72 



BULLETIN 813, U. S. DEPAETMEXT OF AGRICULTURE. 



securing the investigational performance records the same standard of 

 picking was followed each month as that used in the regular commercial 

 picking. Table XIV shows the ring size used for Green-grade fruit at 

 each picking from July, 1911, to June, 1917, inclusive. Fortunately 

 for this study of seasonal variation, it will be noted that there was 

 no change in ring size during the last two years of the study period. 

 Fruit of the Tree-Ripe grade is sometimes picked as soon as it appears, 

 and sometimes it is not picked until it reaches a certain size, which 

 is usually smaller than the standard being used for fruit of the Green 

 grade. The practice varies in different orchards, and in any one or- 

 chard it is usually influenced by climatic and market conditions. On 

 this account it is believed that a consideration of the fruit of the Green 

 grade alone will give the truest index of the production habit of the 

 various strains but the data for the fruit of the Tree-Ripe grade are 

 included as a matter of interest. 



Table XIV. — Diameter of rings used in picking fruits of the Green grade from the lemon 

 trees of the Eureka variety in the investigational performance-record plat during the 

 5-year period from July, 1912, to June, 1917, inclusive. 



Month. 



July 



August 



September 

 October... 

 November 

 December. 



Diameter of picking ring for 

 Green-grade fruit (inches). 



1911- 

 12. 



1912- 

 13 



1913- 

 14 



^ST 



1914- 

 -15 



1915- 

 16 



1916- 

 17 



Month. 



January.. 

 February 



March 



April 



May 



June 



Diameter of picking ring for 

 Green-grade fruit (inches). 



1911- 

 12 



1912- 

 13 



1913- 

 14 



211 



23% 



2 * 



1914- 

 15 



1915- 

 16 



1916- 

 17 



In figure 12 the graphs representing the monthly production of 

 fruit of the Green and Tree-Ripe grades are arranged by strains from 

 left to right, according to their rank for average total production as 

 shown by Table XL To bring out more closely the variations in pro- 

 duction each month between the trees of the different strains the data 

 were rearranged as shown in figure 13. Each graph represents the 

 proportions of fruit produced during a month by the trees of the vari- 

 ous strains, which are presented in each month in the same order from 

 left to right as in figure 12. 



The low production in January of fruits of both the Green and Tree- 

 Ripe grades by the trees of aU the strains is quite marked, and it 

 is probable that if all conditions had been normal the records would 

 indicate a gradual upward curve at that time instead of the break that 

 is shown. Table IX shows that in 1914 and 1916 the time between 

 the November and December pickings was longer than usual, which 



