EFFECTS OF FREEZES ON CITRUS IN CALIFORNIA 263 



the trees usually showed themselves somewhat more tender than 

 orange trees. 



Among the other varieties of citrus trees the tangerines and the 

 Satsuma oranges were more hardy than the navels and Valencias. 

 The tangerine tree is very resistant, and many cases were found 

 where this tree retained its foliage alongside of orange trees that had 

 been entirely defoliated. Only two groves were found containing King 

 orange trees, and in both of these instances they were more seriously 

 injured than near-by navel orange trees. 



Lime trees were more tender than lemons, the Tahite lime being 

 more hardy than the Mexican. The citron was slightly more tender 

 than the lime. Several instances were observed where lime and citron 

 trees were growing in lemon orchards; and in such cases they were 

 entirely defoliated and a portion of the brush or tops killed alongside 

 of lemon trees that merely lost the outer layer of foliage. 



When one considers that the citrus tree is a native of the tropics, it 

 is surprising to find it capable of standing the temperatures of the 

 1913 freeze. In one place young navel orange trees, that were sub- 

 jected to a minimum temperature of 5 F. above zero, came through 

 with trunks alive, notwithstanding that the navel orange was brought 

 to the United States from a place only 12 degrees south of the equator. 



Relative Hardiness of Fruit. The fruit of the pomelo was less 

 injured by the cold than any other of the citrus fruits. Even when 

 the skin was spotted as a result of the freezing the inside pulp often 

 showed no breaking and remained juicy. In this respect the pomelo 

 was quite different from the orange, because there was always a notice- 

 able injury to the pulp of oranges which had spotted skin. 



The comparative injury of navel and Valencia fruits varied with 

 the locality. In many sections there seemed to be little difference in 

 the condition of the two kinds of fruit, but where there was a differ- 

 ence, it was more common to find the injury greater in the Valencias. 

 As the Valencia is the later variety, the fruit was less mature at the 

 time of the freeze than were the fruits of the navels. In Whittier, and 

 in the Sespe Canon in Ventura County, the Valencia proved to be more 

 hardy than the Washington navel. The Thompson Improved navel 

 proved more tender than the Washington navel or the Valencia. 

 Blood oranges ranged about the same as Washington navels. 



Although the tangerine trees are so hardy, their fruit is more 

 easily frozen than the fruits of the navel and Valencia. 



Lemon fruit is injured at a temperature several degrees higher 

 than that which injures oranges, and of course the young, small-sized 

 lemons are more tender than those which are large enough to be picked. 



