308 University of California Publications in Agricultural Sciences [Vol. 3 



56 per cent less in 1917 than in 1916 though the trees were a year older 

 and should have yielded more. The asperity of climatic conditions 

 during the critical period in 1917 as integraded in the Livingston white 

 porous cup atmometer (pi. 41) was approxiiiiatel.y 40 per cent greater 

 than during the same period in 1916. This fact is brought out in 

 table 5, where the water loss from atmometers at different stations in 

 the United States is shown. "Grove" station in 1916 is fairly com- 

 parable with "Cultivated" station in 1917, as is the case with the two 

 "Desert" stations. Further evidence of this correlation is afforded 

 by the mean maximum temperatures obtaining during the critical 

 period in the development of the young fruit (table 2). During this 

 period in 1917 (June and July) the mean maximum temperatures 

 were 95?6 F and 104?4 F respectively, while those for the critical 

 period in 1916 (May and June) were only 81?1 F and 93?0 F. 



TABLE 5 



Comparative Loss from Cylindrical White Porous Cup Atmometers at 

 Different Stations in the United States for the Month of June 



Average daily loss for 

 Station 24 hours in ce. 



Miami, Fla.* 15.9 



Urbana, Illinois* 16.1 



' ' Alfalfa ' ' Station, East Bakersfield, 1917.... 18.5 



Whittier, Calif., 1912 22.8 



Berkeley, Calif., 1917 23.1 



West Raleigh, North Carolina* 28.0 



Gainesville, Florida* 28.7 



"Tree" Station, Edison, 1916 32.9 



San Diego, Calif.* 33.0 



Cameron, Louisiana* 33.4 



' ' Tree ' ' Station, East Bakersfield, 1917 35.8 



Riverside, Calif., 1912 43.4 



Dickinson, North Dakota* 45.0 



"Grove" Station, Edison, 1916 48.1 



"Yard" Station, Edison, 1916 55.1 



"Desert" Station, Edison, 1916 69.1 



Eeno, Nevada* 69.5 



' ' Cultivated ' ' Station, East Bakersfield, 1917 71.7 



Tucson, Arizona* 73.0 



Dalhart, Texas* 80.7 



"Desert" Station, East Bakersfield, 1917 94.0 



* Livingston, B. E., A Study of the Relation between Summer Evaporation Intensity 

 and Centers of Plant Distribution in the United States, Plant World, vol. 14 (1911), 

 pp. 205-22. 



This correlation is again reflected in the comparative yields in 

 general throughout the state in the sea.sons of 1916 and 1917. The 

 latter season has been noted for its long continued, high temperatures 



