ORCHARD HEATING 23 



OCCURENCE OF FREEZING TEMPERATURES IN UTAH ORCHARDS 

 DURING THE BLOOMING PERIODS FOR THE LAST SIXTEEN 

 YEARS. 



In order to determine whether it would pay financially to 

 heat an orchard, one must determine how often freezing tem- 

 peratures are experienced. In other words, we must determine 

 what the frost risk is. We have obtained from the County 

 Agricultural Agents the average dates of the blooming periods 

 of the main fruits !for the five largest fruit-producing counties 

 of the state. They are in the order of highest production : Utah, 

 Boxelder, Salt Lake, Weber, and Cache. We have also selected 

 from the reports of the U. S. Weather Bureau, the freezing 

 temperatures that have been experienced by these counties while 

 the fruit is in bloom. These are tabulated below. 



If thermograph records had been taken at each place and if 

 they were available, then we could note the time of night when 

 the danger temperature was reached and then heaters would need 

 to burn from then till morning and in this way the approxi- 

 mate number of hours of heating and thus the amount of oil 

 necessary could be determined. Since these are not available 'for 

 the important fruit sections, we must be content with the mini- 

 mum temperatures, and we will assume in our calculations that 

 when lighted, on an average, they are kept burning for four 

 hours and that a gallon of oil is consumed in each pot, during 

 the night. 



