EFFECTS OF FREEZES ON CITRUS IN CALIFORNIA 249 



A STUDY OF THE FREEZE OF 1913 IN CALIFORNIA 

 BY C. S. MILLIKEN, A. R. TYLOR, W. W. BONNS, AND H. J. WEBBER 



METHODS OF INVESTIGATION 



In gathering the data for this report a large number of the citrus 

 groves in different districts of southern California were visited. 



In making the observations several trips were necessitated to 

 various sections in order to determine the final effects of different 

 methods of treatment. Wherever an interesting case or experiment 

 was found, the observer continued to follow the recovery of the trees 

 until the full effect of the treatment became apparent. One of the 

 writers of this article made similar extended observations following 

 the great freeze of 189495 in Florida* and in this article frequently 

 a comparison of the conditions and methods of treatment has been 

 made. 



The conclusions which have been drawn are based upon numerous 

 observations, and these have been made in a number of different 

 districts by many different observers. While it is possible to find 

 exceptions to most rules, the value of the rules is not destroyed by the 

 exceptions, and so in this summary of the effects of the freeze, an 

 attempt has been made to state those things which as a rule were found 

 to prevail, believing that the clearest record of conditions can be given 

 in this way. 



GENERAL AND METEOROLOGICAL OBSERVATIONS 



The freeze began Sunday, January 5, 1913. Unlike visitations 

 from frost in previous years, the Sunday cold was accompanied by a 

 strong wind. Somewhat different conditions prevailed in different 

 places. The following are the conditions as noted at the Citrus Experi- 

 ment Station. Sunday, January 5, was a cold day throughout. Ice 

 three-sixteenths of an inch thick was observed in the street about 

 noon, toward evening the wind went down, and between 7 P.M. and 

 11 :30 P.M., the coldest period, there was scarcely any movement of air. 

 The temperature during this period, at a point about 300 feet to 

 the east of the grove, remained between 15 and 18 F. (Compare 

 Chart I). 



* Webber, H. J., The Two Freezes of 1894-95 in Florida, and What They 

 Teach, Yearbook, U. S. Dept. Agr., 1895, pp. 159-174. 



