266 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 



produced. When fruit happened to rest upon the ground it usually 

 remained uninjured, even when all of the rest of the fruit of the tree 

 was frozen so that it soon became juiceless. Because fruit which 

 touched the ground was so protected it does not follow that fruit 

 which was near the ground was less damaged than fruit higher in the 

 tree. The reverse was usually the case. 



While there was no advantage to the fruit in being near, the ground, 

 it did receive some protection when tucked in among the leaves of 

 the tree. One of the most promising sections of an orange tree on 

 which to find fruit good to eat was in the foliage on the south side of 

 the tree. Fruit in this position on the tree very likely passed through 

 more gradual changes in temperature both in freezing and in thawing 

 than fruit in more open situations. 



ARTIFICIAL METHODS OF PEOTECTING GEOVES 



Along with the natural modifying agents of the temperature, such 

 as elevation, hills, and canons, there were a number of artificial causes 

 which modified the cold. The most important of these was the heating 

 which was done in so many groves. Windbreaks, running water, 

 wrapping of the trees, and lath covering are things which must also 

 be considered. 



Windbreaks. The question of windbreaks, their benefit, and det- 

 riment, and the comparative value of different trees for such purposes, 

 has been for many years a constant source of discussion. The ideal 

 windbreak seems to be the Monterey cypress and the blue-gum planted 

 alternately in one row, the trees set five to six feet apart. In such 

 windbreaks the cypress forms a tight base and the Eucalyptus gives 

 the desired height. 



The tendency during the past few years in many sections has been 

 to remove windbreaks, for they have served in some places to prevent 

 air drainage, and increase the damage from frosts, where their need 

 as wind shields was not important. There are other sections which 

 are annually visited by strong winds where they are rightly regarded 

 as indispensable. 



In most groves the three or four rows on the leeward side of the 

 windbreak were less injured by the freeze than those in other parts 

 of the orchard, but it was rare to find any frost protection more than 

 five rows away from the hedge. It is not clear that all of this pro- 

 tection was due to the modifying of the temperature by the wind- 

 break, as the orchard rows next to the windbreak are frequently much 



