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Washington, D. TC. v April, 1925

BEHAVIOR OF COTTON PLANTED AT DIFFERENT DATES IN WEEVIL-
CONTROL EXPERIMENTS IN TEXAS AND SOUTH CAROLINA

By W. W. Batuarp, Senior Scientific Aid, and D. M. Simpson, Assistant Agron-
omist, Office of Crop Acclimatization and Adaptation Investigations, Bureau of
Plant Industry

CONTENTS
Page Page
EM ETOGUCHIONS = eee Mies Nickens ay ewe 1 | A separate late planting at San Antonio_-_-_-_-__-
Soil, climatic, and weevil conditions at San An- Yields from cotton experiments at San Antonio. 28
HOWION MROXS EA di NEG Re ee Ea ee ee 2 | Soil, climatic, and weevil conditions at Charles-
Comparison of successive adjacent plantings at LO) PAS) ROR SEEN ts SOU se i SI cl 29
SATA GOTO Seer uta tc rmupe mcd e i RW ects ext 3 | Comparison of successive adjacent plantings at
Yields from successive plantings at San An- @harlestom 2a a ee
LAD ROU Gs Sa A RE aT A ne Sage ONE 19 | Yields from successive plantings at Charleston_ 38
Percentage of 5-lock bolls on early and late Adverse conditions at Gainesville, Fla________ 41
Planhinesiap SanvAcItONIONss 22 e5 ee ease eed oe ODN GS ULTTUTIT AT AY og ee eR ee a Bin ee La Laas ee 41
INTRODUCTION

More information is needed on the growth and fruiting habits of
early and late planted cotton in relation to cultural control of the
boll weevil. In the season of 1923 comparisons were made of the
behavior of early and late plantings in Texas and South Carolina,
and differences were shown in the rates of growth and the fruiting

-habits of the plants. |

A more rapid formation of nodes during the seedling stage of the
plants was found to occur in the later plantings, resulting in a shorter
interval between the date of planting and the appearance of the first
floral bud. The fruiting capacity of late-planted cotton was found
to equal and in some cases to exceed that of the early-planted cotton.
The large number of floral buds produced in later plantings was due
to the fact that more nodes were produced on the lower fruiting
branches. Also, slightly larger numbers of flowers were recorded on

the late-planted cotton, although the early plantings produced a
larger number of flowers during the first part of the flowering period.

The experiments were made in three places—San Antonio, Tex.,
Charleston, S. C., and Gainesville, Fla. The object of having
similar tests in three widely separated parts of the Cotton Belt was
to secure comparative data of plant development under different
soil and climatic conditions. The experiments consisted of side-by-

side comparisons of cotton planted on four different dates. An
20718°—25t —1

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an

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4 6

2 BULLETIN 13820, U. S. DEPARTMENT OF AGRICULTURE

interval of 10 days between plantings was used in South Carolina
and Florida and 7 days in Texas.

As these experiments were conducted under boll-weevil conditions,
measures were taken to protect the early plantings from infestation
by overwintered weevils. Uncontrolled infestation in the early

lantings would have caused excessive infestation in the adjacent
ater plantings and would have prevented comparable data being
obtained from the different plantings. The method of weevil con-
trol was by removal of squares and the application of poison after
most of the weevils had emerged from hibernation.

At San Antonio, Tex., it was only necessary to apply pois n to
the two later plantings, those of May 5 and May 12, as these plant-
ings had not reached the fruiting stage at the time squares were
removed from the early plantings.

A separate late planting was made at San Antonio on May 12 in
order to compare the development and fruiting habits of cotton in
rows that were left unthinned with rows that were thinned to two
plants in a hill with hills 12 inches apart. This comparison showed
that plants left in hills had a larger individual fruiting capacity than
the unthinned plants, due to the production of more nodes on the
- fruiting branches. But this difference in the fruiting capacity of
individual plants was counterbalanced by the greater number of
plants in the unthinned rows. More flowers were recorded from the
unthinned cotton, and a marked difference in the rate of flowering
occurred during the first half of the flowering period, the unthinned
rows producing flowers at almost twice the rate of the rows that
were thinned.

- No trace of weevil infestation was found in this separate late-
planted field until July 8, after the beginning of the flowering period. ©
Thus, it appeared that the planting of May 12 had been late enough |
to avoid any infestation from overwintered weevils in the season of |
1923 at San Antonio.

SOIL, CLIMATIC, AND WEEVIL CONDITIONS AT SAN ANTONIO, TEX.

The United States San Antonio Field Station is located about 5
miles south of the city. The soil on the farm is typical of a large |
part of the cultivated land in that region and is technically described —
as Houston clay loam. It is of high natural fertility and is fairly |
retentive of moisture. The subsoil is a coarse gravel, which affords |
good drainage but limits the water-storage capacity of the soil. |

The annual precipitation is variable, ranging from 13 to nearly 40 |
inches. The average annual rainfall over a period of 15 years is —
about 26 inches. Although the precipitation is usually sufficient for
cotton production, the distribution is very irregular. Periods of
excessive rainfall are frequently followed by protracted periods of |
hot dry weather which deplete the soil moisture and cause serious |
injury to crops. |

The precipitation during the season of 1923, from January 1 to |
October 1, was 23.47 inches, which was about 4 inches in excess of |
the 15-year average for the same period. The heaviest monthly |
rainfall, 6 inches, was recorded in February. Rains occurring during —
the winter months are often an important factor in this section, as
stored moisture in the soil may enable the plants to continue growth ©

COTTON IN WEEVIL-CONTROL EXPERIMENTS 8

even when surface moisture becomes deficient. June was very dry,
with only 0.55 inch of rain. Precipitation during the growing period
of cotton was fairly well distributed, but effective rains fell on only
six days between May 30 and September 7.

Maximum temperatures during June, July, and August were
comparatively high, and the long periods of hot weather between the
few good rains resulted in droughty conditions in spite of the appar-
ently adequate precipitation.

The average monthly maximum and minimum temperatures and
the monthly precipitation for the season of 1923 are given in Table 1.

TABLE 1.—Average minimum and maximum temperatures and monthly preciptia-
tion at San Antonio, Tex., from April to September, 1923

Items of comparison Tau to Apr. May June July Aug. Sept.
Average temperature (° F.):
IVbsabrog rene Pel Re Se ee eee 59. 3 64.5 72.4 TA.2 72.4 70. 7
IMA SITULIN Soe See ee a ee 77.6 89.0 95. 4 95. 3 97.8 89. 4
Precipitation (inches): |
1h payee see ee eee | 9.27 |" 2. 93 1. 67 OD Soul 2. 50 3. 02
Average, 1907 to 1920 ____-___| 3. 98 3. 11 3. 09 1.88 2 1. 87 Paty |

Favorable conditions for the hibernation of boll weevils in the San
Antonio district are afforded by scattered areas of undeveloped land
covered with mesquite and huisache trees and by large fields of
Johnson grass. A heavy infestation from overwintered weevils
usually occurs in cotton planted in this section. The first new genera-
tion of weevils usually appears before the first of July.

Periods of dry weather often restrict the growth of the plants, and
the shed squares are exposed to direct sunlight, so that a natural
control of the weevils may result from destruction of the larval and
pupal stages in the fallen squares. When heavy rainfalls occur
during the early stages of plant growth, excessive vegetative develop-
ment of the plants results, so that the weevils have more protection
even though there is dry weather later in the season. There is
slight possibility of effective natural control when the plants grow
large and the lanes between rows are shaded so as to protect the
infested squares.

In the season of 1923 weevils were first found on May 28. Squares

were very small at that time, but by the first week in Junc numerous
poe squares could be seen in all cotton which had reached the
ruiting stage. Dry weather throughout the greater part of May
and June retarded the growth of the plants. This small size kept
the lanes open between the rows and afforded favorable conditions
for natural control of weevils by exposing the fallen squares to direct
sunlight. Nevertheless, the weevil infestation increased slowly, until
by the first of August there were enough weevils to destroy practically
all of the squares.

COMPARISON OF SUCCESSIVE ADJACENT PLANTINGS AT SAN
ANTONIO

At San Antonio the successive plantings were made on April 19
and 28 and May 5and12. The Lone Star variety was used, the seed
having been grown on the experiment farm in 1922. The rows were

4 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

200 feet in length and were spaced 4.1 feet apart. (The location of
this test with relation to other cotton plantings on the experiment
farm is shown in Figure 1, and the planting diagram of the test is
shown in Figure 2.

Conditions were favorable for the germination of the seed in the
first three plantings, and good stands were obtained. Dry weather,
following rains which occurred during the last week in April, dried
out the soil to a considerable depth, and a stand of about 30 per cent
resulted irom the planting of May 12, the remainder of the seed lying
in the ground until germinated by a rain on May 30. The seedlings
produced from the seed that germinated first grew rapidly and pro-
duced vigorous plants. The moisture supply in the surface soil was
inadequate to support growth of the seeds that germinated late, and
ne of the resulting seedlings died or remained stunted throughout
the season.

0.
TESTS OF COTTON EROS TEST OF

FLANTED APRIL EY

TESTS OF
COTTON SCOLGHO/T
PLANTED
AVRIL EF 4 N

PLATS OF
COTTON
APAIL 1/2

POTAT/ION

SCALE, /"= 300°

FALLOW CRASS
a4

Minahe sr

Fic. 1.—Diagram of part of the United States San Antonio Field Station, showing the location of successive
plantings and the separate late-planting test of cotton with relation to other cotton plantings

The first three plantings were thinned to two plants in a hill with —
the hills 12 inches apart. Thinning was done by hand in order to |
obtain as regular spacing as possible. The fourth planting was not

thinned, as the poor stand rendered this unnecessary.

The April 19, April 28, and May 5 plantings were thinned on May
25, June 4, and June 8, respectively. At the time of thinning, the

plants in the first two plantings had from five to seven true leaves
and averaged about 20 centimeters in height. The plants in the

third planting were slightly larger when thinning was done, averaging”
22.5 centimeters in height and having from six to eight true leaves. |

\
GROWTH RATE OF SEEDLINGS ~

In order to compare the rate of development during the seediing 9
stage, the height and number of nodes on 10 representative plants in §j
each planting were recorded when the first floral buds, or squares, 9
appeared. ‘The plants in each planting were examined on June 1 and §

#

COTTON IN WEEVIL-CONTROL EXPERIMENTS 5

at weekly intervals thereafter. While this method did not give the
actual date of appearance of the first floral bud on each plant, the
beginning of the fruiting stage of the plants may be determined with
sufficient accuracy from the first week when the presence of squares
was recorded. Table 2 shows the

date when squares were first re- SAC7IOWV A SEC7TIOV ZS
corded in each planting, together
with the average height, number
of nodes,! and the average number VO OME PEANTEDP? USP
of squares formed.

A more vigorous growth of seed-
lings in the later plantings is shown
by these records. The rate of
erowth increases with each later
planting, the rate of formation of
nodes on the axis being more rapid,
while the length of the internodes
also increases. The faster devel-
opment of nodes reduces the in-
terval between planting and the
appearance of the first squares.

The more rapid formation of
nodes on plants of the later plant-
ings probably was due to higher
temperatures during the early

stages of growth. Seedlingsinthe L :
later plantings did not encounter ee bubpes eo
cooler weather, which may have

checked the ;

erowth in earlier

CLOVE. AEE

plantings.

In comparing the rate of nodal
srowth of seedlings, the period from
ee neon of the seed to seek
ance of squares is used. ‘Table 3

ives ie ante when germination {| esate & LAVTED eins
was first noted in each planting, the |
number of days from germination = ;
to the first record of square forma- Fic. 2.—Diagram of successive plantings of cotton
tion, the average number of axis Ee SCHL Barc
nodes formed during that period, and the average maximum and
minimum temperatures for ae same period.

CROWS. are LCV VE

TaBLE 2.—Average development of 10 cotton plants at the beginning of the fruiting
stage as grown in successive plantings at San Antonio on four different dates

= Height | Number |
Squares Pare of of nodes PETAES
Date planted, 1923 Hts : fae plants on aye
recorde a (centi- main

planting meters) ae squares
SET REE RS 2 eee a oe sae ae gL ae eae oe | June 1 43 Zed 6.5 2. 2
Bineseie arm at ere VT ge TRE ea) | June 8 4] 23.4 7a 2.8
LF REC See Roe eee 2 ee ae at Hao seb. i 34 22. 6 6.2 1.9
Jun 5.9 17

Ret hese tee ea ee core eee CN eS PARE | June 15 34 24. 4

6 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

TABLE 3.—Relation of temperature to the development of cotton plants as grown in
successive plantings at San Antonio on four different dates
[The temperatures shown (° F.) cover the petied tou Se date of seed germination to the first appearance
of squares

oo

Average tempera-
Date of | Number | Number NES ture
i Date planted, 1923 germi- |of days to} of nodes Ey a eee i
Nation | squarin formed KR
Piprape per node| Mini- | Maxi-
mum mum
| |
Dp 193k eee ANI ea fos 37 6.5 5.7 64.4 88.5
TARDY 20 ge Meee se ace ee ge | May 4} 35 | Teil 4.9 66. 5 90.8
Tal EA Ry ee ae I See Ay Sep ati ae Re es NY Lear? 2 27 6.2 4.4 68.6 $2.3
IVES ya De NGI ges Rots NE PA on ONE | May 20 26 5.9 4,4 70. 7 94. 0

Tt will be noted that the interval between the development of suc-
cessive nodes decreases when higher temperatures occur during the
period from Sonu eed de to the appearance of squares. The average
rate of nodal development during the seedling stage of the April 19
planting was 5.7 days. During this period the average minimum
temperature was 64.4° and the average maximum 88.5° F. The May
12 planting averaged 4.4 days per node during the seedling stage of
the plants, the average minimum and maximum temperatures having
been 70.7° and 94° F., respectively.

DAMAGE BY OVERWINTERED WEEVILS

The extent of weevil infestation in the successive plantings of cot-
ton was determined on June 5 by recording the numbers and per- |
centages of squares that had been attacked by weevils. On June 5
squares were present only on the April 19 planting. Even on this
there were only a few large squares, and it was necessary to examine
about 200 plants in order to find 100 squares that were regarded as
over 10 days old. Records of growth of squares have indicated that a
period of about 10 days elapses between the time when a square 1s
first visible and the time when it has reached sufficient size to harbor
a weevil larva.”

In block 1 of the April 19 planting, which was located on the south
side of the field, 45 per cent of the squares were punctured by weevils.
Block 2, in the center of the field, had 20 per cent of the squares
punctured, and block 3, on the north side of the field, had 15 per cent
of punctured squares.

The heavier infestation in block 1 may have been due to the fact
that the field adjomed a Johnson grass pasture on the south. A
large part of the weevil emergence probably occurred from this

asture, and a large number of the weevils would doubtless remain in
the first cotton where squares were found.

STRIPPING OF FLORAL BUDS OR “SQUARES”

Squares were removed on June 12 from the first and second plant-
ings, and the entire field was poisoned with calcium arsenate. At
that time the squares on the third and fourth plantings were below
the size for stripping, so that it was necessary only to apply poison.
pete Wes gta 2 ae el ee

2 Martin, R. D., W. W. Ballard, and D. M. Simpson. Growth of fruiting parts in cotton plants. In
Jour. Agr. Research, v. 25, p. 202. 1923.

COTTON IN WEEVIL-CONTROL EXPERIMENTS -

No squares were removed that were less than 10 days old, at which
time the involucre of the square was about three-eighths of an inch
in length. It was found to be impossible to remove squares smaller
than this without breaking the tips of the fruiting branches or injuring
the terminal buds of the plants. Records were obtained of the
number of squares picked from four rows in the April 19 and April 28
plantings. The number of plants to the row and the number of
squares removed from each row are given in Table 4.

Number of squares removed on June 12 from cotton plants of the first
and second plantings in rows 200 feet long at San Antonio

TABLE 4.

r Average Average
N uber Number | number aber Number | number
Date planted, 1923 Pees S lof squares) of squares |; Date planted, 1923 ‘one of squares|of squares
: © | removed to the a removed | tothe
oy plant plant
392 787 2.0 | 300 128 0.4
% aye
Fe eeeenes 1 eral ee mi) us)
| 387 734 1.9 | 334 193 6
| i

An average of two squares removed from each plant corresponds
to the amount of stripping reported in experiments with the stripping
method in Florida.2 A difference of nine days in the planting date of
the first and second plantings resulted in only one-fourth as many
Squares being removed from the second planting as from the first.
In plantings which were deferred until May 5 and May 12 there was
no necessity of square removal to avoid infestation by overwintered
weevils.

The average time required for finding and removing squares was
48 minutes per row in the April 19 planting and 22 minutes per row
in the planting of April 28, the length of rows being 200 feet. On
this basis the time required to strip an acre was estimated at 41 hours
for the first planting and 19 hours for the second. At the rate of
four days per acre, or even two days, the labor requirement for square
stripping is considerable.

Only 2 weevils were found in squares removed from the two blocks
oi the second planting, while 96 weevils were caught in the three
blocks of the first planting. The fact that so few weevils were
caught in the second planting is probably due to the smaller number
of large squares on the later plants. Weevils which are feeding on
the floral bud inside the involucre of large squares are more likely to
be caught.

A hundred squares from each row in the April 19 and April 28
plantings were examined, in order to determine the percentage of
squares that had been punctured. The records of punctured squares
in each block of the first planting gave the following average per-
centages of infestation: Block 1, 23; block 2, 14; block 3,,12. The
- first block of the second planting had 9.7 per cent and the second block
had 6.5 per cent of the squares punctured.

Calcium arsenate in dry-dust form was applied to the entire field
immediately following the removal of squares from the first two

3 Smith, G. D. A preliminary report upon an improved method of controlling the boll weevil. Fla.
Agr. Exp. Sta. Bul. 165, 72 p., illus. 1922.

8 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

ara A hand gun was used in dusting the plants, the poison
eing applied at the rate of about 8 pounds per acre. It remained on
the plants until June 17, when most of it was washed off by a light
rain. No further poisoning was attempted during the remainder
of the season.

A comparison of the development of plants in the four plantings
was made on June 15, three days after squares had been removed
and poison applied.- Data on the height of plants, the number of
nodes on the main stalk, the total number of squares that had been
formed to June 15, and the actual number of squares on the plants
are presented in Table 5.

TABLE 5.—Developmeni of cotton plants, showing the average number of squares
formed on each plant on June 15 as grown in successive plantings at San Antonio
on four different dates

| Average number of
| Squares on plants

Height =
Date planted, 1923 (centi- pee
| meters) Formed | Remain-
| to June | ingon
15 | June 15
THREE acs a
7 PT SR Te ASMA S ORAS SESE NN G BNI WN 6S SONA SI ag ce See 28.6 11.2 10.6 | 5.
DYESS £ 20SS TN A yh A SS EL a As ee A SE 28. 0 9.2 6.5 | 5.
u \, Eh ay a Paes eens Apne ane G1 wae Lee AY aim NEMS bam By |” Hae eregeenen ee 27.8 8.6 557) 5
ds LES 9 9d 7a ein lath Ph SEs a A deren I OS wl hs NR ed a OE 24.3 5.9 chew fis | aE

The difference between the total number of squares that had been
formed by June 15 and the number actually on the plants at that
date represents the loss through square removal and shedding.
Considerable shedding of very small squares occurred in the April |
19 planting, practically all of the squares formed prior to June 1
haying been shed by June 8.

WEEVIL INFESTATION AFTER STRIPPING SQUARES

Although the young squares on the first three plantings had |
developed within a week after stripping and poisoning to a size |
which would render them susceptible to weevil injury, no indication |
of infestation was detected for another week, or until June 25. Three ©
small areas of infested plants were observed on that date in widely.
separated parts of the field. |

The absence of weevil infestation for a period of nearly two weeks ©
after stripping and poisoning indicates that the control measures
had practically exterminated the weevils present in the field on June
12. It is probable that the slight infestation which was first noted
on June 25 resulted from weevils that had emerged from early-punc- —
tured squares. Some of the squares on the first planting which had
been punctured during the first week in June were shed before the
plants were stripped. Some of the squares which had been shed
previous to stripping might have been missed by laborers.

Several scattered points of infestation appeared within a few days |
after the first trace of weevil damage was noted, most of these points |
occurring in the first planting. Infestation increased slowly, and by
the middle of July evidence of weevil injury could be found through- |
out the field.

COTTON IN WEEVIL-CONTROL EXPERIMENTS 9

Although the field became reinfested with weevils after square
removal and poisoning, the degree of infestation was much less than
in untreated early-planted fields on other parts of the experiment
farm. Possibly a more effective control might have been obtained
if the measures had been applied earlier than June 12, as fewer
infested squares would have been shed before the square-stripping
operation.

PLANT GROWTH DURING THE FRUITING PERIOD

Records of the nodal growth of the cotton plants, the rate of
flowering, and ‘the extent of boll shedding were obtained from each
of the four plantings. Comparisons of the rate of formation of
internodes were obtained from 10 representative plants in each plant-
ing, while the flower counts and boll sheds were recorded from 50-foot
sections of rows.

The records of plant development following the appearance of
squares were obtained from diagrams of the same plants which were
used in comparing the rate of growth during the seedling stages.
These diagrams were made at weekly intervals throughout the period
of fruiting of the plants, the final records having been made on August
11, after growth had practically ceased.

A comparison of the rate of formation of internodes on plants in
the successive plantings is shown in Table 6, which gives the average
number of nodes on 10 plants of each planting on the date when
squares were first recorded and 14, 28, and 56 days later. As the
first squares were recorded on different dates, it should be noted that
the nodal development of the plants in each planting is compared
during similar stages of growth and not on the same dates.

TasBe 6.—Development of nodes on the main stalk during the fruiting stage of cotton
plants grown in successive plantings at San Antonio on four different dates

Number of nodes at stated intervals after first appearance of squares

i
Date of planting, pau | 14-day interval | 28-day interval | 56-day interval
soe TECORU SG RA cea ee | ee ee | Potaly | Prob-
ane ; : ; ins, able
n- n- n- crease | error
Actual anes Actual ae Actual a
20) 1g (0 Ne ee eas June 1 6. 5 11.2 4.7 14.8 3.6 18.6 3.8 2 +0. 15
{ORB I2As a aa ae June 8 7.0 TL 4.5 14.9 3.4 18. 2 3.3 1152 =) 22
Boley yy phe 2 aac Gon 6. 2 10. 9 4,7 14. 2 3 16.9 P27) 10.7 | + .37
ML AY LQ or June 15 5.9 11.8 5.9 3.3 : 3. 8 13.0] + .22

The average number of nodes produced on the main stalk during
the first period of 14 days after the appearance of squares was 4.7,
4.5, and 4.7 nodes, respectively, on plants of the first three plantings.
The planting of May 12, however, formed 5.9 nodes during this
period. During the second period of 14 days the rate of formation
of nodes was much slower, the increase in number of nodes having been
3.6, 3.4, 3.3, and 3.3, respectively. The final period comprised 28
days, but the increase in number of nodes was only 3.8, 3.3, 2.7, and
3.8, or about the same as during the preceding period of 14 days.
The total number of nodes formed during the entire period of 56
davs after the appearance of the first squares was 12.1 nodes on plants

20718°—25},——2

q

10 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

of the April 19 planting, 11.2 nodes on the April 28 planting, 10.7
nodes on the May 5 planting, and 13 nodes on the May 12 planting.

In order to show the number of nodes on plants in the different
plantings on the same dates, the weekly records of nodal develop-
ment are graphically presented in Figure 3. These curves show that
the nodal development of the first three plantings was nearly parallel
throughout the period following the appearance of squares until
August 11. The May 12 planting, however, produced nodes more
rapidly throughout this period. From June 1 until August 11, a
period of 71 days, the April 19 planting produced 13.1 nodes. From
June 8 until August 11, a period of 64 days, the April 28 and May 5
plantings produced 11.1 and 11 nodes, respectively. From June 15
to August 11, a period of 57 days, the May 12 planting produced 13
nodes. The average number of days per node for each planting was
5.42, 5.77, 5.82, and 4.38 days, respectively.

S
vy
>
N
:
NX
N
%
:
N
N
<
RN
N
X

GUNE SHYLY AUG.

Fic. 3.—Average number of nodes on the main stalks of cotton plants at weekly intervals following
the appearance of squares at San Antonio, Tex.

i
]
|

Each node produced on the main stalk after the beginning of the.
fruiting stage of the plants represents the formation of a fruiting |
branch. Thus, the May 12 planting produced the same number of |
fruiting branches in 15 days less time than was required by the April |
19 planting. : |

Figure 4 gives the average height of 10 plants in each planting at
weekly intervals from June 1 until August 11. While the height of
plants is a factor of less importance than the nodal development,
it will be of interest as showing the relative size of plants in each
planting. The more vigorous growth of plants in the later plantings
is Shown in these curves. On July 13 the plants of the May 12 plant-
ing were the largest, with the May 5, April 28, and April 19 plantmgs
following in the order named. Although the plants in the April 19
planting maintained a larger number of nodes throughout the season,
after the middle of July they were the smallest. ‘The difference in|
the se of representative plants in each planting is shown in Plates
I and II. |

This tendency toward the development of larger plants in later
plantings is to be expected, especially on the heavier types of Texas)

| -S=s- 7

COTTON IN WEEVIL-CONTROL EXPERIMENTS 11

soils, when the moisture supply is plentiful. In the present experi-
ment the late-planted cotton made considerably more vegetative
erowth than that planted early, in spite of drought conditions.
The larger growth of the late-planted cotton resulted from the devel-
opment of longer internodes on the main stalk and on the fruiting
branches. Although the plants grew taller they had fewer nodes,
as shown in Figure 3.

XQ

|
AN

i

i

il
|
|
ie

.

NANANNNANNAN
\
\ *

SHSLIHASSSGONAG

:
ih
Lith

\

i \
SNL

AVERAGE HEIGHT OF PLANTE (INCHES)

rh go va FAA co zi 4 <o <7

KN GAHOVNGGDS

Fic. 4.—Growth in height of cotton plants at San Antonio, Tex.
PRODUCTION OF FLORAL BUDS

The fruiting capacity of a cotton plant is determined principally
by the number of fruiting branches formed on the main stalk and
the number of internodes formed on the fruiting branches. The
plants in the successive plantings at San Antonio were small and
formed few squares on secondary fruiting branches, and these are
not included in comparisons of the fruiting capacity of plants.

The average number of squares formed on 10 plants in each of the
four plantings is given in Table 7. The numbers of squares were
recorded at 2-week intervals throughout the fruiting stage of the
plants, the final record on August 11 representing the total number
of squares formed on the plants.

TABLE 7.—Average number of squares recorded at 2-week intervals on cotton plants
grown in successive plantings at San Antonio on four different dates

|
| Number of squares recorded on—
Date planted, 1923

|
June 1 | June 15 | June 28 | July 13 July 28 | Aug. 11
BEE QYirs viesse tee ho er = S 2.2 10.6 21.7 26. 6 31.9 | 35.3
2 TOTP SUE eS ee eT Slee ae 0 6.5 18.6 26. 4 SBHS: 38. 7
«SE Gas SB ad SESSA ee oe Dn ee 0 SE 7! 17.6 2a. 25.8 28. 5
2 AST Ge 2 Serer Gat ey, 0 1a 12.8 24. 2 26. 4 30. 9

12 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE |

These records show that the plants in the April 19 and April 28
plantings produced a larger number of squares than those in the
plantings of May 5 and May 12. The number of squares, however,
increased more rapidly on the later plantings during the first half of
the squaring period, as will be seen by a comparison of the number
of squares on the plants by July 13. On this date the average num-
ber of squares on plants of the May 12 planting was 24.2, as compared
with 26.6 on plants of the April 19 planting, although this planting
had reached the fruiting stage two weeks earlier than the planting
of May 12.

The fact that the number of squares formed on the late plants by
the middle of July was almost as great as the number on the early
plants was largely due to a better development of the lower fruiting
‘branches on plants of the later plantings. Table 8 gives the average
number of internodes formed on fruiting branches. The numbers
of internodes are determined from groups of fruiting branches, in order
to simplify the presentation of the data. The first eight fruiting
branches on plants of the May 5 and May 12 plantings developed
more internodes than the first eight branches of the early plantings.
The number of internodes on the upper fruiting branches was approxi-
mately the same on the first and last plantings, while the upper fruit-
ing branches on the second and third plantings were not so well de-
veloped. This tendency toward the formation of more internodes
on lower fruiting branches of late-planted cotton indicates that the
growth of the plants was not retarded by the dry weather during
June and the first part of July to so great an extent as with the early
plants. This is shown in Plates I and IJ by the presence of squares

on plants of the later plantings during the first part of August, after |

all squares had been shed from the plants in the early plantings.

TABLE 8.—Average number of nodes on fruiting branches of cotton planis grown in
successive plantings at San Antonio on four different dates

|
Branches; Branches| Branches} Branches

DEMS TIEICIE Spee - |" 1tod | 5to8 | 9t012 | 13to0 15
WorhigoOist NN GeO NRE A Lee 2.8 2. 45 1.27
AE. 28:08 ive, ee UE vas boy A Ph Ua ek DA A oA alee de BU der 2 BY | Eyes 07 9
erg eee MUP ALLE ben heute earl lL. 27? 3074 2! abr 3
May 10: (oGG AIT Od tere Fein 2 3.62} 2.92 10

The average number of internodes on the first eight fruiting
branches on plants of the May 12 planting was 3.04, as compared
with 2.3 internodes on plants of the April 19 planting. An even
more pronounced tendency toward the formation of a greater number

of internodes on the lower fruiting branches of later plantings was ©

shown in the experiments at Charleston.

FLOWERING RECORDS OF EARLY AND LATE PLANTINGS

Flower counts were obtained from four 50-foot sections of rows in -

the April 19, April 28, and May 5 plantings, and from two 50-foot

sections of rows in the May 12 planting. <A section of row was located |

on the east and west ends of rows in the first and second blocks of
the April 19, April 28, and May 5 plantings. No flower counts were

eS

Bul. 1320, U. S. Dept. of Agriculture PLATE |

SIZE AND FRUITING OF COTTON PLANTS IN SUCCESSIVE PLANTINGS AT SAN
ANTONIO, TEX., ON AUGUST 7.—I

A, Planted April 19; B, planted April 28. (Compare with Plate IT)

Bul. 1320, U. S. Dept. of Agriculture PLATE II

SIZE AND FRUITING OF COTTON PLANTS IN SUCCESSIVE PLANTINGS AT SAN
ANTONIO, TEX., ON AUGUST 7.—II

A, Planted May 5; B, planted May 12. (Compare with Plate I)

Note the larger size and production of vegetative branches on the plants in the May 12
planting, showing the need of closer spacing of plants in late-planted cotton. Also note the
presence of squares and flowers on these plants, produced under drought conditions, which

had checked growth in the early-planted cotton

COTTON IN WEEVIL-CONTROL EXPERIMENTS 13

made in the west end of the May 12 planting because of the very poor
stand.

Flower counts were started on June 26 and were made daily until
July 7. From that time until July 31 they were made every other
day. The counts from each section of row in each planting are given
in Table 9, with the total number of flowers counted each day in each
planting shown graphically in Figure 5.

The total number of flowers counted on the west end of the rows
is usually smaller than the number on the east end. This was due
to retarded plant growth in the west end of the rows caused by
Johnson grass in that part of the field.

(ESE EP SF 28 ED PD ed BN GE
Bp TST TE) A AN
HAN SS +}

oo AEA erases Ino
ae Sn ai eo
BO £2 APR. ca ea ea

20 ES ais eat
Hf}. 4] eNO

=
NS aie Pete ede Ue AN

te ye
AT, IN OG CPE, OE PPA el
S pu 8 Cz ae as

dee
aT TET NS) 8

20

) a a ST os a la a FE FE Ea PO ET
Sl
and TL as Se A YAY NIE IF 2/23. 25 27 2937

SYNE SOLS

Fic. 5.—Total number of flowers recorded daily from all sections of each cotton planting at San
Antonio, Tex.

The flowering of the April 19 and April 28 plantings was delayed
by the removal of early squares from the plants on June 12, as pre-
viously stated. Owing to this delay, the first flowers appeared at
peut the same date in the plantings made on April 19, April 28, and

ay o.

The plants in the April 19 and April 28 plantings were larger than
those in the May 5 planting, however, and produced more flowers
during the first half of the flowering period. During the period from
June 26 to July 13, inclusive, the total numbers of flowers counted
on the respective plantings were 1,966 on the planting of April 19,
as compared with 1,635 for the planting of April 28 and 1,539 for
that of May 5 Only 404 flowers were counted during the same
period on the two 50-foot rows of the M fay 12 planting.

. _ Although the early-planted cotton produced the largest number of
flowers during the first half of the flowering period, ‘the first. three
plantings reached the peak of flower production on the same: day,
the largest number of flowers being recorded on July 13 in each of

14 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

these plantings. During the period from July 13 to July 31, the date
when flowering practically ceased, the May 5 planting produced the
largest number of flowers relative to the number of plants, while the
April 19 planting produced the smallest number. The total number of
flowers counted during the entire season was nearly the same in each
of the first three plantings, being, respectively, 2,606 for the April 19
planting, 2,517 for the April 28 planting, and 2,620 for the May 5
planting. On the two 50-foot rows of the May 12 planting 866
flowers were counted. The small number of flowers produced on
these rows was due to the very irregular stand of plants.

TaBLE 9.—Numbers of flowers counted from 50-foot sections of rows of cotton grown
in successive plantings at San Antonio during the period from June 26 to July
$1, 1928

rt Planted
Planted Apr. 19 Planted Apr. 28 Planted May 5 May 12
ere ae reel cee |e eee Se
Date Block 1| Block 2 Block 1} Block 2 Block 1) Block 2 g| 3
- N
Flael|E |S] ee |B\/ele|al eae |e lee lel] | |eleale|
JUNCI26 S425 ete iL eal Oe VAN 2 asec | pale 10 0 Gieeel! ; LOISOl 2 Ole Os
Fj he ee Seas 6] 8} 13} 13} 40) 6 6 3) 7 22] 12) 14 4! 8 38 Of OF O
esas ae At SL 6} 13} 23} 11 53} 9} «16} «68 «10 43; 8 15) 9 8 40} Oo} OF 9
7 i pete te 11} 23| 21| 22] 77] 12} 21} 20] 191 72] 13 20| 15] 19) 671 of 1] 3
eS oe ae 15] 24) 38)" 35). 112]... 7] 34) 12) 25 78| 18} | 15) 14 Zane) Al Ss
Tulys tok ae 3 32} 43) 31) 29) 135} 22) 35] 16) 25) 98] 22] 25) 20) 27; 94) 7 98 15
BM Pes 19| 28/ 35] 19} 101) 19] 37] 21} 23) 100} 23] 27; 19] 16) 9&5] 11) 10) 21
BY ae | | Al] 26, 41) 131; 15) 37| 6] (37). 95! 22l” 261 16) 23 7{| 11) 9) 20 |
Ai ees 36] 53) 41) 37] 167; 17| 53) 22) 45) - 137 26) 35) 25) 31) 117) 12) 21) 33 |
is ee oes abe 34] 34] 31] 122} 24] 41] 16] 33) 114) 28) 33] 18] 27] 106] 21| 20) 41
(is CELE BS 19| 43] 43] 35} 140} 22) 52) 21) 45) 140] 26] 28] 22} 39] 115] 12) 16] 28 |
YU EP TS Cased 36, 66} 41 46| 189| 22] 64] 34| 411 161) 44| 381 31| 371 150] 21) 931 44
i aed Series 40} 64} 61} 58| 223; 33; 58] 24) 50| 165) 30) 45] 39] 45] 159] 29] 39] 68 |
aie ees sii 32| 68} 52] 59} 211) 27| 67) 20) 54| 168] 42) 46] 29) 45] 162) 24) 29) 53
ieee Rae ae 44} 75| 62} 70) 251] 48] 75} 48] 61} 232) 49) 65] 50} 70} 234! 41 30 77
ae eal ae Sepa 44) 35) 58] 41] 178] 34) 63] 40) 49] 186] 57] 65] 36] 50! 208] 38] 54] 92 |
| (iio tte neae 31, 39} 33] 50) 153] 52! 55] 40} 52| 199) 49] 47] 40} 59} 195! 36] 40| 76 |
OMe = ee! 17/ 31) 30; 27| 105] 27} 40} 38) 39} 144} 38} 41] 43] 59) 181) 33] 32] 65 |
Spree 15} 22) 21) 17; 75| 19] 17| 33] 37] 106} 32| 29) 31| 40| 1321 26] 24! 50 |
ays Aes eae We ee 12} 10} 11} 5| 38) 10} 6] 23) 29] 68] 25} 20] 20] 30; = *95)" 20] 15] 35mm
Depew S| 8! 10; 5) 381i 10) 7 30) 23) 70) 23] 20) 26) 33] 102) 22) 29] 51
DT eT SP 12) 1), BEL AD DAB), GIS} 556/123) 301 7024) 221 hese alee eta
DOR ae the Sas 5} 3} 4) 6 18} 10] 9 14) 12) 45) 17) 13] 10} 10; 50] 18 14] 32
Si Oh aes PR ole TAO 7) bbl) Papas eee Zp Si. QO} 4/5 7] 9) = SOR sipie io oe

ee a ee ee Ss Se Se Se

Rotalaee es | 483 | 740 710| 673] 2, 606) 459) 807) 513) 738) 2,517) 627} 718] 550) 725) 2,620) 422) 444) 866

i

Most of the flowers produced after the middle of July were shed as |

a result of adverse climatic conditions. The ability of late-planted

cotton to continue flowering under severe conditions is to be noted, |

however. This probably was connected with the continued produc-
tion of internodes on the lower fruiting branches of the late-planted
cotton, which occurred both at San Antonio and at Charleston.

SHEDDING OF BOLLS IN EARLY AND LATE PLANTINGS

As a result of dry weather considerable shedding of bolls occurred

in the different plantings. In order to compare the extent of boll
shedding in these plantings, the numbers of shed bolls were recorded.

from the 50-foot sections of rows on which the flower counts were
obtained. These counts do not represent the total number of bolls, |

COTTON IN WEEVIL-CONTROL EXPERIMENTS 15

as many shed bolls undoubtedly were covered with soil when the
plants were cultivated and others were shed later in the season after
the records were obtained. ,

Table 10 gives the number of shed bolls recorded from each section
of row in each planting during the period from June 30 to August 2.
These bolls were picked up every day from June 30 to July 7 and at
intervals of two or three days thereafter.

Boll shedding started about July 1 in the first three plantings
and reached its peak on July 17. Although more bolls were shed
from the April 19 planting during the period from June 30 to
July 17, the larger numbers of bolls from the April*28 and May 5
plantings were shed during the latter part of July. This no doubt
was due to the larger proportion of late flowers produced by these
plantings.

TaBLE 10.—Numbers of shed bolls recorded from 50-foot sections of rows of cotton

grown in successive plantings at San Antonio during the period from June 50
to August 2, 1923

Planted
Planted Apr. 19 | Planted Apr. 28 Planted May 5 May 12
a\%
Date Block 1) Block 2, Block 1| Block 2| * | Block 1| Block 2 g|
o N
Rey | oe AS) 3 ane 4 Ad =
2/4/2/4) 2 )2)2/2]8|) 2 12/3/2131 2 |e 18
Pea Scie ea ee tel ole) SY Ne Mey le Me Ie Ol ear eal
Hume ps0! 4 ks Ores Teele Qe TOOL. Obs Der lei Ol KOLO LOL ies Ohe OMS, OME 0
ag Tl a RS Oe elle Sia menT | enOle el eT a Ol CO ta al Al role Or 10
Peds Oy A eli egos Bac Tolls Ih). Gil oli6| Cai dls ai komen Oie ec O
Soe ee ae Olen me errs ets eet ee rG tO aime Thy Gl Ol, Si a TOK Pe Olen Ole nO
ZU Wai Si 2M WG line com oO oreo nee 8) heen BU 1 helene To OllsanO | 0
Suri AW 2G) azo manele OL eTSIN AS Sit 7 Sl OO\ elie Ol mene
am tina [Sa EO ee eM MA LAGI INES eal star
Ui rae ronan ier mle ole solaane ze 6l tO Ary Oh Sh yori bin) ) Aha OI NG
Pe a OR 15] 24) 31) 27| 97] 13] 34) 16| 33/ 96] 22| 30) 17| 18] 87] 12] 10} 22
I ee 23] 61| 41] 35) 160] 21) 56] 17| 49] 143) 19) 46] 30] 33] 128/ 28| 21| 49
ian Bay. a 42] 76| 67| 61) 246] 44] 80] 48/ 68) 240| 51) 51] 49| 36) 187| 26] 30] 56
jhe Bnei a 46| 106] 92] 65] 309] 49| 97| 44| 64| 254) 48/ 46] 57) 56/ 207| 33] 30| 63
i ae 86| 129] 107) 96) 418} 71) 149} 55] 99] 374] 75] 108} 63] 86] 332] 32| 59} 91
LOR Ee ee 51] 117| 81} 96] 345] 67| 136] 39| 70] 312] 78) 106) 57| 83] 324] 45] 46) 91
ZB awl ie 42} 73| 52] 90| 257| 52| 89] 55| 89| 285] 57| 78) 49| 75] 259| 40| 78] 118
7A Balas ag 22) 33) 31) 26, 112} 29] 44/ 35] 33] 141) 35] 40] 36] 54] 165/ 28| 32] 60
Bip eee pe 24| 12} 34} 17| 87] 36] 27] 45| 41] 149] 54] 39] 40| 63/ 201/ 57] 39) 96
Bit eok lee Ra 21} 24} 23] 24) 92) 25] 28| 32| 66| 151] 50} 60] 44) 74| 228| 50] 58] 105
ANS gle 22| 33| 22] 28) 105 24| 26| 22| 52] 124) 49) 55] 35] 63/ 202| 33] 45| 78
Total______.| 412] 715] 617) 600| 2, 344] 446] 795) 428] 707] 2,376] 561| 695| 503] 683] 2, 442) 390 447) 837

| For the period from June 30 to August 2 the total numbers of
_ shed bolls recorded from the April 19, April 28, and May 5 plantings
| were 2,344, 2,376, and 2,442, respectively, while only 837 shed bolls
were recorded from the two 50-foot rows of the May 12 planting.
The smaller number of bolls shed from the May 12 planting is due
to the fact that fewer flowers were produced.

The fact that the numbers of flowers produced and the numbers
of bolls shed were nearly the same on each of the first three plantings
indicates that there was no significant difference in the proportion of
flowers produced and the extent of shedding during the period of
observation. It is probabie, however, that more boll shedding would
have been recorded on the later plantings if the counts had been
continued in August.

16 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

SHEDDING OF SQUARES FROM WEEVIL INJURY

As previously stated, the first indication of weevil infestation after
the removal of squares and the application of poison was noted
during the last week in June. The progress of the infestation is
shown by records of weevil damage during the period from June 25
to July 31. These records were obtained by counting the number
of weevil-punctured squares that were shed during 2-day intervals
from a 50-foot section of a row in each block of each planting. These
data are graphically shown in Figure 6, the total number of shed
squares from the two blocks in each planting being combined in each
curve. :

FOO
i Ss a A A GO fee) CS ae)
ol | | Es Re ee eee
et
po ey Bee
GO
uy #0 Oo) —— YLIWVIED APRIL 19 BRB Re ay
ea ea |
i 2O-— > —— — ALANTED APRIL 28 | Prsise
OE ae ae sal
S Yo | —-— LANTLD (AR EF ===
8200 aleeeee. coo ALANTED (IY 12 eee ass An
Sie Ss Hed BE 98 2
ee 4 ee ae ee a ae a ee Ss a
Si A a a ES RE a
7 NP a [a2] 3) Slee eee
ES RS ae a a | Fr Hoe ed ee
C FO} Re:
ses MD EO a Cea
Pe cr oak RS Es Ge Be eS EB
S 7 oa Ws ae oo se Poa BaD gio da55
age ES eae DP TE RE St fs
pe MR a BR a an LS ed sa EP
S l | | i ie |
SCs ro Bi BE | as ea Fe ee Se) A Sr
ef eS Are SRE; al eS Pee

27 29 /f 3 & F GU 13 IE AP 192 2325 27 2G
Se a
JUNE SLE

Fic. 6.—Number of weevil-shed squares from two 50-foot sections of rows in each planting of cotton at San
Antonio, Tex.

The first weevil-shed squares in the April 19 planting were found
on June 29 and in each of the three later plantings by July 7. The
first planting showed a higher rate of square shedding during the first
half of July, but the extent of weevil damage in all plantings was

ractically the same by the 19th of that month. The number of
squares shed from the first planting decreased after this date, but
increased very rapidly in each of the later plantings.

This abrupt shift in the extent of shedding is due to the fact that
there were more squares on plants in the later plantings during the
last half of July. It is probable that the absence of squares on the
early plants resulted in a concentration of weevils on the later plant-
ings. This condition of heavy weevil infestation in the late-planted

COTTON IN WEEVIL-CONTROL EXPERIMENTS £7

cotton illustrates the difficulty of obtaining accurate comparisons of
productiveness from adjacent plantings of early and late planted
cotton when complete weevil control is not obtained.

WEEVIL DAMAGE TO BOLLS

Records of the extent of weevil injury to bolls in the different
plantings were made on four dates during the period of boll opening.
These records were obtained from the same 50-foot sections of rows
which were used in comparisons of flowering and boll shedding. The
weevil damage was determined by counting the number of injured
and uninjured locks in each of the bolls that had opened in the
intervals between the four dates when the records were made. This
afforded a means of comparing the extent of the injury to early and
late bolls of the successive plantings.

Table 11 gives the number of bolls picked, the number showing
weevil damage, the total number of locks, and the number and

ercentage of locks damaged by the weevils. The records from the
our 50-foot sections of the first three plantings are summarized and
presented in a single unit corresponding to a 200-foot row.

TaBLE 11.—Exztent of weevil injury to bolls in successive plantings of cotton at San

Antonio
Number Locks damaged by
Number ; of bolls Total weevus

Date planted, 1923 a of bolls |damaged | number

P picked by of locks
weevils Number | Per cent
Aug. 14 243 56 1, 061 92 8.7
pr. 19 Aug. 18 312 57 1, 390 89 6.4
IC ce SS SoS Sea ee oe a Aug. 30 403 175 1, 733 366 21.1
Sept. 10 101 72 432 163 Bad
TRotaliss 2s Bae Fe eee a Mees nh Pd 1, 059 360 4,616 710 15. 4
Aug. 14 161 52 719 66 9.2
Aor. 28 Aug. 18 215 52 968 69 ek
Oe SR ain ee 3 Se Sa oe oer eo Aug. 30 519 249 2, 258 521 pa ik
Sept. 10 138 105 584 239 40.9
Oba ae ee ee ee ee se 1, 033 458 4, 529 895 19.8
Aug. 14 105 25 472 35 7.4
May 5 Aug. 18 216 31 968 52 5. 4
ee Slee oe eee, ee Aug. 30 521 313 2, 387 656 27.5
Sept. 10 198 129 849 35. 2
PROLA Se so eee eee bee OM a he) ot 1, 040 498 4, 676 1, 042 22.3
Aug. 30 300 192 1, 410 433 30. 7
May 12---_------------------------------- Sept. 10 86 69 75 173 46, 1
SRG bale | 2S. eee ee ee Pa Be DE 386 261 1, 785 606 33.9

The maturation period of Lone Star bolls in Texas has been shown
to be about 42 days,‘ so that bolls open before August 18 must have
developed from flowers appearing prior to July 8. The small amount
of weevil injury to these early bolls is due to the slight weevil in-
festation during the first part of the flowering stage of the plants
and also to the presence of squares. While squares are available

{ Martin, R. D., W. W. Ballard, and D. M, Simpson. Growth of fruiting parts in cotton plants. In
Jour. Agr. Research, v. 25, p. 204. 1923.

20718°—25° 3

BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

SVT lf M1
SLNE TS F

SLAIN B Oh
ST LIP eI,
SLO SE

LUGE SASHIMI
2A2 ELNG TA
we

SG NOLIFS ONOLIFIS
SHONOGC MW! NOLLOP DFFE LO ID7TGIA

NVOPGVELR CF -LAIVIS 114 COWS

Q |
XA RALSLARGA

lanted on May 12 at San Antonio, Tex., with no treatment for weevil

SON 0d Nl 'NOLLOP DGFFE AO P7TFA

g
2
S
2
q
5
ic
E
iS
z
q
z
3
\ E
She RR
\ XS 3
NN 2
Nie oe
N 2s
S BB
\ 8 N oe
Ngee. a
S| Sit ee
NAY ee
NS RRR SS
Q \8e S ge
aS . NN S am
VN XS 8) a
LIL SQ ag
Vy SS 2
NA Be
SS N K 29
} YN \\ ~ So
N RSS ae
yd ee SN aa
Sieee N Ee
N N a6
NEE x Ba
\1__ B88 o8
— Sa
| Q& 2
NEN as
NS EE
SS
VLVHHLOHEBVN HDOLOHEHYN 253
F NOWLITS & NOLLIZTS res
E oO
=

a COTTON IN WEEVIL-CONTROL EXPERIMENTS 19

for the weevils to work upon, there is less injury to the bolls, though
the fact that from 7 to 9 per cent of the locks on early bolls were
damaged shows that the presence of squares is not a complete pro-
tection against weevil attack. The greater injury to the later bolls
_ corresponds to the heavier infestation of weevils in the latter part
of July and to the fact that there were very few squares on the plants
at that time.
The increase of about 12 per cent in the injury to bolls in the
lanting of May 12, as compared with that of May 5, as shown in
| Table 11, is due to the fact that practically all the bolls produced
in the last planting were from flowers appearing after July 8, so that
most of the bolls in this planting were immature when the weevil
_ infestation reached its peak during the latter part of July. It is
_ probable also that weevil injury caused the shedding of many late
| bolls that otherwise might have been retained and developed to
maturity.

YIELDS FROM SUCCESSIVE PLANTINGS AT SAN ANTONIO

During the first week in August the first open bolls were found
on the plantings of April 19, April 28, and May 5. Although there
was little difference in the time when the first open bolls appeared
on these three plantings, that of April 19 matured the bulk of its
crop sooner than the others. This was in accord with the larger
number of early flowers produced by the first planting. The entire
crop of all plantings had matured by September 10, but the scarcity
of labor delayed picking until September 19.

TaBLE 12.—Yield of seed cotton from successive plantings at San Antonio

Number of plants Yield Ces cotton
Date planted, 1923 Block

Section! Section| Per | Section! Section
A TOW A B

EN Bk ge ee fe eae! eae a le ec (Oe eee ee ae .25 | 10.00
sen eel |S ae cae | SE a 6. 75 8. 00
Se a ed is See (Ee Soh 6. 25 8. 12
oe ee See io a, 5. 44 7. 25

194 392 5. 87 7. 87
193 375 6. 00 7. 75
198 403 4.75 7. 12
197 386 4. 82 7. 21

782 | 1,556 | 21.44 | 29.95

185 379 | 5.00 |: 6:56
197 3871 5.00 | 7.50

163 300 2. 06 4.75
135 261 2.19 5. 25

608 | 1,165 | 12.20] 23.09
172 321| 4.00! 5.62 9. 62

187 307 | 3.25 5. 00 | 8. 25

177 345 | 3.7 5.79 9. 49
186 371 3. 44 4.69 Sais
193 381 4.52 5. 12 9. 64
181 376 | 3.87 4.18 8. 05
737 | 1,473 | 15.53 | 19. 78 |__ 35.31

189 309 4. 00 4.12 8.12

SCN > -

20 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

TABLE 12.—Yield of seed cotton from successive plantings at San Antonio—Con.

b

Number of plants jag cotton
Date planted, 1923 Block | Row

Section| Section} Per Section} Section; Per

A row A B TOW
Mayleftt Suh 615 VAAL. Bed Es 1 220 164 3841 2.69] 3.25 5.94
2 63 80 143 | 1.00] 1.12 2.12
3 83 105 iss | 1.00] 1.62 2. 62
a 4 146 135 981 | 2.12] 2.00 4.12
5 127 149 276 2.37 1.18 Stolen
6 72 131 203 . 40 TERY! nj
Block “totali-. $2) 2 tee a NSS Tel ma See 428 520 948 5. 89 6.17 12. 06
7| 107 so} 1961 .75 50} 1.25
8 99 133 232 1. 25 2. 37 3. 62
U5 1) ari Vee ee eee, Se eee ect ie if 186 198 384 6. 50 9. 06 15. 56
2 193 169 362 ane 7. 25 13. 00
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3 186 184 370; 5.00| 612] 11.12
2 4 198 196 304| 5.00] 5.75 | 10.75
5 198 196 304 | 5.50] 6.94] 12.44
6 193 195 388 | 4.94| 7.37] 12.31
Block: total. £8. 3 - best 3. ee | lees 775 771 | 1,546 | 20.44] 26.18} 46.62
7 190 194 384 5. 67 6.73 12. 40
8 185 207 392 6. 25 Lckle 13. 62
Appr nose 5. PR. be A be Ee. 1 170 174 | 344 5| 4.69 8. 44

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COTTON IN WEEVIL-CONTROL EXPERIMENTS 91

The rows in this test were divided into two 100-foot sections by
a line stretched across the field, and the weight of seed cotton was
recorded from each section of each row. Section A includes the
western half of the field and section B the eastern half, where the
plants were notably larger. The weight of seed cotton and the
number of plants are stated in Table 12. These data are also shown
graphically in Figure 7. In comparing the yields of the four plant-
ings the weight of seed cotton from only the four inside rows of each
block is used., The yields of the outside rows vary to a considerable
extent, being affected by adjoining blocks of earlier or later planted
cotton.

The highest yield of seed cotton was obtained from the April 19
planting, the yields from three 4-row blocks having been 51.39, 46.62,
and 43.81 pounds, respectively. The yields from the April 28 and
May 5 plantings were about equal. Two blocks of the April 28
planting yielded 35.28 and 35.21 pounds, while the May 5 planting
Peydured 35.31 and 36.56 pounds. Very low yields were recorded
rom the May 12 planting, the two blocks having produced only 12.06
and 13.92 pounds of cotton, respectively.

Consistent differences in the yield of the east and west sections of
rows occurred in all plantings. The lower yields from the west sec-
tion of rows were due to the presence of Johnson grass, which retarded
the growth of plants in this part of the field.

In the May 12 planting no thinning was done in parts of rows
where a stand was obtained, so that the plant counts are not com-

7 parable with those obtained from the other plantings. Though the

ow yields of the May 12 planting may be ascribed very largely to

the poor stand of plants, the larger proportion of bolls injured by the
weevils was also a factor.

The higher yields obtained from the cotton planted on April 19
may also be ascribed, at least in part, to the smaller percentage of
injured bolls, showing that the weevil conditions were not as severe
during the early period of boll development.

Nearly the same numbers of flowers and shed bolls were recorded
from the April 19, April 28, and May 5 plantings, and the totals of
the yields from the four 50-foot sections of rows of each planting
from which these records were obtained were nearly the same, having
been 12.68 pounds from the April 19 planting, 12.15 pounds from the
planting of April 28, and 11.67 pounds from that.of May 5. Never-
theless, the total block yields were considerably higher on the April
19 planting.

It seems possible that the higher yields obtained from the 50-foot
sections of rows in the April 28 and May 5 plantings, as compared
with the total block yields, may have been due to the fact that all
of the weevil-infested squares were picked up under the 50-foot sec-
tions during July for record purposes.

The additional protection that may have been given to the 50-foot
sections by collecting the weevil-shed squares would not render the
yields less significant. On the contrary, the yields that were secured
from these sections of rows may be more indicative of the results that
might have been secured if the later plantings had been apart from
the earliest planting and had not been subjected to the weevil infesta-
tion from the early cotton.

92 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

PERCENTAGE OF 5-LOCK BOLLS ON EARLY AND LATE PLANTINGS AT
SAN ANTONIO :

A feature that was found to differ in the several plantings was the
proportion of bolls with five locks. A record was obtained of the
number of locks in bolls picked from four 50-foot sections of rows in
the April 19, April 28, and May 5 plantings. ;

Data from each planting are presented in Table 13, showing the
number of 4-lock and 5-lock bolls picked on August 18 and September
10 from two 50-foot rows on the east side of the field and two 50-foot
rows on the west side. As stated previously, the presence of Johnson
erass on the west side of the field retarded the development of the
plants, and lower yields were obtained than on the east side.

The data presented in Table 13 show that a consistently higher
percentage of 5-lock bolls were produced on the large plants in the
east end of the rows. In the April 19 planting the large plants pro-
duced 41.2 per cent of 5-lock bolls, as compared with only 23.8 per
cent on the small plants. The large and small plants in the April 28
planting produced, respectively, 49.5 and 23.8 per cent of 5-lock bolls
and in the May 5 planting 50.3 and 27.6 per cent. There was little
difference in the percentage of 5-lock bolls produced on the small
plants in the first three plantings, but the percentage of these bolls
edu on the large pints in the May 5 planting was 9 per cent

igher than in the April 19 planting. ;

TaBLE 13.—Number of bolls and percentage of 5-lock bolls picked on August 18 —
and September 10 from large plants on the east end of rows and from small plants |
on the west end of rows in the successive adjacent plantings of cotton at San
Antonio

Number of bolls Per-
centage
Date planted, 1923 Size picid of
2 i 5-lock
5-lock | 4-lock | 3-lock | Total bolls
Aug. 18 70 162 1 233 30. 0
Apr. 19-_.------------ Small plants- --------------- Sept. 10 37| 179 rig ees ieee ra
ited. facie ere leas ee alge ee 107| 341 21 450 23.8
Aug. 18 146 176 o| 322] 45.3
Large plants---------------- fon 10} 105 181 1} ° 2371 366
Métal seis oes |e oe eo pace meat (elke ae 251 357 1 609 41.2
= |
Apr. 28__.------------ Small plants--_-------------- Neon 0 51, one ee te
Motel gcc ka Sa We neal 0 ape gee |e 93 294 4] 391 23.8
‘Aug. 18| 146 99 0 245 59.6
Large plants- --------------- Sept. 10 172 295 0 397 43.3
at eae ra eNO ty, eat SON A. enh Sa 318 324 0 642} 49.5
Aug. 18 36 95 0 131 27.5
May 5__-------------- Small plants_-__------------ Sept. 10 87 295 3 315 27.6
Ata Ge hoe ee mcg, (e ace ei Ratee AAs tae ee 123 320 3 446| 27.6
‘Aug. 18 120 70 0 190| 63.2
Large plants---------------- Sept.10| 178| 224 1 403 | 44.2
b! BX0Y 2 | oaeieennee eel ge eee Oe Se eee te Ghee, Be! See ee 298 294 1 593 50. 3

a

COTTON IN WEEVIL-CONTROL EXPERIMENTS 23

A SEPARATE LATE PLANTING AT SAN ANTONIO

A separate late planting of cotton was also made at San Antonio
on May 12, the same date as the last of the consecutive adjacent
plantings and from the same stock of seed. The surface soil had
dried, but by using broad sweeps in front of the planter drill the seed
was dropped in moist earth. Germination was rapid, and a fairly
good stand of plants was obtained, although most of the rows had
a few skips due to imperfect germination. Most of the seed in these
skips germinated following a rain on May 30, but the seedlings were
weak and most of them died or remained stunted. The location of
this planting with relation to other fields of cotton on the experiment
farm is shown in Figure 1. ;

CLOSE SPACING IN LATE PLANTINGS

The tendency of late-planted cotton to produce a large “rank”’
type of stalk under certain conditions renders it desirable to leave
the plants closer together in the rows, in order to suppress excessive
vegetative growth. Plants which grow large require a longer season
to mature a crop, and when the season is shortened by late planting
overgrown plants are an added disadvantage.

The principle of controlling the vegetative growth of plants by
spacing the plants closer in the rows has been tested under a wide
range of conditions. Equal or greater yields have usually been
obtained from close-spaced plants when tested in direct comparison
with wide-spaced plants. A greater degree of earliness is usually
obtained by close spacing. In open stands with the plants averag-
ing from 2 to 4 inches apart in the row, larger yields have been
obtained without thinning.

In order to test the effect of close spacing when cotton is planted
late, this experiment was planned as a comparison of plants chopped
to two plants in a hill with plants left unthinned in the rows. The
test consisted of three 4-row blocks of each spacing, the unthinned
blocks alternating with the blocks of thinned plants. The outside

blocks were protected by guard rows.
The plant spacing used in comparison with the unthinned blocks
was the same as that used in the time-of-planting test, two plants
being left in hills with the hills 12 inches apart. Thinning was done
in these rows on June 15, when the plants averaged about 8 inches
in height and had from six to eight nodes.

OVERWINTERED WEEVILS AVOIDED

Although the late-planted cotton was examined at frequent inter-
vals for indications of weevil infestation, no trace of weevil injury
was found during June.

The fact that infestation from overwintered weevils was avoided
in the separate late planting probably was due to hot dry weather
during the first part of June. During this period the plants were
small and had not yet formed squares, so that if weevils came in
they had little protection against the high temperatures and did not
survive to attack the squares when they had reached sufficient size
to enable the weevils to begin breeding. Thus, it appeared that
the planting of May 12 had been sufficiently late to avoid infesta-
tion from overwintered weevils under the conditions encountered at
San Antonio.

24. BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE i

LATER WEEVIL INJURY

The first indication of weevil infestation in the late-planted cotton
was noted on July 8, after the plants had begun to produce flowers.
It is probable that this infestation resulted from migratory or stray
weevils from the nearest field of early-planted cotton. A field of
cotton planted on April 12 was located about 200 feet southwest of
the late-planting test. This early-planted cotton was heavily
infested with weevils, and migration may have occurred from this
field during the first part of July.

In order to show the progress of infestation in the late-planted
cotton, a record was obtained of the number of weevil-punctured
squares which were shed from the plants in two 50-foot sections of
rows. The number of squares shed each day are graphically pre-
sented in Figure 8. The first squares shed as a result of weevil injury
were found on July 11. The shedding was very slight until July 25,
when a rapid increase occurred. The sudden increase at this time

Q 70 ivvereuee)

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CN ie AN

es oN 5

SAIN Gal i eames VAS

Re ogo ae

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= HA Zoi A: “es 70 IE <O ao HH
SUNE SOL

Fig. 8.—Number of weevil-punctured squares shed from a 100-foot section of row in cotton planted on
April 22 and on May 12 at San Antonio, Tex. The upper line represents cotton planted on April 22;
first squares on May 27. The lower line represents cotton planted on May 12; first squares on June 10.
No treatment for the centrol of weevils was given in either field

was probably due to an increased infestation by weevils migrating
from near-by fields of early-planted cotton.

A similar record of weevil-punctured squares was obtained from
a field of cotton planted on April 2, located about 600 feet north of
the late-planted cotton. These data are included in Figure 8 for

purposes of comparison with data regarding the late-planted cotton.

The first squares on the cotton planted April 22 appeared during
the last week in May. Weevils were found on plants in this field by
June 1, and a 12 per cent infestation was recorded on June 6. As
Squares were available early in June, it was possible for the weevils
to deposit eggs and insure the appearance of a new generation of
eons by the latter part of the month. Thus, the May 12 planting
did not get weevils for more than a month later than the April 22
planting, and the breeding of an early generation of weevils during
June was entirely avoided in the late-planted cotton.

Even if favorable conditions for natural control of weevils did not
occur, effective control might be obtained in late-planted cotton by
applying poison just before squares are produced. This method of
control probably would be limited to late-planted cotton which did

COTTON IN WEEVIL-CONTROL EXPERIMENTS 25

not produce squares until the emergence of weevils from hibernation
had been completed. Poison applied before the appearance of
squares in early-planted cotton would be less effective, as late emerg-
ing weevils would reinfest the field.

DEVELOPMENT CF PLANTS IN THINNED AND UNTHINNED ROWS

In order to compare the development of the plants in thinned and
in unthinned cotton, records of plant height and number of nodes
on the main stalk, the number of squares produced, and the number
of internodes on the fruiting branches were obtained on 10 repre-
sentative plants of each spacing. These records were started on
June 27 and were taken at biweekly intervals until August 9.

The average number of internodes on the main stalk and the height
of plants on June 27 were practically the same on plants which had
been thinned to two in a hill on June 15 and on plants left unthinned.
Those in both spacings averaged 11.1 nodes on this date, while the
height averaged 28.8 centimeters for unthinned and 28.9 centi-
meters for the thinned plants.

The number of internodes on plants of both spacings remained
practically equal throughout the period during which data were
obtained. The final records, obtained on August 9, showed that the
unthinned plants averaged 17.2 internodes, while the thinned plants
averaged 18 internodes on the main stalk. The thinned plants had
grown to a slightly greater size, however, their height averaging
67.3 centimeters, as compared with 63.2 centimeters on those un-
thinned. It is apparent that different plant spacings had a negli-
gible effect on the development of internodes of the main stalk and
on the height of the plants. The dry weather at San Antonio during
this season retarded the development of all plants, and it is possible
that greater differences in the size of plants would have resulted if
more moisture had been available.

Although the development of the main stalk was the same on
thinned and unthinned plants in this test, the thinned plants had a
larger number of internodes formed on the fruiting branches, as
shown by records obtained on August 9, when the growth of all
plants had practically stopped. These data, showing the compara-
tive nodal development of groups of fruiting branches on thinned
and unthinned plants: are presented in Table 14. The thinned
plants had a consistently larger number of internodes on each group
of fruiting branches than the unthinned plants.

TaBLEe 14.—Number of squares on plants and average number of internodes on
fruiting branches of thinned and unthinned plants in a late-planting test of cotton
at San Antonio in 1923

Average number of internodes
on fruiting branches on
August 9

Total number of squares on plants at
2-week periods

Plant spacing

Branches Branches | Branches
June 27 | July 12 | July 25 | August 9 1to4 5 to 8 9 to 12

26 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

The average number of squares formed on 10 plants of each spac-
ing is shown in Table 14. The unthinned plants averaged 10.6
squares each on June 27, as compared with 10. 1 squares on thinned
plants. On August 9, when the final record of all squares formed
was obtained, the thinned plants averaged 34 and the unthinned
plants 25.4 squares per plant.

The greater fruiting capacity of individual plants when two plants
are left in hills does not represent the relative fruitfulness of thinned
and unthinned cotton. When equal areas of each spacing are com-
pared, the greater number of plants in unthinned rows, usually more
than offsets the difference in fruiting capacity of individual plants.

This is illustrated in Plate III by the number of bolls set on equal —

sections of rows of thinned and unthinned plants.
PRODUCTION OF FLOWERS ON THINNED AND ON UNTHINNED ROWS

Daily records of the number of flowers were obtained from July 2
to July 7 and at 2-day intervals thereafter until August 6. These
records were obtained from a 50-foot section of rows of thinned and
of unthinned plants, each section being representative of similarly
spaced plants throughout the test. There were 144 plants in the
section of unthinned cotton and 98 plants in the thinned section.
The data of flower production are given in Table 15.

TaBLE 15.—Flowers counted in 50-foot sections of rows of cotton unthinned com-
pared with those on plants thinned to two in a hill with the hills 12 inches apart
at San Antonio

Un- | : | Un- . | Un- :

Date, 1923 fainted | Thinned |} Date, 1923 +Hanned Thinned | Date, 1923 aed Thinned
July 2... 30 10 || July 13___.__ 64 46 || July 29-.____ 30 | 23
ike ae ee July ino 69 41 || July 31______ 19 | 21
pile Soe as 22 14 |] July 17______ 58 || Aug. 2. ___ 4 17
Fahye5 se 31 El aly: 19s 54 48 |} Aug. 4______ 3 14
July 6_______ 52 17 || July 21______ 46 41 || Aug. 6_____- 1 11
Julytea: = 33 22 || July 23______ 41 35
See aces 62 40:\| Joly. goo |? atl "Total 782 566
July (he 24" 50 17 | Satyr 27230 36 41 |

|

Although individual plants of thinned cotton have a greater fruit-
ing capacity than unthinned plants, comparisons of equal areas of
each spacing show that a larger number of flowers were produced
by the unthinned plants. A total of 782 flowers was counted on the
50-foot section of unthinned cotton, as compared with 566 flowers
on an equal section of thinned plants. The difference of 216 more
flowers on the unthinned cotton represents an increase of about
38 per cent in favor of the unthinned plants im this test.

A greater degree of earliness of the unthinned plants is indicated
by the number of flowers produced during the first part of the flower-
ing period. A total of 372 flowers was recorded on the unthinned
plants during the period from July 2 to July 13, as compared with
175 flowers on the thinned plants during the same period.

WEEVIL DAMAGE TO BOLLS

A record of the extent of weevil injury to bolls was obtained from
two 50-foot sections of rows in the late-planted cotton. On August

4
4

(sae te re ee i co _. BEB BERBERS SRR SSeS SES IS Pees eee eee eee ee eee Eee —- --—

Bul. 1320, U. S. Dept. of Agriculture PLATE III

PLANTS IN SEPARATE LATE PLANTINGS OF COTTON AT SAN ANTONIO,
WITH THE VEGETATIVE BRANCHES SUPPRESSED BY CLOSE SPACING

A, Two plants in a hill with the hills 12 inches apart; B, unthinned cotton

Bul. 1320, U. S. Dept. of Agriculture PLATE IV

COMPARATIVE SIZE AND FRUITING OF COTTON PLANTS IN SUCCESSIVE
PLANTINGS AT CHARLESTON, S. C.

A, Planted April 5; B, planted April 25. (Photographed August 14)

COTTON IN WEEVIL-CONTROL EXPERIMENTS oF

20 all open bolis were picked, and the number cf good and weevil-
damaged locks was recorded. Similar data were obtained for bolls
which opened between August 20 and September 1 and between
September 1 and September 18.

A total of 211 bolls was picked from the two sections of rows on
August 20. Of these bolls only 25 locks showed signs of weevil dam-
age, representing 2.6 per cent of the total number of locks. On
September 1, 613 bolls were picked, and 17.9 per cent of the locks
were found to be damaged. Of 259 bolls picked on September 18,
34 per cent had damaged locks. A total of 18.8 per cent of the locks
was damaged ‘on the 1,083 bolls picked during the season. This
weevil injury to bolls was much less than occurred in the other
experiment on the cotton planted on the same date but between the
earlier plantings. As shown in Table 11, the May 12 planting in
the comparison of successive adjacent plantings had 33.9 per cent
of all the locks damaged by weevils instead of 18 per cent in the
separate late planting. This shows that even a slight isolation of
the late plants had a notable effect upon weevil infestation and the
resultant injury to the crop.

YIELDS FROM THINNED AND FROM UNTHINNED ROWS

The late-planted cotton was picked on September 18, at which
time all bolls had opened. The field was divided into two equal sec-
tions by drawing lines across it at right angles to the rows, and the
weight of seed cotton from each section of each row was recorded
separately. The length of rows in each section was 100 feet.

The row yields from this test are presented graphically in Figure
7 in comparison with the row yields obtained from the successive
plantings. The yields and number of plants per row in the late-
planting test are given in Table 16.
| The row yields of seed cotton indicate that soil conditions were very

uniform throughout the field. Most of the difference in row yields
resulted from imperfect stands, some of the rows having short sec-
tions with no plants or with a very irregular stand. ‘This irregu-
larity in stand interfered with an accurate comparison of the two
systems of plant spacing, as some of the unthinned rows had fewer

lants than some rows which had been thinned to two plants in a
ll. The poorest stands occurred consistently on the outside rows
of each block. As a 2-row planter was used it is probable that these
thin stands were due to faulty operation of one side of the planter.

In view of the better stands on the two inside rows of each block, a
more accurate comparison of yields may be obtained from these rows.
The total yield of seed cotton from the inside rows of the three
blocks of unthinned cotton was 67.07 pounds, as compared with a
yield of 61.97 pounds from the inside rows of the three thinned
blocks. From these weights the mean yield of one 200-foot row of
unthinned cotton was found to be 11.18+0.31 pounds, while the
ee eels of an equal length of row of thinned cotton was 10.33 £0.45
pounds.

The difference in average yield of seed cotton between the unthinned
rows and the rows which were thinned to two plants in a hill with
hills 12 inches apart is less than twice the probable error, indicating

that there was no significant difference in yield between the thinned

28 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

and the unthinned cotton. (Pi. III.) The cost of production was
somewhat lower with the unthinned cotton, however, as the expense
of chopping was eliminated.

TasLe 16.—Yield of seed cotton in a late-planting test at San Antonio in 1923

Number of plants Yield of seed soe

(pounds
Plant spacing Block | Row
Section] Section} Per | Section] Section} Per
A B TOW "A B row
Unthinned__.----------- Guned Wood poten ates aes et eee
3 276 282 558 6. 00 4, 81 10. 81
D 1 4 320 347 667 6. 04 5. 62 11. 66
i se ee ie Sa i a i loa 5 325 321 646°] 5.25! | 68709 Tee
6 246 177 423 5. 50 4, 62 10. 12
Blocks totale. os 58 bose. te coe ee eee ee See 1, 167 1,127 | 2,294 22.79 | 20.92 43. 71
1 157 151 308 5. 75 5. 00 10. 75
Two plants in a hill (hills 12 inches \o 2 196 189 385 9215 4.69 10. 44
BPAll) aisee Meee Se A 8 ea a 3 181 189 370 6. 00 5. 25 11. 25
4 149 125 274 4. 25 4, 50 8.75
‘Block totalios 42252 Slee eee | Sea 683 654 1, 337 21. 75 19, 44 41.19
1 179 191 370 5. 00 4, 50 9. 50
: 2 265 307 572) ~~ 6.12 4, 69 10. 81
Unthinned__-------------------------- ae 3| 294) 281] 5751 649| 487] 11.36
4 218 216 434 5. 25 4, 69 9. 94
Block totalecce. ARSE. Pas eee | se ee 956 995 |} 1,95- | 22.86} 18.75 41. 61
i 1 143 158 301 5. 50 5. 50 11. 00
Two plants in a hill (hills 12 inches \4 2 194 195 389 5. 20 5. 15 10. 35
BPArb) ec so Rens ee Soe ra ea Pp meee 3 196 164 360 5. 50 5. 19 10. 69
4 155 157 312 4, 62 5. 00 9. 62
Block totals 2-2 8s 4. See eee eed al ee 688 674 | 1,362) 20.82 | 20.84 41. 66
1 196 169 365 4. 50 4, 62 9, 12
: ‘ 2 269 256 §25 5. 62 5. 00 10. 62
SSE cae Seo oe as ae 31, 260} 271) 531/619) 5.31 | 4g. 50
4 196 202 398 5. 62 §. 12 10. 74
IB OCR CObal es 2 2 ee ee eee cae eee ee een 921 898 | 1,819 | 21.98 | 20.05 41. 98
1 174 140 314 5. 62 5. 00 10. 62
Two plants in a hill (hills 12 inches \5 2 190 191 381 5. 00 5. 00 10. 00
Apart) s: Son LF yeaa oe Re er Mfg ge ep ae 3 177 167 344 5. 12 4,12 9. 24
4 100 56 156 5. 00 3. 12 8.12
Block: totaltes <3 = so Sealer Sok 641 554 | 1,195} 20.74] 17.24 37. 98
Ly jn dates He Sete | es See eee ee 11. 50
WUnthinnedrs: Six a2. ees Se Seen Guard_- Zales LES SAS Vere 8 ae ee era | eos 12. 00
EEL IL UY SE Caw Sal s AL EELS (So ee eee see 11. 50

YIELDS FROM COTTON EXPERIMENTS AT SAN ANTONIO

The yields of seed cotton obtained from the separate field of late-
planted cotton were greater than those from cultural and variety
tests conducted at San Antonio during the same season. The yields
from the late-planted cotton were exceeded only by the April 19
planting in the successive plantings. The average row ain from
the late-planted test, the successive plantings, two cultural tests,
and the Lone Star blocks in the variety test are given in Table 17.
The same variety of seed was used in ail these plantings,

COTTON IN WEEVIL-CONTROL EXPERIMENTS 29

TABLE 17.—Average row yields of cotion in all experiments conducted at San

Antonio
e |
| Average
Date yield
Kind of experiment planted, | Treatment for weevils | Plant spacing pita
192 TOW

(pounds)

a : = hinned == 11.1
Separate late planting_-_-----_- May 27) None 422 seh ee tas 4 = 2 Bianca Fail (oad. Soke 10. re
fApr. HOP Square stripped) poi- |= 24202 2 Sa eee eee 11. 82

soned.

Successive adjacent plantings_!{ Apr. 28 |____- OC) RESUS EL Ret oS oe ae jee GG Vet AO ee LE a 8. 81
\|May 5] Poisoned_____-_-_-_-_- ahs PTICD ae a ps aie ly Sait A 8. 98
Jee SAS eee 0a Rees | RS a CAF aA Sod 1 Ae 3. 25
oops Te + Wnthinne dss: 22222852252 sis 8. 28
Gulturaltest- No.1, feld-@324|A pr. (237|-None2. = 4 22 2s Mt plant to 12 inches tadihs ao 6. 78
= 4 \f1 plant to 10 inches________-_- 5.8

Cultural test No. 2, field C3__|__- GO Se i ee Oey as eee ‘\2 plants to 10 inches_________ 6.5
Lone Star check in variety | Apr. 22 |____- GOL e his. AeA ee NGM CHES ae ha PEAT eee ee a 6. 5

test D3. | q
° |

SOIL, CLIMATIC, AND WEEVIL CONDITIONS AT CHARLESTON, S. C.

A comparison of successive plantings of cotton was made in South
Carolina on the farm of F. P. Seabrook on James Island, about 10
miles southeast of Charleston. The soil where the cotton was
planted is light and sandy, well drained, and representative of the
lighter type of soil of the Sea Islands. It is technically described by
the Bureau of Soils as Norfolk fine sand. This type of soil normally
produces a comparatively small plant and is admirably suited for
cotton.

The winters are mild, and the soil becomes warm early in the
spring. Cotton can usually be planted the last week in March
without danger of frost injury. The summer temperatures are
moderate. Rainfall is abundant and fairly well distributed, although
periods of dry weather are often experienced in the spring and early
summer, while periods of excessive rainfall are common in late July
and August. Records of maximum and minimum temperatures and
of the precipitation were obtained at James Island from March 14 to
October 15. These records are summarized in Table 18.

TABLE 18.— Average maximum and minimum temperatures and monthly precipi-
tation at James Island (near Charleston), S. C., from March to October, 1923

7 ) ] i
| | |

Items of comparison Mar. Apr. May | June July Aug. | Sept. Oct.

Average temperatures (° F.):

Weprarapamn Stee hes eee EE ok 167.3 122 77.0 | 85.6 87. 2 88. 9 85.4 | 276.9
PVITTIMUTT ere eee ee ee OS 54. 6 GE SS | a ae | ee Ne fc aS
Precipitation (inches) __-__-___..--____- 2523 1. 82 6. 27 | 2. 54 9. 36 8. 09 35 IG’ 3. 06
1 March 14 to 31 only. 2 October 1 to 15 only.

During the season of 1923 cold dry weather during April was
unfavorable to the growth of cotton in the seedling stage. With
warmer weather and more abundant moisture in May, growth became
more rapid, and conditions were favorable for setting a crop during
June and the early part of July. Excessive rainfall in the latter part
of July and in August resulted in an abnormally high degree of boll
shedding.

80 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

Heavy infestation from overwintered weevils is to be expected
under normal conditions. The abundant protection afforded by native
vegetation and the mild winters of the Sea Island sections afford
excellent conditions for successful hibernation. Weevil emergence
begins early, the first weevils usually being noted during April,
feeding on the growing tips of the young cotton plants. The bulk of
the cotton in this district is planted during the latter part of March,
and squares begin to appear by the middle of May.

During 1923 many fields in this section were heavily infested with
weevils by June 10, while other fields farther away from favorable
hibernation places showed very slight infestation. Hot dry weather
during June caused high mortality of weevil larve in those fields where
clean cultivation was practiced and the plants were still small, so that
the sunlight could reach the shed squares. Although weevil infesta-
tion was reduced by the natural control factors in June, the appear-
ance of a new generation of weevils early in July caused infestation
to increase gradually, so that in the fields where control measures
oe not applied infestation was practically complete by the middle
of July.

COMPARISON OF SUCCESSIVE ADJACENT PLANTINGS AT
CHARLESTON

Four successive plantings, as shown in Figure 9, were made on
James Island on April 5, 16, 25, and May 4, each planting being in
, duplicate. The arrangement

of the plantings was similar to
those at San Antonio. Plats
numbered 8, 4, 6, 7, and 8 con-
sisted of six rows, while plats
2, 5, and 9 had seven rows,

‘ po aa 7iuN the additional row being con-
Sy Ela it | sidered as a guard, on account
Y ooo JAZ | TL TT of bemg adjacent to a, much
\ [cee ealeaen eed earlier planting. Guard blocks
. |_| ans 1 and 10 were also planted on
: \\} each side of the field on April
N PLANTED APR. E +: 5. The rows were 310 feet
S Bh we eee re. 6 ON NY. longand spacedsa.deetyapark
ewe LAN ILD, Aeon S— 4

| \ % The experiment was planted
with seed of a very uniform
strain of the Meade variety
of Upland long-staple cotton.

ee ere ae This variety has a staple
Fic. 9.—Flowering record of successive plantings of length of 1% inches and is
cotton on James Island, near Charleston, S. C., adapted for use on the South
Ae ae aa ey oe Carolina Sea Islands. The
seed was planted by hand in hills 12 inches apart. The cold
dry weather of April delayed germination and caused a slow
erowth of the ne cotton during the seedling stage. With

higher air temperatures and adequate moisture in May, growth ©

became more rapid. The plants in each planting were thinned

to two to the hill 12 inches apart when they reached a height ©

COTTON IN WEEVIL-CONTROL EXPERIMENTS 31

of about 6 inches. Guard plats numbered 1 and 10 were thinned to
one plant per hill 12 inches apart.

DAMAGE BY OVERWINTERED WEEVILS

While cotton had been grown on an adjoining field in 1922, early
destruction of stalks and unfavorable conditions for hibernation
in the vicinity of the field undoubtedly afforded some protection to
the 1923 planting. Although careful search was made no evidence
of weevil infestation was found until June 14, when punctured
squares were seen at three places in the field. Records made on
June 20 showed that about 1 per cent of the squares had been damaged

by weevils.
STRIPPING OF FLORAL BUDS

The entire field was stripped of squares and poison applied on
June 20. The mode of procedure in the removal of squares was
essentially the same as that used at San Antonio, described on pages
6 and7. The laborers were instructed to remove all squares whose
bracts were one-half inch or more long, a size that is attained in
about 10 days after the young buds are large enough to be distin-
guished readily. There were many squares of this size or larger in
the April 5 and April 16 plantings, but only a few in the April 25 and
May 4 plantings that were large enough to be removed. Counts
were made of the total number of squares removed from representa-
tive rows of each plat, and the average number of squares removed
per plant was found to be as follows: First planting, 4.5; second 3.8;
third, 1.6; fourth, 1.1. During the removal of the squares 78 weevils
were captured.

Field observations indicated that reinfestation from later emerging
weevils would have occurred if the squares had been removed earlier
than June 20 during 1923. The planting made on April 25 was at
the proper stage for stripping on June 20. Plantings made after
May 1 could normally be poisoned successfully without stripping,
as the weevil emergence was practically complete before the squares
were large enough to harbor larve.

Calcium arsenate in dust form was applied to the plants on June
21 with ahand gun. MHeavy rains washed the poison from the plants
during the afternoon of that day. As poison should remain on the
plants a minimum of 48 hours to be dgecinres a second application
was made on June 22, which remained on the plants until June 27.
No further measures were taken to control the weevil during the
remainder of the season.

LATE-SEASON WEEVIL DAMAGE

Examinations were made frequently in this test for indications of
weevil infestation following the removal of squares and poisoning.
On July 12 two small infested spots were found, but infestation re-
mained very slight and on July 27 was only about 3 per cent. There
Was no appreciable difference in the infestation of the different
plantings. Migration of weevils from other fields began early in
August, and by August 13 the experimental field was heavily infested.
No attempt was made to control migratory weevils, as adverse
weather conditions and defoliation of the plants by leafworms pre-
vented the setting of bolls on any of the plantings after July 31.

on BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

Weevil damage to mature bolls was a minor factor as compared with
damage from anthracnoge, boll-rot, and bollworms.

RATE OF SEEDLING GROWTH INCREASED BY LATER PLANTING

In order to compare the rate of plant development in the four
plantings, records of the formation of nodes on the main stalk were
obtained from 10 representative plants in each planting. Differences
in the growth rate during the seedling stage of these four plantings
are shown by the interval between the planting date and the date
of appearance of the first square in each planting.

As shown by the data in Table 19, the period from the date of
planting to the appearance of the first square on the April 5 planting
was 51 days, as compared with 44 days for the planting of April 16,
40 days for that of April 25, and 38 days for that of May 4. The
latter planting reached the fruiting stage of development in 13 days
less time than the planting made on April 5.

TABLE 19.—Rate of nodal growth during the seedling stage of cotton grown in succes-
sive plantings at Charleston on four different dates

Number of days—
Date planted, 1923 Average date of appearance of first fruiting
After
| planting! Per node
PAN TA SE oe fs Ne OEE SOE a ee | Mayi261 bly x PEPE ESE OE RG pea 51 6. 37
JENS OY aa GMs SP Me LOR EN i ei Ere eg Ny INP ay 3 Oe Seer oe ae set ee ar 44 5. 50
PAT ZO ae Be te GG ate Se cael DyUnr en te Bo ee ew Ee eR 40 5. 00
WED ja: Ue Te eee ee ep ee pera ee eee. eee JUNG ile 23 ip AE Es ak eT oe ate al 38 4.75
if i

1 As these records were made from the planting date rather than from the date of germination, a deduction
of about five or six days is necessary in comparing these figures with those that were obtained in Texas.
(See Table 3.)

The April 5 planting required an average of 6.37 days for the
development of each of the first eight nodes, as compared with 4.75
days per node for the May 4 planting, a difference in growth rate of
1.62 days. Higher air temperatures and warmer soil conditions dur-
ing the seedling stage of growth are probably the factors causing this
increased rate of growth in the later plantings. The cotton plant is
very sensitive to low temperatures, and if the young seedlings are
exposed to periods of cold weather their growth may be so checked
that they may not readily resume normal growth when conditions
again become favorable.

PLANT GROWTH DURING THE FRUITING PERIOD

Records of plant growth during the fruiting period indicate that ©
the accelerated development of the internodes He late-planted cotton |
is practically confined to the seedling stage. The average date of |
appearance of the first and twelfth fruiting branches on 10 plants of |
each planting and the average interval between the appearance of |
successive fruiting branches are presented in Table 20. The number |
of days required by each planting for the development of the first |
11 fruiting branches was as follows: April 5 planting, 31 days; April |
16, 27 days; April 25, 29 days; and May 4, 28 days. |

COTTON IN WEEVIL-CONTROL EXPERIMENTS 83

TasLe 20.—Rate of nodal growth during the fruiting stage of cotton grown in suc-
cessive plantings at Charleston on four different dates

© feasts Average number of
Average date Cae of fruiting days for production Total
of fruiting branches fruiting
PALS PIAMTUCG, AOD |CesAN es ES eek EE ee EE Pee eo branches
~ ; ” on Aug.
: Deas or 1 er il
First branch Twelfth branch Den cacen leech
Pavey seit ee hy Le) alee Ney 2Ge eos cee Wh TRATION OG sie Maen ere 31 2. 82 | 20.3
TXT Ee Se A IU Ue Are 80s ete Sere es Ne ra Ko Re ret eR may ie 27 2.45 | 21.5
Abe ceed che ob DUOC Wiaalespe diag maakt aie be ie uly seats i aha ne BA 29 2. 63 | Pil, 9-
INGA Y, Eee OPN RN oF cbse Jane wil seeds cele SEO Dialiy; QA ts beer te te | 28 2. 54 20. 5

While the rate of fruiting-branch production remained fairly con-
stant under conditions of uninterrupted growth during June and early
July, the rate of growth in the older cotton was checked about the
middle of July, making it possible for the younger cotton to overcome
the lead established earlier in the season by the early-planted cotton.
The final measurements on all plantings, made on August 11, showed
very little difference in the number of fruiting branches. The April
5 planting averaged 20.3 fruiting branches Ee plant, as compared
with 21.5 for that of April 16, 21.2 for that of April 25, and 20.5 for
that of May 4.

Each node on a fruiting branch provides for the development of
a floral bud or square. Thus, the theoretical fruiting capacity of
the plant may be measured by the total number of its fruiting nodes.
The average per plant of the total number of squares formed on 10
plants of ek planting on June 20, July 2, July 13, and August 11
are shown in Table 21. The data in this table were afforded by
normal unstripped plants.

Total number of squares per plant on given dates on cotton grown in
successive plantings at Charleston on four different dates

TABLE 21.

Date planted, 1923 : June 20| July 2 July 13 | Aug. 11

BNE) TS tps ¢) Seed em eR E LLORES sity to ET ak 6 2 Sd Siete gee Be eee Sie 22. 5 A 52. 6 66. 9
BOREL eae ee pam AP eR tf tes atte ce Jen Sen he 20. 6 39. 0 53. 3 | 76. 0
wad Olts ARSE Fens Ae 8 8 oe i ae Ae en epee eee ee 13.6 30. 4 45. 6 77.4
A eA ee ees cos een aa en wee a ne eee ee ee 8.3 26. 6 42. 2 | 82. 7

On June 20 the average number of squares on the plants in each
planting was as follows: April 5, 22.5; April 16, 20.6; April 25, 13.6;
and May 4, 8.3, a difference of 14.2 fruiting nodes per plant be-
tween the first and fourth plantings. The greater fruiting capacity
of the April 5 planting was maintained until July 13, at which time
it had been passed by the second planting. Final measurements
oi fruiting capacity were made on August 11. While the total num-
ber of fruiting branches per plant in all plantings was practically
the same on this date, the fruiting capacity of the different plantings
increased progressively with later plantings. The total number of
squares produced on the April 5 planting was 66.9, as compared
with 82.7 on the May 4 planting. Partial cessation of the growth
of the lower fruiting branches in the older plantings rather than a

34 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

slower rate of development is the cause for the complete reversal
oi the position of the four plantings in regard to the total number
oi squares formed on the plants. The later plantings continued
the production of new internodes on the lower fruiting branches
alter the growth of the latter was checked on the older cotton. The
comparative size and fruiting of early and late planted cotton are
illustrated in Plate IV.

EFFECT OF REMOVING FLORAL BUDS

Records of the number of flowers produced on stripped and un-
stripped plants grown in Florida in 1922 indicated that an increased
rate of flowering results from the removal of squares from the plants.>
In an endeavor to analyze the reaction of cotton plants to square
stripping, comparisons of plant development and the fruiting capacity
of a series of stripped and unstripped plants in each of the successive
plantings were made at Charleston, S. C., during 1923. From these
records it is possible to show the effect of square pruning on the
height of plants, number of fruiting branches, number of internodes
on the fruiting branches, and the total number of squares formed
on the plants.

Squares were removed from 10 plants in each planting on June 20.
Table 22 shows the average number of squares removed from these
plants, varying from 10.4 squares per plant in the first to 0.8 in the
last planting. :

TABLE 22.—Number of squares removed on June 20 from cotton plants grown in
successive planiings at Charleston on four different daies

Average number of squares

Date planted, 1923 Squares removed
On plant
Number | Per cent
ING DOF AG ah SERNA CL LEI OR MY. Cee Met Nese ERENT p es) 8 Meee er Pye - 24. 0 10. 4 43.3
TNF) peg) CG) SS) ge ap Seg pc hee eaagd WO EES. Bop eM ke pear ete Mee ik at 2 eo, 2) Hees AN nD Neelee te PAE 8. 2 38. 9
PAN <. Doe Siete e = bibs Be oe oe ek Rae Eee UES Jar oe Bg8 Oe ee PE a 10.9 225 22.9
SY [EA Ae: Sa OSPR NARUTO See a ey A ee ES ae | 7.6 .8 10.5

The height of the plants was recorded weekly from June 21 until
August 11. These ats are presented in Table 23, showing the
weekly growth in height of the stripped and unstripped plants for
the four different plantings.

The plants in the first three plantings from which squares had
been removed on June 20 made slightly more growth during the
period from June 21 to August 11.

The increase in the growth of the stripped plants was 2.9 centi-
meters in the first planting, 17 centimeters in the second, and 4.7 ©
centimeters in the third. The unstripped plants in the last, or May
4, planting made more growth than tHe stripped plants, the increase |
being 11.2 centimeters. While the comparison off growth of stripped

§ Smith, G. D. A preliminary report upon an improved method of controlling the boll weevil. Fla.
Agr. Exp. Sta. Bul. 165, p. 18-24, illus. 1922.

COTTON IN WEEVIL-CONTROL EXPERIMENTS 35
and unstripped plants in the first three plantings shows that the
stripped plants grew larger than those not stripped, the increases are
hardly significant.

TaBLE 23.—Average height of stripped and of unstripped cotton plants grown in
successive plantings at Charleston on four different dates in 1923

Average height on date given (centimeters)

Planting date and ° Growth
condition June | June | June} June) July July | July | July | Aug. } Aug. pon
4 14 21 29 |) ei? 21 27 3 11
21 to
Aug. 11
rie aah OE lee SS = he Mae Ohh. ke ako @ Slt Saeed, ce <f)o- paaReey
April 5 planting: |
Siripped] == ss 1846) 4) = 2054) |\°35..3:>|) 46: 0) }) 542,7 |) 62515) 6856) | 70: 7 |) 7323 | 7423 39. 0
Unstrppedsis= sulin ee. [an 8 34.3 46. 2 51.9 62. 0 67.4 70. 2 71.8 | 73.4 36.1
Increase in |
growth of | |
stripped :
Plan GS as | Ss ee es | ee ee ee ee Jacechee| Settee! ee ks —— ae ee ee 2.9
Apr. 16 planting: ~ | |
Siripped ==. 21.8] 28.2 35.9 45.9 OOs0 63. 5 76. 1 82. 4 85. 2 85. 8 49.9
Paistripnedeeeies chile. rel 33.6 | 41.9} 49.2] 53.0] 5841 61.6] 65.4] 66.5 32.9
Increase in
growth of
stripped i
joe RSS oS ee eo eee aeeeee| Seeeee somes Eee ee (eer | 17.0
Apr. 25 planting: “|
Stripped_______-- TAA) AOU 2554s |S See | a S8orGal 4649 a oS. Onl nos. Sila O70 len6ead 43.3
(Winstiippedsse= 4 |-— eae eee he Zend 3322 41.1 48.8 57.4 61. 2 64. 4 66. 3 38. 6
Increase in
growth of
stripped

PREMIER pe | eee | eed (1 en et |S ego) leg apn ed Fa es cre | ee Ue ce ae 4.7

Stripped_____--__- PO ||, TESS | PAL SS GEO S BSRS 7 ZEA) CERO NE SE aL i GE) 1) Gy 2! 44.]
Umstrpped se o8 | san ee 22-8 | 3125 | 40:8) 50:6) 63859 | 7018} 75.8 | 781 55. 3
increase in
growth of |
uustripped : |
OTe Sees ates ee eae eo fi Sea ae (lees 11.2

If acceleration of fruiting results from the removal of squares this
would be shown by an increase in the number of fruiting branches
or by an increased number of internodes on the branches. Weekly
records ot the number of fruiting branches from June 3 to August 11
en stripped and on unstripped plants are shown in Table 24. In the
stripped plants of the April 5 planting, from which 43.3 per cent of
the squares were removed on June 20, there was a total increase of
only four-tenths of a fruiting branch per plant for the entire season.
The gain in the number of fruiting branches of 2.5 in the stripped
plants of the April 16 planting and 0.3 in that of April 25 with a loss
of 1.4 in the May 5 plantas would indicate that no significant in-
crease in thenumber of fruiting branches was obtained by the removal
of squares. The stimulating effect of the removal of 43.3 per cent of
the squares was not sufficient to change materially the normal rate
of fruiting-branch production.°

} § Martin, R. D., W. W. Ballard, and D. M. Simpson. Growth of fruiting parts in cotton plants. Jn
- Jour. Agr. Research, v. 25, p. 195-208, illus. 1923.

36 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

TasLz 24.—Average number of fruiting branches per plant on stripped and un-
stripped cotton grown in successive plantings at Charleston on four different
dates in 1923

a an gS °
Date when data were recorded sa o0=
= OS
1 PS = [o>)
Planting date and 2A T=
condition = a = ie eS xe a he eee
oO ~ 4 am N AN Oo = = qQ oD tah | PS: i Sg S ad
tas er ka feat aie cal a Pe ce topes fe iis is = 2
3 3 3 3 3 3 3 3 3 3 = pons
5 5 5 5 5 5 5 5 5 5 < < |Z
Apr. 5 planting:
Stripped______- 4.6 | 6.1] 8.1] 10.2 | 13.0] 15.0 | 16.7 | 17.4 | 19.1 | 19.9 | 21.3 | 21.7 TES
UnStElp Peds. 23| 22a /a- Co s|2e aoe 952) WSS) PSST. | SSS P1635) Avevar Sen OU ia ONS Igieht
Apr. 16 planting:
Stripped as |aae 5.5} 6.9] 9.6 | 12.5} 14.4 | 16.4 | 17.6 | 19.5 | 21.0} 22.6 | 24.2 14.6
Umstripped=.22|s. 3s | Zee sae ees 9.4 | 11.6 | 13.4 | 15.4 | 16.2 | 17.5 | 18.6 | 20.8 , 21.5 TPA!
Apr. 25 planting:
Sirp ped ees pee 2.6] 45 | 6.4] 9.0] 10.7] 12.9 | 13.9 | 15.4] 17.3 | 19.6 | 20.3 13.9
WmnStrip ped S22 224s See eee 7.6 | 10.0 | 11.6 | 13.6 | 14.8 | 16.8 | 18.2 | 19.9 | 21.2 13. 6
May 4 planting:
Stripped] 2 ike .4 2.6 8h tl he: OVO D2P4 ss Se| Loe 4a eO } 19.0 | 19.0 13. 7
Unstripped.-— er 9] ea) ee 5.4 | $.5°| 10.0} 12.3 | 132°) 15:3 | 172 | 19934] oss 15.1
} |

The average number of internodes per fruiting branch was ob-
tained for the stripped and unstripped plants in each planting. For
convenience, these data have been arranged in groups of five consecu-

tive fruiting branches and are presented in Table 25.

TaBLE 25.—Average number of internodes per fruiting branch of stripped and of
unstripped cotton plants grown in successive plantings at Charleston on four
different dates in 1923

Number of fruiting branches

Average
Planting date and condition SSS ee Oba
1to5 | 6to0 10 | 41 totd) | Weteetals ea
Apr. 5 planting: |
ISL) ct 0] 0) 210 Meneses RS 5.0 | 4.1 1.4 83. 6
(URTISUTUP DEC sie See ear ee ie en oe eae De 4.3 4.2 } aay 1.4 66. 9
Increase on stripped piants____________________ 1.0 8 9 0 16. 7
Apr. 16 planting:
SEDI DOG aks oaks is ey eh ON res Se 8 Y/ 6. 2 4.8 21 105. 9
WmsStrippedee -ss4> ses tre are ee eee a 4.2 4.8 3.8 24 76. 0
Increase on stripped plants________________=___ 15 | 1.4 1.0 1.0 29. 9
Apr. 25 planting: |
SEN Ped se eS es kt kd esas Te ak hes pe age 4.9 5.4 4.1 ee, 81.6
NSE D DEG taal sae oe, ee ew nope Le See ee ee ee 4.2 | ESI L9 3.9 2.0 77.4
Inerease,on stripped, plants. 32-2 Ss ee 7 | 3 | “2 —.3 4.2
May 4 planting: |
SFr 0) 0 c6 PORE ye aie cla SEMIS Sas ee Pe A 5.6 5.6 4.2 2.0 87.0
Wmstrippediits. 2253.2 tla) tS ee aes 5. 4 523 3.8 1.8 82.7
imerease ontstripped plantse. = 25 ae ee 2 | .4 2 4.3
|

bo
(e\)

A consistently larger number of internodes was formed on the
fruiting branches of the stripped plants in the April 5 and April 16
plantings. As the total hariber of fruiting branches was practically |
the same on the stripped and on the unstripped plants the increase |
in number of internodes on fruiting branches resulted in a greater §j
fruiting capacity of the stripped plants. The stripped plants in the
April 5 planting averaged 83.6 squares per plant, while the unstripped 9

COTTON IN WEEVIL-CONTROL EXPERIMENTS 37

plants averaged only 66.9 squares. An even greater increase occurred
in the April 16 planting, the stripped plants averaging 105.9 squares
as compared with 76 on the unstripped cotton.

Only a slight increase in the number of internodes occurred on
fruiting branches of stripped plants in the April 25 and May 5 plant-
ings. As few squares were removed from these plants, no such stimu-
lation of growth would be expected as occurred on plants from which
a large percentage of squares was removed.

From the foregoing data on the effect of removal of the squares it
would appear that no material increase in height or number of fruiting
branches was caused. The consistent increase in the number of
internodes per fruiting branch indicates, however, that the growth
of the fruiting branches is affected by the removal of the early
squares. A morecontinued or prolonged growth seems to result from
their removal rather than a faster rate of development. A somewhat
analogous though more extreme result of pruning is found in “boll-
weevil cotton” as described by Cook.’

FLOWERING RECORDS OF EARLY AND LATE PLANTINGS

Flower counts were started on July 11 and were made twice a week
until August 17, a period of 838 days. These counts were made on the
four inside rows of two plats of the April 5 planting and on one plat
of the April 16, April 25, and May 4 plantings. The length of the
rows was 310 feet. The flower records for each plat are given in
Table 26 and are graphically shown in Figure 9 (p. 30).

TaBLE 26.—Flowering record of cotton plants grown in successive plantings at
. Charleston on four different dates

Date of counting (number of flowers)

Date : = 2
Plat | planted, | Thinningdistane| = |S |eig|(sx|gilale | e/2/5|_8
1923 Soule FN e| ie gil BS | Feral hry Suh han syle acl ier [eal le fem La sie
Besa) Sobre Wesel eal Al fealS dpsn| =
| 5 5 5 SS 5 5 < < < < | << |
_—_—— | i —— — oo —_———
|
No.2__| Apr. 5 | 2plantsat12inches_] 817/|1, 206)1, 463)1, 750|1, 348}1, 496)1, 064/1, 4382/1, 172) 449) 120/12, 317
[ORR UE 0) cage CS ee GORE ees 616}1, 109)1, 200}1, 519}1, 400)1, 428/1, 260)1, 593)1, 384) 714) 282/12, 505
No: 4-5) Apr 25 | 72-2 Qa esse hE | 549 976\1, 095}1, 459)1, 112)1, 427|1, 200}1, 798)1, 789! 923) 335/12, 663
INO. 52s) May 4/222 = 6 (oy ire eee 390} 841) 875)1, 264/1, 087|1, 3858/1, 158]}1, 689)1, 765}1, 218) 384/12, 029
INO. 6221 5A pre ahs GOES es Se 728)1, 014/1, 1841/1, eee 113)1, ae 103}1, 311\1, 286 a8 190} 11, 237
|

Although the first flowers appeared in all plantings at nearly the
same date, the more advanced development of the early-planted
cotton resulted in a higher flowering rate for this planting during the
first part of the flowering period. On July 11, the date on which the
first counts were made, 817 flowers were counted on the first planting,
as compared with 616 for the second, 549 for the third, and 390 for
the fourth. A higher rate of flowering was maintained by the first
planting until July 27, at which time a larger number of flowers was
recorded on the second planting. Beginning on August 6, the April
25 and May 4 plantings were flowering more profusely than the two
earlier plantings.

The sudden decline in the rate of flowering which occurred during

the second week in August is attributable to infestation from migrat-
ing weevils and the defoliation of the plants by the cotton leafworm.

7 Cook, O. F. Boll-weevil cotton in Texas. U.S. Dept. Agr. Bul. 1153, 20 p., illus. 1923.

|

88 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

In plats 5 and 6, where the April 5 and May 4 plantings were grown
side by side, 7 per cent more flowers were recorded from the May 4
planting. Owing to a high rate of boll shedding during late July and
in August, few bolls were matured from flowers produced during that
time.

Data were obtained from 20 plants of each of the four plantings,
showing the number and percentage of bolls set from flowers which
opened during weekly periods from July 7 to August 14. Data from
these 80 plants are combined and presented in Table 27. During the
week from July 7 to 14, 80.9 per cent of the flowers were set as bolls.
Only 47.1 per cent of the flowers produced during the following week
were set and 15.2 per cent during the third week. This declining rate
of boll setting continued during the period from August 7 to 14,
when only 3.1 per cent of the flowers set. Thus, the larger numbers
of flowers produced by the later plantings during late July and August
were of little value in setting a crop under the conditions of this
experiment.

TABLE 27.—Numober of flowers recorded and number and percentage of bolls set on
80 cotton plants at Charleston during each of five weekly periods in 1923

Tent July 7 July 15 | July 23 |} July 31 | Aug.7
to 14 to 22 to 30 to Aug. 6 to 14
ESR CES ete ec eae eeepc A ee leg NL Sah cape aye ee 157 276 296 205 162) 4
Bolls:
INGULTUTD OT Fe Sr te ete ieee ee ada 127 130 45 14
Percentagejw ss et ier se BO Nb mena ean | 80. 9 47.1 15.2 6.8 3.1

YIELDS FROM SUCCESSIVE PLANTINGS AT CHARLESTON

As a result of complete defoliation of the plants by leafworms, the
bolls opened rapidly during the latter part of August, and the bulk of
the crop was open the first week in September. ‘The first picking was ©
made on September 10 and a small second picking on October 4. The —
field was divided into equal sections by a line across the center of the ©
field at right angles to the rows. Hach section of each row was picked
separately and weighed on scales graduated to one-tenth of a pound.
The picking results are given in Table 28 and graphically presented in
Figure 10.

Plant counts for each section of row are included in Table 28. |
Irregular stands resulted in considerable variation in the number of —
penis per row. While higher yields would be expected in rows

aving a perfect stand, it has been found impracticable to make cor-_
rections in the yields on account of deficient stands.

The yields from the four inside rows in each plat are used for com-_
parisons between different plantings. The yields of outside rows
were affected by adjoining plats of earlier or later plantings.

The total yields from the first and second plats of each planting |
are as follows: April 5, 279.5 pounds; April 16, 244.9 pounds; April |
25, 235 pounds; May 4, 222.4 pounds. While these figures show an |
increase for the early-planted cotton, reference to the plat yields in
Table 28 indicate that most of the gain was due to better soil on one |
side of the field. Plat 2, planted April 5, yielded 158.5 pounds, while |
plat 6, planted on the same date, yielded 121 pounds. Plats 3 and 7, |

|
al
a

PLATE V

Bul. 1320, U. S. Dept. of Agriculture

COMPARATIVE FRUITING OF EARLY-PLANTED AND LATE-PLANTED COTTON IN SUCCESSIVE PLANTINGS AT
CHARLESTON, S. C.

The April 5 planting is at the left and the May 4 planting at the right

Bea
mest

a
EN

COTTON IN WEEVIL-CONTROL EXPERIMENTS 89

lanted April 16, yielded 136.8 and 108.1 pounds, respectively.
Piats 4 and 8, planted April 25, yielded 130.6 and 104.4 pounds, and
Nos. 5 and 9, planted May 4, yielded 111.8 and 119.6 pounds,
respectively.

The fact that such wide differences in yield occurred on the first
and second plats of the first three plantings indicates that the high
yields from the first plats were due to more fertile soil in that part
of the field. The yields from the first and second plats of the May 4
planting were practically equal, and comparatively small differences
in the yield of the different plantings occurred on plats 5, 6, 7, 8, and
9. Plat 5, planted on May 4, yielded only 10 pounds less than plat 5,
planted on April 5.2. (Pl. V.)

SLC7VIONW 2

%

120.15 APL ZE\IIAY F \ APES VIE | APELE AY #\ APCS

74 reg 7 F¥ a So “a oa a 7?
SLATS
Fic. 10.—Row yields from successive plantings of cotton at Charleston, S. C., April 5 to May 4

TABLE 28.—Yield of seed cotton grown in successive plantings at Charleston on four
different dates in 1923

Yields of seed cotton (pounds)
|
Number of plants First Gaeond
Po picking, | picking, Total
Date planted and plat number NG Sept. 10 Oct. 4
See- | See- See- | See- | See- | Sec- | Sec- | Sec-
tion | tion | Total] tion | tion | tion | tion | tion | tion | Row
A B i B A | B A B
| TBS SESS acl ek ea RA peo et oe 1 | 214 |. 226 440 | 17.1 | 16.1 LES alle Davy Be toy |! aie (es 37.4
| 2 208 | 207 415 | 17.8 | 18.1 1.6 2.0 | 19.4 | 20.1 39.5
Plat No. 2 3 241 209 450 | 18.7 | 19.5 igy 1.4 | 19.9 | 20.9 40.8
Teg a ee ee 4 242 231 473 | 17.2 | 17.4 1.4 2 NLS 6a L900 38. 1
3 232 240 472 | 17.0 | 19.6 1.6 TOE T8263 2105 40.1
AN) 21 tee ate 1 Jar aire aL | 923 887 |1,810 | 70.7 | 74.6 5.8 7.4 | 76.5 | 82.0 | 158.5
6 242 | 294 466 | 18.1 | 20.2 1.8 250) (TON9s 2282 42.1
Ze 136 211 347 | 15.6 | 17.6 eG 2.4 | 17.3 | 20.0 3.3

_ § By calculating the probable error of the average row yield of these two plats, the difference in yield
was found to be only three times the probable error of the difference. As the average row yields were
“Obtained from only eight rows, a difference of three times the probable error is not considered significant.

1

40 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE ‘

TABLE 28.—Yield of seed cotton grown in successive plantings at Charleston on {
four different dates in 1923—Continued 4

Yields of seed cotton (pounds)

Number of plants Haret

Firs Second
Row picking, picking, Total
Date planted and plat number Not Sept. 10 Oct. 4
See- | Sec- Sec- | Sec- | Sec- | See- | See- | Sec-
tion | tion | Total] tion | tion | tion | tion | tion | tion | Row
A B A B A B A
IG edi eater a eee Ni Spe ha Veg Fae 1] 246| 224] 470|1761!17.0] 20] 1:9] 19.6 | 18.9 | 38.5
as — |
fe Diil 248.4 255.1: 503.4 13e4. 1G Sit. Bol ILS alehs 6) NaAaiee
Tees [J 3 | R2323/< 220+=461 | 16.3°)41 | 24 | 2.0 (18 4:1 Tet team
HED NSC Soi ea SSR ar i 4|. 226 | 253} 479| 15.6] 15.8] 1.6} 1.6| 17.2] 17.4] 346
[| 5 | 214] 217] 431} 16.2)142] 18] 1.4] 1801156] 33.6
TMOtal weasels OOF Cre 920 | 954 |1,874 | 61.5] 609] 7.3] 7.1] 688 | 680] 136.8
6} 243} 250| 493/186]|16.3] 1.8] 1.5 | 20.4] 17.8] 382
Ar 25 eer Se LU he | 1| 201 | 234] 435/143/142] 25] 1.5|]1681157| 325
2} 198 | 242) 440|123]/148] 22] 22/145)170| 315
Plat No. 4 3| 221 | 242) 463|148/144] 19] 22) 167 | 16.6 je333
UENO nice SSE SRR S SS aae 4 || 204 | 1936 |. 4409) 1999 [15.5 | | 198 ie One tmaaeeoees
"5 |F 220 | 288 | 456) | 14 2 ta 45 0 | 19 16. 2) Tess: jaca
| eae
HN eilca se one RR a ici 844 | 955 |1,799 | 55.2 | 59.1] 82] 81 | 63.4 | 67.2 | 130.6
| 6] 217 | 202] 419 | 15.0) 141} 17) 12] 16.7] 15.3] 320
Ma yib foe as. peed oh Ee 1} 206:| 189 | 395.12.0)11-7| 1.4 9|13.4|126| 26.0
if 2 |. 194] 152.) 346] 13.8]10.8] 20] 1.9-] 15.8 | 12°71)" 985
Plat No. eee ke ) 8} 196} 195) 301] 112)125] 15] 18)127)143]| 27.0
4) 217.) 205) 422)) 13:5 1112.5 | 26} 1.5 05. © 140 loos
5) 184-| 9173" | 357, | Aes irs Pk 9 | 22 13.7 ies. | ee
Re ete elas 2 RO NO SE eee 791 | 725 |1,516 | 50.3 | 47.1 | 7.0]. 7.4] 57.3 | 54.5 | 111.8
6 | 224] 197] 421)113.6}127| £4] 1.7] 15.0) 144 oom
ZW 208.1 207. C415) TOG Made Zl 2 6 | 11.3,| 12°37" 3308
INRA Ree eC. a oh ae 1 | 259 | 230 |” 489 | 15.0} 149 | 10 6|16.0| 15.5 | 31.5
| 2| 225 | 226 | 451 [125 | 144 Ee en ee en | 29.0
Plat No. 6 3 | 236) 244,| 480 | 13.7] 13:8] 12 .9| 14.4] 993
Sete ane aay eco |} 4] 226 | 242 | 468/164] 138] .6 0} 145] 315
5] 248 | 241 | 489 }16.0]/1401 2.5 BAe St
Pot tle Nee nome tN nest (fesse 935 | 953 |1,888 | 58.6 | 56.0} 3.5 | 62.1 | 58.9 | 121.0
eran! PRA Tal cS 520 | akee Ol ise 9 6 | 13.9 | 13.9] 27.8
PAR IG Moscoun Amar eRe A Toa ike eae i oe ee ie ee Ee oe 6 | 15.4 | 11.1 | 265
ie 239.| 233°| 472 | 1219 | 4017 | B41 oe (aes) sss eee
Plat No.7 H- 31 250 | 244 | 494 | 12.4) 10:8 |. 1.9 ]> 2) 143.) 122s eee
ELE ON Gy (esec Saac aS cana | 4 | 249 | 243 | 492 | 1386 | 14.14) 1) oe SR Ie aa eee
lt" By256 | 293 | - 479°| 1014 | sara Wet te een Sel ei eee
otal sok BROS 810 a 994 | 943 |1,937 | 49.3 | 50.0| 5.5] 3.3 | 54.8 | 53.3 | 108.1
i 6) 236 | 232 | 458 | 12.0) 162.))..%4 mobi 207. | Gae eeoeee
i Nya Ree ey hace aga ads NASI aaa Oe | 1 | 231 | 245 | 476 | 13.5) 130 | 10| .9| 145 | 13.9 | 28 4m
{ 2| 249 | 287| 486 |11.7}120] 1.0| .7112.7| 127) 24am
Plat No. 8 He 3 (252 | 2438 "495790 54 1380 ka) he ah Zee eee
Wo Gh Wins eSae seeaa Gees ares | Woe | 2477) 427 PAT 124 fo 6s 9 Se | ee eee
(( 5 | 245 | 256] 501} 11.5] 11.6] 19] 1.2| 13.4] 128 | 262mm
Roraliecct okt erie en ae 956 | 953 11,909 | 45.8 | 49.0] 5.7] 3.9 | 51.5 | 52.9 | 104.4 7
| 6 |-220 |" 256 |° 476 |15.2 | 14.0) 1.4 | 1.7 [16.6 | tor eee
May 40 tie Pe Pet eS ed) Fue [ee2is |) 1940 41 2AS04, be | 15) O | aad (6 | RGNG OR ee ime
2 | 203 | 196°). 399 | 13 L | 137] -1.6-) 1.3) dee) 16.0 |= 200m
Plat No. 9 I} 3 | 64. 186 |. 350 112.2 )120| 23| 25/145 )945)° 208
Se Snsriaiega pe tas earns pas }- 4} 169 | 198-| 362 |--9.3} 419] 25] 24)118/[143] 261
it 5 | 149 | 164] 313} 10.1 | 11.3 | 28 }-2111241)138 4) 258
"Potal ah ais 88 Ae Sond ees 685 | 739 |1,424 | 44.7 | 489 | 87 |- 8.3 | 53.4 | 57.2 | 110.6
6 | 156-|--125-| 281 |-2-71-10.1 [| 29 |} 27 Pas6 AG S| see
71.155 | 173 | 228| 994| 9.3 |-26| 24) 120) 11.7 |2e0m

COTTON IN WEEVIL-CONTROL EXPERIMENTS 4]

The uniformity of yields from plats 5 to 9 are shown by the graphic
presentation of row yields, Figure 10.

ADVERSE CONDITIONS AT GAINESVILLE, FLA.

A series of successive plantings and a separate late planting similar
_ to the experiments in Texas and South Carolina were also located at
Gainesville, Fla., in cooperation with the Agricultural Experiment
Station of the University of Florida, but owing to very adverse sea-
sonal conditions the comparisons could not be carried out as at the
other locations. The soil upon which these plantings were made is
of a light sandy character with a subsoil not retentive of water.
Owing to the lack of fertility in this soil cotton production is largely
dependent upon the use of commercial fertilizers. |

Extremely dry weather through March and April delayed germina-
tion and caused poor stands and was followed by excessive rainfall
during May and June. From May 15 until July 4, a period of 51
days, rainfall was recorded on 44 days, the total precipitation being
19.37 inches. Owing to this excessive rainfall the fertilizer was
leached from the soil and plant growth was greatly retarded. Even
the earliest planted cotton reached a height of only 12 to 18 inches,
and the growth of the late-planted cotton was so checked that many
plants never reached the fruiting stage.

Weevils were present in the successive plantings before squares
appeared on the plants. Squares appeared on the early plantings
during the latter part of May, and on June 6 they were removed
from the plants and poison was applied. The method of stripping
and poisoning was the same as that used in Texas and South Carolina.

Records of weevil emergence from hibernation are maintained by
the experiment station. An abnormally high percentage of hiber-
nated weevils survived the winter of 1922-23, and emergence con-
tinued over an unusually long period. Only about 6 per cent of the
weevils placed in hibernation cages normally survive the winter. On
June 6, when the squares were removed from the plants in the suc-
cessive planting test, 22.6 per cent of hibernated weevils had emerged.
Emergence continued until July 31, at which time 26.86 per cent of
the weevils placed in hibernation cages had emerged.

As a result of this prolonged period of emergence cotton became
reinfested with weevils after the squares had been removed and
poison appled. On July 2, however, the average infestation of
squares on all cotton planted at the experiment station was only 3.24
percent. This indicated that square removal and poisoning had been
effective in delaying the appearance of the new generation of weevils,
aeaieks the conditions were such that no significant data could be
secured.

SUMMARY

In the season of 1923 four successive plantings of cotton were made
at San Antonio, Tex., Charleston, S. C., and Gainesville, Fla., to
compare the growth and fruiting habits of the plants as affected by
the time of planting. :

The successive plantings were treated for control of overwintered
weevils by removing and destroying early squares, followed by an
application of calcium arsenate. At San Antonio a separate late

42 BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE

planting, more remote from other cotton, was made on May 12 and
was not protected by poison or square stripping.

In the successive plantings at San Antonio the squares were
removed from plants of the first two plantings, and poison was
applied to the entire field on June 12. Reinfestation was found two
weeks afterwards, probably from weevils bred in early squares which
had been shed before the control measures were used.

At Charleston the squares were removed from the plants and poison
applied on June 20. No trace of weevil injury was found until

uly 12.

At Gainesville the squares were removed on June 6. Abnormally
late emergence of weevils caused reinfestation after control measures
were applied.

Infestation from overwintered weevils was avoided in the separate
late planting made on May 12 at San Antonio. This planting became
infested early in July, however, probably from weevils migrating
from near-by plantings.

Comparisons of plants from which’ the squares were stripped with
unstripped plants were made at Charleston. No increase in height
of plants or number of fruiting branches resulted from the removal
of squares. More nodes developed on the fruiting branches of
stripped plants, indicating that removal of early squares tended to
pro ae the period of growth of fruiting branches. (Tables 22, 23,
94, 25.

At San Antonio and Charleston late-planted cotton grew more
rapidly during the seedling stage. Nodes were produced on the mam
stalk at a faster rate, and the internodes were longer than on the
early-planted cotton. The first squares on the later plantings were
produced in fewer days after planting. (Tables 2, 3, 9.)

The last of the successive plantings at San Antonio on May 12
produced nearly as many fruiting branches as the first planting on
April 19. The lower fruiting branches of the later plantings pro-
duced gee nodes than the early plantings. (Tables 6, 7, 8; figs. 3
and 4.

At Charleston the growth of the early-planted cotton was checked
about the middle of July, while the later plantings continued normal
growth. By August 11 the average number of fruiting branches was
practically the same on all plantings. (Table 20.)

Owing to the production of more nodes on the lower fruiting
branches, the later plantings produced a larger total number of
floral buds than the early-planted cotton. (Table 21.)

The later planted cotton at San Antonio and Charleston contmued
a high rate of flowering later in the season and produced a slightly
larger total number of flowers than the early-planted cotton.
(Tables 9, 26; figs. 5 and 9.)

In the separate late planting on May 12 at San Antonio plants in
unthinned open-stand rows when compared with plants left two in a
hill showed that 38 per cent more flowers were produced in the
unthinned cotton than where the plants were left in hills. More than
twice as many flowers were recorded on the unthinned plants during
the first 10 days of the flowering period. (Table 15.)

Data on flower production and boll shedding during the period
from June 25 to August 2 indicated that the proportion of shed bolls

COTTON IN WEEVIL-CONTROL EXPERIMENTS 43

was practically the same on cotton planted at San Antonio on April 19,
April 28, and May 5.

In the first half of July at San Antonio a larger number of squares
was injured by weevils on the first planting, while during the latter
part of July the number of weevil-damaged squares rapidly increased
in the later planted cotton. This crease was due to the presence
of many young squares on the later planted cotton, while the forma-
tion of squares on the early-planted cotton had almost ceased.

No shedding of weevil-infested squares occurred in the separate
planting of May 12 at San Antonio until July 11, after flowering had
started. The weevil injury to squares in this planting was much
less than in the successive plantings (fig. 8). ;

Also there was a larger amount of injury to bolls of the later
successive plantings which had a larger percentage of young bolls
during the latter part of July. (Table 11.) The damage to bolls in
_the separate planting made on May 12 was less than occurred in
the successive plantings.

The early-planted cotton yielded more than the later planted
cotton in the successive plantings at San Antonio, but the last planting
_had a very poor stand in addition to greater weevil injury to bolls.
(Table 12; fig. 7.)

The yields of the separate late planting on May 12 nearly equaled
the yield of the first of the successive plantings on April 19 and ex-
_ ceeded the yields of the second and third plantings on April 28 and
May 5. (Tables 16 and 17; fig. 7.) °

The highest total yields at Charleston were produced by early-
planted cotton, but with a wide variation of soil conditions in different
parts of the field. Comparison of yields from a uniform part of the
field showed only slight differences in the yields of the early and late
plantings. (Table 28; fig. 10.)

Considering the variations that appeared in the results of the
experiments and the fact that the later rows of the successive plantings
were only partially protected against weevils from the earlier rows,
the experiments do not show that later planting is impracticable

either in Texas or South Carolina. From the nature of the problem
a wide range of seasonal and soil conditions must be tested Defies a
general advantage can be demonstrated.

|

ORGANIZATION OF THE
UNITED STATES DEPARTMENT OF AGRICULTURE

January 27, 1925

Secretary of Agriculture_______ sh Wek pulis! pu pen Howarp M. Gores.

TSA ON DIE TSAGRGACH Up ott e ee ee ae See Senay

Derector-of iScventijie W oTks= 2" ee apes cee E. D. BALL.

Director of Regulatory Work:.2:--_4-_4-2= = WALTER G. CAMPBELL.
Directorio tixtensvon, Wonk 2 ice paee, oe BE C. W. WARBURTON.

ASYOYAS 0 4| Sgeaee Rao ae Reg nN ERIE 9 ok oa A) RA SW 1 R. W. WILLIAMs.

Weather Bureqws 28 5.3 be ee es CHARLES F. Marvin, Chief.
Bureau of Agricultural Economics________-_- Henry C. Taytor, Chief.

Bureau of Animal dndustry= . 22.27) Bie JOHN R. MoutuEr, Chief.

Bureau of Plant Undusinysn 2 epee es WiuuiaM A. Taytor, Chief.
Honest iS Cr vt Cee ys gi cia eae BA figs a ye W. B. GREELEY, Chief.

BS URCGW Of AC METICESCIU) = ais sone ak Pentel Brey pt giaet soe C. A. Browne, Chief.

SUT CGU Of GSOULS s We A SOF oN yo ey ee a Mitton WHITNEY, Chief.

Bureau Of: EL NL@molog yd. pies 2 Ee Sek Sle, L. O. Howarp, Chief.

Bureau of Biological. Surey_— =. 5s be E. W. Neuson, Chief.

Burncauzof public hoads=s. 3.4 Panes Sa a Tuomas H. MacDona tp, Chief.
Bureau of Home. Economies.s— 22-2 2 Lovis& STANLEY, Chief.

Bureau of WIGATY LING) 2s Ay be ay We 2 gue ee aoe C. W. Larson, Chief.

Fixed Nitrogen Research Laboratory _-___-_-_- F. G. Cottre uu, Director.

Office of Experiment Stations_______-__--_- E. W. ALLEN, Chief.

Office of Cooperative Extension Work__-_-_-_-_- C. B. Smita, Chief.

Office of Publications___-_-- A er ae, Pye ead L. J. Haynss, Director.

PADROTY Ae Cy 2 cla PS Soa pet Nays een eae ---- CLARIBEL R. Barnett, Librarian.
Kederal. Horticultural: Board 22 422 8 a C. L. Maruatt, Chairman.
Insecticide and Fungicide Board__________- J. K. Haywoop, Chairman. !
Packers and Stockyards Administration __-__- ee Morriuu, Assistant to the |}
Grain Futures Administration___.-----_-_- Secretary.

This bulletin is a contribution from—

Bureau oj selantAndustrys 2 ee ae aoe Wiuuiam A. Taytor, Chief. .
Office of Crop Acclimatization and Adap- O. F. Coox, Senior Botanist in |
tation Investigations. - Charge. .

44

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