The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
Bulletin 520 July 1953
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
WILLARD M. FIFIELD, Director
(A contribution from the Everglades Experiment Station)
Sweet Corn Production
Sandy Soils of the Florida Lower East Coast
WALTER A. HILLS, N. C. HAYSLIP, J. F. DARBY and
W. T. FORSEE, JR.
Fig. 1.-General view of sweet corn experiments at Indian River Field
Laboratory, Spring 1952.
Single copies free to Florida residents on request to
AGRICULTURAL EXPERIMENT STATION
BOARD OF CONTROL EDITORIAL
J. Francis Cooper, M.S.A., Editor3
Hollis Rinehart, Chairman, Miami Clyde Beale, A.B.J., Associate Editor
J. Lee Ballard, St. Petersburg J. N. Joiner, B.S.A., Assistant Editor a
Fred H. Kent, Jacksonville William G. Mitchell, A.B.J., Assistant Editor
Wm. H. Dial, Orlando
Mrs. Alfred I. duPont, Jacksonville ENTOMOLOGY
George W. English, Jr., Ft. Lauderdale Tissot, Ph.D., Entomologist
W. Glenn Miller, Monticello AN. Tissot, Ph.D., Entomologist
W. F. Powers, Secretary, Tallahassee L. C. Kuitert, Ph.D., Associate
H. E. Bratley, M.S.A., Assistant
EXECUTIVE STAFF F. A. Robinson, M.S., Asst. Apiculturist
R. E. Waites, Ph.D., Asst. Entomologist
J. Hillis Miller, Ph.D., Presidents
J. Wayne Reitz, Ph.D., Provost for Agr.3 HOME ECONOMICS
Willard M. Fifield, M.S., Director Oda D. Abbott, Ph.D, Home Econ.'
J. R. Beckenbach, Ph.D., Asso. Director Ouida Abbott, PhD, Home Econ.1
L. 0. Gratz, Ph.D., Assistant Director R. B. French, Ph.D., Biochemist
Rogers L. Bartley, B.S., Admin. Mgr.3 HORTICULTURE
Geo. R. Freeman, B.S., Farm Superintendent HORTICULTURE
G. H. Blackmon, M.S.A., Horticulturist 1
F. S. Jamison, Ph.D., Horticulturist '
MAIN STATION, GAINESVILLE Albert P. Lorz, Ph.D., Horticulturist
R. K. Showalter, M.S., Asso. Hort.
R. A. Dennison, Ph.D., Asso. Heort.
AGRICULTURAL ECONOMICS R. H. Sharpe, M.S., Asso. Horticulturist
H. G. Hamilton, Ph.D., Agr. Economist 3 V. F. Nettles, Ph.D., Asso. Horticulturist
R. E. L. Greene, Ph.D., Agr. Economist 3 F. S. Lagasse, Ph.D., Horticulturist
M. A. Brooker, Ph.D., Agr. Economists R. D. Dickey, M.S.A., Asso. Wort.
Zach Savage, M.S.A., Associate L. H. Halsey, M.S.A., Asst. Hort.
A. H. Surlock, M.S.A., Agr. Economist C. B. Hall, Ph.D., Asst. Horticulturist
A. E. Alleger, M.S., Assogr. Economistiate Austin Griffiths, Jr., BS., Ast. Hort
D. L. Brooke, M.S.A., Associate S. E. McFadden, Jr., Ph.D., Asst. Hort.
M. R. Godwin, Ph.D., Associate2 C. H. VanMiddelem, Ph.D., Asst. Biochemist
W. K. McPherson, M.S., Economist2 Buford D. Thompson, M.SA., Asst. Hort.
Eric Thor, M.S., Asso. Agr. Economist M. W. Hoover, M.S.A., Asst. Hort.
Cecil N. Smith, M.A., Asso. Agr. Economist LIBRARY
Levi A. Powell, Sr., M.S.A., Assistant
Orlando, Florida (Cooperative USDA) Ida Keeling Cresap, Librarian
G. Norman Rose, B.S., Asso. Agri. Economist
J. C. Townsend, Jr., B.S.A., Agricultural PLANT PATHOLOGY
J. B. Owens, B.S.A., Agr. Statistician 2 W. B. Tisdale, Ph.D., Plant Pathologist 1
Phares Decker, Ph.D.. Plant Pathologist
AGRICULTURAL ENGINEERING Erdman West, M.S., Botanist & Mycologist 3
Robert W. Earhart, Ph.D., Plant Path.'
Frazier Rogers, M.S.A., Agr. Engineer s Howard N. Miller, Ph.D., Asso. Plant Path.
J. M. Myers, M.S.A., Asso. Agr. Engineer Lillian E. Arnold, M.S., Asso. Botanist
J. S. Norton, M.S., Asst. Agr. Engineer C. W. Anderson, Ph.D., Asst. Plant Path.
AGRONOMY POULTRY HUSBANDRY
Fred H. Hull, Ph.D., Agronomist 12 N. R. Mehrhof, M.Agr., Poultry Husb. 3
G. B. Killinger, Ph.D., Agronomist J. C. Driggers, Ph.D., Asso. Poultry Husb.S
H. C. Harris, Ph.D., Agronomist
R. W. Bledsoe, Ph.D., Agronomist SOILS
W. A. Carver, Ph.D., Agronomist
Fred A. Clark, M.S., Associate 2 F. B. Smith, Ph.D., Microbiologist'
E. S. Horner, Ph.D., Assistant Gaylord M. Volk, Ph.D., Soils Chemist
A. T. Wallace, Ph.D., Assistant J. R. Neller, Ph.D., Soils Chemist
DI. E. McCloud, Ph.D., Assistant 3 Nathan Gammon, Jr., Ph.D., Soils Chemist
G. C. Nutter, Ph.D., Asst. Agronomist Ralph G. Leighty, B.S., Asst. Soil Surveyor s
G. D. Thornton, Ph.D., Microbiologist 8
ANIMAL HUSBANDRY AND NUTRITION C. F. Eno, Ph.D., Asst. oils Microbiologist
T. J. Cunha, Ph.D., Animal Husbandman' H. W. Winsor, B.S.A., Assistant Chemist
G. K. Davis, Ph.D., Animal Nutritionist R. E. Cadwell, M.A., Asst. Chemist
R. L. Shirley, Ph.D., Biochemist V. W. Carlisle, B.S., Asst. Soil Surveyor
A. M. Pearson, Ph.D., Asso. An. Husb.' J. H. Walker, M.S.A., Asst. Soil Surveyor
John P. Feaster, Ph.D., Asst. An. Nutri. William K. Robertson, Ph.D., Asst. Chemist
H. D. Wallace, Ph.D., Asst. An. Husb.3 0. E. Cruz, B.S.A., Asst. Soil Surveyor
M. Koger, Ph.D., An. Husbandman W. G. Blue, Ph.ID., Asst. Biochemist
J. F. Hentges, Jr., Ph.D., Asst. An. Husb s J. G. A. Fiskel, Ph.D., Asst. Biochemist 3
L. R. Arrington, Ph.ID., Asst. An. Hush. L. C. Hammond, Ph.D., Asst. Soil Physicist2
H. L. Breland, Ph.D., Asst. Soils Chem.
E. L. Fouts, Ph.D., Dairy Technologist 1
R. B. Becker, Ph.D., Dairy Husbandman 3 D. A. Sanders, D.V.M., Veterinarian 1
S. P. Marshall, Ph.D., Asso. Dairy Husb.3 M. W. Emmel, D.V.M., Veterinarian 3
W. A. Krienke, M.S., Asso. Dairy Tech.3 C. F. Simpson, D.V.M., Asso. Veterinarian
P. T. Dix Arnold, M.S.A., Asso. Dairy Husb. 2 L. E. Swanson, D.V.M., Parasitologist
Leon Mull, Ph.D., Asso. Dairy Tech.3 W. R. Dennis, D.V.M., Asst. Parasitologist
H. H. Wilkowske, Ph.D., Asst. Dairy Tech.3 E. W. Swarthout, D.V.M., Asso. Poultry
James M,. Wing, Ph.D., Asst. Dairy Hush. Pathologist (Dade City)
BRANCH STATIONS F. T. Boyd, Ph.D., Asso. Agronomist
M. G. Hamilton, Ph.D., Asst. Horticulturist
NORTH FLORIDA STATION, QUINCY
SUB-TROPICAL STATION, HOMESTEAD
W. C. Rhoades, Jr., M.S., Entomologist in
Charge Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
R. R. Kincaid, Ph.D., Plant Pathologist D. 0. Wolfenbarger, Ph.D., Entomologist
L. G. Thompson, Jr., Ph.D., Soils Chemist Francis B. Lincoln, Ph.D., Horticulturist
W. H. Chapman, M.S., Agronomist Robert A. Conover, Ph.D., Plant Path.
Frank S. Baker, Jr., B.S., Asst. An. Husb. John L. Malcolm, Ph.D., Asso. Soils Chemist
Frank E. Guthrie, Ph.D., Asst. Entomologist R. W. Harkness, Ph.D., Asst. Chemist
Mobile Uni, RMo o Bruce Ledin, Ph.D., Asst. Hort.
Mobile Unit, Monticello J. C. Noonan, M.S., Asst. Hort.
R. W. Wallace, B.S., Associate Agronomist M. H. Gallatin, B.S., Soil Conservationist
Mobile Unit, Marianna WEST CENTRAL FLORIDA STATION,
R. W. Lipscomb, M.S., Associate Agronomist BROOKSVILLE
Mobile Unit, Pensacola Marian W. Hazen, M.S., Animal Husband-
R. L. Smith, M.S., Associate Agronomist man in Charge
Mobile Unit, Chipley
Mobile n Unit, Chiple RANGE CATTLE STATION, ONA
J. B. White, B.S.A., Associate Agronomist RANGE CATTLE STATION, ONA
W. G. Kirk, Ph.D., Vice-Director in Charge
CITRUS STATION, LAKE ALFRED E. M. Hodges, Ph.D., Agronomist
A. F. Camp, Ph.D., Vice-Director in Charge D.W. Jones, M.S., Asst. Soil Technologist
W. L. Thompson, B.S., EntomologistNTRAL A SATI
R. F. Suit, Ph.D., Plant Pathologist CENTRAL FLORIDA STATION, SANFORD
E. P. Ducharme, Ph.D., Asso. Plant Path. R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
C. R. Stearns, Jr., B.S.A., Asso. Chemist J. W. Wilson, ScD., Entomologist
J. W. Sites, Ph.D., Horticulturist P. J. Westgate, Ph.D., Asso. Hort.
H. 0. Sterling, B.S., Asst. Horticulturist Ben F. Whitner, Jr., B.S.A., Asst. Hort.
H. J. Reitz, Ph.D., Horticulturist Geo. Swank, Jr., Ph.D., Asst. Plant Path.
Francine Fisher, M.S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
J. W. Kesterson, M.S., Asso. Chemist WEST FLORIDA STATION, JAY
R. Hendrickson, B.S., Asst. Chemist C. E. Hutton, Ph.D., Vice-Director in Charge
Ivan Stewart, Ph.D., Asst. Biochemist H. W. Lundy, B.S.A., Associate Agronomist
ID. S. Prosser, Jr., B.S., AssA. Engineer
R. W. Olsen, B.S., Biochemist
F. W .Wenel, Jr., Ph.D., Chemist SUWANNEE VALLEY STATION,
Alvin H. Rouse, M.S., Asso. Chemist LIVE OAK
H. W. Ford, Ph.D., Asst. Horticulturist
L. C. Knorr, Ph.D., Asso. Histologist4 G. E. Ritchey, M.S., Agronomist in Charge
R. M. Pratt, Ph.D., Asso. Ent.-Pathologist
W. A. Simanton, Ph.D., Entomologist GULF COAST STATION, BRADENTON
E. J. Deszyck, Ph.D., Asso. Horticulturist E. L. Spencer, Ph.D., Soils Chemist in Charge
C. D. Leonard, Ph.D., Asso. Horticulturist E. G. Kelsheimer, Ph.D., Entomologist
W. T. Long, M.S., Asst. Horticulturist David G. A. Kelbert, Asso. Horticulturist
M. H. Muma, Ph.D., Asso. Entomologist Robert O. Magie, Ph.D., Plant Pathologist
F. 3. Reynolds, Ph.D., Asso. Hort. J. M. Walter, Ph.D., Plant Pathologist
W. F. Spencer, Ph.D., Asst. Chem. S. S. Woltz, Ph.D., Asst. Horticulturist
R. B. Johnson, Ph.D., Asst. Entomologist Donald S. Burgis, M.S.A., Asst. Hort.
W. F. Newhall, Ph.D., Asst. Entomologist C. M. Geraldson, Ph.D., Asst. Horticulturist
W. F. Grierson-Jackson, Ph.D., Asst. Chem.
Roger Patrick, Ph.D., Bacteriologist
Marion F. Oberbacher, Ph.D., Asst. Plant FIELD LABORATORIES
Evert J. Elvin, B.S., Asst. Horticulturist Watermelon, Grape, Pasture-Leesburg
R. C. J. Koo, Ph.D., Asst. Biochemist
J. R, Kuykendall, Ph.D., Asst. Horticulturist J. M. Crall, Ph.D., Associate Plant Path-
ologist Acting in Charge
EVERGLADES STATION, BELLE GLADE C. C. Helms, Jr., B.S., Asst. Agronomist
L. H. Stover, Assistant in Horticulture
W. T. Forsee, Jr., Ph.D., Chemist in Charge
R. V. Allison, Ph.D., Fiber Technologist Strawberry-Plant City
Thomas Bregger, Ph.D., Physiologist A. N. Brooks, Ph.D., Plant Pathologist
J. W. Randolph, M.S., Agricultural Engr.
R. W. Kidder, M.S., Asso. Animal Husb. Vegetables-Hastings
C. C. Seale, Associate Agronomist A. H. Eddins, Ph.D., Plant Path. in Charge
N. C. Hayslip, B.S.A. Asso. Entomologist E. N. McCubbin, Ph.D., Horticulturist
E. A. Wolf, M.S.. Asst. Horticulturist T. M. Dobrovsky, Ph.D., Asst. Entomologist
W. H. Thames, M.S., Asst. Entomologist
W. G. Genung, M.S., Asst. Entomologist Pecans-Monticello
Frank V. Stevenson, M.S., Asso. Plant Path. A. M. Phillips, B.S., Asso. Entomologist
Robert J. Allen, Ph.D., Asst. Agronomist John R. Large, M.S., Asso. Plant Path.
V. E. Green, Ph.D., Asst. Agronomist
J. F. Darby, Ph.D., Asst. Plant Path. Frost Forecasting-Lakeland
V. L. Guzman, Ph.D., Asst. Hort. Warren 0. Johnson, B.S., Meteorologist in
J. C. Stephens, B.S., Drainage Engineer 2 Charge 2
A. E. Kretschmer, Jr., Ph.D., Asst. Soils
Chem. 1 Head of Department
Charles T. Ozaki, Ph.D., Asst. Chemist 2 In cooperation with U. S.
Thomas L. Meade. Ph.D., Asst. An. Nutri. o Cooperative, other division-s, U. of F.
D'. S. Harrison, M.S., Asst. Agri. Engr. 4 On leave
This bulletin is a result of coordinated research at the Ever-
glades Station's Field Laboratories near Lake Worth and Fort
Pierce. Walter A. Hills, Associate Horticulturist, and W. T.
Forsee, Jr., Chemist in charge, have contributed their findings
in the Lake Worth-Boynton area on cultural requirements and
methods, fertility, hybrids and harvesting and packing; John
F. Darby, Assistant Plant Pathologist, and Norman C. Hayslip,
Associate Entomologist, have recommended disease and insect
control measures based largely upon their research at the Indian
River Field Laboratory near Fort Pierce.
Growers in areas other than the sandy soils of the lower east
coast may find part of the information applicable. However,
they should consult their county agents for any local modifica-
tions of the recommendations outlined. Those wishing more
detailed information on specific phases of sweet corn production
may find the bibliography at the end of this publication useful.
INTRODUCTION ............. ..-................ ......-------..... 5
CULTURAL REQUIREMENTS ............-- .........----- .. .--.---.. ....----.. 5
FERTILIZERS AND SOIL AMENDMENTS ....-........ ----... .. ...-.....--.-- ...-- 6
CULTURAL METHODS .........-............................--- -- -...- ...- 10
HYBRIDS .--..... ....---- -..--- ......---.... ------------.. -------.. .... ...... ... 12
HARVESTING AND PACKING ......--..--- -.. .--....-......-- ..--.- ... .... -. ........ 16
DISEASES AND THEIR CONTROL ..------ .... ... ...----------.---....... 16
Northern Leaf Blight ..... ...... ----- ... ................-- ----- .....---- ...... 17
Southern Leaf Blight .--..-...-..-..-..- ...-..- ... -- ......-- ...---- 19
Rust ..--- ...... .......-....... .... ... -..---. ................ -- 20
INSECTS AND THEIR CONTROL ....... ........ ...------............... ..... 20
Corn Earworm .....-............................-------- ----- .---- ... ......---. 20
Sweet Corn Insect Reference Chart .............................. ..-- ..- 22
Fall Armyworm ........-- -..-.... -.....- .... .....-....-- 24
Corn-silk Fly .. .............--------- ............. ---...... 25
Cutworms ............. ......------ ------...------- .....--..--.... ... 26
Wireworms ........ -..---. ----..-... --.. --....-..--..--... .--.-.........-.... 26
Lesser Corn-stalk Borer ...........-- ..-- ..------.....--- .. ......... .. 27
W ebworms .... .. - --..-.... -.. ---.--- .-- -------- --- ..- ..-- -...... ............ 27
A phids .....-.. ............... ... --...--..-......... ............ .. ..---- ..----- .... 28
Sugarcane Borer .......................-- ....... -------- -... -..---...-....- 28
Precautions on the Use of Insecticides .............-.. ----.......... .-- .. 28
Insecticide Applicators ........- .........-......------...------ ......--- ....... 28
SUMMARY .......... ......--- .............------- ----------.......--..--......--- .. 30
BIBLIOGRAPHY .....-..... ---.. ------.....------- ..----.- -..... -......... --.... .......---...- 31
Sweet Corn Production on the Sandy
Soils of the Florida Lower East Coast
WALTER A. HILLS, N. C. HAYSLIP, J. F. DARBY and
W. T. FORSEE, JR.
The commercial production of sweet corn in Florida began in
1947 and has developed rapidly since that time. As reported
by the Florida State Marketing Bureau (5),1 33,500 acres of
sweet corn were produced in Florida in 1951-52, having a total
value of $8,955,000. The mid-winter and early spring acreage
on the sandy soils of the lower east coast has increased steadily
in the past three years.
This increase is due to several factors: less danger from frost
injury as compared with the Everglades muck soils; a normally
strong market from November to May; introduction of better
adapted hybrids; more effective insect and disease control; and
improved methods in handling from field to consumer.
Recent investigations indicate that an early spring crop of
sweet corn can be produced successfully following the fall tomato
crop in the Indian River area. At this time sweet corn in this
area is a minor crop.
This publication presents information on cultural practices,
fertility, water requirements, hybrids and insect and disease
control-each of which is highly important to the successful
production of sweet corn.
Climate.-For best development, sweet corn requires warm
weather with relatively long days, such as generally occurs in
the spring months. During the winter months when the days
are short and nights cool, many of the commercial hybrids do
not perform satisfactorily. However, since sweet corn is har-
vested for use before it begins to harden, its production is not
limited by climatic conditions to the same extent as is field
corn for grain.
SItalic figures in parentheses refer to Bibliography in the back of this
6 Florida Agricultural Experiment Stations
Soil.-Sweet corn, like field corn, can be grown on a great
variety of soils. Light, sandy soils have not been considered
very desirable for sweet corn production. However, with ade-
quate water control, proper fertilization, and suitable hybrids,
excellent yields can be obtained on these soils even during the
Moisture.-Sweet corn is among the most shallow-rooted vege-
table plants. During the early stage of growth it requires
abundant available soil moisture for germination and rapid root
development. The plants must be kept growing. If growth is
checked temporarily by a shortage of water, the plants are
stunted; this results in reduced yield. The water requirement
becomes more critical at time of silking and remains so until
maturity. A lack of moisture during this period often causes
improper ear development and also affects tip-fill.
FERTILIZERS AND SOIL AMENDMENTS
Success in growing sweet corn depends on production of high
quality corn. Good yields of corn with desired high quality
depend to a large extent upon the fertility program, including
amounts of fertilizer applied, mineral balance and time of ap-
plication. Efficient utilization of the applied fertilizer depends
upon soil-water relationships which must be optimum through-
out the entire growing period.
Liming.-Sweet corn, when grown on Immokalee, Sunniland,
Pompano and related soil types, seems to produce well over a
somewhat wider range of pH values than some other vegetable
crops. Although no significant yield increases have been ob-
tained, acid sands with initial pH values as low as 4.6, when
limed to bring the pH up to 5.5 to 5.7, have produced earlier
maturing corn than unlimed soils. There also appeared to be a
trend toward the production of larger and better filled ears.
Good yields of high quality corn have been obtained on sandy
soils with pH values in excess of 7.0. However, corn growing
on soils with the higher pH values may require some manganese
applied as a nutritional spray in order to avoid a deficiency of
this element. Manganese deficiency symptoms appear as a yel-
low striping of the leaves and may cause substantial decreases
Liming acid soils to a pH value of 5.5 to 6.0 should maintain
good production, and is at the same time consistent with good
soil conservation practices. Experiments have indicated that
Sweet Corn Production on Florida Lower East Coast 7
dangers of over-liming are remote as long as insoluble sources,
such as high calcic or dolomite lime or basic slag, are used. In
areas where magnesium is a limiting factor, as is the case with
many of the sandy soils of the Florida lower east coast, a mag-
nesium-bearing material is recommended at least for periodic
The insoluble sources of lime should be applied in the summer.
No liming material should be applied until its need has been
determined by accurate pH tests on representative soil samples.
Hydrated lime may be used on palmetto and other highly acid
areas where rapid action is imperative. Otherwise, the more
insoluble sources are recommended for safety against the dan-
gers of over-liming. Experiments have indicated an increase
in the assimilation of calcium with no harmful effects to the
plants from hydrated lime side-dressed on the bed after plant-
ing. Such a procedure, however, is recommended only when
it is made necessary through a failure to determine lime re-
quirements before planting.
Fertilizing.-Heavy yields of high quality sweet corn require
large amounts of fertilizer, especially nitrogen. Experiments
conducted to date have given highly significant yield increases
with applications of up to 160 pounds N per acre. Some response
has been seen from up to 220 pounds of N when leaching rains
occurred. The greatest response to nitrogen has been an in-
crease in numbers of U. S. No. 1 ears; this indicates its tre-
mendous effect on quality as reflected in grade.
More than 200 percent increase in number of U. S. No. 1 ears
has been obtained as applied nitrogen was increased from 40
to 100 pounds N per acre. An additional 20 percent increase
was realized by raising to 160 pounds ihe amount of N applied.
Yield responses to heavier applications of nitrogen have been
even greater in terms of pounds than in numbers of ears per
acre. This indicates that a large part of the response to the
highest levels of N was due to increased size of individual ears.
Increasing the nitrogen applications from 40 to 130 pounds per
acre has also increased the length of ears as much as 8 percent,
as determined by actual measurement in two experiments.
Most sandy soils along the lower east coast of Florida that
have been cropped repeatedly to vegetables show relatively high
residual levels of water-soluble phosphorus. Such a condition
is due to the frequent and repeated use of fertilizer mixtures
high in phosphate. This fertilizer element does not leach as
8 Florida Agricultural Experiment Stations
readily as nitrogen and potash, especially where adequate pH
values have been maintained by liming.
Experiments conducted on such soils have failed to show much
response to applications of phosphate. Only slight increases
of U. S. No. 1 ears have been obtained to applications of phos-
phorus up to 100 pounds of P205 per acre on soils which had
been used repeatedly for vegetable production. Phosphate ap-
plications in excess of this amount, up to 200 pounds of P2O0
per acre, along with various application rates of nitrogen and
potassium, have indicated no beneficial or harmful effects from
the phosphate with respect to plant growth, corn yields, or
Experiments to date have indicated a lower potash require-
ment than that for nitrogen. One experiment has indicated a
small increase in number of U. S. No. 1 ears per acre as potash
was increased beyond 60 pounds of K20 per acre. The potash
also gave a slight increase in length of ears. No indications of
beneficial effects have been obtained beyond 120 pounds K20
Previously reported experiments (1) have indicated that the
fertilizer, particularly nitrogen and potash, is more efficiently
utilized when applied in two or more separate applications. Ap-
plying all the phosphate at planting time, along with a portion
of the nitrogen and potash, and adding the balance of the ma-
terials as side-dressed applications, gave as good a yield as using
50 percent more mixed fertilizer at planting time and side-
dressing with nitrate only.
These differences were not due to leaching of the initial ap-
plication, because no rains occurred during the growth of the
crop until the week before harvest. Since sweet corn may re-
quire 80 to 100 days for growing, some organic nitrogen, 25 to
30 percent, may be included in the initial application. All side-
dress applications should contain nitrogen derived from soluble
sources, including 50 percent derived from nitrate.
To guard against possible minor element deficiencies, certain
of these may be included in the fertilizer mixture. Deficiencies
of magnesium, manganese, zinc and borax have been observed
and diagnosed in corn growing on the sandy soils of the area.
It is recommended that the initial application of fertilizer made
at time of planting include 0.3, 0.5, 0.3, 0.2 and 2.0 percent,
respectively, of CuO, MnO, ZnO, B20s and MgO. No minor
elements need be included in the side-dress fertilizer applications.
Sweet Corn Production on Florida Lower East Coast 9
Nutritional Sprays.-Sweet corn has shown outstanding re-
sponses to nutritional spray applications of some of the minor
elements in areas where such elements are deficient. Those
minor elements which may be used most effectively as sprays
are manganese (Fig. 2),
zinc and iron. Under
certain conditions the
sulfates of manganese
and zinc may cause se-
vere burning when used
as sprays even at low
concentration, such as 2
to 3 pounds per 100 gal-
lons. For this reason
the neutral salts of these
two elements are recom-
mended. These have been
found to be entirely safe
even at concentrations of
4 to 6 pounds per 100
gallons. Either manga-
nese or zinc, if included
in the carbamate fungi-
cides, will act as nu-
trients in correcting de-
ficiencies of these ele- Fig. 2.-Sweet corn leaves unsprayed
ments. (left) and sprayed with manganese and zinc
The following recom- (right). Note leaf stripes in left leaf.
mendations are based on results of experiments recently
conducted and herein discussed briefly. Sweet corn, planted on
the sandy soils of the Florida lower east coast area, should re-
ceive 1,000 pounds per acre of a 4-12-6 fertilizer. Apply this
in bands to either side and just below the seed at time of plant-
ing, followed by two side-dressings of a 12-0-6 mixture applied
at the rate of 500 pounds each per acre.
The side-dressings should be timed to allow application of
the second side-dressing at the time of the last cultivation and
lay-by. This will give a total application of 160 pounds per
acre of N, 120 pounds P205 and 120 pounds K20. These amounts
are approximately the minimum requirements for maximum
yields of high quality corn. If leaching rains occur, the amounts
of side-dress nitrogen may need to be increased. In such even-
10 Florida Agricultural Experiment Stations
tualities nitrate of soda at the rate of 300 pounds per acre may
be used as a top-dress, applied in the alleys between corn rows.
Preparation of the Land.-A well prepared seedbed is highly
important. The amount of preparation required will depend
a great deal upon the previous cropping of the soil. If manure
or cover crops are to be turned under, plowing should come early
enough for the material to rot thoroughly before planting time.
Soil containing a large amount of undecomposed organic matter
is undesirable for immediate seeding.
If adequate water control is maintained and there is no danger
that surface water may accumulate, bedding the soil is not es-
sential. It is easier to maintain a proper water table on flat
than on bedded land. Cultivating, spraying, and harvesting are
less difficult on flat lands. Many soils-especially those in the
Indian River area-are not quite uniform in elevation and have
a shallow sub-soil that is impervious to water. These should
be bedded to prevent excessive standing water in the low areas.
Beds should be only as high as is necessary to allow for run-off
of excess water.
Planting.-Several different types of seeders are used for
planting the commercial sweet corn crop. Seeds are drilled in
rows 32 to 36 inches apart, with seeds spaced 8 to 12 inches
apart in the drill, and covered to a depth of 11/2 to 21/2 inches-
depending upon available soil moisture and soil type. Seeds
can be covered to a greater depth in light sandy soil than in
the darker, heavier soils. For planting on beds in the Indian
River area, the rows may be spaced farther apart, the distances
depending upon the type of equipment available for cultivation.
For example, the tomato producer planting on 7-foot beds could
use 42-inch corn rows in order to use his tomato equipment.
The quantity of seed used per acre for rows spaced 36 inches
apart varies from 10 to 15 pounds. Every effort should be
made to insure a good stand of corn, since poor stands seldom
make a profit. Commercial plantings are begun in October and
continued through January. In much of the Indian River area,
plantings should be made in December, January, and February.
Temperatures, market demand, and insect and disease preva-
lence should be considered by the grower to determine the most
favorable planting dates.
Sweet Corn Production on Florida Lower East Coast 11
Cultivation.-Sweet corn is usually cultivated with tractor
tools designed on the unit system. These allow cultivation of
two or more rows at a time. Type of cultivating tools used
varies with the preference of the grower. As sweet corn plants
are shallow-rooted, too deep cultivation must be avoided, lest
it destroy many of the feeder roots near the surface of the soil.
Two to four cultivations may be necessary, depending upon
condition of the soil at planting and number of weed and grass
It is usually desirable to throw some soil to the base of the
young plants to help support them when the ears begin to ma-
ture. This is particularly desirable if high winds are encountered
during the latter part of the growing period. Working soil to
the plants can be done during the last cultivation when the corn
is laid-by-usually when it is from 15 to 20 inches high-or a
small amount of soil can be worked to the plants at each cultiva-
tion. The latter method will probably destroy fewer roots and
provide better weed control. Only shallow cultivation should
be given after the roots extend across the rows, since deep
cultivation results in destruction of many roots.
Water Control.-Before seeding, the water-table should be
adjusted to such a level that sufficient available soil moisture
is present for germination and root development. Where the
land is not level it is often necessary during the normally dry
winter months to use overhead irrigation on the high spots to
get a stand. A uniform stand is extremely important to avoid
having irregular maturity in a field. Most growers make only
one harvest. Therefore, uniform maturity is necessary to avoid
a reduction in yields.
After the plants are established, the water table should be
lowered to the desired level and held as constant as possible
throughout the growing season. A fluctuating water table
leaches the fertilizer, retards growth, and lowers yields. Pump-
ing facilities should be adequate for lowering the water level
whenever rains are heavy. This tends toward a fluctuating
water table, but frequently cannot be avoided.
Suckering.-The removal of suckers from the base of the plant
is not considered practical. It adds to the cost of production
and when delayed sometimes reduces yield. The practice is
more likely to result in loss than in gain under most conditions.
The number of suckers produced by any one hybrid varies with
the season and growing conditions. Some hybrids, when grown
12 Florida Agricultural Experiment Stations
during the winter months will produce only a few small suckers,
whereas the same hybrids grown during the spring months may
produce many vigorous suckers.
For commercial production in this area, based on the number
of days from seeding to maturity, sweet corn can be classified
into two rather broad groups: (1) early hybrids and (2) inter-
mediate to late hy-
brids. In general the
.early hybrids per-
only when grown in
the spring months;
whereas, the inter-
mediate to late group
performs with vary-
ing degrees of suc-
cess throughout the
fall and winter
GOLDEN SECURI months. Table 1 gives
a comparison of per-
formance of hybrids
planted on several
different dates. Fig.
3 shows ear charac-
teristics of four hy-
brids grown exten-
sively in the area.
The heritable vege-
tative size of corn
plants varies greatly
OA ILL COLDDN'4j with variety and re-
The sweet corn plant
Fig. 3.--Four sweet corn hybrids. is easily damaged by
frost and grows best in hot weather; the higher the temperature,
up to a high maximum, the more rapid the development. Warm
days with cold nights during the winter months are not favor-
able for rapid development.
Day length also plays a role in development: in general, the
shorter days, the shorter the hybrids are in height at maturity.
Sweet Corn Production on Florida Lower East Coast 13
TABLE 1.-COMPARISON OF PERFORMANCE OF SEVERAL SWEET CORN HYBRIDS,
PLANTED AT DIFFERENT DATES IN 1950-51-52 IN THE BOYNTON-LAKE
S 58S' ,S
SDate Z In 4 3 a
Hybrid Dt ni n 0'
Hybrid Seeded _' g 'u
Carmel- Oct. 26-50 83 46 5.54 0.19 0.56 --
cross Oct. 26-50 83 48 5.12 0.75 0.49
Dec. 19-51 78 50 6.76 1.35 0.57 988
Feb. 5-51 72 61 6.94 0.84 0.63 478
Mar. 5-52 69 60 7.88 0.61 0.69 538*
F-M Cross Oct. 26-50 90 64 6.70 0.52 0.62 628
Oct. 26-51 | 100 61 6.75 0.83 0.55 897*
Dec. 7-51 85 64 7.31 0.52 0.60 1058
| Feb. 5-51 84 77 7.46 0.25 0.81 1366
Ioana Oct. 26-50 92 74 6.76 0.43 0.55 598
Oct. 26-51 100 67 7.04 0.19 0.44 1009*
Dec. 7-51 88 64 6.83 0.47 0.57 1065
Feb. 5-51 84 77 7.50 0.20 0.66 1163
Mar. 5-52 76 77 7.72 0.39 0.70 1316
Golden Oct. 26-50 92 60 6.55 1.10 0.54 606
Cross Oct. 26-51 103 63 6.67 0.88 0.51 881*
Bantam Dec. 7-51 90 60 6.93 1.20 0.51 490*
Feb. 5-51 80 71 7.31 0.70 0.71 620
Golden Oct. 26-50 97 66 7.01 1.06 0.55 680
Security Oct. 26-51 103 70 7.27 0.85 0.51 1114*
Dec. 7-51 90 68 7.55 1.10 0.55 588*
Dec. 19-51 90 68 7.24 0.76 0.64 958
Feb. 5-51 84 76 7.32 0.90 0.61 880
Mar. 5-52 I 78 79 7.72 0.33 0.71 912*
Calumet Oct. 26-51 103 73 7.80 0.75 0.60 861*
Feb. 5-51 84 84 8.02 0.34 0.62 771
Illinois Oct. 26-50 94 75 6.61 0.49 0.57 619
Golden Oct. 26-51 103 67 6.70 1.11 0.53 1102*
No. 10 I Dec. 7-51 85 72 7.51 0.83 0.71 833*
"* Calculated yields from observational plots. Not as accurate as other yields recorded.
A combination of factors influences development: temperature,
moisture, day length, fertilization and others. With the above
facts in mind, the grower should pay particular attention to
the selection of hybrids for a commercial acreage that will de-
velop satisfactorily when all factors are not expected to be ideal.
There are numerous hybrids suitable for growing on the sandy
soils of the lower east coast. Only the more widely grown ones,
14 Florida Agricultural Experiment Stations
along with a number of others that have shown some promise
when grown under local conditions, are discussed below.
Carmelcross.-Carmelcross produces medium sized, gently
tapering ears, with 12 to 14 rows of yellow kernels. Height of
stalks in fall or winter planting varies from 4 to 41/ feet; in
spring plantings from 41/2 to 51/2 feet. Length of ears in winter
plantings varies from 6 to 61/2 inches; in spring plantings from
61/ to 71/ inches. Days to maturity in winter plantings vary
from 75 to 85; in spring plantings from 69 to 75. Recommended
for spring only.
Gold Rush.-Gold Rush is very similar to Carmelcross in plant
and ear characteristics and adaptability. In four separate ex-
perimental plantings it was considered slightly inferior to Car-
melcross in overall performance. Adapted for spring plantings.
INTERMEDIATE TO LATE HYBRIDS
Calumet.-Calumet is a late-maturing hybrid. The ears are
long, slender and cylindrical. Kernels are light yellow, medium
wide, in 12 to 14 rows. It is a high yielder under widely vary-
ing conditions and the ears fill well to the tips. Height of stalk
varies from 6 to 7 feet; length of ears from 7 to 81/ inches.
Days to maturity, depending on month seeded, vary from 80
in the spring to 103 in the winter. Adapted to fall, winter and
F-M Cross.-F-M Cross is a yellow-kerneled intermediate-
maturing hybrid. It is a high yielder under most conditions but
is less tolerant than some hybrids to adverse growing conditions.
The kernels are narrow and deep in 14 to 16 rows. Ears fill well
to tips. Length of ears is from 6%/ to 71/ inches; height of
stalk from 5 feet in the winter to 6 feet in the spring. Days
to maturity, depending on month seeded, may be from 80 in
the spring to 100 in the winter. Adapted to late winter and
Golden Cross Bantam.-Golden Cross Bantam is intermediate
to late maturing, is adapted to growing under varied conditions,
but is not widely grown on the sandy soils of the lower east
coast of Florida. Kernels are of rich yellow color, medium in
depth and width, in 10 to 14 rows. Ears vary in length from
61/ to 812 inches; height of stalk from 5 feet in winter to 6
Sweet Corn Production on Florida Lower East Coast 15
feet in spring. Days to maturity, depending upon date of seed-
ing, are from 80 in the spring to 93 in winter.
Golden Security.-Golden Security is a late-maturing high-
yielding hybrid. It produces medium sized, long, tapering ears.
Kernels are light yellow, medium depth and narrow, with 12
to 14 rows per ear. Length of ear unhusked is from 71/2 to 81/2
inches; height of stalk in winter 5% feet, in spring to 61/ feet.
Days to maturity, depending upon date of seeding, are from
84 in the spring to 103 in the winter. Adapted to fall, winter
and spring plantings.
Ioana.-Ioana is a widely adapted hybrid, producing uniform,
attractive, well-filled ears under a wide range of growing con-
ditions. It is intermediate to late maturing; ears are 12 to 14
rowed, well-filled, with medium-narrow, light yellow kernels.
Ears average 8 inches in length. Height of stalk in winter is
51/2 feet, in spring to 63/ feet. Days to maturity, depending
upon date of seeding, vary from 76 in spring to 100 in winter.
Recommended for fall, winter and spring plantings.
Illinois Golden No. 10.-Illinois Golden No. 10 is fairly well
adapted to relatively short days and will produce well-filled large
ears when grown during the winter months. The ears are
slightly tapered with 12 to 14 rows of large to medium yellow
kernels. Ears are thick, heavy, and from 7 to 8 inches in length.
Stalks are sturdy and average from 6 feet in height in winter
to 7 feet in spring. Days to maturity, depending upon date of
seeding, vary from 80 in spring to 94 in winter. The eating
quality of Illinois Golden No. 10 is only fair.
The hybrids described above are some of the more popular
ones grown on the sandy soils at present. However, many
sweet corn hybrids will perform satisfactorily under average
conditions. The following is an additional list of hybrids that
have been grown with varying degrees of success along the
Florida lower east coast: Aristogold Bantam Evergreen, Erie,
Evergold, Flagship, Golden Hybrid No. 2439, Huron, lochief,
Kennebec, Surecross, and Victory Golden.
There has been very little difference in susceptibility to the
Helminthosporium diseases between the hybrids described. In
selecting a hybrid it should be noted that H. maydis is more
severe in fall plantings; whereas H. turcicum is more prevalent
in spring plantings. F-M Cross and Golden Security are some-
what resistant to H. maydis, while loana, Evergold and Flagship
are quite susceptible. None of the commercially available hy-
16 Florida Agricultural Experiment Stations
brids tested to date show enough resistance to H. turcicum to
warrant mentioning; however, F-M Cross is quite susceptible.
Hybrids better adapted to short days and cool nights and
having resistance to Helminthosporium are likely to be intro-
duced in the future through the combined efforts of the experi-
ment stations and those commercial agencies active in sweet
HARVESTING AND PACKING
Eating quality of sweet corn begins to decline immediately
after harvest-especially if the corn is not handled properly.
Corn remains sweet much longer in a cold refrigerator than in
a warm vegetable bin. Tender, sweet corn held at ordinary
temperatures is quickly converted to tough, starchy, unpalatable
Sweet corn should be pre-cooled with the least possible delay
after it is picked, bringing the temperature of the corn to 400 F.
if at all possible. It should be as near 400 F. as possible when
loaded into cars or trucks for transit. The most up-to-date
refrigeration practices should be used in transit to insure a high
grade product reaching the retailer.
Continuation of proper refrigeration at the distributing cen-
ters is necessary to insure a top quality product to the consumer.
The grower can do much to improve quality of sweet corn on
the market by rapid harvesting and proper precooling before
it leaves his packing plant. This will increase the demand for
his product through repeat sales.
Most of the sweet corn in this area is harvested in tractor-
drawn wagons and hauled to packing sheds nearby. There it
is graded and packed in wire bound boxes, measuring approxi-
mately 22 x 111/2 x 91/2 inches. This type crate holds from
four to six dozen ears, depending upon size. There has usually
been a difference of $2.00 or more per crate between U. S. No. 1
and U. S. No. 2 grades. Therefore proper grading and packing
is very desirable.
DISEASES AND THEIR CONTROL
Several diseases occur on sweet corn in southern Florida.
None of them has been serious enough, until recently, to warrant
special control measures. The severity of the leaf blights has
increased somewhat in proportion with the increase in acreage
Sweet Corn Production on Florida Lower East Coast 17
of sweet corn. Symptoms and recommended control measures
for two leaf-blighting species of Helminthosporium are de-
Northern Leaf Blight.-Northern leaf blight is caused by the
fungus HOmltifn tho.plwo ; turcicum Pass. It usually makes its
appearance on sweet corn in late fall or early winter and con-
tinues for the duration of the spring crop. The disease is
favored by a weekly mean temperature between 60 and 80'
F. (8). If environmental conditions are favorable for the de-
velopment of the fungus, the first visible evidence of the disease
appears in the form of small yellow flecks approximately 1/16
inch in diameter about a week after the spores (seeds) of the
fungus come in contact with the leaves.
Within 10 days many of these yellow flecks increase in size
to about 1/ inch wide and %4 inch long and have a blue-green
faded color with a tan center. In about two weeks these lesions
increase to one or two inches in length but only slightly in
width. At this stage they are tan or straw-colored over the
whole lesion. From this point on the lesions elongate and have
tapering ends, often extending from the tip of the leaf blade
into the leaf sheath.
As the lesions get older the color changes to brown and dark-
colored spores are produced abundantly over their surface in
dark, sooty masses, Fig. 4. The disease occurs only on the
leaves. It usually starts on the lower leaves first and may
extend all the way to the top leaf. Under an environment favor-
able for the development of the disease the entire plant may
be killed by a withering of the leaves, beginning with the lower
leaves and progressing upward through the plant.
Control.-During the winter and spring 14 or 15 applications
of 2 quarts of nabam and 3% pound of zinc sulfate (36 percent
or the equivalent) per 100 gallons of water at 3- to 5-day inter-
vals-beginning when the plant is 4 to 6 inches high and con-
tinuing until 10 days before harvest-have been found to give
an excellent and economical control in experimental plantings
at Fort Pierce. Zineb at 2 pounds per 100 gallons of water has
given results equally as good as nabam plus zinc sulfate.
Manganese ethylene bisdithiocarbamate has given good con-
trol. Although a slight burning of the leaves in the whorls has
been noted, there was no corresponding reduction in yield. This
fungicide may be obtained as a wettable powder (Manzate) or
prepared by mixing nabam with manganese sulfate. The tank
18 Florida Agricultural Experiment Stations
Fig. 4.-Sections of corn leaves showing Northern (left) and Southern
(right) leaf blight.
mix product should be prepared as directed by the dealer; mix-
ing it in the same way as nabam-zinc sulfate usually results
in an inferior product. This fungicide should be used on a small
scale until it has proven to be effective over several seasons.
Nabam-zinc sulfate and nabam-manganese sulfate are com-
patible with recommended insecticides. Zineb and Manzate are
not compatible with some DDT emulsions. An addition of 4
ounces of dried skimmed milk or casein to each 100 gallons has
been found to eliminate satisfactorily the incompatibility.
Timing of the applications and amount applied per application
are of utmost importance. The statement that applications
should be made at 3- or 5-day intervals is, at best, an arbitrary
one. Since fungicides act as protectants and not as cures, it
would be wise to add another application as soon as possible
after rain, and resume the spray schedule after this extra ap-
plication. Many infections occur in the whorl, as is shown by
the fact that, from 10 days to 2 weeks after a rain, a band of
lesions is often formed on the leaves 4 to 8 inches from the
A minimum of 150 to 200 gallons of spray per acre is neces-
sary to protect the leaves of plants approaching the tassel stage.
Sweet Corn Production on Florida Lower East Coast 19
Enough material must be applied so that there is some "run
down" into the whorls. High-clearance sprayers are a necessity
if large acreages of tall-growing types of sweet corn are to be
planted in the spring. High-clearance tomato spray rigs are
satisfactory for certain low-growing varieties.
In the fall Northern leaf blight is not as prevalent as it is
later in the winter and spring. When there is little evidence
of the disease in the vicinity during the fall season, timely ap-
plications once a week, beginning when the corn is approximately
6 inches high and continuing until 14 days before harvest, have
been found to be sufficient to give good commercial control. If
the disease shows signs of increasing the interval should be
Spores of the fungus are spread principally by wind. Fields
that have been harvested should be turned under as soon as
possible so that no crop residue remains exposed. This greatly
reduces the supply of inoculum in the area. A rotation program
of at least one season will also reduce the inoculum.
Dusting for the control of Northern leaf blight may give com-
mercial control in some seasons when the disease is mild. How-
ever, results of this method are uncertain and should not be
relied upon altogether. Dusts are helpful in emergencies, when
they can be used until spraying can be resumed.
Some growers have used tomato sprayers during the first
part of the season until the corn was too tall for these rigs.
Zineb dust was then applied by airplane for the remainder of
the season. This combination spray-and-dust program has been
reasonably successful in the past; but it would probably be
insufficient for serial plantings or during periods when the spray-
ers were not able to hold the disease in check during the first
part of the season.
Southern Leaf Blight.-Southern leaf blight is caused by the
fungus Helminthosporium maydis Nisikado and Miyake. It
usually attacks sweet corn in Florida during warmer weather
than Northern leaf blight. However, the two may occur simul-
taneously on the same leaf. The lesions of Southern leaf blight
are smaller and more irregular in shape than Northern leaf
blight. The first evidence of the disease is the appearance of
small yellow flecks on the leaves, which later become elongated
between the veins. When mature, the sides of the lesions are
usually parallel instead of tapering, as is the case with North-
ern leaf blight.
20 Florida Agricultural Experiment Stations
Mature lesions measure from 1/8 to about 1 inch long and
up to /q inch wide. The color of the spots is tan or creamy white,
and they may have a reddish or purplish-brown margin. The
spore masses are not so distinct as they are in Northern leaf
blight, Fig. 4. In severe cases the disease brings about the
death of the leaf by a gradual progressive withering, but it
rarely kills the entire gl:1.1nt.
Control.-Southern leaf blight does not cause as much damage
as does Northern leaf blight. The control recommended for
the latter disease will also control Southern leaf blight. In fall
plantings this disease is quite prevalent, while Northern leaf
blight is not usually serious. Weekly applications of nabam plus
zinc sulphate or zineb have given good control of this disease in
fall plantings, when northern leaf blight was not prevalent.
Rust.-Rust is caused by the fungus Puccinia sorghi Schw.
Sometimes it may be serious enough to be of some concern to
the growers. However, the control measures recommended for
the leaf blights should be adequate to control rust.
INSECTS AND THEIR CONTROL
Sweet corn is a preferred host plant for a number of insects.
Serious losses are sure to result in most plantings unless the
grower watches his crops closely for insects and makes timely
and thorough applications of the proper insecticides. Since the
market does not accept worm-damaged corn, it is of great im-
portance that the grower be prepared, before he plants, with cor-
rect information on insecticides, equipment and their proper use.
Figures 5a and 5b are included for quick reference. They deal
with the major insects attacking sweet corn from time of seeding
until harvest. A discussion of major insects, precautions on the
use of insecticides, and insecticide applicators is included. This
should aid the grower, first in recognizing the insects and their
damage, second in setting up a control schedule which will give
protection from insect damage, and third in selecting and adapt-
ing spray and dust applicators. The bibliography gives sources
of additional information.
Corn Earworm.-The corn earworm, Heliothis armigera
(Hbn.), often feeds as a budworm in the whorl of young corn,
but it is a more serious problem in the ear. Eggs deposited by
moths on and near the silks hatch into tiny worms. These feed
down the silk channel to the ear tip where they develop as they
Sweet Corn Production on Florida Lower East Coast 21
feed on the kernels. This insect is widespread and serious on
corn. It is difficult to control, especially when the infestation
is heavy. Control measures described here must be carried out
carefully. Corn earworms are most abundant in late spring.
Fall, winter, and early spring corn silkingg not later than April)
has generally escaped heavy earworm attacks.
One quart of 25 percent DDT emulsion, or 2 pounds of 50
percent wettable DDT per 100 gallons of spray, is recommended
for control of corn earworms feeding as budworms. Apply 75
to 150 gallons of spray per acre at weekly intervals, directing
it into the whorls. For protection of the ears mix 3 quarts of
25 percent DDT emulsion per 50 gallons of water and apply to
one acre, directing the spray toward the silking zone to thor-
oughly wet all silks. Make first application one day after the
first silks appear and repeat at two-day intervals for a total of
For severe infestations a highly refined mineral oil may be
added to the formulation as follows: mix 3 to 4 quarts of 25
percent DDT emulsion with 2.5 gallons of mineral oil, and add
to enough water to make 50 gallons of spray while the water is
being agitated. In some cases yield reductions have occurred
where mineral oils were used. For this reason their use is
recommended only when severe infestations of earworms are
expected. Corn silking later than April may need oil added to
the spray in order to maintain a high percentage of worm-free
ears, Fig. 6.
Five to 10 percent DDT dust is effective in controlling ear-
worms under light to moderate infestations, but will not control
heavy infestations. Dust should be applied on the silks in late
afternoon or evening at the rate of 30 to 40 pounds per acre
when first silks appear. Additional treatments should be made
at two-day intervals until the silks have turned brown.
If control methods have failed, this can be determined by
clipping the tips of the ears and examining these tips for small
earworms or their tunnels in the silk channel. This inspection
should be made when the silks have wilted, but before they
turn brown. If insects are present in the silk channels, neither
DDT dust nor spray will control them.
In such a case, they can be controlled by injecting % C.C. of
white mineral oil containing 0.2 percent pyrethrins into the tip
of each ear after the silks are wilted, but before they are brown.
Applications must be made by hand with a calibrated force
Fig. 5a.-SWEET CORN INSECT CONTROL.
WEBWORM CUTWORM Y EGG MASS LEAF FEEDING
WEBWORM CUTWORM /-t- //
WIREWORM / -
CORN STALK BORER 1 \ \
7.\ 2$\ 7 cU-
Cutworms, wireworms, web- Weeds are destroyed; crop is Wilted plants often caused Moths lay eggs on leaves. On larger corn, large worms
worms, etc. feed on weeds planted. Soil insects will at- by wireworms or cornstalk Tiny worms feed on leaves, feed deep into buds and are
& grass. Plowing destroys tack corn as soon as it is borers. Plants cut off may then migrate into buds. difficult to control.
insect's food, but leaves hun- seeded and begins to germ- be caused by cutworms or Look for leaf feeding, when Use same spray formula, but
gry worms in soil. mate. webworms. Examine dam- found spray with 2 Ibs. 50% increase dosage up to 150
Destroy weeds & grass 4 to Arrange for Toxaphene or aged plants and surrounding wettable Toxaphene or DDT gals. per acre. Direct most
6 wks. before planting. If Aldrin spray or dust. Get soil for insects, per 100 gals. water-75 gals. spray into the buds. Failure
wireworms are present apply application equipment ready For cutworms treat at once per acre. Three nozzles per to control budworms usually
4 lbs. Tech. Chlordane or 2 and apply pre-emergence with 2 lbs. 50% wet. Toxa- row. Repeat each week, or can be corrected by increas-
Ibs. Aldrin per acre broad- spray or 2 Its. 20% Aldrin phene per acre in 100 gals. as needed. ing amount of spray applied.
cast & disced, or mixed with per acre or equivalent and water, or dust 25 Ibs. 10%
fertilizer & banded to each when corn germinates check Toxaphene per acre. For
side of seeds, field daily for insect damage. other insects, 2 1' s. 50% wet.
Chlordane or 2 lbs. 20% wet.
Aldrin per acre in 100 gals.
water may reduce damage.
Fig. 5b.-SwEET CORN INSECT CONTROL.
FALL ARMYWORKM CORN EARWORM EGGSON-SIK FY
CORN-SILK _. APHID CO-SLK FLY RN EARIORM LARVA
Worms & aphids often pres- Graph shows budworms mi- Earworm moths deposit eggs. When silks are witled, but When silks are brown and
ent in tassels. As tassels grating from tassels to ears: Worms feed on silks to tips not brown, clip the tips off the worms have reached the
push out worms migrate to silk-fly depositing eggs in ear of ears. Infestations heavy & examine for small worms ear tips they cannot be con-
the young ears, tip, and locations of aphids. in late spring, in silk channel. If present, trolled.
Examine field when first tas At this stage it is late for Plant early spring. Spray 3 neither dust nor spray will Clip tips or ears to remove
sels appear. If worms are treatment, qts. per acre of 25% DDT control them. worms when corn is har-
found apply Toxaphene or Kill adult corn-silk flies & emul. or dust 35 Ibs. per acre Inject :% cc per ear of vested.
DDT spray as recommended aphids before silks appear of 5 to 10% DDT every white mineral oil containing
for tudworm, or apply 35 with 2 lbs. 15% Parathion second day during silking 0.2% Pyrethrins after silks
lbs. per acre of 10% DDT or per acre in 100 gals. water period until silks are brown, are wilted but before they
Toxaphene dust. Repeat at or 1% Parathion dust, 35 Direct dust or spray at silks, are brown. Apply by hand
2 to 3 days intervals until lbs. per acre. Follow pre- each side of row. About 6 with calibrated force oiler.
all tassels are out. If silk- cautions on Parathion label, spray or 8 dust applications Treating before silks wilt
flies or aphids also present required, will interfere with pollina-
use Parathion as substitute. tion.
IMPORTANT.-Study the entire chart (Fig. 5a and 5b), reading left to right. It will then be noted that the chart must
be considered as a whole, and that recommended control measures are not always intended for the insect illustrated in the same
section of the chart.
24 Florida Agricultural Experiment Stations
Fig. 6.-Corn earworm control with DDT-mineral oil emulsion (left);
DDT dust (center); and untreated (right). DDT-mineral oil sprays, while
most effective, may cause slight yield reduction.
oiler, and it may be necessary to treat at two dates in order
to make applications at the proper time. Ears treated before
the silks wilt will not fill out properly, and ears treated after the
silks are brown will be damaged by the worms.
Fall Armyworms.-The fall armyworm, Laphygma !' ir ejp dli
(A. and S.), on corn is generally referred to as a budworm.
The :dult. moths deposit egg masses upon the leaves. After the
eggs hatch the small worms feed upon the leaves for a short
time, Fig. 7, then migrate into the buds, where they remain
until full grown. If present when the tassels appear, the worms
will migrate from the exposed tassels to the developing ears,
which they enter through the tips, sides or butts.
One quart of 25 percent DDT emulsion, or 2 pounds of 50
percent DDT or Toxaphene wettable powder, per 100 gallons of
water will control fall armyworms. From 75 to 150 gallons per
acre should be applied, depending upon the size of the plants.
Arrange the nozzles so that the spray will run down into the
It is usually necessary to spray corn at weekly intervals, be-
ginning when the first insects are found on the small plants.
If worms are present in the whorls when the tassels begin to
Sweet Corn Production on Florida Lower East Coast 25
appear it is important to make insecticide treatments at close
intervals while the tassels are emerging and exposing the worms.
Two to three applications of DDT or toxaphene spray or dust at
two-day intervals are recommended as the tassels appear.
Corn-silk Fly.-The corn-silk fly, Euxesta stigmatias Loew,
is about 1/4 inch in length, with wings distinctly banded with
black cross stripes.
It appears restless,
running up and down
the surface of the
leaves, stalks an d
corn ears, occasion-
ally extending i t s
wings as if it is
stretching. This fly
deposits tiny white, r
elongated eggs in the
ear tips. In two to
four days the mag-
gots hatch and begin
feeding down the silk
channel. Their dam-
age is concentrated
on the ear tips, al-
though some mag-
gots attack a kernel
here and there along
the entire length of
the ear. This results
in a soggy, unattrac- Fig. 7.-Fall armyworm damage to unsprayed
tive ear. corn leaf (left) and leaf (right) sprayed with
Control is aimed at DDT. These insects do most damage in the buds
Control is aimed at of the plants and are often called budworms.
killing the adult flies
before they deposit eggs in the ear tips. Two pounds of 15
percent parathion per 100 gallons of water, or 1 percent para-
thion dust applied at about 35 pounds per acre, is suggested.
Applications should be made after tassels begin to emerge
but before any silks appear. If re-infestation occurs, as often
happens in smaller plantings due to a heavy marginal migra-
tion, it may be necessary to apply a second or third treatment.
However, parathion should not be applied later than two weeks
26 Florida Agricultural Experiment Stations
In general, the larger plots will require fewer treatments than
small ones. It is important to learn to recognize the adults,
and when they are found they should be treated with parathion.
Chlordane is also effective against this pest when used at the
rate of 2 pounds of 50 percent wettable powder per acre in 100
gallons of water, or 3 percent chlordane dust applied at 35
pounds per acre. Precautions should be noted before using
Cutworms.-Cutworms are often present in the soil when
weeds and grasses are plowed under. If corn is planted imme-
diately following plowing, these cutworms may destroy the
stand within a few days after germination. It is important
to watch a newly seeded corn field closely to detect the presence
of cutworms before they have seriously reduced the stand.
These worms feed upon the plants at night and often leave parts
of them on the ground uneaten. By scratching around freshly
cut plants the worms may be found in the upper inch or two
As a preventive treatment, the seeded field may be sprayed,
just before the corn emerges, with 2.5 pounds of 40 percent
toxaphene or 2 pounds of 20 percent aldrin wettable powder per
acre in 50 to 100 gallons of water. Ten percent toxaphene dust
may be applied at the rate of 25 pounds per acre if dusting is
preferred. Poisoned baits containing 2.5 percent technical toxa-
phene in wheat bran have given good cutworm control when
broadcast in the late afternoon at the rate of 20 to 30 pounds
per acre. After the initial cutworm infestation is eliminated
the budworm treatments are sufficient to hold cutworms in
check. Where possible, weeds and grasses should be destroyed
at least one month before planting corn to reduce the number
Wireworms.-Wireworms are sometimes troublesome on sandy
soils, but they are less serious than on the organic soils in the
Everglades area and on the marl soils in the Homestead area. The
long, slender, hard, wire-like worms live in the soil and destroy
the seeds, as well as the young seedlings. They eat holes in
seeds and stalks, causing the seeds to fail to germinate and the
young plants to wilt and die. By scratching around freshly
wilted plants, wireworms can be found nearby. Wireworms
develop into adult click beetles which are active fliers in the
spring and summer months.
Sweet Corn Production on Florida Lower East Coast 27
Soil heavily infested with wireworms should not be planted
to corn. If moderate or light infestations occur, damage can
be reduced by the application of chlordane or aldrin to the soil.
Spray or dust over the entire soil surface at the rate of 4 to 5
pounds of actual chlordane or 2 to 3 pounds of actual aldrin
per acre and disk into the soil several weeks before planting.
The high rates should be used if the infestation is severe.
Mixing the insecticides with fertilizer and placing this mixture
in two bands to each side of the seeds will give satisfactory re-
sults in some cases. The recommended dosages of insecticides
may be mixed with the amount of fertilizer which is to be ap-
plied to one acre at time of planting.
The Lesser Corn-stalk Borer.-The lesser corn-stalk borer,
Elasmopalus lignosellus (Zell.), causes damage similar to wire-
worms. It lives in the soil and bores into corn plants near the
soil surface, causing smaller plants to wilt and die. A dirt-
covered silken tube is generally attached to the hole in the corn
plant, and the soft purplish-green worm can be found in the
host plant or in this dirty webbing.
These insects are more numerous in dry sandy soils. In-
festations are caused by the adult moths depositing eggs on
leaves or stems of the plants. Often by the time the worms
are detected, much damage has been done. For this reason a
pre-emergence spray of 2 pounds of 20 percent aldrin in 100
gallons of water applied to one acre is suggested on dry sandy
soils in areas where this insect causes frequent damage. After
plants emerge, a spray containing 2 pounds of 20 percent aldrin,
15 percent parathion, or 50 percent chlordane wettable powder
per 100 gallons of water, applied on the soil at the base of the
plants before any soil is worked to the corn, may reduce damage.
Early destruction of weeds and grasses as suggested for cut-
worms will eliminate larvae already present in the soil.
Webworms.-Webworms, Crambus spp., sometimes attack
young corn, feeding around the base of the plants. They are
soft worms with dark spots on their backs. They spin silken
tunnels and loose webbing in the soil near the base of the plants.
Like cutworms, these insects feed upon weeds and grasses. If
corn is planted soon after plowing under natural vegetation, the
worms are left without food except for the corn crop, which
they attack soon after it germinates. The use of a pre-emer-
gence spray of 2 pounds of 20 percent aldrin per acre, in addition
to toxaphene sprays applied for cutworms when the corn germi-
28 Florida Agricultural Experiment Stations
nates, should prevent serious damage from webworms. Early
destruction of weeds and grasses should reduce the number
Aphids.-Aphids often develop on corn tassels and on silks
and husks of ears. While they probably do little actual damage
to the crop, they reduce the attractiveness of the corn by their
presence in the husks and by secreting a sticky honeydew. Two
pounds per acre of 15 percent parathion wettable powder in 100
gallons of water, or 25 to 35 pounds per acre of 1 percent para-
thion dust at tasseling time, is suggested for the control of aphids.
Sugarcane Borer.-The sugarcane borer, Diatraea saccharalis
(F.), is a minor pest on corn. Usually it does not become abun-
dant enough to warrant special control measures. The white,
dark-spotted worms tunnel into the corn stalks, often causing
them to break over. Sugarcane borers look somewhat like
European corn borers, which have not yet been found in Florida.
PRECAUTIONS ON THE USE OF INSECTICIDES
Insecticides are poisonous to humans and must be handled
with care. They constitute a hazard to the operator applying
them and as a residue on the crop. Insecticides can be used
safely if the following precautions are observed:
1. Keep insecticides out of the eyes, nose, and mouth. Wear
goggles and respirator if necessary.
2. Wear protective clothing, including long sleeves, gloves,
and hat. Take a shower and change to clean clothes each day
to prevent absorption of the insecticide through the skin.
3. Store insecticides in a safe place.
4. Do not contaminate food, tobacco, drinking water, etc.
Wash hands before smoking or eating.
5. Use extreme care in applying parathion, as it may cause
sickness or death.
6. Bury or burn all insecticide containers.
7. Discontinue parathion two weeks before harvest and other
insecticides at least one week before harvest.
8. Do not feed to livestock the corn forage treated with the
9. Observe precautions on manufacturer's label.
A high-clearance power sprayer is recommended for commer-
cial sweet corn plantings. The sprayer should have enough
Sweet Corn Production on Florida Lower East Coast 29
clearance (about five to six feet) to enable spraying until one
week before harvest. Pump capacity should be adequate for
applying up to 200 gallons of spray per acre at 200 to 300 pounds
pressure per square inch. The boom should be rigid enough to
prevent swinging of the nozzles, and easily adjustable for rais-
ing or lowering. Efficient screens and agitators are necessary
to prevent clogged nozzles and insure thoroughly mixed spray
The operator of the corn sprayer should be well trained,
capable, and dependable. The high-clearance power sprayer can
be used for all insect and disease problems from time of seeding
until harvest. A standard-clearance power sprayer may be
use for insect control until the tassels begin to appear.
Some growers without high-clearance machines leave un-
planted strips wide enough for their sprayer and tractor and
use a "T" boom which will reach out on each side over three
to four corn rows. Nozzles can then be attached to drop pipes for
insect and disease control on tall corn. The market and home
gardener may use a 3- to 5-gallon compression-type hand sprayer
or a knapsack sprayer. However, a thorough coverage is neces-
sary, and it is difficult to keep the sprays properly agitated in
Ground power dusting and airplane dusting may be used for
insect control. The power duster boom should be designed so
that the nozzles may direct the insecticides into the ear zone
from above the silks on each side of the row for corn earworm
control, and directly into the whorls for budworm control. The
machine should be equipped with lights for dusting at night.
Airplane dusters offer a rapid way to treat and are useful when
the soil is too wet for ground equipment. Calm weather is
necessary for airplane dusting and the ..ath-l should be narrow
enough to insure an even distribution of the insecticides. Hand
dusters are available for market and home gardens, the rotary-
type being preferred.
Careful spray and dust applications are necessary for success-
ful insect control. Make final adjustments of nozzles in the field
to insure thorough coverage as recommended for the various
insects described. Frequent inspections of the sprayer or duster
nozzles are important, since one clogged nozzle could mean a
heavy loss due to insect damage. The sweet corn producer
should make sure that his application equipment is adequate to
take care of the acreage to be planted.
30 Florida Agricultural Experiment Stations
Sweet corn can be grown successfully during fall, winter, and
spring months on the sandy soils of the lower east coast of
Florida and in the Indian River area.
Adequate water control, along with proper cultural practices,
is essential to the successful production of sweet corn.
Lime acid sands to bring the pH up to 5.5 to 6.0. Apply 1,000
pounds per acre of a 4-12-6 fertilizer at time of planting, fol-
lowed by two side applications of a 12-0-6 fertilizer at the rate
of 500 pounds per acre. In the event of leaching rains, increase
nitrogen applications by top-dressing with 300 pounds per acre
of nitrate of soda.
Proper selection of hybrids adapted to seasonal conditions
encountered is highly important. In general, early hybrids
are not adapted to fall and winter plantings. Calumet, F-M
Cross, Golden Security and loana are recommended for fall,
winter and spring plantings. Illinois Golden No. 10 is recom-
mended for fall and early winter. Carmelcross and Gold Rush,
early hybrids, should be used only for spring plantings.
Proper harvesting, grading, packing, and handling are essential
to successful sweet corn production. Harvest, grade, and pack
rapidly; precool immediately to a commodity temperature of
approximately 400 F.
Materials per 100 gallons of water, listed below in descending
order of preference, are recommended for the control of diseases
caused by two leaf-blighting species of Helminthosporium: (1)
Nabam, 2 quarts plus zinc sulfate (36 percent) % pound; (2)
Zineb, 2 pounds. It is important to turn under the sweet corn
stalks as soon after harvest as possible to keep down the con-
centration of inoculum.
Serious losses are sure to result unless the sweet corn plant-
ings are watched closely for insects, and timely and thorough
applications of the proper insecticides made. Recommendations
for controlling the major insects, including a quick reference
chart, are given. Insecticides constitute a hazard if used care-
lessly, but they can be used safely if the precautions listed are
followed. A high-clearance power sprayer is recommended for
commercial acreage; however, dust may be used in fall, winter,
and early spring plantings when the earworm infestations are
normally light. Small hand-type applicators are available for
market and home gardeners.
Sweet Corn Production on Florida Lower East Coast 31
1. FORSEE, W. T., Jr., and WALTER A. HILLS. Fertilizer experiments
with some vegetable crops on sandy soils of eastern Palm Beach
County. Proc. Fla. State Hort. Soc. 64:92-95. 1951.
2. HAYSLIP, NORMAN C. Corn-silk fly control on sweet corn. Fla. Agr.
Exp. Sta. Cir. S-41. 1951.
3. HAYSLIP, NORMAN C. Corn earworm control-formulations. The Fla.
Ent. 35:51-56. 1952.
4. KELSHEIMER, E. G., N. C. HAYSLIP and J. W. WILSON. Control of bud-
worms, earworms and other insects attacking sweet corn and green
corn in Florida. Fla. Agr. Exp. Sta. Bul. 446. 1950.
5. SCRUGGS, FRANK H. Annual fruit and vegetable report. Fla. State
Mkt. Bureau. 1952.
6. THAMES, WALTER H., JR. Corn earworm control-timing and number
of applications. The Fla. Ent. 35:47-50. 1952.
7. THOMPSON, HOMER C. Vegetable crops. McGraw-Hill Book Co., Inc.
Ed. No. 4. 1949.
8. ULLSTRUP, ARNOLD J. Leaf blights of corn. Purdue University, Sta.
Bul. 572. 1952.
9. WILSON, J. W. Corn earworm control-spraying methods. The Fla.
Ent. 35:3-9. 1952.
10. WILSON, J. W., W. H. THAMES, JR., and N. C. HAYSLIP. Corn earworm
control-summary and recommendations. The Fla. Ent. 35:57-61.
11. WINSTON, J. R., R. CUBBEDGE and J. KAUFMAN. Crated sweet corn in
transit. Fla. Grower. 60, No. 6. 1952.