18 BULLETIN 184, U. S. DEPARTMENT OF AGEICULTURE. 



comparisons made between the yield with treated seed and with 

 nontreated seed, both as to quality and quantity. 



Correlatio7is. — Problems in arithmetic growing out of comparisons 

 between yields of treated and nontreated seed, together with cost 

 of production in either case, including cost of treating compared with 

 increase in yield, will be found valuable. 



Written reports on treating seed potatoes and of the planting pro- 

 cesses will afford language material. 



LESSON X. 



Subject. — Cultivation — first. Later. 



Prohlem. — To study the correct methods of potato crop cultivation 

 in order that the maximum yield may be secured. 



/Sources of inforrrhoMon. — Farmers' Bulletin 365 (5 cents), 386 (5 

 cents) , 407, and bulletins from State agricultural college. 



Illustrative material. — Clip from farm papers pictures showing 

 cultivation of potatoes; pictures of various kinds of cultivators and 

 tools for tillage. If possible, have some of these cultivators brought, 

 to school where they may be examined. Visit a farm and see these 

 tools in actual operation. 



Class exercise. — The following principles in potato cultivation are 

 noted and should be discussed as a basis for the practice work in 

 growing potatoes : 



Early cultivation: 



1. Is it safe to assert that the major part of the cultivation of the 

 potato crop should be done before planting. 



2. Poor cultivation often the cause of poor yields. 



3. Before potatoes are up, the field should be blind cultivated with 

 a spike-toothed harrow or weeder. 



4. Weeds should be destroyed and ground mulched. 



5. After potatoes are up, deeper cultivation should be practiced, 

 depth up to 8 to 10 inches, depending upon soil and locality. 



6. Usually level cultivation brings better results than hilling. 

 (Under what circumstances is ridging the better practice?) 



7. The frequency of early cultivation depends largely upon the 

 character of the season. 



8. The things to be accomplished: Keeping down the weeds and 

 conserving moisture. 



Later cultivation : 



1. Depth, shallow; form, level; ridge slightly after tubers are 

 formed to prevent sunburn. 



2. How long kept up should be determined largely by the season 

 and condition of crop. As long as plants are green they are pro- 

 ducing tubers. 



