TUBER CROP PROJECTS 219 



6. Name several arsenical poisons and describe their use on 'potatoes. 



CL : 147-148. 



7. When should the spray he applied? CL : 148. 



8. What is another common potato beetle f CL : 149. 



9. What are the host plants of the potato aphis? CL : 151. 



10. What is its life history? CL : 151-152. 



11. Describe the appearance of an injured plant. CL : 152. 



12. How should potato vines be sprayed for aphis, and with what 



material? CL:153. 



13. Name other serious pests of white potatoes. CL : 155-167. 



11. Harvesting. — Early potatoes may be dug whenever they 

 have attained a marketable size, though it may be profitable to 

 let them grow to full maturity. This will depend mainly on market 

 prices. Late potatoes, unless there is an unusual demand, should 

 not be dug until the tops are practically dead or there is danger 

 of the tubers freezing in the ground. As long as the tops are 

 green, starch will be formed and stored in the tubers, thus improv- 

 ing their quality. 



A great variety of tools are used for digging potatoes. If 

 nothing else is available, an ordinary mold-board plow may be 

 employed, followed by a spike-tooth harrow. The various types 

 of special diggers are generally regarded as great labor-savers. 



1. When should early potatoes be dug ? Late potatoes ? 



Fr : 143. Gi : 226-230. 



2. What are some of the best tools for digging potatoes ? 



Fr : 143-146. Gi : 230-232. 



