306 AGRICULTURE ON THE PACIFIC SLOPE 



Where sun-drying is difficult on account of summer rains, 

 as in the Eastern states and in parts of Oregon, Washington, 

 and Idaho, fruit is dried with artificial heat in driers, where 

 the trays are stacked so as to make dry, hot air pass zig- 

 zagging over them. Such driers are little used in California 

 now. 



CITRUS FRUITS 



Oranges, lemons, and grape fruits can be grown only 

 where frosts occur rarely or last but a very short time ; 

 as in southern California, and on the lower slopes of 

 the mountains and valley borders, where cold air 

 flows away soon. They are sometimes protected from 

 frost injury by clouds of smoke smudging. Their 

 original home was probably southeastern Asia, from 

 India to Cochin China, and perhaps southern China 

 also. The wild orange is sour, and is used as hardy 

 stock for the sweet kinds and for lemons. Having 

 been so long cultivated, citrus fruits have innumerable 

 varieties, ranging in size from that of a pecan nut to 

 that of a child's head, and grown for various purposes 

 in different countries. In California we grow for mar- 

 keting about a dozen varieties of oranges and half as 

 many of lemons. Oranges are less affected by frost 

 than lemons, and are grown as far north as Tehama 

 county. They ripen earlier in middle California than 

 in the south. 



Citrus trees need much moisture and are mostly grown 

 with irrigation, which should be done in deep furrows, so as 



