164 AGRICULTURE 



keep down weeds and to check the evaporation of moisture. 

 If the beds are thrown up very high, they dry out rapidly 

 and make the crop smaller. Several diseases attack sweet 

 potatoes, and the germs that cause them remain in the soil. 

 Hence sweet potatoes ought not to be grown on the land 

 where a diseased crop grew the year before. 



Storing. Sweet potatoes must be dug before frost or 

 immediately after the first frost. The utmost care should 

 be taken in handling them to prevent bruises. Cuts and 

 bruises admit germs, which cause rotting. 



Sweet potatoes are generally stored in banks under 

 shelter. They are heaped on straw or leaves on a well- 

 drained spot. Straw, hay, or corn stalks are placed in a 

 thin layer around the heap. A covering of earth nearly 

 to the top of the pile is then put on, leaving the extreme 

 top of the pile uncovered with earth for better ventilation. 

 When freezing weather threatens, the top of the pile 

 should be covered more completely. 



A house built for the purpose of storing is more satis- 

 factory for large amounts of sweet potatoes. It should 

 have double walls, filled in with sawdust. There should be 

 slatted bins, open on all sides, ventilators for the house, 

 and a stove for heating and drying the air when needed. 



EXERCISE. Examine an Irish and a sweet potato. Do the roots 

 extend through and beyond the sweet potato? Beyond the Irish potato? 

 Which of these is a true root? 



NOTE TO THE TEACHER. If this lesson is studied before frost, 

 pupils should bring in sweet potato leaves for comparison and for draw- 

 ing. If sweet potatoes are extensively grown in your neighborhood, 

 write to Experiment Stations and the Department of Agriculture, 

 Washington, D.C., for bulletins on that crop. 



