ROOTS AND TUBERS 235 



8. In a state where the average yield of potatoes per acre was 118 

 bushels, one farmer produced 386 bushels on a test acre. He estimated 

 that his added expense above the average was 535 for labor, fertilizer, and 

 spraying. If potatoes were worth 50 cents per bushel, what was his gain 

 over the average yield? 



EXERCISES 



1. In a box of soil in the schoolroom, plant cuttings of potatoes, 

 and after two weeks remove some of them and study the develop- 

 ment of the different parts. 



2. Place a potato upon the earth in a box, and when it begins to 

 grow, observe the way in which new stems grow from the eyes. 

 Sometimes these stems will form new small tubers in the open air 

 of the room. 



3. Plant sweet potatoes in soil in the schoolroom and see if you 

 can start new plants. 



4. If an experimental plot is available, plant one row of potatoes 

 with cuttings which have one eye each, and another with cuttings 

 having two or three eyes each. Cultivate alike and compare yields. 



5 Secure from your state experiment station directions for spray- 

 ing potatoes to prevent damage from insects and the blight. Spray 

 one plot and leave another unsprayed, and compare yields. 



REFERENCES 



FITZ, J. Sweet Potato Culture. Orange Judd Company. 



GRUBB, KK;I:M: H.. and (HILFORD. \V. S. The Potato. Doubleday, 



Page & Company. 

 PINK, J. Potatoes : How to Grow and Show Them. The U. Van Nostrand 



Company. 



Potato Culture, Farmers' Bulletin jj, United States Department of Agri- 

 culture. 

 Potato Diseases and their Treatment, Farmers* Bulletin gi, United States 



Department of Agriculture. 

 Potatoes and Other Root Crops as Food. Farmers' Bulletin 295, United 



States Department of Agriculture. 

 Suggestions to Potato Growers on Irrigated Lands, Circular go, Bureau of 



Plant Industry-, United States Department of Agriculture. 

 Sweet Potato, Farmers" Bulletin 129, United States Department of 



Agriculture. 



