58 The Sweet Potato 



eases, such as soil-stain and foot-rot, can be controlled 

 effectively by selection and the danger even from soft- 

 rot and black-rot can be greatly lessened by careful 

 culling and the use of proper disinfecting agencies on 

 the seed to be bedded. (Chapter VIII.) Only sound 

 potatoes free from soft spots should be selected for bed- 

 ding. Tubers with suspicious looking spots should be 

 avoided for seed purposes. It is best to obtain these 

 seed from plots known to be free from field diseases. 

 Freedom from disease should be the governing factor 

 in selection rather than disease resistance. The tiibers 

 for bedding should be selected at time of harvesting, 

 carefully handled to prevent bruising and consequent 

 infection by disease, and carefully stored to prevent 

 freezing and injury from other sources. 



For yield and qimiity. 



It is now commonly recognized that the only basis 

 for the improvement of the sweet potato is the hill 

 unit. Bin selection is not sufficient. Hill selection, 

 followed for two years on the eastern shore of Virginia, 

 practically doubled the yield. -^ The practice in Vir- 

 ginia is to select from hills with five or more marketable 

 potatoes. Quicker results will be secured if the stand- 

 ard is placed higher and selection made from hills show- 

 ing ten or more marketable potatoes. The market de- 

 mands a smooth, medium-sized, spindle-shaped potato; 

 and this standard should be kept in mind in selecting 

 the seed stock, although use of the small tubers from 

 high yielding hills seems to have no bad effect., 



1 Report of the conference on sweet potato problems and on 

 diseases of cotton, corn and tomatoes, Birmingham, Ala., Feb., 

 1919. 



