers are enlarged underground stems, and their vitality may be 

 measured by that of the vines which produce them. A small potato, known 

 as a second, may have been set late by a vine of strong vitality which 

 produced also a big crop of merchantable tubers. In that case the small 

 potato makes fairly good seed, and would be just as desirable as a section 

 of a large potato if it did not put out any more sprouts than the cut portion 

 of a large tuber. On the other hand, many seconds are small because the 

 vines producing them lacked in vitality. Experience has taught that 

 growers depending upon seconds soon have a large percentage of plants 

 that lack full productive power. Potato yields in the warmer latitudes of 

 the Northern states are kept low by the use of home-grown seed which 

 necessarily has had vitality impaired. 



The amount of seed per acre depends somewhat upon variety, but 

 relatively heavy seeding is profitable. The grower wants sufficient foliage 

 to cover and shade the soil thoroughly, and ordinarily, that requires the 

 use of thirteen or fourteen bushels of seed per acre. The seed piece should 

 be a block of potato sufficiently large to average two eyes to the piece. The 

 size of the seed piece is important in insuring a good stand, and the cutting 

 should be related more to size of the piece than to number of eyes. In some 

 instances there will be only one bud which may produce two or three good 

 stalks, and in other cases a seed piece of right size may have three eyes. 

 Close cutting and any skimping of the amount of seed result in loss under 

 ordinary conditions, however successful they may be in a very fine and 

 fertile soil having the right amount of moisture immediately after planting. 



Fertilization. — Large areas of sandy loams are planted with potatoes 

 because they have right physical condition and partly because they mature 

 a crop early in the season. Sandy soils are badly deficient in potash, and it 

 has come about that most growers think of the potato as a plant requiring 

 unusually heavy applications of potash. Manufacturers of fertilizers have 

 fostered this idea, but the results of careful experiments have shown within 

 recent years that phosphoric acid should be the controlling element in the 

 potato fertilizer, just as it is in the fertilizer for corn and most other staple 

 crops. In normal soils of great natural strength no commercial fertilizer 

 may be used, but when need first develops, phosphoric acid is the require- 

 ment. This occurs even where clover and stable manure are freely used. 

 Commercial growers, as a rule, make no use of stable manure direct to 

 potatoes, as it furnishes ideal conditions for the development of disease, 

 and especially of the scab. In the case of naturally fertile land the manure 

 applied for corn and the legumes in the rotation may furnish the most of 



