ROOT, TUBER, AND BULB CROPS 97 



growth and save time after the potato is in the ground. 

 Another means of obtaining an early and rapid growth is by 

 placing the tuber-cuttings in moist sand in a warm place 

 until the tops are two or three inches high, when the plants 

 are set out in the field. Such plants grow very rapidly during 

 the first weeks and are much ahead of those resulting from 

 tubers set in the ordinary way. In the northern states, the 

 depth of planting should be about four inches. In the South, 

 it should be greater, especially in light sandy soil. 



Potatoes require a plentiful and even supply of moisture. 

 Should the ground become dry when the plants are partly 

 grown, the growth will be halted, and if it is started again 

 by renewal of the water supply, gnarled and uneven tubers 

 will result. This is one reason why the potato is planted 

 deep. Cultivation to retain the moisture should be frequent. 

 Irrigation is practiced in many of the dry sections of the 

 country. 



Potatoes require an abundance of plant-food. This may 

 be supplied by plowing under a cover-crop, or by the appli- 

 cation of manure, but the material should be thoroughly de- 

 cayed before the potatoes are planted, since otherwise scab 

 and similar diseases are likely to result. For this reason as 

 well as others, it is advisable to rotate crops on potato land, 

 the manure being applied to one of the other crops. If a 

 commercial fertilizer is used, it should contain in most cases 

 the three elements, nitrogen, phosphorus, and potassium. 

 Frequently potassium is the element most needed. 



Potatoes are dug by hand with a fork, or by a machine 

 known as a potato-digger. They are then picked up and 

 stored in cool dark cellars, or buried in pits at a depth 

 sufficient to prevent freezing. Potatoes should not be allowed 

 to stand in the light for any length of time. 



The most common diseases of the potato are blight and 

 scab. Blight may be controlled by spraying with bordeaux 

 mixture at intervals during the growing season. Scab is kept 



