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Title: Potash in relation to cotton wilt
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Title: Potash in relation to cotton wilt
Physical Description: Book
Creator: Walker, M. N.
Publisher: University of Florida Agricultural Experiment Station
Publication Date: 1939
Copyright Date: 1939
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Bibliographic ID: UF00027125
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aen4072 - LTUF
18173576 - OCLC
000923521 - AlephBibNum

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Bulletin 213 April, 1930
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
Wilmon Newell, Director









POTASH IN RELATION

TO COTTON WILT
By M. N. WALKER










TECHNICAL BULLETIN








Bulletins will be sent free upon application to the
Agricultural Experiment Station
GAINESVILLE, FLORIDA












BOARD OF CONTROL
P. K. YONGE, Chairman, Pensacola RAYMER F. MAGUIRE, Orlando
A. H. BLENDING, Leesburg FRANK J. WIDEMAN, West Palm Beach
W. B. DAVIS, Perry J. T. DIAMOND, Secretary, Tallahassee

STATION EXECUTIVE STAFF
JOHN J. TIGERT, M.A., LL.D., President IDA KEELING CRESAP, Librarian
WILMON NEWELL, D. Sc., Director RUBY NEWHALL, Secretary**
S. T. FLEMING, A.B., Asst. Director K. H. GRAHAM, Business Manager
J. FRANCIS COOPER, M.S.A., Editor RACHEL McQUARRIE, Accountant
R. M. FULGHUM, B.S.A., Asst. Editor

MAIN STATION-DEPARTMENTS AND INVESTIGATORS

AGRONOMY ECONOMICS, AGRICULUTRAL
W. E. STOKES, M.S., Agronomist C. V. NOBLE, Ph.D., Agricultural Economist
W. A. LEUKEL, Ph.D., Associate BRUCE McKINLEY, A.B., B.S.A., Associate
G. E. RITCHEY, M.S.A., Assistant* M. A. BROOKER, M.S.A., Assistant**
FRED H. HULL, M.S.A., Assistant JOHN L. WANN, B.S.A., Assistant
J. D. WARNER, M.S., Assistant
ECONOMICS, HOME
ANIMAL HUSBANDRY
OUIDA DAVIS ABBOTT, Ph.D., Head
A. L. SHEALY, D.V.M., Veterinarian in L W. GADDUM, Ph.D., Biochemist
Charge C. F. AHMANN, Ph.D., Physiologist
E. F. THOMAS, D.V.M., Asst. Veterinarian
R. B. BECKER, Ph.D., Associate in Dairy ENTOMOLOGY
Husbandry
W. M. NEAL, Ph.D., Assistant in Animal J. R. WATSON, A.M., Entomologist
Nutrition A. N. TISSOT, M.S., Assistant
C. R. DAWSON, B.S.A., Assistant Dairy H. E. BRATLEY, M.S.A., Assistant
Investigations
HORTICULTURE
CHEMISTRY A. F. CAMP, Ph.D., Horticulturist
R. W. RUPRECHT, Ph.D., Chemist M. R. ENSIGN, M.S., Assistant
R. M. BARNETTE, Ph.D., Associate HAROLD MOWRY, B.S.A., Assistant
C. E. BELL, M.S., Assistant A. L. STAHL, Ph.D., Assistant
H. L. MARSHALL, M.S., Assistant G. H. BLACKMON, M.S.A., Pecan Culturist
J. M. COLEMAN, B.S., Assistant
J. B. HESTER, B.S., Assistant PLANT PATHOLOGY
COTTON INVESTIGATIONS W. B. TISDALE, Ph.D., Plant Pathologist
G. F. WEBER, Ph.D., Associate
W. A. CARVER, Ph.D., Assistant A. H. EDDINS, Ph.D., Assistant
E. F. GROSSMAN, M.A., Assistant** K. W. LOUCKS, M.S., Assistant
RAYMOND CROWN, B.S.A., Field Assistant ERDMAN WEST, B.S., Mycologist


BRANCH STATION AND FIELD WORKERS

R. R. KINCAID, M.S., Assistant Plant Pathologist (Quincy)
JESSE REEVES, Foreman, Tobacco Experiment Station (Quincy)
J. H. JEFFERIES, Superintendent, Citrus Experiment Station (Lake Alfred)
W. A. KUNTZ, A.M., Assistant Plant Pathologist (Lake Alfred)**
B. R. FUDGE, Ph.D., Assistant Chemist (Lake Alfred)
W. L. THOMPSON, B.S., Assistant Entomologist (Lake Alfred)
GEO. E. TEDDER, Foreman, Everglades Experiment Station (Belle Glade)
R. V. ALLISON, Ph.D., Soils Specialist in charge Everglades Experiment Station (Belle Glade)
FRED YOUNT, Office Assistant (Belle Glade)
E. R. PURVIS, B.S., Laboratory Assistant in Soils (Belle Glade)
L. O. GRATZ, Ph.D., Associate Plant Pathologist (Hastings)
A. N. BROOKS, Ph.D., Associate Plant Pathologist (Plant City)
A. S. RHOADS, Ph.D., Associate Plant Pathologist (Cocoa)
STACY O. HAWKINS, M.A., Field Assistant in Plant Pathology (Homestead)
L. R. TOY, B.S.A., Assistant Horticulturist (Homestead)
D. G. A. KELBERT, Field Assistant in Plant Pathology (Bradenton)
R. E. NOLEN, M.S.A., Field Assistant in Plant Pathology (Monticello)
FRED W. WALKER, Assistant Entomologist (Monticello)**
D. A. SANDERS, D.V.M., Associate Veterinarian (West Palm Beach)
M. N. WALKER, Ph.D., Associate Plant Pathologist (Leesburg)
W. B. SHIPPY, Ph.D., Assistant Plant Pathologist (Leesburg)
C. C. GOFF, M.S., Assistant Entomologist (Leesburg)
J. W. WILSON, Ph.D., Assistant Entomologist (Pierson)
*In cooperation with U. S. Department of Agriculture.
**On leave of absence.










POTASH IN RELATION

TO COTTON WILT
By M. N. WALKER
INTRODUCTION
Before the true cause of cotton wilt was known to be a fungus,
planters often attributed the disease to a disturbed nutritional
balance incident to excessive or injudicious applications of com-
mercial fertilizers. Various soil treatments for the control of
wilt were tried, both before and after the discovery of Fusarium
vasinfectum by Atkinson, and the conclusion was reached that no
soil treatment was of value in controlling the disease. Recently,
however, potash has been reported from Arkansas and Mississippi
as being of benefit in lessening the injuries caused by wilt. These
favorable reports of the effects of potash on wilt led to a few tests
to determine the effect of potash on wilt infection. The tests were
made on a field near Gainesville which was heavily infested with
F. vasinfectum, the fungus causing the wilt disease. It is the
purpose of this brief paper to report the results of these experi-
ments, and to draw such conclusions from the work as seem
warranted.
METHODS
A piece of ground a little over one-half acre in area was selected
for the tests. Wilt experiments had been run for a number of
years on this field and it was known to be heavily infested with
the wilt organism. The land, after plowing and smoothing, was
laid off in 20 300-foot rows, 4 feet apart, four of which were used
for each treatment. A ready-mixed fertilizer analyzing 4-7-5
(N-P-K) and having nitrogen from both organic and inorganic
sources was used as the basic fertilizer and was used at the rate of
500 pounds per acre. A fixed amount of this fertilizer with addi-
tions of different amounts of potash was used on each plot of four
rows. Since the proportions of potash varied somewhat in the
three trials, the percentage of potash applied to each plot will be
given under the discussion of the different trials. The fertilizer
was applied in the drill, mixed, and covered; the rows were re-
opened, and the seed planted. The variety Trice was used for the
experiments on account of its being extremely susceptible to attack
by wilt, and as it was thought that the effects of the potash would
be more apparent under such conditions. The seed were delinted








4 Florida Agricultural Experiment Station

before planting to sterilize the seed and to make planting easier.
When the plants were five or six inches high they were chopped
to a stand, and side-dressed with nitrate of soda at the rate of 100
pounds per acre. The plants were then counted at weekly inter-
vals until just before blooming time, the percentage of wilt being
recorded on each count. At this time the plants were pulled up
and cut in order to get a final accurate count of the wilt-infected
plants and as a check on the preceding counts. On account of the
fact that breeding work with another variety of cotton was being
conducted in the same field it was necessary to remove the Trice
plants to prevent cross-pollination, consequently no records on
comparative yields were available, but in view of the high per-
centages of infection and killing in all the plots this was consid-
ered a minor point.


FIRST FIELD TEST

On March 28, 1928, the fertilizer was put down in the five plots
and the seed planted. The general field fertilizer, containing 5%
potash, was put down in Plot 1 as a check. In Plot 2 the propor-
tion of potash was raised to 71/2%, by the addition of sulphate of
potash; in Plot 3, to 10%; in Plot 4, to 121/2%; and in Plot 5, to
15%. On May 12 the plants were chopped to a stand and three
days later a side-dressing of nitrate of soda was applied. Counts
were begun on May 24 and were made at approximately weekly
intervals until June 26, when the plants were pulled up and cut
to note the blackening of the vasculars.
In Table I the results of these counts are set forth with the per-
centage of wilt found in each plot. At the bottom of the table for
each plot is given an average percentage of wilt for the season
which was obtained by considering all plants that died as being
infected by wilt, totalling them with the wilt plants found at the
end of the season, and computing the percentage on the basis of
the total plants at the beginning of the season. Since the counts
were started after the plants were out of danger from damping-
off by Rhizoctonia, and since there was no other factor to which
much killing could be attributed, this percentage is considered
rough but legitimate. It is, however, thought that there was
possibly some killing from some other cause in this first test, since
the percentages of total killing are generally somewhat higher
than in subsequent trials, though this might possibly be consid-
ered as an evidence of the cumulative effect of the potash treat-












TABLE I.-EFFECT OF POTASH ON THE CONTROL OF COTTON WILT-RESULTS OF FIRST TEST, 1928.

Plot 1, 5% Potash Plot 2, 7.5% Potash Plot 3, 10% Potash Plot 4, 12.5% Potash Plot 5, 15% P'.tash



--- -- -- -- -- - a

5/24 955 813 142 14.87 975 797 178 18.25 1,012 861 151 14.92 1,106 967 139 12.56 1,102 948 154 13.97

5/31 733 578 155 21.14 750 605 145 19.33 784 659 125 15.94 840 727 113 13.45 806 694 112 13.89

6/ 6 606 372 234 38.61 660 383 277 41.96 679 417 262 38.58 749 500 249 33.24 740 502 238 32.16 S

6/12 536 281 255 47.57 599 349 250 41.73 658 387 271 41.18 708 470 238 33.61 693 452 241 34.77

6/19 452 196 256 56.63 503 262 241 47.91 575 350 225 39.13 629 365 264 41.97 636 372 264 41.50

6/26 339 88 251 74.04 397 125 272 68.51 460 203 257 55.86 528 171 357 67.61 508 214 294 57.87

Average for Season. 90.1 ................ 87.2 ................ 79.9 ................ 84.5 ............. 80.58

---


cn+








6 Florida Agricultural Experiment Station

ments, for the different trials were planted on the same ground
and the plots were continued in the same order.
The first wilt plants were found on May 24, and after this time
infection was rapid. It will be noticed in Table I that the percent-
ages for the first three counts correspond rather closely, but that
there is a considerable spread in the percentages of later counts.
The variation, however, is not consistent and the averages of total
infection for the season in the different plots would indicate that
potash did not reduce infection nor retard the development of
the disease sufficiently to justify recommendations for using
more than four or five percent potash in cotton fertilizers.

SECOND FIELD TEST
Immediately after pulling out plants of the first test, the land
was prepared and planted for the next test on June 27. The
seeming failure of potash to show any effect on the abundance of
wilt in the first test led to much larger proportions of potash
being used in subsequent tests, in spite of the fact that the reports
from Arkansas and Mississippi, previously mentioned, indicated
that benefits were derived from fertilizers containing approxi-
mately the same proportion of potash as the check-fertilizer used
in these experiments. The same basic fertilizer (4-7-5) was used
in this trial, and the proportion of potash on the five plots was 5%
in Plot 1, 16 % in Plot 2, 27.5 % in Plot 3, 35 % in Plot 4 and 40% in
Plot 5. Germination was rapid, and, as there was no danger of
Rhizoctonia injury, the plants were chopped to a stand on July 10
and side-dressed with nitrate of soda. Three days later the first
count was made and very few wilt plants were found. In subse-
quent counts the percentage of wilt increased rapidly and by
August 21 the stand was extremely ragged. The plants were
pulled up on this date and were cut to gain a final and more accu-
rate idea of the prevalence of wilt. A summary of the results is
given in Table II.
From the results set forth in Table II, it would appear that in
the two plots receiving 16 and 27.5% potash there was some re-
duction in the amount of wilt. When, however, the percentages of
wilt in the two plots receiving the largest applications of potash
and in the check plot receiving a normal application of potash are
considered, the effect of potash on cotton wilt would appear neg-
ligible. There was no plot, however, having no potash, and it is
possible that a comparison of potash and no potash plots would
have shown greater relative differences.









TABLE II.-EFFECT OF POTASH ON THE CONTROL OF COTTON WILT-RESULTS OF SECOND TEST, 1928.
Plot 1, 5% Potash Plot 2, 16% Potash Plot 3, 27.5% Potash Plot 4, 35% Potash Plot 5, 40% Potash




7/13 1,712 1,704 8 .47 1,953 1,940 13 .66 2,002 1,978 24 1.19 1,949 1,928 21 1.07 2,042 2,03J1 11 .53
7/17 1,606 1,399 207 12.88 1,839 1,628 211 11.47 1,901 1,631 270 14.20 1,761 1,470 291 16.52 1,897 1,688 209 11.01 Z
7/24 1,532 1,166 366 23.89 1,777 1,386 391 22.00 1,829 1,424 405 22.14 1,718 1,335 383 22.29 1,852 1,501 351 18.95
7/31 1,383 1,041 342 24.72 1,620 1,365 255 15.74 1,638 1,293 345 21.06 1,517 1,177 340 22.41 1,673 1,232 441 26.35
8/ 7 1,205. 803 402 33.36 1,517 1,226 291 19.18 1,501 1,191 310 20.65 1,353 1,004 349 25.79 1,472 1,024 448 30.43 ?
8/17 908 489 419 46.14 1,311 935 376 28.68 1,270 905 365 28.74 1,133 754 379 33.45 1,180 794 386 31.18
8/21 822 395 427 51.94 1,301 851 450 34.58 1,219 842 377 30.92 1,042 662 380 36.46 1,084 654 430 39.66
8/29 695 386 309 44.46 1,157 812 345 29.81 1,156 825 331 28.63 969 656 313 32.30 1,000 643 357 35.70
Average for Season. 77.5 ................ 58.4 ................ 58.8 ................ 66.4 ............. 68.5
1,00,.







8 Florida Agricultural Experiment Station

THIRD FIELD TEST
The following spring a third field test was planted on May 2.
The seed was planted late in order to avoid the heavy Rhizoctonia
injury that usually occurs following planting at the usual time in
early April. The same piece of land used in the two previous tests
was used for this test, and the plots were laid off in the same
order to take advantage of any cumulative effects of the previous
applications. The potash applications made were the same as for
the second test; a general field fertilizer in Plot 1, the same in
Plot 2 with the percentage of potash raised to 16%, to 27.5% in
Plot 3, to 35% in Plot 4, and to 40% in Plot 5. The field fertilizer
used was of a little different constitution and proportion (a 4-6-5)
than that used in the two earlier tests. The first count was made
on May 25 and at weekly intervals to June 29. A count was made
on this date, but before the plants could be pulled up and cut they
were plowed up by mistake. From the results of the preceding
experiments, however, this is not considered as a particularly
serious loss. The results of the test are summarized in Table III.
The percentages obtained at the last count on June 29 are in very
close agreement and the average percentages for infection
throughout the season show an actual increase in the percentage
of wilt on the plots receiving the highest applications of potash.
It was thought possible that the excessive applications of potash
might have been directly responsible for some of the killing, but
no evidence of this could be observed.
CONCLUSIONS
Two general conclusions may be made from the results of the
three tests of the effect of potash on the control of cotton wilt
reported here. Although no plots were planted without potash,
it would appear that potash is of little direct value in reducing
the infection of cotton by Fusarium vasinfectum; and, in the case
of a susceptible variety of cotton on heavily infested soil, it is not
possible to increase the yield of the uninfected plants by special
fertilization enough to counteract the high mortality that occurs.
Where a field is not extremely heavily infested with the wilt
organism it is no doubt possible to increase yields sufficiently to
offset to some degree the injuries resulting from wilt, but this
increase in yield, however, will result from the use of increased
applications of a complete fertilizer, and not from the action of
any particular constituent of the fertilizer. The degree to which
this latter means of combating wilt is successful will depend on
the natural fertility of the soil, the susceptibility of the variety













TABLE III.-EFFECT OF POTASH ON THE CONTROL OF COTTON WILT-RESULTS OF THIRD TEST, 1929.

Plot 1, 5% Potash Plot 2, 16% Potash Plot 3, 27.5% Potash Plot 4, 35% Potash Plot 5, 40% Potash

*a S -S S a a


5/25 2,350 2,077 273 11.61 1,556 1,317 239 15.35 1,454 1,224 230 15.81 1,163 1,029 134 11.52 1,016 915 101 9.94

6/ 1 2,042 1,863 179 8.76 1,328 1,200 128 9.63 1,171 1,003 168 14.34 999 847 152 15.21 890 802 88 9.88
6/ 8 1,940 1,615 325 16.75 1,241 1,016 223 18.13 1,013 741 272 26.85 872 637 235 26.94 803 654 149 18.55 w
6/15 1,639 1,306 333 20.31 1,055 802 253 23.98 821 557 264 32.15 666 452 214 32.13 618 488 130 21.03 :
6/22 1,369 1,086 283 20.67 876 659 217 24.77 628 434 194 30.89 490 341 149 30.40 504 401 103 20.43
6/29 1.144 907 237 20.71 741 599 142 19.16 508 368 140 27.55 390 304 86 22.05 370 308 62 16.75
AveraforSeason. 61.4 61.5 74.7 3.9 69.7








10 Florida Agricultural Experiment Station

of cotton grown, the degree to which the soil is infested, and the
injuries resulting from other causes.
For Florida conditions, where the cotton soils are generally of
low fertility and the limit to which fertilizer applications can be
economically increased is low, and where the stands, development,
and set of bolls of cotton are often adversely affected by weather,
diseases and weevils, the use of anything other than resistant vari-
eties on wilt-infested soils is not recommended. The use of a
complete fertilizer containing 3 to 5 percent potash is recom-
mended, since potash has been found requisite on all Florida
cotton soils as an aid in reducing the so-called rust disease of cot-
ton.





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