Frost and the Prevention of Damage by It. 



31 



good business policy to have frost-fighting equipment, even though it 

 is necessary to use it only one season out of five. 



In cases of the second type it is obvious that the frost hazard is 

 so great that fruit growing will not be profitable in the long run and 

 the trees will eventually have to be removed. 



The statement is often made that the policy of growing fruit on 

 the colder low ground is wrong and that orchards should be confined 

 to the higher and more frost-free locations. This is not always true. 

 In some parts of southern California the difference in the cost of 

 irrigation more than 

 makes up for the ex- 

 pense of protecting 

 the orchards on the 

 lower ground from 

 frost. In addition 

 to this the cost of 

 cultivating steep 

 hillsides is greater. 

 The same is true of 

 certain deciduous 

 fruit districts in 

 Oregon. 



On a farm near 

 San Francisco po- 

 tatoes have been 

 grown successful 1 y 

 during the winter 

 months for several 

 years with the aid of 

 open lard -pail oil 

 heaters. Irrigation 

 water necessary for 

 crops grown during 

 the summer is scarce 

 and expensive, while 

 the rainfall during 

 the winter months is 

 ample. The new crop is harvested in the spring, and reaches the 

 market so early that exceptionally good prices are obtained. 



The degree of success attained in protecting potatoes at this 

 place indicates that low-lying crops may be protected against ordi- 

 nary spring frosts by using the small open lard-pail heaters, 

 set from GO to 80 to the acre. In addition to the heating of the 

 air over the plants, the direct radiation of heat from the heaters 



FIG. 15. Young lemon tree almost entirely stripped of 

 foliage by frost. The fruit was a total loss and most of 

 the the remaining leaves dropped later. 



