SWEET-POTATO 455 



improbable that this treatment destroys that part of the fungus 

 lying below the surface, but it doubtless reduces the amount of 

 disease. No slips should be purchased without a guarantee that 

 they are grown from potatoes known to be free from black-rot. 



Soft-rot causes stored sweet-potatoes to shrivel and decay. 

 To minimize this injury, avoid bruising the sweet-potatoes and 

 remove and burn all diseased roots as soon as seen. 



For dry-rot, destroy all diseased roots. Sweet-potatoes are 

 also attacked by 'other diseases. The general recommendation 

 is to avoid growing this crop twice in succession on the same land 

 or even at short intervals. 



LABORATORY EXERCISES 



1. If practicable, prepare and plant a propagating bed of 

 sweet-potatoes. If this cannot be done, place at least a few sweet- 

 potatoes in damp soil in a box kept in a warm place. As soon 

 as buds and shoots develop make drawings of 



(a) A sweet-potato, with sprouting buds, and of 

 (6) A detached slip or shoot long enough to be trans- 

 planted, showing especially the location of the roots. 



2. Make a drawing showing the position and direction of the 

 enlarged roots (potatoes) as they grow in the soil. 



3. Students should participate in any of the operations con- 

 nected with the growing of this crop, which may be in progress 

 when this chapter is studied. 



4. If this subject is studied in the fall, a storage bank of sweet- 

 potatoes should be made by the students, or else inspection made 

 of a bank or potato-house on some farm in the neighborhood. 



LITERATURE 



FITZ, JAMES. Sweet Potato Culture. N. Y., 1890. 



PRICE, R. H. Sweet Potatoes. Buls. Nos. 28 and 36, Tex. 



Expr. Sta. 

 DUGGAR, J. F. Sweet Potatoes. Farmer's Bui. No. 26, U. S, 



Dept. Agr. 



