May, 1929] Potato Production Costs in New Hampshire 17 



TABLE XIV. 

 Influence of Spraying on Various Cost Factors 



part of the state, where potatoes are higher priced, 10 bushels in- 

 crease in yield offsets increases in cost up to 500 pounds of fer- 

 tilizer. 



Spraying 



The effects of spraying are shown in Table XIV. Even in Coos 

 and Grafton Counties the yield of potatoes in both 1926 and 1927 

 was increased by 28 bushels in 1927 and by 49 bushels in 1926. 

 In the southern part of the state yields were increased by from 42 

 to 76 bushels. The important factor in spraying seemed to be the 

 thoroughness of application rather than the number of sprays, al- 

 though thoroughness is indicated by number of applications and 

 cost of materials. In a rainy season more frequent sprayings are 

 necessary to keep the new growth covered with a protecting film 

 of copper. 



