98 HORTICULTURE FOR SCHOOLS 



down by selecting smooth, clean, seed potatoes and soaking 

 them a short time in a solution of formalin or corrosive 

 sublimate. 



The Colorado potato beetle is the most troublesome insect. 

 It is controlled by spraying the plant with paris green or with 

 other arsenical sprays. It is easy to kill the young larvae 

 soon after they hatch and begin feeding, but it is difficult to 

 poison the old beetles. 



158. The sweet potato constitutes an important crop in 

 the southern states where the warm days and nights are 

 especially suited to its growth. The plants are propagated 

 in hotbeds and transplanted to the field. The thickened 

 roots, commonly miscalled tubers, are placed just far enough 

 apart in the hotbed to prevent their touching each other, 

 and are covered with a few inches of sand. A large number of 

 slips are produced by each potato. These slips are pulled up 

 from the bed, while the parent potato remains in place to 

 produce more slips. The slips are set out in the field, usually 

 in ground that has been ridged. 



Light sandy soils produce the best sweet potatoes. Good 

 drainage is important. Moisture during the growing season 

 is desirable, but too much moisture should be avoided when 

 the roots are maturing. Frequently shallow cultivation 

 should be given, and considerable hand hoeing is necessary. 



The sweet potatoes are usually harvested by being loosened 

 by means of a special plow and then pulled up and sorted by 

 hand. They require different storage conditions than do 

 Irish potatoes, a warm dry place being most suitable. 



159. Radish. It is probable that the original home of the 

 radish was in western Asia and southern Europe. It was well 

 known to the ancients. Radishes are mentioned in old Chi- 

 nese books as early as 1100 B. C. Pliny gives interesting 

 accounts of radishes grown in Rome. Several varieties were 

 cultivated in England in Queen Elizabeth's time. Since then 

 many varieties have been produced. 



