Propagation 57 



recognized the importance of seed selection as a means 

 of controlling disease and popular opinion seems to 

 have indicated merit in the theories commonly advanced 

 with reference to the influence of more careful selec- 

 tion over yield and characteristics of the resulting crop. 

 Eecent experiments on the eastern shore of Virginia 

 have strengthened this belief. There are several con- 

 siderations in selecting seed which plain judgment would 

 dictate as being worthy of practical execution for the 

 sake of a conservative system on the farm if for no 

 other. One of the greatest hindrances to systematic 

 marketings, especially from the more southern areas,, 

 is the mixed condition of the varieties. As the only 

 means of mixing is by mechanical mixture of the tubers 

 themselves, this condition is inexcusable. It can be 

 entirely eliminated by careful selection and handling 

 of the seed stock. 



Selecting "seed" (tvJjers) for disease control. 



Seed selection is of the very first importance in sweet 

 potato growing from the standpoint of controlling dis- 

 eases. A number of diseases seriously affect the crop 

 in the field and unless care is taken to choose clean 

 healthy seed, these diseases may be carried into storage 

 and later into the seed-bed where they are transmitted 

 to the propagating plant stock. One of the greatest 

 troubles in the way of a successful storage is the bring- 

 ing in from the field of decay organisms which would 

 never have been present had proper precautions been 

 taken in selecting the seed which produced the field 

 crop. A comparatively short time ago sweet potato 

 diseases were practically unknown, but now it is often 

 difficult to secure disease-free seed. Many of the dis- 



