272 



The Principles of Fruit-growing 



In the vast majority of Indiana orchards, spraying, prun- 

 ing and good management must become the rule instead 

 of the exception before heating will pay. Considering the 

 necessity of a reserve of extra heaters for emergency, 

 supply of fuel for several successive nights, labor of dis- 

 tributing and filling heaters, and labor-cost of firing, the 

 initial investment to prepare for protecting a 10-acre 

 orchard from frost-injury probably is not far from $500." 



FIG. 98. Smudge in an Oregon orchard. 



They found oil-heaters to give better results than coal- 

 heaters, considering the price and the quick response of 

 the oil-burners. A maximum rise of temperature of 10.2 

 was secured with 126 heaters to the acre. When using 

 80 to 100 oil-heaters to the acre, the usual temperature 

 rise was 5 to 7. 



In Iowa, Greene found heating of orchards to be 

 practicable; the estimated cost for a 10-acre orchard, with 

 65 oil-heaters to the acre, was about $375 to $675 (Iowa 

 Bull. No. 129). Church and Fergusson report gratifying 



