May 31,1924 Comparison of Pima Cotton with Upland Varieties 
943 
later in the fall than the other varieties, had a shorter period of active flowering 
than Acala or Durango in 1922, and shorter than Acala or Hartsville in 1923. 
Occasional flowers appeared in all of the varieties after the regular flower counts 
were discontinued. It was noted that this casual flowering continued longer in 
Pima than in other varieties. 
COMPARISON OP BOLL SHEDDING 
Egyptian and Upland cottons differ considerably in susceptibility to shedding, 
both of squares and of young bolls. Shedding has been studied in Upland cot¬ 
ton by Lloyd (4, 5) 2 t Ewing (2) and others in the United States, and in Egyptian 
cotton by Balls (I). Lloyd found in Alabama that about 50 per cent of the 
shedding in Upland varieties consisted of squares, but Ewing asserts that shed¬ 
ding in the square stage is relatively unimportant in Mississippi. Balls reports 
that “shedding in Egypt takes place almost entirely in the flower stage,” probably 
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meaning 2 or 3 days after flowering. In Arizona it has been found that most 
of the shedding in both Egyptian and Upland varieties occurs soon after flowering, 
before the bolls are 10 days old. Under some conditions, however, the shedding 
of squares also becomes an important factor and causes reduction in yields. 
Shedding data covering two seasons at Sacaton, Ariz., are contained in Tables 
V and VI. Pima cotton in 1922 retained 82.5 per cent of its bolls and in 1923 
70.7 per cent, under conditions where Upland varieties usually retained less than 
30 per cent of their bolls. 
The greater ability to retain its squares and bolls enables the Pima Egyptian 
cotton to produce satisfactory yields in the Southwestern States, notwithstanding 
the smaller bolls. In some years the shedding of Pima bolls at Sacaton has been 
even less than in this experiment. In 1920 Martin and Loomis (7) reported a 
loss of only 11.2 per cent from a total of 10,317 flowers. Willett 3 recorded a loss 
of 15.8 per cent in 1922 from a total of 7,291 flowers. Other data on boll shedding 
in 1923 showed Pima at Sacaton retaining 86.4 per cent of the bolls, and Acala 
30.5 per cent, while at Shatter, Calif., 90.2 per cent of Pima bolls were retained, 
and only 31 per cent of Acala bolls. 
2 Reference is made by number (italic) to “Literature cited,” p. 953. 
* Unpublished data communicated by Dr. T. H. Kearney. The data from Sacaton in 1923 were secured 
by Max Willett and Dow D. Porter, and those from Shafter by R. H. Peebles. 
96039—24t-8 
