68 BULLETIN 623, U. S. DEPARTMENT OF AGRICULTURE. 



The following notes regarding some of the methods of compiling 

 Table III may assist the reader in understanding it. 



During the season of 1910 when these investigations were begun, 

 the fruit of the several sizes was not separated into the Orchard and 

 Standard grades and no record of the fruit of the Cull grade was made 

 in securing the data, but in determining the average annual produc- 

 tion of cull fruit the 6-year period was used as a basis, so that the 

 results would be comparable with the averages for the other grades 

 and the total crop. 



Variable fruits were first recorded during the season of 1912. In 

 succeeding years the observers gradually became familiar with an 

 increasing number of forms of such variations and recorded them as 

 they were observed. This accounts for the general increase from 

 year to year in the number of such fruits recorded in these lists. 

 This increase in the number of variable forms observed and recorded 

 results in a lower average than would have been the case if all the 

 forms had been recognized and recorded for the entire period of the 

 investigation. 



In expressing the averages of weights in these tables it was found 

 impracticable to retain more than one decimal. The exact decimal 

 expression of ounces as a fractional part of a pound extends to four 

 places, but only one decimal place has been retained. In expressing 

 the averages for the number of fruits occurring in different groups, no 

 decimal has been retained except when the average number is less 

 than unity. Hence, it will be found that the totals of averages will 

 sometimes vary slightly from the average of the totals of the corre- 

 sponding numbers. 



The fruits of the Cull grade are not assorted into sizes, and on this 

 account the total figures for the weights and numbers of fruits of the 

 various sizes represent only the commercial crops of the trees. 



A very heavy freeze occurred over most of the citrus sections of 

 southern California in the winter of 1912-13, resulting in more or less 

 injury to the foliage or trees in many groves. In nearly all localities 

 many mature fruits on the trees were frozen, so that they became 

 partly dry and hollow. Where it was possible to distinguish the 

 frozen fruits from the sound ones they were assorted into the Cull 

 grade, which accounts for the large number of cull fruits in the rec- 

 ords of many of the trees for the year 1913. 



In order to show the method of interpreting these individual-tree 

 performance records and of applying the knowledge gained from them, 

 the following discussion is presented of the data recorded from repre- 

 sentative high and low producing trees of the Washington strain. 



The records of tree No. 7: 2-37-1, listed in rank 11 in Tables II 

 and III, show it to have produced an annual crop during the 6-year 

 period averaging 298.8 pounds, and except for the reduced yield in 

 the year of the freeze it produced a fairly uniform quantity each 



