424 FIELD CROPS 



each rain till the vines cover the ground quite completel}^ 

 when the field should be 'laid by" by throwing some earth 

 toward the row at the last cultivation. 



580. Digging. Sweet potatoes should be dug before frost, 

 as they are easily injured. If the vines freeze before they are 

 dug, they should be cut awaj^ at once to prevent the frozen 

 sap from going back into the roots. The potatoes are usually 

 plowed out, a rolling coulter being used to cut the vines. 

 Care should be used in harvesting and marketing to avoid 

 injuiy to the potatoes. The ordinary potato digger is quite 

 Ukely to bruise them, and a bruised sweet potato does not 

 keep long. The potatoes are usually picked up by hand and 

 carried to the packing shed for grading. Those which are to 

 be shipped some distance are generally packed in ventilated 

 barrels, while those which are marketed near by are sold in 

 baskets or crates. For winter storage, a dry room or cellar 

 maintaining a temperature of 35 degrees F. is best. 



581. Uses. Sweet potatoes are ordinarily used as food 

 for man, and may be prepared for the table in manj^ ways. 

 They form one of the principal articles of food throughout 

 the South, where they are much more generally used than 

 are white, or Irish, potatoes. The vines have some slight 

 value as feed for stock, and some of the coarser varieties of 

 potatoes are grown for feeding to hogs and other animals. 

 When these varieties are grown for hog pasture, they are not 

 dug, but the hogs are turned in and allowed to root out the 

 potatoes. While they grow well on this food, the hogs must 

 be given some corn in order to fatten them. 



LABORATORY AND FIELD EXERCISES 



1. Obtain at least 100 potatoes of some standard variety and select 

 from them the 10 that best represent the variety. Compare these with 

 any that show signs of running out as indicated by elongation and 

 pinching up of the seed end. 



2. If possible, obtain a sample of potatoes affected by internal 

 brown rot. Cut open several tubers to become familiar with the effect 

 of the disease and to learn to identify it. 



