214 Effective Farming 



9. Why should sweet potatoes not follow sweet potatoes on the 

 same piece of ground ? 



10. Describe the methods of propagating sweet potatoes. 



11. How can you tell when a sweet potato root is mature? 



EXERCISES 



1. Size of white potato seed pieces. Plan and carry out a plot 

 experiment with white potatoes using seed pieces of different sizes. 

 Also, plan one comparing whole and cut seed pieces. 



2. Treatment for scab. Treat seed potatoes for scab before 

 planting them as directed in the chapter. Use both methods and com- 

 pare results. Always plant a small plot with potatoes that have not 

 been treated in order that the results of the treatment may be known. 

 Treat quantities of the tubers for farmer patrons of the school. 



3. Spraying of white potatoes. In a portion of white-potato field 

 spray an area every two weeks during the summer with bordeaux 

 mixture and arsenate of lead and leave an equal area unsprayed. At 

 harvest time compare results. Bordeaux mixture is made of copper 

 sulfate, quick-lime, and water. The quantities of copper sulfate and 

 lime to use vary somewhat according to the kind of plant to be sprayed. 

 For white potatoes a satisfactory formula to use is : 



Copper sulfate . . . . 5 Ib. 



Quick-lime 6 Ib. 



Water 50 gal. 



This is known as the 5-6-50 formula. 



To make fifty gallons of the bordeaux mixture, dissolve the copper 

 sulfate in twenty-five gallons of water and in a separate vessel slake 

 the lime and dilute it to twenty-five gallons. Pour the two solutions 

 simultaneously through a brass wire strainer into the spray tank. The 

 arsenate of lead, three pounds of the paste form, should be thinned 

 with water and poured into the tank. 



4. Fertilizer experiment with white potatoes. In rows across 

 a field to be planted to white potatoes try different quantities of ferti- 

 lizer. For example, in one row use the kind of fertilizer being used on 

 the field at the rate of one ton to the acre ; on a second row use it at 

 the rate of one thousand pounds to the acre ; on a third row use it at the 

 rate of five hundred pounds to the acre ; leave a row without any 

 fertilizer as a check. At harvest time compare the yields of the differ- 

 ent rows. 



