ROOTS AND TUBERS 233 



305. Time of planting. The Irish potato and the sweet potato 

 are both easily injured by frost. In many sections the earliness 

 of the crop determines the profit, and it is a matter of impor- 

 tance that they be planted at a time which will insure an early 

 crop and yet escape the frost. In the Southern states Irish 

 potatoes are planted for the principal crop from December to 

 February and are harvested and marketed in April or May. In 

 the Central states potatoes are usually planted in March or early 

 in April to supply the July and August market. The principal 



FIG. in. A potato digger 



In potato production, digging the crop is one of the most laborious and costly parts 

 of the work. The use of such machines as that here shown is the least expensive 

 method, when the potatoes are grown in large quantities ; such machines also dig the 

 potatoes with less injury to them, and at the same time put the soil in better condition 

 for subsequent crops 



crop is grown in the Northern states, and is planted as soon 

 as danger from frost is past, and is harvested (Fig. 1 1 1) in the 

 fall before the ground freezes. The yield per acre is larger 

 in the Northern states than in the Southern or Central states, 

 but the acre-value of the crop does not vary widely, because the 

 potatoes that are sold as new potatoes bring a higher price. 



306. The potato. The potato is propagated by means of the 

 tuber, each "eye," or bud, possessing the power, under favorable 

 conditions, of producing a new plant, which in turn stores in the 

 new tubers the plant food prepared by the leaves, Tubers which 



