32 DROUGHT RESISTANCE OF OLIVE IN SOUTHWESTERN STATES. 

 Taijlk VI. — Annual rain/all at Los Angeles, Cal., 187S to 1907, inclusive.^ 



a For the data usel on the c-limale of California, the writer is indebted to Mr. A. 15. Wallaber, jf the 

 Climate and Crop Service of the United Stites Weather Riireau at Lo.s .Vnjieles. Cal. 



Table V'II. — Mean relative humidity at Los Angeles, Cal." 



Month. 



January. 

 February 

 March . . . 

 April... 



May 



Julie 



July 



Month. 



August 



September 

 October. . . 

 November. 

 December. 



Year 



5 a. m. 



o p. m. 



82 

 78 

 64 

 61 



78 



63 

 63 

 68 

 65 

 64 



64 



a For the data used on the climate of California, the writer is indebted to Mr. A. B. Wallaber, of the 

 Climate and Crop Service of the United States Weather Bureau at Los .Vngeles, Cal. 



The rainfall of this region is enhanced by frequent coast fogs. The 

 mean relative humidity from month to month is an important factor 

 in all such cultural problems, but this is obtainable only for Los 

 Angeles, with which point we may fairly compare Los Angeles County 

 and Orange County. This, it will be seen from Table VII, ranges 

 from 61 to 90 per cent for the 5 a. m. observation, and from 61 to 68 

 per cent for the 5 j). m. observation. This condition of atmospheric 

 moisture would give orchards in these locahties a great advantage, 

 for instance, over the one studied at Palm Springs in the edge of the 

 Colorado Desert, except that the trees suffer more from the attacks 

 of parasites in the more humid climate. 



One of the most extensive examples of olive culture without irriga- 

 tion in this region is to be found on a large ranch in the southern part 

 of Los Angeles County, near La Mirada, Cal. Here are 500 acres in 

 olives, the oldest set sixteen years ago and others as recently as seven 

 or eight years ago. The planting distance was only 20 feet, giving 

 108 trees to the acre. The olives occupy rolling hillside land for the 

 most part, difficult of irrigation even if a water supply were at hand. 

 The soil is as a rule a rather strong adobe, with some admixture of 

 sand in i)arts of it. The nature of the hills nearest would indicate an 

 abundance of lime in this soil, wdiich is so important for olive produc- 

 tion. Some degree of cultivation is given between the rows, but with 



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