EFFECTS OF FREEZES ON CITRUS IN CALIFORNIA 275 



6. Accumulation in the pots of a residue of asphaltum, which 

 burned with difficulty. 



7. Growers relying upon other people's reports of temperatures 

 in other groves rather than keeping track of the temperatures in 

 different parts of their own groves. 



8. Discouragement after partial failure. This sometimes proved 

 disastrous. 



9. Insufficient amount of labor. 

 10. Incapable labor. 



Costs of Heating. The exact cost of firing in most cases has been 

 difficult to ascertain, and, although considerable data has been gath- 

 ered on this subject, most of it is too incomplete to make it of value 

 for general conditions. From the data given in connection with a 

 twenty-five acre orchard in the San Fernando Valley we find, after 

 figuring 6 per cent interest on the total equipment and 20 per cent 

 depreciation of the latter, besides cost of fuel and labor, the total cost 

 amounted to 5.09 cents per gallon of oil burned. The pots were 

 lighted on nine different nights. A similar estimate from one ranch 

 in Ventura County, which had one hundred acres of orchard pro- 

 tected with heaters, gives 5.78 cents as total cost per gallon of oil 

 burned. In this case the pots were lighted fourteen different nights. 

 Near Santa Ana the heaters on an eight-acre orange grove were lighted 

 three different nights, thus saving the fruit from considerable frost 

 injury. In this case the cost amounted to 6.13 cents per gallon of 

 oil burned. In the Pacific Rural Press, May 24, 1913. figures given 

 by Mr. T. R. Woodbridge of Upland show a total cost of 6.5 cents per 

 gallon of oil consumed. 



The cost of the heating operations have varied of course with the 

 amount of heating which was done. In table 2 data are given on 

 the cost of heating in twelve groves selected from different parts of 

 Southern California. These groves were more or less successfully 

 heated. One grower, who kept a very accurate account of all of his 

 expenditures, found that his average cost of heating an acre for one 

 hour was $1.24. His grove was one-half lemons and one-half oranges, 

 and the cost of heating the lemons was 64 per cent of the entire cost. 

 The fruit was saved in the oranges and in half of the lemons, but in 

 the other half of the lemons the equipment was inadequate and the 

 fruit was lost. 



In the tables the total number of nights fired is given. On some 

 of these nights the heating was required for only a few hours, while 

 at other times it was needed during the entire night. The interest 

 on the investment has been figured at 7 per cent. The amount charged 



