Front Cover
 Table of Contents
 Corn stocks for Florida growin...
 Selection of land
 Preparation of land
 Planting the cormlets
 Planting the corms
 Fertilizing practices
 Minor element deficiences
 Drainage and irrigation
 Harvesting flowers and corms
 Curing and storage of corms
 Insect pests
 Leaf and flower diseases
 Spray programs
 Corm diseases
 Neck rots
 Miscellaneous diseases and...
 Summary of control measures for...
 Historic note

Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 535
Title: Commercial gladiolus production in Florida
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00028042/00001
 Material Information
Title: Commercial gladiolus production in Florida
Series Title: Bulletin - University of Florida Agricultural Experiment Station ; 535
Physical Description: Book
Language: English
Creator: Magie, R. O.
Magie, Robert O.
Cowperthwaite, W. G.
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville, Fla.
Publication Date: 1954
 Record Information
Bibliographic ID: UF00028042
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Front Cover
        Page 1
        Page 2
        Page 3
    Table of Contents
        Page 4
        Page 5
        Page 5
    Corn stocks for Florida growing
        Page 6
    Selection of land
        Page 7
    Preparation of land
        Page 8
    Planting the cormlets
        Page 9
    Planting the corms
        Page 10
        Page 11
    Fertilizing practices
        Page 12
        Page 13
        Page 14
    Minor element deficiences
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
    Drainage and irrigation
        Page 21
        Page 22
    Harvesting flowers and corms
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
    Curing and storage of corms
        Page 29
        Page 30
    Insect pests
        Page 31
        Page 32
        Page 33
    Leaf and flower diseases
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
    Spray programs
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
    Corm diseases
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
    Neck rots
        Page 56
    Miscellaneous diseases and injuries
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
    Summary of control measures for the most destructive diseases
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
    Historic note
        Page 68
Full Text

p 13 i954

Bulletin 535

January 1954

(A Contribution from the Gulf Coast Experiment Station)


Gladiolus Production in Florida


Fig. 1.-A fine crop of Florida gladiolus spikes nearly ready for harvest.


Hollis Rinehart, Chairman, Miami
J. Lee Ballard, St. Petersburg
Fred H. Kent, Jacksonville
Wm. H. Dial, Orlando
Mrs. Alfred I. duPont, Jacksonville
George W. English, Jr., Ft. Lauderdale
W. Glenn Miller, Monticello
J. B. Culpepper, Secretary, Tallahassee
J. Wayne Reitz, Ph.D., Provost for Agr.S
Willard M. Fifield, M.S., Director
J. R. Beckenbach, Ph.D., Asso. Director
L. O. Gratz, Ph.D., Assistant Director
Rogers L. Bartley, B.S., Admin. Mgr.3
Geo. R. Freeman, B.S., Farm Superintendent

H. G. Hamilton, Ph.D., Agr. Economist'
R. E. L. Greene, Ph.D., Agr. Economists
M. A. Brooker, Ph.D., Agr. Economist 3
Zach Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Agr. Economist
D. E. Alleger, M.S., Associate
D. L. Brooke, M.S.A., Associate
M. R. Godwin, Ph.D., Associates
W. K. McPherson, M.S., Economists
Eric Thor, M.S., Asso. Agr. Economist
Cecil N. Smith, M.A., Asso. Agr. Economist
Levi A. Powell, Sr., M.S.A., Assistant4
Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. Agri. Economist
J. C. Townsend, Jr., B.S.A., Agr. Statisticians
J. B. Owens, B.S.A., Agr. Statistician
F. T. Calloway, M.S., Agr. Statistician
C. L. Crenshaw, M.S., Asst. Agr. Economist
B. W. Kelly, M.S., Asst. Agr. Economist
Frazier Rogers, M.S.A., Agr. Engineer3s
J. M. Myers, M.S.A., Asso. Agr. Engineer
J. S. Norton, M.S., Asst. Agr. Engineer
Fred H. Hull, Ph.D., Agronomist 1 2
G. B. Killinger, Ph.D., Agronomist
H. C. Harris, Ph.D., Agronomist -
R. W. Bledsoe, Ph.D., Agronomist
W. A. Carver, Ph.D., Agronomist
Fred A. Clark, M.S., Associate 2
E. S. Horner, Ph.D., Assistant
A. T. Wallace, Ph.D., Assistant 3
D. E. McCloud, Ph.D., Assistant '
G. C. Nutter, Ph.D., Asst. Agronomist
I. M. Wofford, Ph.D., Asst. Agronomist
T. J. Cunha, Ph.D., Animal Husbandman18
G. K. Davis, Ph.D., Animal Nutritionist
It. L. Shirley, Ph.D., Biochemist
A. M. Pearson, Ph.D., Asso. An. Husb.s
John P. Feaster, Ph.D., Asst. An. Nutri.
H. D. Wallace, Ph.D., Asso. An. Husb.S
M. Koger, Ph.D., An. Husbandman 3
J. F. Hentges, Jr., Ph.D., Asst. An. Hush. 3
L. R. Arrington, Ph.D., Asst. An. Hush.
A. C. Warnick, Ph.D., Asst. Physiologist

E. L. Fouts, Ph.D., Dairy Technologist I '
R. B. Becker, Ph.D., Dairy Husbandman 3
S. P. Marshall, Ph.D., Asso. Dairy Husb.S
W. A. Krienke, M.S., Asso. Dairy Tech.3
P. T. Dix Arnold, M.S.A., Asso. Dairy llusb. s
Leon Mull, Ph.D., Asso. Dairy Tech.3
H. H. Wilkowske, Ph.D., Asst. Dairy Tech.3
James M. Wing, Ph.D., Asst. Dairy Hush.

J. Fr'ancis Cooper, M.S.A., Editor 3
Clyde Beale, A.B.J., Associate Editor
William G. Mitchell, A.B.J., Assistant Editor
Samuel L. Burgess, A.B.J., Assistant Editor a

A. N. Tissot, Ph.D., Entomologist
L. C. Kuitert, Ph.D., Associate
H. E. Bratley, M.S.A., Assistant
F. A. Robinson, M.S., Asst. Apiculturist
R. E. Waites, Ph.D., Asst. Entomologist
S. H. Kerr, Ph.D., Asst. Entomologist

Ouida D. Abbott, Ph.D., Home Econ.1
R. B. French, Ph.D., Biochemist

G. H. Blackmon, M.S.A., Horticulturist 1
R. A. Dennison, Ph.D., Hort. & Interim Head .
F. S. Jamison, Ph.D., Horticulturist3
Albert P. Lorz, Ph.D., Horticulturist
R. K. Showalter, M.S., Asso. Hort.
R. II. Sharpe, M.S., Asso. Horticulturist
V. F. Nettles, Ph.D., Asso. Horticulturist
F. S. Lagasse, Ph.D., Horticulturist2
R. D. Dickey, M.S.A., Asso. Hort.
L. H. Halsey, M.S.A., Asst. Hort.
C. B. Hall, Ph.D., Asst. Horticulturist
Austin Griffiths, Jr., B.S., Asst. Hort.
S. E. McFadden, Jr., Ph.D., Asst. Hort.
C. H. VanMiddelem, Ph.D., Asst. Biochemist
Buford D. Thompson, M.S.A., Asst. Hort.
M. W. Hoover, M.S.A., Asst. Hort.

Ida Keeling Cresap, Librarian
W. B. Tisdale, Ph.D.. Plant Pathologist'
Phares Decker, Ph.D., Plant Pathologist
Erdman West, M.S., Botanist & Mycologist'
Robert W. Earhart, Ph.D., Plant Path.2
Howard N. Miller, Ph.D., Asso. Plant Path.
Lillian E. Arnold, M.S., Asso. Botanist
C. W. Anderson, Ph.D., Asst. Plant Path.

N. R. Mehrbof, M.Agr., Poultry Hush.' 3
J. C. Driggers, Ph.D., Asso. Poultry Husb.s
F. B. Smith, Ph.D., Microbiologist'
Gaylord M. Volk, Ph.D., Soils Chemist
J. R. Neller, Ph.D., Soils Chemist
Nathan Gammon, Jr., Ph.D., Soils Chemist
Ralph G. Leighty, B.S., Asst. Soil Surveyor
G. D. Thornton, Ph.D., Microbiologist s
C. F. Eno, Ph.D., Asst. Soils Microbiologist
H. W. Winsor, B.S.A., Assistant Chemist
R. E. Caldwell, M.S.A., Asst. Chemist34
V. W. Carlisle, B.S., Asst. Soil Surveyor
J. H. Walker, M.S.A., Asst. Soil Surveyor
William K. Robertson, Ph.D., Asst. Chemist
0. E. Cruz, B.S.A., Asst. Soil Surveyor
W. G. Blue, Ph.D., Asst. Biochemist
J. G. A. Fiskel, Ph.D., Asst. Biochemists
L. C. Hammond, Ph.D., Asst. Soil Physicists
H. L. Breland, Ph.D., Asst. Soils Chem.
W. L. Pritchett, Ph.D., Soil Technologist

D. A. Sanders, D.V.M., Veterinarian's
M. W. Emmel, D.V.M., Veterinarian 3
C. F. Simpson, D.V.M., Asso. Veterinarian
L. E. Swanson, D.V.M., Parasitologist
W. R. Dennis, D.V.M., Asst. Parasitologist
E. W. Swarthout, D.V.M., Asso. Poultry
Pathologist (Dade City)

W. C. Rhoades, M.S., Entomologist in Charge
R. R. Kincaid, Ph.D., Plant Pathologist
L. G. Thompson, Jr., Ph.D., Soils Chemist
W. H. Chapman, M.S., Agronomist
Frank S. Baker, Jr., B.S., Asst. An. Husb.
Frank E. Guthrie, Ph.D., Asst. Entomologist
Mobile Unit, Monticello
R. W. Wallace, B.S., Associate Agronomist
Mobile Unit, Marianna
R. W. Lipscomb, M.S., Associate Agronomist
Mobile Unit, Pensacola
R. L. Smith, M.S., Associate Agronomist
Mobile Unit, Chipley
J. B. White, B.S.A., Associate Agronomist

A. F. Camp, Ph.D., Vice-Director in Charge
W. L. Thompson, B.S., Entomologist
R. F. Suit, Ph.D., Plant Pathologist
E. P. Ducharme, Ph.D., Asso. Plant Path.
C. R. Stearns, Jr., B.S.A., Asso. Chemist
J. W. Sites, Ph.D., Horticulturist
H. O. Sterling, B.S., Asst. Horticulturist
H. J. Reitz, Ph.D., Horticulturist
Francine Fisher, M.S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
J. W. Kesterson, M.S., Asso. Chemist
R. Hendrickson, B.S., Asst. Chemist
Ivan Stewart, Ph.D., Asst. Biochemist
D. S. Prosser, Jr., B.S., Asst. Engineer
R. W. Olsen, B.S., Biochemist
F. W .Wenzel, Jr., Ph.D., Chemist
Alvin H. Rouse, M.S., Asso. Chemist
H. W. Ford, Ph.D., Asst. Horticulturist
L. C. Knorr, Ph.D., Asso. Histologist'
R. M. Pratt, Ph.D., Asso. Ent.-Pathologist
W. A. Simanton, Ph.D., Entomologist
E. J. Deszyck, Ph.D., Asso. Horticulturist
C. D. Leonard, Ph.D., Asso. Horticulturist
W. T. Long, M.S., Asst. Horticulturist
M. H. Muma, Ph.D., Asso. Entomologist
F. J. Reynolds, Ph.D., Asso. Hort.
W. F. Spencer, Ph.D., Asst. Chem.
R. B. Johnson, Ph.D., Asst. Entomologist
W. F. Newhall, Ph.D., Asst. Biochemist
W. F. Grierson-Jackson, Ph.D., Asst. Chem.
Roger Patrick, Ph.D., Bacteriologist
Marion F. Oberbacher, Ph.D., Asst. Plant
Evert J. Elvin, B.S., Asst. Horticulturist
R. C. J. Koo, Ph.D., Asst. Biochemist
J. R. Kuykendall, Ph.D., Asst. Horticulturist

W. T. Forsee, Jr., Ph.D., Chemist in Charge
R. V. Allison, Ph.D., Fiber Technologist
Thomas Bregger, Ph.D., Physiologist
J. W. Randolph, M.S., Agricultural Engr.
R. W. Kidder, M.S.. Asso. Animal Hush.
C. C. Seale, Associate Agronomist
N. C. Hayslip, B.S.A. Asso. Entomologist
E. A. Wolf, M.S., Asst. Horticulturist
W. H. Thames, M.S., Asst. Entomologist
W. G. Genung, M.S., Asst. Entomologist
Robert J. Allen, Ph.D., Asst. Agronomist
V. E. Green, Ph.D., Asst. Agronomist
J. F. Darby, Ph.D., Asst. Plant Path.
V. L. Guzman, Ph.D., Asst. Hort.
J. C. Stephens, B.S., Drainage Engineer2
A. E. Kretschmer, Jr., Ph.D., Asst. Soils
Charles T. Ozaki, Ph.D., Asst. Chemist
Thomas L. Meade, Ph.D., Asst. An. Nutri.
D. S. Harrison, M.S., Asst. Agri. Engr.

F. T. Boyd, Ph.D., Asso. Agronomist
M. G. Hamilton, Ph.D., Asst. Horticulturist
J. N. Simons, Ph.D., Asst. Virologist
D. W. Beardsley, M.S., Asst. Animal Husb.

Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
D. O. Wolfenbarger, Ph.D., Entomologist
Francis B. Lincoln, Ph.D., Horticulturist
Robert A. Conover, Ph.D., Plant Path.
John L. Malcolm, Ph.D., Asso. Soils Chemist
R. W. Harkness, Ph.D., Asst. Chemist
R. Bruce Ledin, Ph.D., Asst. Hort.
J. C. Noonan, M.S., Asst. Hort.
M. H. Gallatin, B.S., Soil Conservationist

Marian W. Hazen, M.S., Animal Husband-
man in Charge 2

W. Kirk, Ph.D., Vice-Director in Charge
E. M. Hodges, Ph.D., Agronomist
D. W. Jones, M.S., Asst. Soil Technologist
R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
J. W. Wilson, ScD., Entomologist
P. J. Westgate, Ph.D., Asso. Hort.
Ben F. Whitner, Jr., B.S.A., Asst. Hort.
Geo. Swank, Jr., Ph.D., Asst. Plant Path.
C. E. Hutton, Ph.D., Vice-Director in Charge
H. W. Lundy, B.S.A., Associate Agronomist
G. E. Ritchey, M.S., Agronomist in Charge
E. L. Spencer, Ph.D., Soils Chemist in Charge
E. G. Kelsheimer, Ph.D., Entomologist
David G. A. Kelbert, Asso. Horticulturist
Robert 0. Magie, Ph.D., Plant Pathologist
J. M. Walter, Ph.D., Plant Pathologist
S. S. Woltz, Ph.D., Asst. Horticulturist
Donald S. Burgis, M.S.A., Asst. Hort.
C. M. Geraldson, Ph.D., Asst. Horticulturist


Watermelon, Grape, Pasture-Leeshurg
J. M. Crall, Ph.D., Asso. Plant Path. in Chg.
C. C. Helms, Jr., B.S., Asst. Agronomist
L. H. Stover, Assistant in Horticulture
Strawberry-Plant City
A. N. Brooks, Ph.D., Plant Pathologist
A. H. Eddins, Ph.D., Plant Path. in Charge
E. N. McCubbin, Ph.D., Horticulturist
T. M. Dobrovsky, Ph.D., Asst. Entomologist
A. M. Phillips, B.S., Asso. Entomologist
John R. Large, M.S., Asso. Plant Path.
Frost Forecasting-Lakeland
Warren O. Johnson, B.S., Meteorologist in
1 Head of Department
2 In cooperation with U. S.
Cooperative, other divisions, U. of F.
On leave



INTRODUCTION ........... .......... .- ......... ......... ... ........... ... .. ------- ..-- 5

VARIETIES .--.... ...-....... .. ----....... --...... ----.. .- -- -. --- ----------.........------ 5

CORM STOCkS FOR FLORIDA GROWING ...........-.....--....--.-....--......-- ..-- 6

SELECTION OF LAND .................... .... --- .......--.....---.... -----..------ 7

PREPARATION OF LAND ......--........----- --......... -- ---- -.......------------ 8

PLANTING THE CORMLETS .-------......... ------- ---- --.........-------.------- 9

PLANTING THE CORMS .............. .---.......---.........-------- -- ------------. 10

FERTILIZING PRACTICES ....................-...---......-............ .- -- .... ----12

MINOR ELEMENT DEFICIENCIES ......... ------..... -- -----.. ..........------------- 15

CULTIVATION .... ......... .........---- ................ .-..-.--.-----..... 20

DRAINAGE AND IRRIGATION ...-....................--........... ------ ------------ 21

HARVESTING FLOWERS AND CORMS ................. ......... ----------------. 23

CURING AND STORAGE OF CORMS ---............. ... ---- ..... ......------------- 29

INSECT PESTS ............--- .............. ....... ......- ....--- ...........---- ..- ..--- 31

LEAF AND FLOWER DISEASES ....--.................-..--.- .......---.---...... 34

Curvularia ..----......... ..................--- ....----....-....- ------. 34

Botrytis ........... ................. ............... .......... ...... ......... 37

Stemphylium Leaf Spot ....--......-........------- ......----- -....--.----.. 41

SPRAY PROGRAMS .... ............ ........- ..-......----- .........-- -- ........-------- 42

CORM DISEASES .....--.....-- ....... ...... ................--.... ----.....- ....---. 47

Bacterial Scab .......--....-.--.--.. ...................-...------- --- .......-- --- 47

Fusarium Disease ......---.---- .............--.--------...----.. 48

Control of Fusarium Disease -................ ----- -......----........ 50

NECK ROTS -..... ---...................-......---.-.. .........-- .- --...... ... 56

MISCELLANEOUS DISEASES AND INJURIES ........ ................ ................... 57

DISEASES ...........-----------........--------- ....-----.-- 63

N EMATODES ..................... ......-----. ........ .. ............... 66

ACKNOWLEDGMENTS ............. -----------......................... ----............ 67

Gladiolus Production in Florida

Since 1925 gladiolus cut-flower plantings in Florida have ex-
panded from a few acres to over 8,000. About 90 percent of
the acreage is now located in the relatively frost-free areas of
Lee, Charlotte, Manatee, Hillsborough, St. Lucie, Indian River,
Brevard and Palm Beach counties. Commercial plantings are
made in about 12 other counties, the largest being located near
Clearwater, Hastings, Sanford and Marianna.
It is estimated that about 15 million dozen flower spikes are
shipped from Florida each year to points all over the United
States. The flowers are shipped by railway express, refrigerated
trucks and air express.
Due to the differences in soil and climate, gladiolus produc-
tion problems in Florida differ from those in other sections of
the United States. For instance, experience has shown that
experimental results obtained in studies on fertility and disease
control in other areas often do not apply to conditions in Florida.
Gladiolus are propagated vegetatively. The gladiolus corm,
or "bulb" as it is commonly called, is an enlarged underground
storage stem with a husk of dried leaf bases. In the axil of each
leaf is a bud which is capable of producing a shoot. Normally,
only one, two or three of the topmost buds develop. Each bud
that grows usually produces a flower spike and new corm. Glad-
iolus are also propagated from cormlets or bulbletss", which
develop near the base of the newly developing corm. Cormlets
are planted for rapid increase of a variety. Two years generally
are required to develop flowering-sized corms from cormlets.

Only a few of the hundreds of commercial gladiolus varieties
are suitable for cut-flower production in Florida. The relatively
short day lengths of the winter growing season cause many
varieties to have shorter flower spikes and stems and fewer
florets per spike than the same varieties in Northern States.
Flower spikes destined for Northern markets must be cut in
1 Pathologist and former assistant horticulturist, Gulf Coast Experi-
ment Station.

Gladiolus Production in Florida

Since 1925 gladiolus cut-flower plantings in Florida have ex-
panded from a few acres to over 8,000. About 90 percent of
the acreage is now located in the relatively frost-free areas of
Lee, Charlotte, Manatee, Hillsborough, St. Lucie, Indian River,
Brevard and Palm Beach counties. Commercial plantings are
made in about 12 other counties, the largest being located near
Clearwater, Hastings, Sanford and Marianna.
It is estimated that about 15 million dozen flower spikes are
shipped from Florida each year to points all over the United
States. The flowers are shipped by railway express, refrigerated
trucks and air express.
Due to the differences in soil and climate, gladiolus produc-
tion problems in Florida differ from those in other sections of
the United States. For instance, experience has shown that
experimental results obtained in studies on fertility and disease
control in other areas often do not apply to conditions in Florida.
Gladiolus are propagated vegetatively. The gladiolus corm,
or "bulb" as it is commonly called, is an enlarged underground
storage stem with a husk of dried leaf bases. In the axil of each
leaf is a bud which is capable of producing a shoot. Normally,
only one, two or three of the topmost buds develop. Each bud
that grows usually produces a flower spike and new corm. Glad-
iolus are also propagated from cormlets or bulbletss", which
develop near the base of the newly developing corm. Cormlets
are planted for rapid increase of a variety. Two years generally
are required to develop flowering-sized corms from cormlets.

Only a few of the hundreds of commercial gladiolus varieties
are suitable for cut-flower production in Florida. The relatively
short day lengths of the winter growing season cause many
varieties to have shorter flower spikes and stems and fewer
florets per spike than the same varieties in Northern States.
Flower spikes destined for Northern markets must be cut in
1 Pathologist and former assistant horticulturist, Gulf Coast Experi-
ment Station.

Florida Agricultural Experiment Stations

relatively tight bud, as they may be in transit for three or four
days. Many varieties when cut in this manner either do not
open properly or fail to develop satisfactory size and color.
The varieties now grown successfully on a commercial scale
are listed below under each color class in the approximate order
of their suitability for shipping to distant markets. Those in
black type often show severe corm rot caused by fusarium dis-
ease which is described on pages 48 to 50 of this bulletin.
White and Creamy White.-Leading Lady, Morning Kiss,
June Bells, Snow Princess, Margaret Beaton (red throat).
Cream.-Wanda, Lady Jane, and White Gold.
Yellow.-Spotlight, Hopmans Glory, and Nugget.
Salmon Pink.-Picardy and Margaret Fulton.
Scarlet.-Valeria and New Europe.
Pink and Light Rose.-Evangeline, Spic and Span, Phantom
Beauty, President Truman, Rosa van Lima, Ethel C. Cole, and
Red.-Dr. F. E. Bennet.
Violet Red.-Modern Times.
Lavender.-Elizabeth the Queen and Lavender Prince.
Purple.-Purple Supreme and Paul Rubens.
Other Colors.-Corona (cream with rose edge).
In variety tests at Bradenton the following varieties appear
worthy of limited commercial trial in Florida: Carrara and White
Standard (white); Prof. Goudriaan (cream-white); Gold (yel-
low); October Sunshine (orange yellow); Benares and Lipstick
(pink); Gwen (rose); Benjamin Britten and Col. Atkinson

Florida growers purchase corms from many different sources.
The major source has been bulb growers in the Northern States,
but in the past few years foreign sources have become increas-
ingly important. One difficulty with these corms for Florida
production is that they are not ready to plant until January or
later. There are thus insufficient corms available for early fall
planting. There is a definite need for corm production in south-
ern areas to enable Florida growers to purchase stocks for fall
plantings. Corms for early plantings are in such great demand
that old, diseased stocks no longer suitable for flower produc-

Commercial Gladiolus Production in Florida

tion are often purchased by some growers from other flower
growers who have discarded them. Likewise, some corm stocks
purchased from bulb growers are heavily infected with the fu-
sarium fungus and are not suitable for planting in Florida. Any
corm source or stock should be carefully checked for incidence
of disease prior to purchase. It is not advisable to buy cheap
corms or old stocks for flower production.
Extra corms needed for early fall planting should be grown
in the South from planting stock planted before January 15 in
soil not previously planted to gladiolus. Old corm stocks should
be replaced by new stocks when the rotting of corms or reduc-
tion of flower quality becomes serious. Growers find it profitable
to grow or purchase some new corm stocks each year so that
old stocks can be replaced every third, fourth or fifth year,
according to the variety.
Corms with brown or black root traces or with discolored
vascular tissue are generally unsuitable for flower production.
To inspect corms for discolored vascular tissue, shave thin slices
off the root base. Stocks with more than 5 percent of the corms
rotted or visibly infected with Fusarium at planting time should
be rejected as unfit for flower production. Although corms may
appear sound on receipt, holding them under a shed for three
or four weeks before planting will often show up the fusarium
Only the healthiest corm stocks should be used for propaga-
tion. The diseases most difficult to control are carried in the
cormlets. It is poor economy to plant cormlets from any dis-
eased stock.
Gladiolus corms are graded according to size for selling and
planting purposes as follows:
Jumbo-over 2 inches in diameter
No. 1-1/2 to 2 inches
No. 2--11 to 1% inches
No. 3-1 to 11/ inches
No. 4-- to 1 inch
No. 5-- to 34 inch
No. 6-%- to % inch
Corms smaller than No. 2 are seldom planted in Florida for
flower production.

The major portion of the acreage devoted to winter gladiolus
growing is located in relatively frost-free areas on sandy soils.
The loamy or dark sands are preferred. Marl and heavier clay

Florida Agricultural Experiment Stations

soils should be avoided. Fields selected for gladiolus culture
should be well-drained; an adequate supply of water for irriga-
tion should be available when needed; and salty wells should
be avoided. Protection against all except perhaps the heaviest
rains can be secured by using enough water furrows, ditches,
tiles, and canals to remove water rapidly from the fields. Pumps
may be needed to remove water from low-lying fields. Tiles
are perferred for drainage and irrigation in the Bradenton and
Fort Myers areas so that all of the tillable land in fields can be
planted. In North Florida, particularly in the Hastings area,
fields are drained and irrigated by means of ditches and water
Areas with good frost protection are most desirable for mid-
winter flower production. Although gladiolus leaves may tol-
erate two to three degrees below freezing, a light frost may kill
the developing flower buds which are very susceptible to cold
damage while still inside the protecting leaf sheaths or stalk.

Once land has been cleared and leveled and adequate water
control established, the soil should be adjusted to a reaction
ranging between pH 5.8 and 6.5.2 For this purpose dolomitic
limestone is probably the best material to use because of its
magnesium content. If high-calcium limestone is used, mag-
nesium should be included in the fertilizer. It is also beneficial
on newly cleared mineral soils of the east and Gulf coasts to
add superphosphate at the rate of 800 to 1,000 pounds per acre
and copper sulfate or "bluestone" at the rate of 40 to 50 pounds
to the acre a month prior to planting. The phosphate and
copper sulfate can be mixed and applied in one broadcast ap-
plication. This application of copper often has been found neces-
sary on newly cleared land in the Bradenton-Fort Myers area
because the relatively high content of organic matter tempo-
rarily decreases the availability of the copper. After the land
has been cultivated for a season the organic matter content
decreases markedly, and the usual amounts of copper added in
the fertilizer are sufficient.
On land that has been used previously for gladiolus or other
crops a cover crop such as Crotalaria spectabilis, sesbania or
hairy indigo is recommended. Enough limestone to maintain
2 For information on amounts of liming materials needed to adjust soil
pH, refer to Fla. Agr. Exp. Sta. Circ. S-39.

Commercial Gladiolus Production in Florida

the desired pH is applied before planting the cover crop. The
use of a cover crop will improve the physical condition, aeration,
drainage and water-holding capacity of the soil. Also, some
plant nutrients are supplied by the decomposing cover crop.
Where seep ditches or sub-tiling is used it is very important
to smooth or level the land before planting.
For maximum production of large spikes some varieties need
a soil pH, above 6.5 to 7, an abundant supply of calcium and
plenty of water. Observations indicate that Snow Princess,
Elizabeth the Queen and probably other varieties produce longer
spikes and better flowers when grown under these conditions.

Since cormlets or bulbletss" grow well in Florida, many grow-
'rs plant them to increase their corm stocks. Cormlets often
fail to germinate because they are dormant or because the husks
are not easily softened by water. Valeria is one of the varieties
in which cormlets are difficult to germinate. Germination is
improved by holding cormlets in cold storage for 12 to 18
months and by keeping them wet for several days before plant-
ing. Do not soak in stagnant water. Frequent sprinkling of
the cormlets in shallow trays is better than prolonged soaking.
Cormlets should not be planted until some of them begin to
germinate. Do not delay planting beyond the first signs of
germination and do not allow the cormlets to dry out between
sprinklings. They should be stirred every other day in order
to detect the first signs of germination.
New land is usually used for cormlets because of its relative
freedom from weed growth. If new land is unavailable, cormlets
should be grown on land that is not contaminated as a result of
a recent crop of gladiolus. From four to six bushels of corm-
lets commonly are planted per acre, or 20 to 40 cormlets per
foot of row. A wide furrow is often used so that the cormlets
are less crowded. Cormlets are planted 11/2 to 2 inches deep.
Level culture is used where possible. To get good germination
and a production of large-sized corms, it is necessary to keep
the soil continuously moist with a minimum of drying out be-
tween irrigations and to apply fertilizer frequently in doses of
about 300 pounds per acre.
The control of weeds is a serious problem in growing corm-
lets because the crop is in the ground about six months and the
plants are too weak to withstand hilling up with soil to cover

Florida Agricultural Experiment Stations

weeds in the row. At present no weed killers can be recom-
mended for general use, because experiments have been limited
to a few fields and few varieties. A grower who wishes to try
an herbicide on gladiolus should limit his experiments to small
plots for two or three years.

Growers in south Florida plant weekly over a period of
five to six months-from September to February. Corms are
ready to plant when the root swellings begin to show. If
root "buds" are not visible when the corms are removed from
cold storage hold the corms in a shed with good ventilation
until the swellings develop. Smaller corms are slower in de-
veloping root buds and generally need to be held a week or
two in a warm place before they are ready to plant. Planting
should not be delayed beyond the initial stages of root forma-
tion. Corms received from other regions, especially those
shipped in tight containers, frequently show excessive root
development. When the roots have grown beyond the bud stage
plant the corms as soon as possible.
Growers usually obtain Northern-grown fall-harvested corms
for growing part of their spring flower crop. Generally, such
corms are ready to plant early in January, seldom before the
middle of December. Treatment with ethylene chlorhydrin to
break dormancy for earlier planting is not recommended because
the flower yield may be reduced by this treatment. These fall-
harvested corms should be shipped about two weeks after they
are cleaned, and upon receipt should be placed in cold storage
until a week or two before planting time. If shipment is de-
layed until late December, excessive rooting is often encountered
unless packages are ventilated and shipped under dry, cool con-
At time of planting the soil should be moist but not wet.
Furrows are opened just ahead of planting and the corms cov-
ered as soon as possible. In well-drained soils, large corms are
planted in furrows made three or four inches deep. In heavy
soils and in fields where drainage is slow after rains plant corms
about one inch deep and hill or bed the soil to cover them. High
beds are especially suitable for the fall crop and on land with
inadequate drainage.
The corms are strewn in the furrows and all but the smaller
corms are planted upright and spaced by hand (Fig. 2). Some

Commercial Gladiolus Production in Florida

hand labor can be saved by distributing corms from a tractor-
drawn wagon carrying a large bin (Fig. 3). Outlets at the base
of the bin are spaced to scatter the corms in two rows at a time.
The flow of corms is controlled by workers who sit behind the
bin. After spacing by hand, the corms are usually covered and
fertilized in one operation, as shown in Figure 4.
About three flowering-sized corms are planted per foot of row.
The space between corms should be at least one and one-half
inches or the width of two fingers. With large corms that are
not to be pruned to one shoot, the distance between corms could
be three to four inches. Depending on the size of corm and on
row spacing, the number of flowering-sized corms planted per
acre varies from 35,000 to 60,000, with an average of about
The distance between rows is usually three to three and one-
half feet, or the distance required to accommodate the mecha-
nized equipment. A distance of three and one-half or four feet
is desirable where very high beds are used. Planting two rows
of corms in a wide bed is preferred by some growers. The dis-
tance from the center of a double-row bed to the center of the
next is about six feet. The distance between the two rows in
the bed is about two feet. The direction of rows should be such

Fig. 2.-Gladiolus corms being planted upright and spaced after distribution
in furrows by tractor-drawn hopper.

Florida Agricultural Experiment Stations

that surface water can drain away without standing in any part
of the planting.
Some varieties tend to "split" excessively, or to produce sev-
eral plants from each corm. These may be pruned to one or
two shoots per corm in order to produce a better grade of spike.
The pruning is done when the shoots are three or four inches
above the soil. If the pruning is done carelessly or delayed beyond
the second week of growth the plants may be seriously stunted
as a result of root injury. The shoot must be broken off at its
base to prevent further growth. The shoot is removed by
pressing it to the side and downward against the soil with a
finger thrust down to within one or two inches of the corm.
The soil is held firmly over the corm with the other hand so
that the roots are not disturbed.

The sandy soils of Florida suitable for the production of glad-
iolus are low in native fertility. Not only are these soils low
in nitrogen, phosphorus and potassium, but they are often de-
ficient in one or more of such minor elements as boron, manga-
nese, iron, copper and zinc. Thus, the production of gladiolus in

Fig. 3.-Distributing corms from bins into two rows at a time.

Commercial Gladiolus Production in Florida 13

Florida is dependent upon the use of commercial fertilizers, even
though a heavy cover crop has been turned into the soil.
In general, a fertilizer with a 1-2-2 or 1-2-3 ratio is recom-
mended for gladiolus. Examples of such fertilizers commonly
used are the 4-8-8 and 4-8-12 formulas. These mixtures can be
altered to suit local conditions.
The sources of nutrient elements that are used in fertilizers
for gladiolus should be considered carefully. Organic nitrogen
sources should be used and should constitute from 25 to 50 per-
cent of the nitrogen in the fertilizer. For early fall and late
spring crops the higher organic nitrogen content is more suit-
able, while for mid-winter production less organic nitrogen may
be used. The remainder of the nitrogen should be predominantly

Fig. 4.-Covering corms and fertilizing in bands in one operation
of tractor.

Florida Agricultural Experiment Stations

from nitrate-nitrogen sources, with a low percentage of am-
moniacal nitrogen.
Muriate of potash should not be the sole source of potash
if there is an appreciable quantity of soluble salts in the irriga-
tion water. If the irrigation water does not contain excessive
quantities of chlorides, half of the potash may be derived from
muriate of potash. The phosphate source commonly used is
superphosphate, although ground rock phosphate is being used
in some areas.
The amount of fertilizer to be applied per acre depends to a
large extent upon the amount of rainfall during the growing
period. If no leaching rains exceeding 11/2 inches occur, a total
of 1,500 to 2,000 pounds of fertilizer is required per acre of
flowering stock to produce a good crop on some sandy soils.
After leaching rains use extra fertilizer to compensate for the
loss. The first application of fertilizer is made either prior to
or at planting time. The best method is to broadcast on each
acre 400 to 800 pounds before making the planting bed. In
forming the bed with disks, the fertilizer is mixed into the bed.
Where high beds are not used distribute the fertilizer in one or
two broad bands over the row so that, in the process of making
the furrow and covering the corms, the fertilizer will be dis-
tributed in the bed. The remainder of the fertilizer is applied
in small doses, starting two or three weeks after planting, and
using 300 to 400 pounds per acre per application every two
weeks. Thus, three or four applications of fertilizer will be
made after planting. Research has shown that frequent and
small applications as suggested result in improved quality as
compared to larger applications made less frequently during the
growing period. It was also found that while the spike is elongat-
ing rapidly, beginning about two weeks prior to cutting, the
gladiolus utilizes large quantities of potash. To furnish this
potash, 150 to 250 pounds of a potash salt is applied at the time
the spike first shows above the leaves. Potash side-dressings
are most useful in the late winter and early spring to avoid
the soft spikes that may develop with the onset of warm weather.
Varieties such as Snow Princess that tend to split excessively
respond with better flower production when more fertilizer is
used than that suggested for the average variety. Corms smaller
than No. 2 and cormlets benefit from fertilizer rates higher than
those suggested for flowering stock. Increases in bulb size can
be expected when as much as 3,000 to 3,500 pounds of fertilizer

Commercial Gladiolus Production in Florida

are used on cormlets and planting stocks. Individual applica-
tions should be small and renewed frequently during the grow-
ing period. A light application of fertilizer after the spikes are
cut increases the size and weight of the corms in flowering
The method of application of fertilizer is as important as the
kind and amount of fertilizer used. Common practice has been
to bar off and side-dress in bands. This method of application
can damage the root system in two ways: first, by cutting the
roots and, secondly, by burning new roots in the area imme-
diately surrounding the fertilizer through the action of high
salt concentration. To reduce this root injury broadcast the
fertilizer on the bed and sweep it into the soil. The success of
this method of fertilization depends upon adequate soil moisture,
but it has been found to be practical and beneficial on tiled land
and should be just as successful on land that is irrigated by
seep ditches.
"Feeding" gladiolus by way of the leaves is sometimes help-
ful. During prolonged cold weather the plants usually respond
favorably to sprays containing about 5 pounds per 100 gallons
of a soluble nitrogen fertilizer such as ammonium nitrate, urea
and nitrate of potash. During prolonged water-logging of the
soil and for several days thereafter apply nutrient sprays con-
taining the major and minor elements weekly. At such times,
when root growth is largely restricted to the upper three or
four inches of soil, applications of dry fertilizers or soil condi-
tioners to the soil often cause root injury and severe leaf burning.
A nutrient spray is most conveniently made with a completely
soluble fertilizer, several of which are on the market. Use a
concentration suggested by the manufacturer, or about 5 pounds
per 100 gallons.

Gladiolus require minor or trace elements for optimum flower
production. Unlike small-seeded crops, gladiolus corms produced
in areas where minor elements are not deficient will usually con-
tain enough of these elements to produce a good crop on land
that is deficient in one or more of them. Symptoms of minor
element deficiencies usually are not evident until the second
consecutive year of growth in a deficient soil.
When symptoms of a deficiency appear, prompt use of a nutri-
tional spray usually is helpful. Remedial steps should always

Florida Agricultural Experiment Stations

be taken to insure that a sufficient amount of the deficient ele-
ment is added to benefit the developing corm. Even though the
deficient elements are supplied promptly and adequately, flower
quality usually is impaired where the deficiency has progressed
far enough to show as symptoms. Minor element deficiencies
in the crop usually can be avoided by adding to the fertilizer
the elements in which the soil is deficient.
The value of the gladiolus crop per acre is considered to be
high enough to justify the expense of including minor elements
in most fertilizer applications in order to avoid any possible re-
duction in quality or quantity of crop yield because of soil de-
ficiency. However, manganese, copper and zinc used for 10 to
20 years or more in spray or fertilizer mixtures may accumulate
in the soil and build up to toxic levels. Also, an excess of one
element in the soil can cause deficiency symptoms of another
element to appear in the plants. It is known that some virgin
soils in Florida contain enough of certain minor elements. It is
also true that toxic levels of copper have already been reached
in some old fields. Therefore, no blanket recommendation can
be made for using minor elements in gladiolus culture.
For the first three or four years on newly-cleared sandy soils
the following minor elements may be included in gladiolus fer-
tilizers: magnesium as MgO, 2 percent; copper as CuO, 0.2 per-
cent; manganese as MnO, 0.4 percent; zinc, 0.1 percent; and boron
as B203, 0.1 to 0.2 percent. The zinc is omitted where zinc fungi-
cides are used and the magnesium is omitted where dolomitic
limestone is used before every crop season. Two years' results
with molybdenum on experimental plantings showed no increase
in flower or corm production by adding this element.
Manganese deficiency has been identified only on marl or alka-
line soils. Affected plants have greenish-yellow leaves with
veins that tend to remain green. For gladiolus on these soils
the fertilizer should contain 0.5 to 1.0 percent manganese as MnO.
Iron deficiency has been identified only on land where vege-
tables were sprayed with copper fungicides over a period of many
years. Iron deficiency appears to be correlated with high copper
residues in the soil. Other crop plants were apparently not
affected by the copper residues in many of these fields.
The younger leaves of iron-deficient plants are greenish-yellow
with veins that tend to remain green, but in severe cases the
green color may be entirely absent from the veins as well as the
interveinal areas of the youngest leaves and from the flower

-; '

Fig. 5.-The wilted-leaf symptoms of copper deficiency in the Valeria
variety resulting from growing corms in a new piece of land for two years
in succession. The normal plant (left) grew from corm produced in another

Florida Agricultural Experiment Stations

spike. Iron deficiency can be avoided or cured by spraying the
plants with an acidified solution of iron sulfate or by applying
chelated iron to the soil in amounts recommended by the manu-
facturer. Use 11/2 pounds ferrous sulfate and about 1/2 cup of
muriatic acid per 100 gallons of water with spreader added. A
pH of 5 to 5.5 will keep the iron sulfate in solution. Several
applications may be necessary to cure the deficiency.
Copper deficiency has been found only in gladiolus plants grown
two years in succession on newly or recently cleared land. As
shown in Figures 5 and 6, stems and leaves may be somewhat
stunted and very weak. Leaf color is not affected. In mild cases
the only symptoms may be leaves that droop abnormally for the
variety or spikes that are soft and limber. In severe cases of
copper deficiency the leaves droop markedly and the flower spikes
are too soft to be marketable.
Copper deficiency is avoided by broadcasting and disking into
the soil about 45 pounds of copper sulfate per acre of new land
before planting gladiolus. Use more copper sulfate on muck
soils and less on white sands. One treatment is sufficient for

Fig. 6.-Copper-deficient Valeria plants (left) are produced from corms
growing in the same field the previous year. Normal plants (right) are
from out-of-state corms.
", I W0 "NEW

Commercial Gladiolus Production in Florida

sandy soils. There is a
danger of applying too
much copper. Moderate
amounts carried in mixed
fertilizers have been suf-
ficient after the broad-
cast application.
Zinc and magnesium
deficiencies have not
been identified in the
field culture of gladiolus.
Boron deficiency
causes young leaves to
be stunted, thickened
and brittle. The leaf edge
is often thin, colorless
and cracked, as in Figure
7. Cracks may develop
in the flower stem. Boron
deficiency usually is
avoided by using 0.1 to
0.2 percent boron as
B203 in all applications of
mixed fertilizer, includ-
ing an application after
flower harvest. Where
less than 1,500 pounds
of fertilizer is used per
acre the percentage of
B203 may be raised to as
much as 0.3. Boron de-
ficiency symptoms appar-
ently are corrected by
spraying every 10 to 14
days until flowering with

Fig. 7.-Valeria leaves
are stunted and distorted by
boron deficiency and show the
typical cracking of the thick,
brittle leaves and the thin,
colorless leaf edge. The pale
streaks and spots in leaf are
infrequently associated with
boron deficiency.

Florida Agricultural Experiment Stations

1 pound borax in 100 gallons of water, adding the borax to the
fungicidal spray mixture for convenience.
Too much boron causes a severe leaf burn. In northern Flor-
ida and other areas where the soils contain enough boron for
other crops, it is suggested that boron be omitted from the fer-
tilizer or that the minimum amount be used.

The purpose of cultivating the soil is two-fold: to break up
and aerate the soil when it becomes waterlogged by rain and
packed by the wheels of heavy equipment and to kill weeds. The
soil can be cultivated without breaking gladiolus roots by using
proper methods and equipment. When glads are grown on
raised beds it is necessary to sweep the soil to the rows to
keep the beds built up after rains erode them. By building up
the bed gradually it is possible to cover-up and kill the small
weeds in the row. Some growers cover the corms about six
inches at planting time, then scrape off about two inches just
before the shoots emerge in order to kill the first crop of weeds.
At one- to two-week intervals, as the weed growth develops,
the soil may be alternately swept to the plants and then scraped
away, with the tools going only one-half to one inch deep. The
corms should be covered four to five inches by the time the
spikes slip. A neck rot may develop if leaves are injured or
if wet soil is pushed against the plants in warm weather. Gen-
erally, no cultivating is done from the time the spikes slip until
they are cut out because heavy spikes are titled if the soil is
loose. However, shallow cultivations may be made to control
weeds during this period if necessary. Deeper cultivations to con-
trol weeds should be made after flower harvest, care being taken
not to cover gladiolus leaves lying on the soil.
Gladiolus should be cultivated as soon as possible after heavy
rains to facilitate aeration of the soil. If water is allowed to
stand in the fields, or if the soil surface is not broken, poor
aeration may result in severe injury to the roots, curtailing
both corm and flower production. Very young plants from
large corms are most susceptible to injury from wet soils. The
soil should be barred off deeply on either side of the row as soon
as possible after heavy rains, care being taken to avoid cutting
roots. Such deep cultivation is not recommended for older

Commercial Gladiolus Production in Florida

Water control is probably the most important factor in pro-
ducing high quality flowers. High quality cannot be obtained
if soil moisture fluctuates widely. Irrigation during the grow-
ing season is necessary, and rapid removal of excess moisture
from heavy rains is usually necessary at some time during the
crop season.
There are three methods of irrigation commonly used for glad-
iolus production in Florida: seep or sub-irrigation, surface or
flood irrigation by running water down the rows, and overhead.
Seep or sub-irrigation is the method most commonly used on
level land that has a water-impervious layer within three feet
of the surface. The land can be tiled, or seep ditches (Fig. 8)
can be placed at suitable distances, usually 20 to 40 feet apart.
This type of irrigation has the distinct advantage in that the
soil moisture can be kept more or less at a constant level by
maintaining water in the ditches or in the tile.
Down-the-row or furrow irrigation is often used where seep
irrigation cannot be used or where rapid wetting of soil is de-
sired. It is satisfactory if the water is allowed to run down the
row slowly. If it runs down the row too rapidly the soil is
not sufficiently wetted.
Overhead irrigation is used on land that is not level or on
land that has no hardpan. If water is applied often enough to
maintain uniform soil moisture very satisfactory results can be
obtained. On sandy soils one inch of water wets the soil to a
depth of about 12 inches, and usually no less than this amount
of moisture should be supplied by overhead irrigation at any one
Leaf and flower diseases are greatly increased in severity if
the plants are kept wet for the greater part of a day. Where
overhead irrigation is used during daylight hours the plants
should be allowed to dry off before nightfall. Prolongation of
the wetting period may be avoided also by sprinkling at night
or very early morning while the plants are wet with dew.
If a constant water level has been maintained by the use of
tile or seep ditches, no change in irrigation practice is neces-
sary as the spikes develop. If overhead or furrow irrigation
has been used, two to three applications weekly may be neces-
sary to supply enough water. If the water table in the soil
has been held at a moderately deep level, feeder roots become
established at or near this level. Raising the level of standing

Florida Agricultural Experiment Stations

water at time of spiking will injure roots and interfere with
water uptake by the plants and may bring about a physiological
disturbance of bud tissues.

Fig. 8.-Seep ditches spaced at eight-row intervals. The tile placed under
the roadway connects seep ditch with main drainage ditch.

When roots are damaged by heavy rains, maintain a good
moisture until new roots replace those killed below the first
few inches of soil. The common practice of allowing the soil
to return to the usual moisture content after heavy rain-fall often
results in poor quality flowers because a higher level of moist-
ure is needed for shallow-rooted plants. Good drainage is essen-
tial for removal of excessive moisture. Ditches must be deep
enough and properly placed to drain satisfactorily. Sandy soils

Commercial Gladiolus Production in Florida

without hardpan are generally no problem to drain but require
more frequent irrigation.
After the flowers are cut the soil is kept somewhat less moist
than during flower harvest. The soil should not be allowed to
become dry around the corms; if this occurs, dig them promptly.

Fig. 9.-Harvesting the flower spikes. Stems are cut three or four
inches above the ground, leaving four leaves on each plant to mature the
new corms.

Cutting Flower Spikes.-The flower spike is ready to cut when
the floret buds swell so that the petals begin to show (Fig. 9).
In warm weather spikes are often cut with only three or four
florets showing petal color if they must be shipped without
refrigeration. In cool weather or with refrigerated transport
five or six florets are allowed to swell so that the petals show.
Some varieties which develop several florets at a time and open

Florida Agricultural Experiment Stations

them slowly are allowed to show more color before being cut.
Spikes for distant markets are cut before the petals of the bottom
floret begin to separate and open. For local markets spikes may
be cut after the first or second floret opens.
With refrigerated transport and air transport being used more
generally, growers allow the spikes to develop further before
cutting. Even those varieties that open well from tight bud
have a better color, larger florets and a stronger stem when
given a few more hours of growth before the spike is cut.
Spikes are harvested once each day unless the weather is
very warm, when two cuttings may be made. Stems are cut a
few inches above the soil in such a manner as to leave four or
more large leaves on each plant to nourish the new corms. The
spikes are bundled and taken to the packinghouse promptly.
Grading and Packing.-Spikes are "graded" according to the
number of florets, the weight and length of the flower head, and
the over-all length of the spike (Fig. 10). The so-called grades
are actually size classes and are modified somewhat to suit the

Fig. 10.-Grading gladiolus spikes on moving belts.

^- -1^ I- P ii- r11'

Commercial Gladiolus Production in Florida

growth characters of different varieties. These grades are fancy,
special, A, B, and C (Fig. 11). Generally, the larger and heavier
spikes are better in quality or performance than the smaller.



. r


S. ..

Fig. 11.-Graded gladiolus spikes. Left to right: fancy, special,
A, B and C.

Florida Agricultural Experiment Stations

Varieties are separated and one dozen of a kind and grade are
bunched with the tips together and the stems cut to uniform
length. The bunch is tied with string or held together with
rubber bands. Two ties are used, one a few inches below the
florets and the other near the stem end. In warm weather the
bunches are often set in shallow trays of water or on ice. A
few of the larger packinghouses are air-conditioned. With air-
conditioning or in cooler weather, spikes are usually kept out of
water. When held in water from some artesian wells, Picardy
and certain other varieties develop bleached petal edges.
Spikes are packed in rectangular cardboard or veneer-wood
hampers about 13 inches square and long enough to accommodate
the spike length (Fig. 12). Hampers hold from 10 to 16 dozen
of the larger spikes and about 24 dozen of the small spikes.
Before being placed in the hamper the bunches are wrapped
with paper. Several layers of newspaper as well as heavy kraft
are used in cold weather. In hot weather only a single sheet of
kraft paper is used and the top is left open. Perforations or
slits in the sides of the hamper are necessary for ventilation.
Banana hampers or "glad hamps" are preferred by some grow-
ers because of the ventilation provided, especially in warm
weather. After being packed, spikes are pre-cooled for several
hours at about 350 F. The benefits of refrigerated transport
are often greatly reduced by lack of pre-cooling and by insuffi-
cient air circulation between the hampers. Spikes are usually
kept upright before and after bunching and during shipment.
Proper pre-cooling makes it possible to ship spikes in the hori-
zontal position without tip curvature.
Digging the Corms.-Corms are harvested over a period of
six months, extending from January through June. The time
to harvest may be judged by: number of weeks since peak of
flower harvest, vigor and health of plants, development and
coloration of corms and cormlets, softening of stalk, and condi-
tion of roots. Some growers dig corms four or five weeks after
the peak of flowering because early harvesting tends to reduce
losses by corm rotting. Other growers allow corms to mature,
digging them six to 10 weeks after flowering. It is generally
agreed that they should be dug before the tops die and while
the roots are healthy and active. Some growers, recognizing
that some varieties mature early and others late, harvest them
accordingly. Probably the signs of corm maturity used most
commonly are the degree of coloration of cormlets and the de-

Commercial Gladiolus Production in Florida 27

generation of roots. Corms from cormlets are judged to be
mature when the white husks begin to darken.
Experiments with Picardy and Snow Princess show that
corms dug two months after flowering produced more flower
spikes than corms harvested a month earlier.

Fig. 12.-Gladiolus shipping hampers, made of cardboard and wood,
hold from 12 to 24 dozen spikes.

Florida Agricultural Experiment Stations

Methods of harvesting corms are seldom alike on any two
farms. Various types of equipment are used, some of which are
made to order. A popular type of mechanical topper is shown in

Fig. 13. Revolving disk or "topper" removes weeds, gladiolus tops and
soil from raised beds, so that corms may be harvested with less labor and
without losing many corms in weedy land.

Commercial Gladiolus Production in Florida

Figure 13. The gladiolus stalks, as well as weeds, are cut off be-
low the soil surface with a revolving disk placed near the front of
the tractor. This removes the soil to within about two inches of
the tops of corms. Another tractor with plow or blade lifts the
corms so they may be picked up by hand.
Where there are no weeds and the soil is loose the corms may
be turned up with a plow. Growers who do not use the topper
usually bar off the row with disks or a small plow before digging
the corms. Some mechanical harvesting machines raise the
corms on a platform where most of the soil is shaken off and
then deposit them in trays. These have been found to injure
the corms and increase rotting.
Fields harvested during May and June should be irrigated
moderately to keep the soil from getting dry and hot. Corms
were found to be "cooked" where the soil was very dry late in
May. In hot weather, corms should not be uncovered in the sun
for more than a few minutes and the topper should not be used
more than two hours ahead of harvesting if the soil is dry and
hot. When the weeds and soil surface are removed with the
topper, the covering soil remaining may become hot enough to
injure the top of corms.

Immediately after digging, the tops are cutoff close to the
corm and corms are placed in wooden trays, not over two or
three corms deep. Trays are made in two standard sizes:
22.5 x 20 x 6 and 30 x 20 x 5 inches. Corner posts project one
inch above tray so that, when stacked, a one-inch gap is left
between trays. Ventilation is provided by this separation and by
openings between wooden slats which form the sides and bottom.
Trays are stacked in open sheds or in the field with an empty
tray or other platform at base of stack. A cap of wood or metal,
wide enough to shed rain, should be placed on top of stacks in
fields. Dusting corms in the stacked trays with 5 percent DDT
will protect them from thrips.
After digging, the corms are cleaned, a hand operation in which
the mother corms, roots and cormlets are removed from the base
of the new corms. This usually is done two or three weeks after
digging, when the mother corm can be removed most easily,
leaving a smooth "scar".
In cool, moist weather corms should be cured with artificial
heat. Heated air is blown around the corms for five to eight

Florida Agricultural Experiment Stations

days, after which they are ready to clean. After being cleaned,
they are returned to the heated air for another period of four
to seven days and then placed in cool storage. A temperature
of about 95 F. during the first five to eight days is reported to
help in controlling Fusarium rot. Another method of keeping
the Fusarium fungus from growing into some of the new corms
from the mother corms is to clean the corms immediately after
digging them. When cleaned at this time, or before the forma-
tion of an abscission layer, a dust or dip treatment must be
applied to prevent new Fusarium infections and, if the corms
are artificially cured, a lower temperature and a fairly high
relative humidity must be used.
If corms are warm-cured in a room, the air may be recircu-
lated to hold a relative humidity of about 80 to 85 percent, which
is satisfactory in promoting healing of cuts and bruises. In
heating air the relative humidity may be lowered so much that
the corms are dried too rapidly and injured where air movement
is rapid. Recirculation of all the air is, however, dangerous.
Some fresh air should be admitted to the heater to guard against
accumulation of toxic gases.
After they are cleaned corms should be graded for size and
placed in trays, and each tray labeled as to variety, date of
harvest, storage date and source of stock. Hold the corms in a
well-aerated shed for six to 10 weeks, or until root buds begin
to develop. Do not wait for root development on corms har-
vested after April or on those matured in warm soil. These are
placed in cool storage as soon as they are well-cured. Roots
are very slow in developing on them.
Practically all Florida corms are placed in cold storage for a
period varying from one to six months. At least two months of
cold storage usually are required to bring Florida-grown corms
out of dormancy and to cause them to sprout and flower as
uniformly as possible. Only three or four weeks may be suffi-
cient for some lots of corms dug in winter or early spring. Three
months or more are often needed for corms dug in late spring-
and summer.
Cold storage temperatures commonly used range from 360 to
450 F., with 38-40 F. being most common. With good air circu-
lation to all parts of the room, temperatures of 450 to 48 F. are
suitable if the humidity is held low enough to prevent growth
of sprouts and roots. Relative humidities below 50 to 60 percent
may injure corms by causing excessive desiccation. A tempera-

Commercial Gladiolus Production in Florida

ture variation of only a few degrees is considered better than
wide fluctuations that tend to cause condensation of moisture
and root growth. The relative humidity in cold storage rooms
ranges from 65 to 92 percent, with an average of 70 to 75 per-
cent. A humidity of 80 to 85 percent is preferred at tempera-
tures of 36-400 F. if air circulation is adequate to prevent "moist-
ure pockets" and consequent rooting of corms. Some rooms are
packed too full for proper air distribution. Space for air circula-
tion should be provided between the trays and the walls and
above and below the stacks of trays. Storage rooms packed with
corms should be aerated every two to four weeks to replenish
oxygen in air. It is especially important to renew air occasion-
ally in storage containing many rotting corms.

All varieties appear to be susceptible to damage by various
insects. Chewing larvae or "worms" are usually numerous in
summer and fall. Thrips are a serious pest during late winter
and spring. Red spider mites often cause damage in warm,
dry weather. Wireworms are a pest in some fields. Other
insects such as leaf-hoppers and aphids seldom attack gladiolus
in damaging numbers. Recommendations on the spraying and
dusting of insecticides are given under Spray Programs.
Gladiolus thrips ruin flowers for market and are most difficult
to control during March, April and May. Adult thrips are
about 1/16 inch long, slender and dark brown or black. There
is a white band back of the head. The immature thrips are
bright, pale yellow, and are found under leaf folds and in florets.
Thrips rasp away the green part of the leaf and leave conspic-
uous, silvery-white scars, especially at the base of leaves. Flow-
er buds are scarred and deformed and petals show white streaks
(Fig. 14).
Active, light brown thrips are often found in the open flowers.
These are common flower thrips which do no harm, since they
feed largely on nectar and pollen. Growers often waste insecti-
cides by trying to kill flower thrips with sprays or dusts. In-
secticides applied more often than once each week may reduce
the quality and marketability of the spikes.
Armyworms and cutworms attack gladiolus at all stages of
growth. Besides chewing holes or cutting off leaves, some
larvae bore into stems, florets and leaf stalks. To control the

Florida Agricultural Experiment Stations

boring larvae it is necessary to maintain on the plants a film
of insecticide that will kill the young larvae as they enter the
Cutworms are controlled by applying fresh chlordane or diel-


f 7

Fig. 14.-Flowers ruined by feeding of gladiolus thrips. Badly scarred
florets do not open.

Commercial Gladiolus Production in Florida

drin dust or spray over the row before emergence of shoots
and at the base of plants when they begin to emerge. Two or
three applications usually are required.

Fig. 15.-Valeria corms injured by feeding of wireworms.

Red spider mites infest gladiolus leaves in warm, dry weather,
particularly where DDT has been used. The mites are found
under a delicate web on the under side of the leaves. They suck
the plant juices, causing numerous small white dots. The leaf
becomes dull green and finally brown under severe attacks. A
thorough dusting with sulfur every two weeks controls mites.
Wireworms bore holes in shoots and corms in the upper four
inches of soil. Leaves of young planting stock may be cut off
so that the plants die. Injured corms show dark brown or black
scabby spots of various sizes (Fig. 15). Sometimes the injury
leaves a hole in the corm, but usually the scabs are shallow. New
as well as old land may be infested with this pest. The slender,

Florida Agricultural Experiment Stations

brown, hard-shelled larvae have a black head. Some varieties
of gladiolus are attacked much more severely than others.
Excellent control is obtained with chlordane or aldrin applied
to the soil as a spray or dust, or broadcast with the fertilizer
mixture and double-disked into
the soil about four inches deep
before planting. For each acre
use 12 pounds of 40 percent
chlordane or 5 pounds of 40 per-
cent aldrin. Although broadcast
Application is recommended,
Some growers have obtained fair
control by dusting or spraying
with aldrin or chlordane in the
planting furrow or by adding 2
pounds of aldrin, lindane, or
chlordane to 50 gallons of the
preplanting corm dip.

The disease caused by the
f u n g u s, Curvularia lunata
(Wak.) Boed., h as damaged
plantings throughout the year
since its discovery in Florida
and Alabama early in 1947.
The fungus attacks all parts of
the plant and is very destructive
during warm, rainy weather.
Fig. 16.-Curvularia leaf spots Some of the best commercial
on Picardy. Very young spots tend varieties are susceptible. Flow-
to be broader than long. Spots
grow longer along leaf edge. Dark- er spikes and young cormlet
colored centers in light tan areas plants are attacked most severe-
represent groups of the fungus
spores. ly. Disease spots on leaves,
shown in Figure 16, are oval and
1/2 to 1 inch long. The central, tan area of the spot is ringed by
a dark, reddish-brown zone, outside of which is a pale green or
yellow halo. The central area of the spot is peppered or covered
with back spore masses. Spotting of florets and stem is shown

Commercial Gladiolus Production in Florida

in Figure 17. Infected florets may not open. Stem spots are
long and dark brown and the rotted tissue is firm. Infection
of young cormlet plants, appearing as yellowing of leaf tips and

Fig. 17.-Curvularia spots on stem and florets of Picardy. Dark spores
of the fungus make spots appear black.

Florida Agricultural Experiment Stations

damping-off, may kill a planting three weeks after the first ap-
pearance of symptoms.


Fig. 18.-Corm lesions caused by Curvularia are sunken, dark brown or
black, and irregular in size and shape.

Corms infected by the curvularia fungus have dark brown or
black, sunken spots of various sizes as shown in Figure 18. The
rotted tissue is usually shallow, separating easily and cleanly
from the healthy tissue. Although samples of wholly rotted
corms have been received from other states, only surface in-
fections have been noted in Florida. Some varieties resistant
to curvularia leaf spot are very susceptible to corm rot. Infec-
tion of corms may occur in soil where a previous crop was badly
diseased, but more frequently occurs where leaves of the present
crop are infected. Infection reaches corms by way of spores
washed off leaves and by growth of the fungus along the stalk
and soil.

Commercial Gladiolus Production in Florida

Control.-Leaf and flower infection is controlled by spraying
or dusting with nabam or zineb as recommended under Spray
Programs. Two or three years should elapse before replanting
gladiolus in a field where cormlets were severely diseased.
Cormlets and planting stock should not be planted thickly.
Cormlets of susceptible varieties should not be planted next
to susceptible flowering stocks because of the danger of disease
spread from the cormlets. Overhead irrigation should be lim-
ited to middle of the day or early morning so that the leaves
dry off before night. Where leaves are infected harvest corms
in dry weather, if possible, and cure corms with artificial
heat immediately after digging them. If corms are muddy
wash them in running water and soak 15 minutes in a solution
of 11/ pounds Dowicide B in 50 gallons of water before curing
them with warm air which is circulated by fans.

The gladiolus botrytis fungus, B. gladiolorum Timmermans,
attacks leaves, spikes and corms during winter and early spring.
In Florida the disease is most destructive on flowers. Infections
that are invisible when spikes are packed may cause extensive
rotting of flowers in transit and storage. Spread of disease in
the field is favored by cool, moist weather and the presence of
dead leaf tips and bloomed-out spikes. The disease makes its
appearance after a few cold nights and spreads slowly, causing
little or no damage until rainy weather occurs. Three days of
windy, wet weather with temperatures between 500 and 700 F.
may result in total loss of flowers in unsprayed fields.
The fungus lives from one year to the next in the form of
sclerotia. These are black, irregularly-shaped bodies, about
1/16 inch in diameter, produced on diseased plant parts left in
the field, on discard piles and on corms in cold storage. Scle-
rotia remain dormant in the soil until cold weather occurs. The
disease was not found during two successive years in peninsular
Florida when air temperatures went below 38 F. for only a
few hours during the winter.
The disease usually appears first on the leaves causing round,
brown spots about 1/ to 11/ in. in diameter. In warm, dry weather
the spots tend to be smaller and rusty colored, the smallest being
about 1/16 inch in diameter and visible on the upper leaf surface
only. These small spots among the larger, and the gray, fuzzy
spore growth on the large spots, usually serve to distinguish

38 Florida Agricultural Experiment Stations

botrytis disease from spots caused by Curvularia. Botrytis leaf
spots tend to be round and the central, light brown area is bor-
dered by a dark brown ring (Fig. 19). Differences between the

lT Jf '

Fig. 19.-Different types of leaf spots caused by Botrytis. Large spots
are light brown; smaller spots are dark reddish brown with tan centers.
A gray mold may develop on large spots.


Commercial Gladiolus Production in Florida

smaller botrytis spots and stemphylium leaf spots are shown
in Figure. 20.
The gray mold is especially abundant on dead florets and can
be seen easily when wet with dew. The easiest way to identify
botrytis disease is to look for the day-old petal infections which
are clear, water-soaked spots, pin-point in size. Two- to three-
day-old spots disintegrate under pressure of the fingers. Petal
infections show up after rains or heavy dews if the disease is
well established on neighboring plants. Large petal spots turn
brown and under wet conditions the flowers become mushy with
wet rot. Stem lesions are brown and soft and frequently located
at the base of florets after heavy rains.
The botrytis fungus attacks corms in the field and in cold
storage, where the disease spreads from corm to corm. The
disease is easily identified, since the rotted corms are soft and
spongy and often show a white, cottony growth of the fungus
(Fig. 21). In earlier stages of rotting the tissue is light brown
and watery, later developing into a soft, spongy, dark-brown rot.
Soft rot has affected Picardy corms after a growing season with

Fig. 20.-Leaf spots caused by Botrytis on left, Stemphylium on right.
Light shines through the spots caused by Stemphylium and they generally
have a small reddish brown center.
-I~ m I-

Florida Agricultural Experiment Stations

no leaf or flower infection, indicating that the fungus lives in the
corms through two growing seasons, passing from the old to the
new corms.

Fig. 21.-Corms affected with Botrytis soft rot. Sectioned corms at
right show internal symptoms, including spongy nature of rot and exten-
sion of rotting from core to surface. Black sclerotia and white mold of
fungus are shown on surface of corms at left.

Commercial Gladiolus Production in Florida

Control.-After the disease has spread throughout a planting,
a period of rainy weather makes it difficult or impractical to con-
trol infection of flower spikes by spraying or dusting. However,
sprays and dusts are highly effective when used as recommended
under Spray Programs. The following practices are helpful in
controlling botrytis by spraying and should be followed as far
as practical where the disease has been destructive in previous
1. Keep plantings of similar age together. Most destructive
outbreaks of the disease occur where botrytis spores drift from
an older planting. During the season which is favorable for dis-
ease development, older plantings should be sprayed weekly un-
til corm harvest, especially if younger plantings are nearby.
2. Remove spikes from fields before they bloom out. Burn or
bury a foot deep all infected material, including corms, spikes
and leaves. In large plantings where removal of diseased mate-
rial may not be feasible, broadcast 500 pounds of calcium cyana-
mid per acre, disk it in and plow trash under immediately after
corm harvest.
3. During botrytis epidemics dip cut spikes in a fungicide to
reduce rotting in transit to market. Use nabam plus zinc sulfate
as mixed for spraying or use 1 pint Puratized Agricultural Spray
in 100 gallons water. Add 2 ounces of a good wetting agent,
such as Glim or Joy. Dip spikes in solution for two to four
seconds as they are brought into the packinghouse.
4. Unless the weather is warm, cure corms from infested fields
with artificial heat and fans. Warm curing for five to seven
days at 80 to 90 F. effectively controls soft rot.
5. If soft rot appears in storage, soak the sound corms for 20
minutes in a suspension of 5 pounds thiram wettable (e.g. Tersan
"70") in 50 gallons of water before planting. Instead of the
soak treatment, corms may be dusted with thiram (e.g. "Arasan"
SF-X Thiram Seed Disinfectant), diluted 1 part to 3 parts of an
inert dust such as clay or pyrophyllite.

Another fungus, Stemphylium sp., attacks the leaves of some
varieties, causing them to turn yellow and brown. Leaves may
be killed early enough to prevent flowering and corm produc-
tion. More commonly the disease becomes serious after flower-
ing, killing leaves prematurely and reducing corm size. Heavy

Florida Agricultural Experiment Stations

dews and fogs are very favorable to its development. The dis-
ease is seldom destructive except during January through May
in peninsular Florida. Disease spread usually begins from one
or a few isolated centers of infection in a field and these centers
usually originate in the more susceptible varieties. Generally it
appears later and is less serious in plantings which do not include
the most susceptible varieties.
There are at least two strains of the fungus and these attack
certain varieties differently. One or more strains produce large
as well as small spots on leaves (Fig. 22). The large spots are
from 1/4 to 1 inch or more in diameter and light brown in color.
Spores are produced abundantly on the large, dead spots and on
dead leaves.
In some fields and on some varieties only the small spots are
seen. Their appearance is very different from that of the large
spots, their size usually being less than 1/8 inch in diameter.
These small, round spots are yellow and translucent and show
on both sides of the leaf. No other round spot on gladiolus
leaves appears as bright when held against the light. This char-
acteristic makes identification of the disease simple (Fig. 20).
On the upper side of the leaf or on the side where infection
occurred, a small reddish brown dot develops in the center of
the yellow spot. When sprayed with an eradicative fungicide
such as Manzate, this brown dot may increase in size and cover
the pale translucent spot on one side of the leaf.
Control.-Very susceptible varieties, such as Stoplight, Mar-
garet Beaton, Chamouny, King David, and Florence Nightingale,
should not be planted next to varieties of moderate suscepti-
bility, such as Picardy, Hopmans Glory, Ethel C. Cole, and sports
of Picardy. Successive plantings of susceptible varieties should
be separated by plantings of resistant varieties. When isolated
centers of infection involve only a few plants, disease spread
may be checked by destroying the infected plants and by spray-
ing the immediate area thoroughly with Manzate. This spray is
also effective in protecting the plants after the disease has begun
to spread through the plantings.

Each of the three diseases which attack the leaves or flowers
has its own season of maximum development and is most severe
on certain varieties. Disease development also varies from one
section of the state to another. Some varieties do not need

Commercial Gladiolus Production in Florida

fungicidal protection at certain times of the year because they
are resistant to the only disease which is active. It is obviously
impossible to suggest any one spray or dust schedule that would
be most suitable at all seasons or on all varieties in each pro-
ducing area. The tendency of some growers to follow one spray
schedule regardless of season, weather conditions or variety can
be wasteful or inadequate.

Fig. 22.-Stemphylium leaf spots on Picardy.

44 Florida Agricultural Experiment Stations

The recommended fungicides are not curative in their action.
They can only protect the plant from further infection and must
therefore be applied before the rain or dew period when infec-
tion occurs. Excellent control is obtained by spraying fre-
quently in wet weather and by supplementing the spray sched-

Fig. 23.-High-clearance spray rig (above) typical of those used in
spraying gladiolus. Less expensive rig, as used on many vegetable crops,
may be used until spikes appear, when an orchard-type duster (below) is
operated along the seep ditches.
^ .

Commercial Gladiolus Production in Florida

ule with dust applications. Dusts can be applied rapidly and are
most useful when weather conditions hamper the application of
sprays. One type of sprayer and a duster are shown in Figure
Only one fungicide has been found to be highly effective
against both curvularia and botrytis diseases. That is zinc
ethylene bis-dithiocarbamate, which is sold as a 65 percent wet-
table powder under the common name, zineb, and under several
trade names, including Dithane Z-78, Parzate, and Ortho-zineb.
It is used at the rate of 2 pounds in 100 gallons of water. The
recommended zineb dust contains 6 percent of the active in-
The fungicide may be prepared by the grower, using a solution
of sodium ethylene bis-dithiocarbamate (nabam) which is sold
under several trade names, including Dithane D-14, Parzate
Liquid, Thiodow and Ortho-nabam. Nabam and water are mixed
in the spray tank with a solution of zinc sulfate according to
the manufacturer's directions. It is very important to weigh the
zinc sulfate because it varies in density. Sift zinc sulfate into
the water while stirring, or wash it through a screen. A spread-
ing agent such as Triton B-1956 or Tergitol No. 7 is added to the
spray mixture to cause the spray droplets to cling to the waxier
parts of the plant. Only enough spreading agent is used to keep
the droplets from running together.
The tank mix (nabam plus zinc sulfate) fungicide or zineb
dust is preferred to zineb spray on flowers because zineb spray
is more visible after drying on the plant. However, this spray
residue is not objectionable on the leaves. Zineb spray tends to
be less injurious to the plants, especially where applications are
repeated as often as two or three times weekly. Both zineb
and nabam sprays are injurious to petals of open florets, but
the dust is often used with no signs of injury. The best time
to apply dust or spray is in the evening when the air is calm
and before dew has formed.
Seasonal Spray Schedules.-Curvularia is the only disease of
leaves and flowers to be controlled in summer and fall. Until
spikes appear susceptible varieties such as Picardy, Picardy
sports, Corona, Ethel C. Cole and Purple Supreme need to be
sprayed every four or five days when there are periods of rain
or dew. After spikes appear all varieties should be sprayed or
dusted about twice weekly if the disease is present in a nearby

Florida Agricultural Experiment Stations

planting. Direct the spray toward the spikes, using two nozzles
per row, Keep nozzles clean and operating properly. Replace
disks when aperture becomes enlarged because of wear.
Spray cormlet plants with zineb each week, starting at emer-
gence. At the first sign of yellow leaf tips and killing at ground
line, spray two, three or four times weekly, according to the
weather, until curvularia disease is checked. Many varieties
that are resistant when grown from large corms are suscep-
tible as cormlet plants. Therefore, during the first eight weeks,
spray cormlets of all varieties, except those which are known to
be resistant. Some varieties which develop resistance rapidly,
even when grown from cormlets, are: June Bells, Snow Prin-
cess, Morning Kiss, Nugget, Spotlight, Hopmans Glory, Oc-
tober Sunshine, Spic and Span, Elizabeth the Queen, and Modern
Add DDT to the spray or dust mixture every week or 10 days
to control chewing larvae. If large worms are seen, use chlor-
dane or dieldrin in place of DDT. Apply the insecticide to grassy
areas near edges of gladiolus fields to kill armyworms before
they migrate to the crop.
To control botrytis disease begin spraying all varieties with
the fungicide by December 1, or earlier if frost is forecast in
November. Apply the fungicide on a weekly schedule, increas-
ing to twice weekly in moist, cool weather. After botrytis in-
fection shows up, spray or dust the spikes three times each week.
After flower harvest, spray once or twice each week until corm
When stemphylium leaf spot appears, substitute Manzate
for zineb in every other application. Until more is known about
its effect on plant growth, Manzate should be used not oftener
than once each week at the rate of 2 pounds in 100 gallons.
Beginning March 1 or whenever gladiolus thrips appear, sub-
stitute benzene hexachloride for DDT. Benzene hexachloride
should not be used if the land will be planted to vegetables
during the next two years. Use chlordane or dieldrin if worms
are to be controlled also. Dieldrin, chlordane and benzene hexa-
chloride are very effective in thrips control. Follow the manu-
facturer's directions in the use of these insecticides. Concen-
trations recommended for most vegetable plants are suitable for
gladiolus. To control red spider mites dust with sulfur every
other week beginning March 1.

Commercial Gladiolus Production in Florida

Pseudomonas marginatum (McCull.) Stapp is a bacterium
which attacks only the corm and its husk in Florida. The dis-
ease persists when affected corms are planted in some of the
heavier, dark types of soil, but in other soils the disease may
disappear. The sandy soils used for gladiolus in south Florida
are not conducive to the disease, but in north Florida scab

Fig. 24.-Corms of Beacon (top) with husks removed to show typical
scab spots. Unhusked corms of same variety below; scabby corm at left,
showing blackened husks, and healthy corm at right.

has been severe in some fields. Corms are not rotted, but their
market value is reduced by the unsightly scabs, and severe in-
fection may lower the vigor of the corms. Flower production is
apparently not affected by slight to moderate scab infection.
Husks of scabby corms are blackened (Fig. 24). Scab spots
are generally round and 1/8 to 1/4 inch in diameter. The border
of the spot is raised and the center is sunken. A bacterial

Florida Agricultural Experiment Stations

slime oozes from the spots and dries to a varnish-like glaze
which is the distinguishing sign of the disease. The scab lesion
is easily lifted off with the point of a knife, leaving a clean, bowl-
shaped depression.
Control.-Wireworm injuries bring about bacterial scab in-
fection. In some areas scab is controlled by preventing wire-
worm damage. Where scab continues to be a problem after
wireworms are controlled, some degree of control may be ob-
tained by soaking the corms in a fresh solution of corrosive
sublimate for three hours just before planting. Prepare the
solution by dissolving 1/2 pound of corrosive sublimate in 60
gallons of water and add 2 pounds aldrin or lindane. Use some
hot water to get it into solution. Since the chemical attacks
metal, the solution should be used in a wooden or concrete tank
which has no metal parts.

Brown rot of corms, yellowing of foliage and "cow-horn"
plants are caused by the soil-borne fungus, Fusarium oxysporum
f. gladioli Snyder and Hanson. This is the most destructive dis-
ease of gladiolus in Florida. It is estimated that from 40 to 50
million corms have rotted in Florida each year since 1948. The
fungus is carried in corms and cormlets that appear to be
healthy. These corms frequently rot when planted in warm,
sandy soils and fertilized for flower production.
It is not difficult to distinguish fusarium rot in corms grown
in peninsular Florida. In central and southern sections of the
state this disease causes over 97 percent of the corm rotting.
Except for the soft rot caused by Botrytis, there is no other
disease in peninsular Florida that commonly involves the whole
corm. Dry rot, hard rot and penicillium rot apparently do
not occur in south Florida.
In some varieties fusarium infection may be limited to the
roots, to the vascular tissue near the base of the corm, to the
core, or to the husk. In more susceptible varieties infection
often results in corm rotting. When corms or vascular tissue
are visibly rotted the plants exhibit one or more of the follow-
ing symptoms: (1) plant stunting; (2) leaf yellowing or brown-
ing, beginning on older leaves; (3) curvature of leaf growth
as shown in Figure 25; (4) abnormal florets with smaller, less
ruffled petals, with colors that may be intensified or washed out,
and petals with conspicuous veins (Fig. 26) ; (5) a spike which

Commercial Gladiolus Production in Florida

is weak-stemmed and often curved below the florets. Compared
to a healthy spike, the stem and bracts are often darker green
and the flower buds are thinner and "toe-in".

Fig. 25.-Young leaves of many gladiolus varieties respond to Fusarium
infection of corm with a curving of growth. The leaves bend away from
the side of the corm showing rot. Healthy plant on right.


Florida Agricultural Experiment Stations

Fusarium rot in stored corms is a firm rot, light tan to dark
brown in color. Disease spots occur in the corm surface, usually
at the base, and the rotting often progresses up and outward
from the core as shown in Figure 27. Rotted corms are mummi-
fied or greatly shrunken in storage and sound like a stone when
dropped. When rotting begins after corms are planted, the
rotted tissue remains soft and is invaded by other organisms.

Fusarium corm rot can be traced to latent infections carried
in corms, to infection of roots and to injuries caused in the
handling of corms. Control measures applicable to each mode
of infection are discussed separately below.
Latent Infection.-No treatment is known that will eradicate
latent fusarium infections in corms. These dormant infections
tend to break out as rot if corms are bruised and begin to sprout
when they are shipped in air-tight packages or in bulk; if soil
is warm and excessively wet at planting or after growth begins;

Fig. 26.-Fusarium infection of corms may result in stunted spike with
smaller, non-ruffled petals. Picardy spikes on left and right have a darker
pink color than normal because corms were slightly rotted. Normal spike
in center.

Commercial Gladiolus Production in Florida 51

if soil temperatures are above 700 F.; if the plants' growth is
checked by unfavorable conditions affecting the roots; if am-
monia nitrogen or undecomposed forms of organic nitrogen are
used liberally; and if corm harvest is delayed in warm, wet

F.. .a.
,l .,

K!! .. .

Fig. 27.-Fusarium brown rot symptoms generally found in corms of
susceptible varieties. In more resistant varieties rotting may be limited
to the corm surface, to the core or to the husks. Within any one variety
symptoms also vary because of different fungus stains, some of which are
more virulent than others.

Florida Agricultural Experiment Stations

Some corm stocks contain much latent infection. Only stocks
which have proven to carry little or no fusarium infection should
be propagated for planting stocks. A good test for latent infec-
tions is to plant samples of the corm stocks in warm, wet soil
and follow the fertilizing practices commonly used in growing
gladiolus in Florida.
Root Infection.-The fusarium fungus lives in the soil for
many years after it is introduced with corms or by water and
soil from nearby infested fields. The fungus enters healthy
gladiolus roots without the aid of injuries. The fungus enters
corms and cormlets by way of the roots. It grows and survives
in soil in the absence of gladiolus. However, moderately infested
soils may become relatively free of the fungus by not replanting
with gladiolus for at least five years. It is doubtful that the
fungus could ever be entirely eliminated from the soil, except
by thorough fumigation with methyl bromide or a similarly
effective fungicide. Root infection has not been serious where
gladiolus were replanted every three years, but since a slight
infection of roots usually results in corm infection, cormlets and
planting stock should be grown only on "clean" or uninfested
land. If both planting stock and soil are free of the gladiolus
Fusarium, the soil would remain so for many successive years
of replanting gladiolus, provided the fungus is not introduced
with other corms or infested soil.
Corm Injuries.-Infection of corms commonly occurs through
the very small wounds and bruises caused in the digging and
handling of corms at harvest and during the curing period.
Immature and large corms are most susceptible to mechanical
injury. Injuries should be avoided as far as practical by care-
ful handling, by removing protruding nails in trays and sharp
edges on bulb graders, and by using rubber padding on mechani-
cal graders. Separation of larger corms into different sizes
could be done by the workers as they clean the corms, thereby
eliminating one handling operation. Warm curing immediately
after harvest is recommended to heal wounds and dry the
corms so as to make conditions less favorable for fungus in-
Clean off the old corms as soon as they break away cleanly
and easily and dust the new corms immediately with Spergon
wettable powder diluted 1 to 1 or with Arasan SF-X Thiram
Seed Disinfectant diluted 1 to 3. These powders may be diluted
with an inert dust, such as pyrophyllite, or with 5 percent DDT

Commercial Gladiolus Production in Florida

dust if thrips are to be controlled. All varieties should be
treated. The dust may be applied as the corms pass along the
grading belt or through a revolving drum. Any method of
applying the dust is suitable if the corms are not badly bruised
and provided the "cleaning scar" is coated and the dust is not
wasted. Arasan should be used only with meticulous care to
avoid breathing the dust. Persons sensitive to Arasan should
use Spergon. Neither dust should be used in a closed building.
In case the dust cannot be applied immediately after clean-
ing the corms, one of the following dip treatments is recom-
mended. Never treat corms twice with the same chemical, be-
fore and after storage.
1. Ferbam (Fermate, Ferradow or similar formulations con-
taining 65 percent ferbam) 2 pounds plus 11/2 pounds Dowicide
B in 50 gallons of water. Soak corms 30 minutes.
2. Dowicide B, 2 pounds in 50 gallons. Soak corms for 30
to 60 minutes in cool weather, or 20 minutes in hot weather.
Add a detergent if corms are not thoroughly wetted.
3. Spergon wettable powder 4 pounds plus N.I. Ceresan 1/2
pound in 50 gallons water. Soak corms 10 minutes. Spergon-
Ceresan treatment is recommended for diseased Picardy stocks
Wait 4 to 18 hours after cleaning corms before soaking them,
because these dips may not be so effective if the scar is wet. The
dipping mixtures may be used for treating up to eight batches
or loads of corms. When corms are properly treated at the
time of cleaning there is generally no advantage in treating
them before planting. If a cleaning-time treatment is not used
one of the following pre-planting treatments is recommended:
1. Dowicide B, 3 pounds in 50 gallons. Soak corms for 30
minutes. Dowicide B treatment is preferable to N.I. Ceresan
for Valeria and Dr. F. E. Bennett, and is as good or better for
large Picardy corms. Treated corms may be held for a few
days before planting.
2. Soak 15 minutes in 1 pound N.I. Ceresan in 50 gallons and
plant immediately in moist soil. Do not use on rooted corms.
N.I. Ceresan is recommended especially for Picardy planting
stocks and cormlets.

Florida Agricultural Experiment Stations


Fig. 28.-Neck rot caused by unknown Fusarium species on Snow Prin-
cess. Outer leaves are shredded and very dark brown. Inner leaves are
spotted reddish brown and sometimes rotted through.

Commercial Gladiolus Production in Florida


Fig. 29.-Sclerotinia neck rot on Ethel C. Cole variety. Young in-
fections on left and later stages of disease on right. Sclerotia are barely
visible on older plant near middle of photograph. Outer leaves of older
plants are beginning to shred.

Florida Agricultural Experiment Stations

Dry neck rot, caused by an unidentified species of Fusarium,
commonly occurs in the fall after wet weather. Beacon, Snow
Princess and Early Dawn are very susceptible. Picardy appears
to be very resistant. Young plants are attacked near the ground
line and the infection spreads upward and inward as the new
leaves grow through the diseased leaves, resulting in reddish-
brown spots which tend to run together and turn dark brown
(Fig. 28). Although dry weather may arrest the infection
before the inner leaves are severely attacked, the disease may
rot enough of the neck to reduce or prevent flowering. Corms
are not attacked.
The following measures are suggested as helpful in controlling
this neck rot. Avoid injuring the plants and promote drying of
the soil surface. Weekly applications of nabam and zinc sul-
fate spray mixture often control the neck rot effectively if begun
as soon as the plants emerge.
Sclerotinia neck rot, caused by Sclerotinia gladioli Drayton, is
aptly called "cool weather neck rot" because it occurs during
and following unusually cool weather. It is usually most severe
where the soil or plants are deficient in boron. Plants of sus-
ceptible varieties are killed before flowering. The freshly rotted
neck has a sharp, musty odor. The color of the rotted tissue
is at first light brown, then gradually turns dark brown (Fig.
29). Small black sclerotia are imbedded in the dead tissue
(Fig. 30) which becomes shredded. The scale leaves over the
new corm are charred and black spots penetrate into the corm
along the leaf attachments (Fig. 31).
Some control of this neck rot is obtained by broadcasting,
1,500 pounds of calcium cyanamid per acre of sandy soil. Disk
and keep the soil moist; wait at least 50 days after treatment
before planting gladiolus. It is usually less expensive to move
to land that is not contaminated with this fungus. It has been
noted that neck rot is rare in plantings that mature before cold
weather or in plantings made after January 15. If corms carry
sclerotinia infections or if the soil is infested with the fungus,
make a late summer planting or a late winter planting.
Wet neck rot, caused by the Southern blight fungus, Pellicu-
laria rolfsii (Curzi) West, occurs in hot weather on mature
plants. Because affected plants resemble those killed by the
fusarium disease, growers tend to rogue them. However, unless

Commercial Gladiolus Production in Florida

the corms are rotted, it is suggested that the plants need not
be removed. Although the necks are susceptible, the corms
of some varieties are resistant. Small, round, white or brown
sclerotia are often found in the soil near the rotted tissues
(Fig. 32). A white, stringy fungus growth also may be seen.
The rotted neck tissue is usually moist in early stages of infec-
Curvularia neck
rot commonly occurs
in soil where a recent
crop was badly af-
fected by the leaf-
spotting phase of the
disease. The neck
may be completely
rotted in young
planting stock and
cormlet plants. On
young shoots from
large corms the dis-
ease causes a dark
brown spot which is
seldom visible above
ground. The rot may
penetrate two or
three leaf bases and
produce spots an inch
or more in length.
Most varieties are at-
tacked, even some
which always resist
Fig. 30.-Sclerotia or resting bodies of the
leaf infection above Sclerotinia neck rot fungus. These small black
ground. Infection bodies are embedded in the dead tissues of the
neck region. (Magnified about 4 times.)
of large shoots does
not seem to affect production of flowers. Planting stock and
cormlets should not be planted where a crop was damaged by
Curvularia during the previous two or three years.

Virus diseases are found in practically all stocks of the older
commercial varieties. Certain virus infections appear to affect
flower production only slightly, if at all. Others stunt the plants

Florida Agricultural Experiment Stations

or ruin the flowers. When flower production is reduced the af-
fected plants should be removed and destroyed. Corm stocks
showing signs of such virus infections should not be used for
propagating new planting stocks because these diseases are
carried in the corms and cormlets.
Bud rot is a physiological breakdown which causes severe
losses at times on some farms. It has been most troublesome
in Picardy, Spotlight and Valeria varieties. The larger spikes
are affected much more than the smaller ones. Generally only
the lower two, three or four buds are affected. The edges of
the petals are discolored and water-soaked before the floret
opens. The affected tissue turns brown on drying (Fig. 33).
Affected spikes are generally not marketable.
Bud rot tends to occur where cultural conditions favor large
plants, uninterrupted growth and early flowering. It often

Fig. 31.-Picardy corms spotted with Sclerotinia infection. The black
spots are generally small and shallow. They are often located along the
line of husk attachment.

Commercial Gladiolus Production in Florida

occurs where water is supplied abundantly during the spiking
period. Experiments indicate that low pH or low calcium sup-
ply and poor soil aeration are two of the factors that tend to
cause bud rot. Therefore, it is suggested that, for susceptible va-
rieties, limestone be applied to maintain a pH above 6 or gypsum
be used to supply plenty of calcium if lime is not needed. Avoid
heavy irrigations after spikes slip and scratch the soil surface
after rains to promote good soil aeration.
Fat bud is similar to bud rot in some respects. Although
fat bud and bud rot may occur in the same planting, each is
frequently found separately. Fat bud also affects the lower
florets of the larger spikes. Spotlight is very susceptible. The
principal symptoms are an inward curling of the petal tips
and proliferation of petal tissue in the throat of the floret,
which make the bud appear to be blunt and "fat". The quality

Fig. 32.-Neck, roots and husk of Picardy corm rotted by Southern
blight fungus. The small white, pink or brown sclerotia and the white
threads of fungus growth are unmistakable signs of this neck rot fungus.



Florida Agricultural Experiment Stations

Fig. 33.-Florets of Spotlight affected with bud rot, a physiological
breakdown caused by cultural conditions. Tips and edges of petals are
watersoaked and discolored; florets open poorly.

Commercial Gladiolus Production in Florida 61

of affected spikes is reduced to the extent that they are gen-
erally unmarketable.

Fig. 34.-Yellow bands on young leaves caused by bright sunny days
and cool nights. The yellow areas turn green as the leaf attains full size.

Florida Agricultural Experiment Stations

Fat bud is usually limited to plantings with good nutrition
and near-optimum water relations. Fat bud can be controlled
by growing suscep-
tible varieties with
much less water, es-
pecially just before
flower harvest. Grow-
ers who have trouble
with fat bud should
grow Spotlight and
other susceptible va-
rieties in a separate
field and use one-
third to one-half as
much fertilizer and
water as ordinarily
Yellow banding of
leaves (Fig. 34) oc-
curs in many plant-
ings as the shoots
emerge. This ab-
normality is associat-
ed with growth dur-
ing the light and
dark periods of each
day. The yellowing
is often most pro-
nounced on the side
of the leaf receiving
less protection from
the short, sheathing
leaves. The leaf may
be weakened in the
yellow band so that
the leaf dies. Yellow
banding occurs when
Fig. 35.-Injuries caused by the sun. Edges the leaves grow rap-
of bud sheaths (left) are dried by sun and wind idly and when nights
when the spike head wilts, exposing the sheath
tips. Small, irregularly shaped brown spots are relatively cool
found only on side of leaf facing sun are prob- and the sunlight is
ably caused by action of sun through drops of
dew. brilliant.

Commercial Gladiolus Production in Florida

Sun injury may reduce the market value of spikes. A bud
sheath burn (Fig. 35) is usually caused by the drying action
of wind and sun when the rapidly growing spike is wilted. The
direction in which the flower head bends in relation to the sun
often determines the severity of the bud sheath burn. Some
varieties are fairly resistant to this injury but other varieties
are so susceptible that they should not be planted for flower-
ing in the warmer months.

Fig. 36.-White, yellow or brown spots on short, sheathing leaves near the
soil result from sun injury.
Portion of leaves receiving direct sunlight may show small,
dark brown spots (Fig. 35). White, yellow or brown areas on
the short, sheathing leaves near the soil (Fig. 36) are found
on the side of the plant facing the sun. These discolored spots
are associated with cool nights and sunny days during the first
few days of growth.

Profitable production of gladiolus cut flowers for Northern
market depends largely on the following methods of culture
and disease control:
Start with healthy corms grown from planting stock.

Florida Agricultural Experiment Stations

Replace flowering corms every three to four years with healthy
corms grown on uncontaminated land from planting stock. Num-
ber each corm stock and keep a record of its source, disease de-
velopment and performance. Never mix different corm stocks.
Have corms shipped while dormant so that there is less tend-
ency for roots to develop during shipment. Corms should be
packed in ventilated crates and be kept dry and cool. They are
usually bruised in transit unless precautions are taken. Unless
aeration is good, bruising may result in much fusarium rot. Pack-
ing corms for shipment in vermiculite or a similar material has
reduced injuries and resulted in better growth.
Aerate corms as soon as received and hold them in cold stor-
age if root swellings are developed. If not developed, hold corms
in a warm, ventilated room for a week or more before planting.
Use fans to circulate the air.
Plant gladiolus in any field not oftener than once in three years,
growing summer and winter cover crops or other cash crops
in the other years. Plant Picardy, Leading Lady, Spotlight,
Corona and other varieties extremely susceptible to fusarium in
the fields which are least contaminated by previous plantings of
diseased corms. Land that is leased for three years should be
planted to the most susceptible varieties the first year, to the
moderately susceptible varieties such as Valeria, June Bells and
Elizabeth the Queen the second year, and to the less susceptible
varieties such as Snow Princess, Hopmans Glory and Modern
Times the third year.
Varieties susceptible to Curvularia can be planted together in
order to simplify the spray program. Because of the danger of
diseases spreading from older plants to spikes and cormlets, keep
large fields of flowering corms and planting stocks separated by
at least one-half mile.
Begin spraying the recommended fungicide on all varieties at
least two weeks before cold weather is expected.
Spray once each week or 10 days to protect healthy plants from
leaf and flower diseases, but after disease appears, spray at least
twice each week in order to control spread of disease. Spray less
frequently during periods of no dew, fog or rain. If botrytis
disease is present, continue after flower harvest to spray all fields
weekly. Large plantings need to be sprayed more frequently
than small plantings.

Commercial Gladiolus Production in Florida

Avoid unnecessary spraying of fungicide on varieties resistant
to curvularia in summer and early fall when stemphylium and
botrytis are inactive.
Do not spray with insecticides more often than once every 7
to 10 days because of the danger of lowering quality of spikes.
For this reason, do not try to control common flower thrips
(Frankliniella sp.) by spraying.
Pick out rotted corms before planting and treat the sound
corms with a recommended fungicide if they were not previously
Never plant corms in wet soil. Provide good soil drainage
and a steady, uniform supply of moisture throughout growing
Keep plants growing steadily and provide two or three times
as much potash as nitrogen in the fertilizer program for sandy
soils. Avoid a checking of the plants' growth by such factors
as variations in water supply, poor drainage, unbalanced nutri-
tion and root injury.
Rogue diseased plants as they appear, removing and destroy-
ing corms as well as tops.
Harvest when cormlets begin to turn brown or when con-
tractile roots from new corms begin to turn brown. Avoid in-
juring corms during harvest. Place in shallow layers to cure.
Use heat and fans to cure corms immediately after harvest if the
weather is cool. Protect corms from rain.
Clean corms as soon as they are ready and treat immediately
with a recommended fungicide.
Bulb trays may be disinfected by soaking the trays over-night
or longer in a solution of Dowicide B, 6 pounds in 100 gallons.
Place corms in cold storage when sufficiently cured. A weight
loss of 15 to 20 percent indicates sufficient curing in some lots of
corms. Keep corms dry and in moving air during curing and
Include at least one heavy cover crop in the soil rotation. A
legume usually is preferred. Fertilize the cover crop immediately
preceding the gladiolus crop.
Apply dolomitic limestone to supply calcium and magnesium
where needed or use gypsum if the pH is high enough. These
materials should be applied when planting the last cover crop
before gladiolus.

Florida Agricultural Experiment Stations

Many gladiolus plantings show evidence of root damage by
nematodes at corm harvest. Occasionally, the roots are damaged
early enough in the plants' development to reduce flower yield
severely. Plantings subject to extreme fluctuations in water
supply and those damaged in the earlier stages of growth by
heavy rainfall are very susceptible to injury by nematodes. Root-
knot nematodes usually cause swellings of roots and knot-like
growths as well as killing of the roots. Root-knot nematodes
become imbedded in the corms and may be carried through the
storage period. Externally-feeding nematodes kill roots without
causing them to enlarge.
Two chemical soil fumigants are being used to control nema-
todes: DD (dichloropropene-dichloropropane) and EDB (ethy-
lene dibromide), the latter for the most part diluted to 20 per-
cent concentration with mineral spirits. These materials are
applied in-the-row about two weeks before planting at the rate
of 1/ pint per 100 feet. If the soil is loose and moist, and if the
fumigant is prevented from escaping from the soil too rapidly,
the treatment is usually effective in reducing nematode popula-
tions so that roots are not attacked severely while plants are
young. Though only 48 hours are required for these chemicals
to give their maximum effects in killing nematodes, it is not
advisable for the treated soil to be planted until the odors pro-
duced by the chemicals are fairly well dissipated. During rainy
weather it may be necessary to open the rows several times to
accomplish sufficient aeration. Until more is known about the
effects of the chemicals on the soil and on the crop, no general
recommendation for soil fumigation of large acreages can be
The injury from nematodes may be reduced adequately in some
fields without resorting to fumigation. The following cultural
practices are suggested:
Summer Fallowing.-Disk and plow frequently enough for a
month during the summer preceding gladiolus planting to pre-
vent weed growth and to allow the sun to dry and heat the soil.
The period of time required for effective control of nematodes
by summer fallow depends on the weather and the frequency of
stirring the soil. A period of three weeks of dry, hot weather
is very helpful if the soil is turned or disked twice each week.

Commercial Gladiolus Production in Florida 67

Keep plants growing vigorously by holding a uniform soil
moisture and by maintaining a balanced supply of nutrients ap-
plied in such a manner as to avoid root injury.
Crop Rotation.-Grow gladiolus not oftener than once in three
years and include leguminous cover crops. There are indications
that corn is not suitable in the rotation.

The writers are indebted to members of the Gulf Coast Experiment
Station for helpful criticisms and corrections of the manuscript; to mem-
bers of the Florida Gladiolus Growers Association who supplied corms
for some experiments; and to many individual growers for access to their
fields and packinghouses. Acknowledgments are due Dr. H. N. Miller for
the photographs used in figures 22 and 25, and A. & W. Glads, Inc.,
for photographs used in figures 2, 3, 4, 9 and 10.


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.

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of Florida

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