74 
BULLETIN 813, IT. S. DEPARTMENT OF AGRICULTURE. 
these strains is so low as to make them expensive boarders for the 
grower. 
This difference in time of production between the trees of two of 
the most important strains is very clearly shown in figure 14. This 
diagram indicates the relative percentage of the total yield of fruit of 
the Green grade that was produced each month by the trees of the 
Eureka and Shade-Tree strains, showing the large proportion of fruit 
borne by the trees of the Eureka strain from February to May, in- 
clusive. During that period the. trees of the Shade-Tree strain were 
yielding a relatively small proportion of their crop, the time of their 
heaviest production being from September to December, inclusive. 
Additional data regarding the season of production is given in 
Table XV, which shows the production from the entire study plat at 
each picking during the 3-year period from July, 1914, to June, 1917, 
inclusive. This is the record of the number of field boxes of fruit 
produced each month, including the culls. Stated in this concise 
form, the normal variations in yield from month to month are clearly 
shown. A study of the second half of the table shows that there are 
variations in the season of production in succeeding years. These 
differences are probably due partly to varying climatic conditions in 
the different years, partly to unavoidable changes in the intervals be- 
tween the pickings, partly to changes in the size of the ring used for 
picking the fruit of the Green grade, and partly to variations in the 
plan for picking the fruit of the Tree-Ripe grade. 
Table XV. — Fruit yields of the lemon trees of the Eureka variety in the investigational 
performance-record plat for each month during the 3-year period from July, 1914, to 
June, 1917, inclusive. 
[The yields are expressed in terms of the number of field boxes of fruit, including the culls.] 
Total production (field boxes). 
Monthly percentage. 
Month. 
1914-15 
1915-16 
1916-17 
3-year 
total. 
1914-15 
1915-16 
1916-17 
3-year 
average. 
July 
August 
September 
October 
November 
December -. 
January 
February 
March 
April 
May 
18 
m 
19* 
43| 
92 
13J 
112 
95 
147 
126| 
62 
25 
39 
50J 
56! 
44J 
69 
32 
50! 
84 
97| 
143 
37 
14 
9 
10 
194 
26! 
53! 
18 
57 
53! 
77" 
95! 
114J 
214! 
63f 
a 200| 
217J 
368i- 
378! 
117" 
2.40 
0.73 
2.20 
2.60 
5.79 
12.25 
1.83 
14.91 
12.65 
19.57 
16.84 
8.25 
3.43 
5.35 
6.93 
7.76 
6.07 
9.47 
4.39 
6.93 
11.53 
13.42 
19.63 
5.08 
2.93 
1.88 
2 09 
4.08 
5.55 
11.20 
3.77 
2.91 
2.73 
3.93 
4.88 
5.84 
10.96 
3.26 
a 10. 26 
76! 
123! 
109" 
18 
16.02 
25.86 
22.83 
3.77 
11.10 
18.81 
19.34 
5.98 
Total 
751* 
728! 
477! 
1, 957i 
April. 
August. 
May. 
July. 
April. 
August. 
May. 
August. 
a February is credited with half of the production for March in 1917. . 
In order to show in a more striking manner the variations in fruit 
production by trees of the different strains, Table XVI has been pre- 
pared. This presents the calculated yields per acre of fruit of the 
