16 



BULLETIN NO. 161 



Table I. 

 ing. 



Results Obtained by Various Investigators on Orchard Heat- 



1 Farmers' Bulletin 104. 



2 Oregon Station Bulletin 110. 



3 Indiana Station Bulletin 154. 



*They report one pot to a tree and a rise- in temperature of 6 deg. F. 

 Using 100 oil pots and 50 coal baskets to an acre, they saved their 

 lemon crop against temperatures lower than 20 deg. F. 



From the above results it is seen that one can expect to keep 

 the orchard, when near the freezing point, at least 4o F. warmer 

 than the outside temperature when 100 heaters are used to the 

 acre ; and no less than that number should be used if one expects 

 success. If cold winds of velocity more than ten miles an hour 

 are bringing to the orchard large quantities of cold air besides 

 disturbing the temperature inversion condition, unless whole 

 communities are heating simultaneously it is not feasible to heat 

 the orchard because a warming of even IQ to l^o is obtained 

 with difficulty under such conditions. 



HEATING IN CALIFORNIA 



Thousands of acres of oranges and lemons are successfully 

 heated by oil pots in California and with reported financial suc- 

 cess even though they have had to heat as many as thirty times 

 a season. These crops have been saved against freezing tem- 

 perature as low as 20o F. (j). Although they recommend but 

 100 heaters to the acre, yet against the above mentioned extreme 



(j). Monthly Bulletin, State Commission of Horticulture, Sacra- 

 mento, California, January, 1914. 



