• TABLE OF CONTENTS
HIDE
 Title Page
 Credits
 Table of Contents
 Introduction
 Diseases
 Nutritional deficiencies
 Injuries
 Acknowledgement
 Literature cited














Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; no. 492
Title: Diseases, deficiencies and injuries of cabbage and other crucifers in Florida
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027343/00001
 Material Information
Title: Diseases, deficiencies and injuries of cabbage and other crucifers in Florida
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 63 p. : ill. ; 23 cm.
Language: English
Creator: Eddins, A. H ( Auther Hamner ), b. 1893
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1952
 Subjects
Subject: Cruciferae -- Diseases and pests -- Florida   ( lcsh )
Cruciferae -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 62-63.
Statement of Responsibility: by A.H. Eddins.
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00027343
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000925757
oclc - 18266288
notis - AEN6413

Table of Contents
    Title Page
        Page 1
    Credits
        Page 2
        Page 3
    Table of Contents
        Page 4
    Introduction
        Page 5
    Diseases
        Page 6
        Major diseases
            Page 6
            Page 7
            Page 8
            Page 9
            Page 10
            Page 11
            Page 12
            Page 13
            Page 14
            Page 15
            Page 16
            Page 17
            Page 18
            Page 19
            Page 20
            Page 21
            Page 22
            Page 23
            Page 24
            Page 25
            Page 26
            Page 27
            Page 28
            Page 29
            Page 30
            Page 31
            Page 32
            Page 33
            Page 34
            Page 35
        Minor diseases
            Page 36
            Page 37
            Page 38
            Page 39
            Page 40
            Page 41
    Nutritional deficiencies
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
    Injuries
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
    Acknowledgement
        Page 62
    Literature cited
        Page 62
        Page 63
Full Text
MAY 29 1952

March 1952


Bulletin 492


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
WILLARD M. FIFIELD, Director
GAINESVILLE, FLORIDA


PATALOGEL1


Diseases, Deficiencies and Injuries of
Cabbage and Other Crucifers in Florida
By A. H. EDDINS


Fig. 1.-Cabbage leaf affected with black rot.


Single copies free to Florida residents on request to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA







BOARD OF CONTROL

Frank M. Harris, Chairman, St. Petersburg
Hollis Rinehart, Miami
Eli H. Fink, Jacksonville
George J. White, Sr., Mount Dora
Mrs. Alfred I. duPont, Jacksonville
George W. English, Jr., Ft. Lauderdale
W. Glenn Miller, Monticello
W. F. Powers, Secretary, Tallahassee
EXECUTIVE STAFF
J. Hillis Miller, Ph.D., President8
J. Wayne Reitz, Ph.D., Provost for Agr.'
Willard M. Fifield, M.S., Director
J. R. Beckenbach, Ph.D., Asso. Director
L. 0. Gratz, Ph.D., Asst. Dir.,
Rogers L. Bartley, B.S., Admin. Mgr.3
Geo. R. Freeman, B.S., Farm Superintendent

MAIN STATION, GAINESVILLE

AGRICULTURAL ECONOMICS
H. G. Hamilton, Ph.D., Agr. Economist'
R. E. L. Greene, Ph.D., Agr. Economist
M. A. Brooker, Ph.D'., Agr. Economist s
Zach Savage. M.S.A., Associate
A. H. Spurlock, M.S.A., Associate
D. E. Alleger, M.S., Associate
D. L. Brooke, M.S.A., Associate4
M. R. Godwin, Ph.D., Associate3
H. W. Little, M.S., Assistant4
Tallmadge Bergen, B.S., Assistant
W. K. McPherson, M.S., Economist
Eric Thor, M.S., Agr. Economist
J. L. Tennant, Ph.D., Agr. Economist
H. W. Little, M.S., Asst. Agr. Economist

Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. Agr. Economist
J. C. Townsend, Jr., B.S.A., Agr.
Statistician 2
J. B. Owens, B.S.A., Agr. Statistician 2
J. K. Lankford, B.S., Agr. Statistician

AGRICULTURAL ENGINEERING
Frazier Rogers, M.S.A., Agr. Engineer1
J. M. Johnson, B.S.A.E., Agr. Eng.3
J. M. Myers, B.S., Asso. Agr. Engineer
J. S. Norton, M.S., Asst. Agr. Eng.

AGRONOMY
Fred H. Hull, Ph.D., Agronomist
G. B. Killinger, Ph.D., Agronomist3
H. C. Harris, Ph.D., Agronomist
R. W. Bledsoe, Ph.D., Agronomist
W. A. Carver, Ph.D., Associate
Darrel D. Morey, Ph.D., Associate
Fred A. Clark, B.S., Assistant
Myron C. Grennell, B.S.A.E., Assistant *
E. S. Horner, Ph.D., Assistant
A. T. Wallace, Ph.D., Assistant
D. E. McCloud, Ph.D., Assistant 3
H. E. Buckley, B.S.A., Assistant
E. C. Nutter, Ph.D., Asst. Agronomist

ANIMAL HUSBANDRY AND NUTRITION
T. J. Cunha, Ph.D., An. Hush.13
G. K. Davis, Ph.D., Animal Nutritionist
S. John Folks, Jr., M.S., Asst. An. Hush. '
Katherine Boney, B.S., Asst. Chem.
A. M. Pearson, Ph.D., Asso. An. Hush.s
John P. Feaster, Ph.DI., Asst. An. Nutri.
H. D. Wallace, Ph.D., Asst. An. Husb.3
M. Koger, Ph.D., An. Husbandman 3
G. E. Combs, Jr., B.S.A., Asst. Animal
Husbandman
E. F. Johnston, M.S., Asst. Animal Husband-
man
DAIRY SCIENCE
E. L. Fouts, Ph.D., Dairy Tech.'
R. B. Becker, Ph.D., Dairy Husb.3
S. P. Marshall, Ph.D., Asso. Dairy Husb.3
W. A. Krienke, M.S., Asso. Dairy Tech. 3


P. T. Dix Arnold, M.S.A., Asst. Dairy Husb.'
Leon Mull, Ph.D., Asso. Dairy Tech.
H. H. Wilkowske, Ph.D., Asst. Dairy Tech.
James M. Wing, M.S., Asst. Dairy Husb.

EDITORIAL
J. Francis Cooper, M.S.A., Editors
Clyde Beale, A.B.J., Associate Editor
L. Odell Griffith, B.A.J., Asst. Editor
J. N. Joiner, B.S.A., Assistant Editor

ENTOMOLOGY
A. N. Tissot, Ph.D., Entomologist1
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

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

HORTICULTURE
G. H. Blackmon, M.S.A., Horticulturist1
F. S. Jamison, Ph.D., Horticulturist
Albert P. Lorz, Ph.D., Horticulturist
R. K. Showalter, M.S., Asso. Hort.
R. A. Dennison, Ph.D., Asso. Hort.
R. H. Sharpe, M.S., Asso. Horticulturist
V. F. Nettles, Ph.D., Asso. Horticulturist
F. S. Lagasse, Ph.D., Asso. Hort.
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 Thompson, M.S.A., Asst. Hort.

LIBRARY
Ida Keeling Cresap, Librarian

PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist 1s
Phares Decker, Ph.D., Plant Pathologist
Erdman West, M.S., Mycologist and Botanist
Robert W. Earhart, Ph.D., Plant Path.5
Howard N. Miller, Ph.D., Asso. Plant Path.
Lillian E. Arnold, M.S., Asst. Botanist
C. W. Anderson, Ph.D., Asst. Plant Path.
POULTRY HUSBANDRY
N. R. Mehrhof, M.Agr., Poultry Husb.'1
J. C. Driggers, Ph.D., Asso. Poultry Hush.
SOILS
F. B. Smith, Ph.D., Microbiologist a
Gaylord M. Volk, Ph.D., Soils Chemist
J. R. Henderson, M.S.A., Soil Technologist3
J. R. Neller, Ph.D., Soils Chemist
Nathan Gammon, Jr., Ph.D., Soils Chemist
Ralph G. Leighty, B.S., Asst. Soil Surveyor3
G. D. Thornton, Ph.D., Asso. Microbiologist3
Charles F. Eno, Ph.D., Asst. Soils Micro-
biologist 4
H. W. Winsor, B.S.A., Assistant Chemist
R. E. Caldwell, M.S.A., Asst. Chemistsa
V. W. Carlisle, B.S., Asst. Soil Surveyor
James H. Walker, M.S.A., Asst. Soil
Surveyor
S. N. Edson, M.S., Asst. Soil Surveyor a
William K. Robertson, Ph.D., Asst. Chemist
O. E. Cruz, B.S.A., Asat. Soil Surveyor
W. G. Blue, Ph.D., Asst. Biochemist
J. G. A. Fiskel, Ph.D., Asst. Biochemist
H. F. Ross, B.S., Soils Microbiologist
L. C. Hammond, Ph.D., Asst. Soil Physicist s
VETERINARY SCIENCE
D. A. Sanders, D.V.M., Veterinarian
M. W. Emmel, D.V.M., Veterinarians
C. F. Simpson, D.V.M., Asso. Veterinarian
L. E. Swanson, D.V.M., Parasitologist
Glenn Van Ness, I.V.M., Asso. Poultry
Pathologist
W. R. Dennis, D.V.M., Asst. Parasitologist









BRANCH STATIONS

NORTH FLORIDA STATION, QUINCY
W. C. Rhoades, Jr., M.S., Entomologist
R. R. Kincaid, Ph.D., Plant Pathologist
L. G. Thompson, Jr., Ph.D., Soils Chemist
W. H. Chapman, M.S., Asso. Agronomist
Frank S. Baker, Jr., B.S., Asst. An. Hush.
T. E. Webb, B.S.A., Asst. Agronomist

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

CITRUS STATION, LAKE ALFRED
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. 0. 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. Horticulturist
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 4
R. M. Pratt, Ph.D., Asso. Ent.-Pathologist
J. W. Davis, B.S.A., Asst. in Ent.-Path.
W. A. Simanton. Ph.D., Entomologist
E. J. Deszyck, Ph.D., Asso. Horticulturist
C. D. Leonard, Ph.D., Asso. Horticulturist
I. Stewart, M.S., Asst. Biochemist
W. T. Long, M.S., Asst. Horticulturist
M. H. Muma, Ph.D., Asst. Entomologist
F. J. Reynolds, Ph.D., Asso. Hort.
B. J. Elvin, B.S., Asst. Hort.
W. F. Spencer, Ph.D., Asst. Chem.
I. H. Holtsberg, B.S.A., Asst. Entomologist-
Pathologist
K. G. Townsend, B.S.A., Asst. Entomologist-
Pathologist
J. B. Weeks, B.S., Asst. Entomologist
E. C. Lundbert, B.S.A., Asst. Biochemist
N. F. Shimp, M.S., Asst. Chem.
R. B. Johnson, M.S., Asst. Entomologist

EVERGLADES STATION. BELLE GLADE
R. V. Allison, Ph.D., Vice-Director in Charge
Thomas Bregger, Ph.D., Physiologist
J. W. Randolph, M.S., Agricultural Engr.
W. T. Forsee, Jr., Ph.D., Chemist
R. W. Kidder, M.S., Asso. Animal Hush.
C. C. Seale, Asso. Agronomist
N. C. Hayslip, B.S.A., Asso. Entomologist
E. A. Wolf, M.S., Asst. Horticulturist
W. H. Thames, M.S., Asst. Entomologist
W. N. Stoner, Ph.D., Asst. Plant Path.
W. A. Hills, M.S., Asso. Horticulturist
W. G. Genung, B.S.A., Asst. Entomologist
Frank V. Stevenson, M.S., Asso. Plant Path.
Robert J. Allen, Ph.D., Asst. Agronomist
V. E. Green, Ph.D., Asst. Agronomist
J. F. Darby, Ph.D., Asst. Plant Path.
H. L. Chapman, Jr.. M.S.A., Asst. An. Husb.
Thos. G. Bowery. Ph.D., Asst. Entomologist
V. L. Guzman, Ph.D., Asst. Hort.
M. R. Bedsole, M.S.A., Asst. Chem.


SUB-TROPICAL STATION, HOMESTEAD
Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
D. 0. 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

WEST CENTRAL FLORIDA STATION,
BROOKSVILLE
William Jackson, B.S.A., Animal Husband-
man in Charge 2

RANGE CATTLE STATION, ONA
W. G. Kirk, Ph.D., Vice-Director in Charge
E. M. Hodges, Ph.D., Agronomist
D. W. Jones, M.S., Asst. Soil Technologist

CENTRAL FLORIDA STATION, SANFORD
R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
J. W. Wilson, Sc.D., 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.

WEST FLORIDA STATION, JAY
C. E. Hutton, Ph.D., Vice-Director in Charge
H. W. Lundy, B.S.A., Associate Agronomist
W. R. Langford, Ph.D., Asst. Agron.

SUWANNEE VALLEY STATION,
LIVE OAK
G. E. Ritchey, M.S., Agronomist in Charge

GULF COAST STATION, BRADENTON
E. L. Spencer, Ph.D., Soils Chemist in Charge
E. G. Kelsheimer, Ph.D., Entomologist
David G. A. Kelbert, Asso. Horticulturist
Robert O. Magie, Ph.D., Plant Pathologist
J. M. Walter, Ph.D., Plant Pathologist
Donald S. Burgis, M.S.A., Asst. Hort.
C. M. Geraldson, Ph.D., Asst. Hort.
W. G. Cowperthwaite, Ph.D., Asst. Hort.
Amegda Jack, M.S., Asst. Soils Chemist

FIELD LABORATORIES

Watermelon, Grape, Pasture-Leesburg
C. C. Helms, Jr., B.S., Asst. Agronomist 4
L. H. Stover, Asst. in Hort.

Strawberry-Plant City
A. N. Brooks, Ph.D., Plant Pathologist

Vegetables-Hastings
A. H. Eddins, Ph.D., Plant Path. in Charge
E. N. McCubbin, Ph.D., Horticulturist
T. M. Dobrovsky, Ph.D., Asst. Entomologist

Pecans-Monticello
A. M. Phillips, B.S., Asso. Entomologist2
John R. Large, M.S., Asso. Plant Path.

Frost Forecasting-Lakeland
Warren 0. Johnson, B.S., Meteorologist2

1 Head of Department
2 In cooperation with U. S.
3 Cooperative, other divisions, U. of F.
SOn leave.







CONTENTS
Page
INTRODUCTION .......... ..........................---.....-- -.. -- -----... 5
D ISEASES -.... .... ---.. ....-- -- --.-. -...-.- ..--- .--..- -- -------- 6
M ajor D diseases .. ... .. ...-.--- ..-.- -----.---. --.- ... ...... 6
Alternaria Leaf Spot .............. ......... .. .............. 6
Bacterial Soft Rot -........--..-.... -...-.... ..........- ........ 11
Black Rot .... -.. ----....- ............ ..-- ....... .... 14
Dam ping-off ....... ............................. ...-- -- --- .... 19
Downy M ildew ......... ...................-..... ....---.. ........-- 20
Rhizoctoniose --.................. ...............- ..............................- 26
Sclerotiniese -.-....--- .......................................--- 28
Y yellow s -............ .................-........ ... --- 31
M inor Diseases .........-......... .... .............. ... .......... 36
A nthracnose ..----.... ................... .. .-.... .- ..- -.---. 36
Bacterial Leaf Spot ....... ..- ........ ..... ................. ----... 37
Blackleg ........- -..... .............................. 37
Cercospora Leaf Spot -....-...--....... -. ... -- ---........ 37
Clubroot .................. .................. ......... ..................... ....... 37
Gray Mold __..-----_---- -------------------------------- ------------------------ ----------- 40
Gray M old ......................................... ..................... -.... .... 40
Mosaic and Virus Diseases ..........-. .-.............................. ----.. 40
Powdery Mildew ...... -- .. ..-....- .- ...................... .... 41
White Rust ...- ------------............ ..-- ...-----.. 41
W white Spot --....-- ---...... ... .. ... ... 41
NUTRITIONAL DEFICIENCIES .... ........ ....---- --.....-------... 42
Boron Deficiency -...- ...- .... -- --.. ------.--.. ...-............. -......--- 42
M anganese Deficiency .......... .............. ............---------...-.. 45
N itrogen Deficiency ..... ............................-- .....- ..-...-.... 47
Potash Deficiency -...-........ ... ...- ....---.......... ......- 47
W hiptail of Cauliflower ...... ......-- ........... ......... .....-- 48
INJURIES .......... ...... .. ...... ............. ................- ........-.- ------ ... 51
Bolting ... ................................... ..... 51
Drought Injury ............... .................... ............... ... ... 53
Fertilizer Injury and Salt Sickness ....-- .............. ......................... 53
Freezing Injury ................................ ... .......... .. ..... ......... 54
G row th Cracks .......... .. ... ... .... .. .... ........... .. ............... 57
Oedem a --... .... ...... ...... ..... .. ...-.. ... ... ... -......... 57
Root-Knot ........... 57
Spray and Dust Injury .... .... ----. .. -...-..---... -.---.. ..... 59
Variegated Leaves .......-...-- ....-- ......................--.----.... 61
W after Injury -.. .. ........ ... .....--. ..- .... 61
ACKNOWLEDGMENTS ... ................. ...... 62
LITERATURE CITED ..... ... .... ................. ......... 62









Diseases, Deficiencies and Injuries of

Cabbage and Other Crucifers in Florida

By A. H. EDDINS
Plant Pathologist in Charge, Vegetable Investigations Laboratory

INTRODUCTION

Crucifers include many wild and cultivated plants belonging
to the botanical family Cruciferae. Crucifers referred to in
this bulletin are members of the genus Brassica and include
cabbage, cauliflower, Chinese cabbage, collards, broccoli, brussels
sprouts, kale, kohlrabi, mustard, rutabaga and turnip. Cabbage
is the most important crucifer grown in Florida. According
to USDA, Bureau of Agricultural Economics, commercial acre-
ages planted to crucifers in Florida in the 1949-1950 season were
cabbage, 18,000 acres and cauliflower, 850 acres. In addition
to acreages reported for cabbage and cauliflower, commercial
quantities of collards, broccoli, Chinese cabbage, mustard, tur-
nips, rutabaga and kale are grown in Florida. Cabbage and
other crucifers are grown also in home gardens.
The main crucifer-growing season in Florida begins in August
when the earliest plant beds and fields are seeded and ends the
following May when the latest crops are harvested. Most of the
cabbage crop is grown and harvested during the five-month
period November 1 to March 30. Collards, mustard and turnips
are the only crucifers grown during the summer in Florida.
They are planted in home gardens and in some localities they
are grown more extensively to supply local markets.
Diseases of crucifers are caused by fungi, bacteria and viruses.
Most diseases which have been found on crucifers in different
parts of the world are present in Florida.
Nutritional deficiencies may cause a discoloration and mal-
formation of the foliage and in extreme cases stunting and
premature death of cabbage and other cruciferous plants. They
occur if the proper nutrients are lacking in the soil or if the
nutrients are present in an unavailable form.
Other injuries of crucifers may be caused by insects, nema-
todes, excesses of fertilizers, soluble soil salts and chemicals in
sprays and dusts, hereditary defects, mechanical agents and the
weather.






Florida Agricultural Experiment Stations


The characteristics of diseases, nutritional deficiencies and
injuries which have been observed on cruciferous plants in
Florida are described in this bulletin as they appear on crucifers
most seriously affected. Control measures or preventive known
to be effective in reducing losses from these troubles are dis-
cussed.

DISEASES
Diseases discussed in this bulletin are classified as major or
minor. One or more of the major diseases occur every year in
some parts of the state and cause the heaviest losses; the minor
ones are not as prevalent and destructive. Some diseases are
transmitted in the seeds and others are caused by organisms
which live in the soil from one season to the next and by those
which spread from diseased crucifers and other host plants to
healthy crucifers.
A program for controlling diseases of crucifers involves (1)
planting of yellows-resistant varieties of cabbage in yellows-sick
soil, (2) use of disease-free seeds and plants, (3) treatment of
seeds with hot water and chemicals, (4) soil treatments, (5)
rotation of seedbeds, (6) treatment of plants with fungicides,
(7) careful handling to prevent unnecessary bruising during
harvesting and packing, (8) rejecting diseased plant parts for
shipment, (9) precooling and refrigeration of shipments to
prevent development of diseases in transit and (10) plowing
under diseased plants and crop refuse in abandoned seedbeds
and harvested fields.

MAJOR DISEASES
ALTERNARIA LEAF SPOT
Alternaria leaf spot, Alternaria spot or black spot, is a common
disease of cabbage and other crucifers. It is known also as
brown rot or browning of cauliflower. The principal causal
fungus is Alternaria oleracea Milbrath (11).1 A similar but less
important leaf spot of cabbage and cauliflower is caused by A.
brassicae (Berk.) Sacc., which is a common parasite on turnip
and Chinese cabbage (8). During warm, moist seasons plants
in seedbeds may be injured or killed by Alternaria spot and
stands and yields may be reduced in fields set with plants affected
with the disease. Losses occur also when the disease causes

SItalic figures in parentheses refer to Literature Cited.






Florida Agricultural Experiment Stations


The characteristics of diseases, nutritional deficiencies and
injuries which have been observed on cruciferous plants in
Florida are described in this bulletin as they appear on crucifers
most seriously affected. Control measures or preventive known
to be effective in reducing losses from these troubles are dis-
cussed.

DISEASES
Diseases discussed in this bulletin are classified as major or
minor. One or more of the major diseases occur every year in
some parts of the state and cause the heaviest losses; the minor
ones are not as prevalent and destructive. Some diseases are
transmitted in the seeds and others are caused by organisms
which live in the soil from one season to the next and by those
which spread from diseased crucifers and other host plants to
healthy crucifers.
A program for controlling diseases of crucifers involves (1)
planting of yellows-resistant varieties of cabbage in yellows-sick
soil, (2) use of disease-free seeds and plants, (3) treatment of
seeds with hot water and chemicals, (4) soil treatments, (5)
rotation of seedbeds, (6) treatment of plants with fungicides,
(7) careful handling to prevent unnecessary bruising during
harvesting and packing, (8) rejecting diseased plant parts for
shipment, (9) precooling and refrigeration of shipments to
prevent development of diseases in transit and (10) plowing
under diseased plants and crop refuse in abandoned seedbeds
and harvested fields.

MAJOR DISEASES
ALTERNARIA LEAF SPOT
Alternaria leaf spot, Alternaria spot or black spot, is a common
disease of cabbage and other crucifers. It is known also as
brown rot or browning of cauliflower. The principal causal
fungus is Alternaria oleracea Milbrath (11).1 A similar but less
important leaf spot of cabbage and cauliflower is caused by A.
brassicae (Berk.) Sacc., which is a common parasite on turnip
and Chinese cabbage (8). During warm, moist seasons plants
in seedbeds may be injured or killed by Alternaria spot and
stands and yields may be reduced in fields set with plants affected
with the disease. Losses occur also when the disease causes

SItalic figures in parentheses refer to Literature Cited.






Diseases, Deficiencies and Injuries of Cabbage


spotting and decay of cabbage and cauliflower heads. The dis-
ease has been important in north and central Florida during
three of the last five years. Damage has been heaviest in the
Hastings area in fields set with diseased plants imported from
Georgia and other nearby states.
In Florida the causal fungi
may live over on collards and
other hosts which grow during
the summer. Alternaria-in-
fected seed, spores on seeds and
debris from a previous crop and -r
diseased plants are sources of ,
Alternaria spot. Spores are '
disseminated by the wind and
also by rain, irrigating water,
farm machinery and insects. Al-
ternaria fungi are able to infect
the host at any age and inde-
pendently of any injury. A
spore in contact with a leaf
germinates in rainwater or dew
and the fungus grows into the
leaf. The Alternaria spot ap-
pears within two to five days
after inoculation. The disease
develops at temperatures rang-
ing between 35' and 950 F.; the "
most favorable temperatures are
770 to 860 F. (28). Frequent
rains and heavy dews which
keep plants wet until midmorn-
ing or longer cause rapid de-
velopment and spread of the
disease. Fig. 2.-Alternaria cankers on a
cabbage stem.
Symptoms.-Alternaria fungi
cause damping-off of seedlings and produce spots on leaves and
spots and cankers on stems of cabbage, cauliflower and other
susceptible plants (11, 15, 16, 27, 28). Size and shape of the
spots and other characteristics of the disease depend on the part
of the plant affected and on the temperature and humidity.
The first symptoms on the aerial part of a cabbage or cauli-
flower stem consist of dark brown, longitudinal spots about 1/16






Florida Agricultural Experiment Stations


to 1/8 inch in length and 1/64 inch in width. They may enlarge
and become 1/ to 1 inch in length, and longitudinal cracks
frequently appear in the dead and discolored epidermis. Brown
lesions may appear on the stem below ground. If the lesions
develop into cankers and girdle the stem the young plant may
wilt and die before it becomes large enough for transplanting.
Roots invaded by the fungus also turn brown. Discolored parts
of stems and roots are brittle. Severely-affected plants die
within a few days after transplanting and others produce new
roots on healthy parts of the stem below ground but seldom
develop into strong plants, Fig. 2.
Spots on stalks, petioles, veins and on thick, basal parts of
leaves are longitudinal, purple to brown, few to many, but
generally remain under 1/ inch in length and 1/16 inch in width,
except during warm, wet weather, when they may enlarge and
coalesce to form lesions two inches or more in length.
The oldest leaves near the bottom of the plant are the first
ones affected. Small, brown, sunken spots appear on the leaf
blade and usually are surrounded by a narrow yellow zone which
blends with the normal green of the leaf. Spots are circular,
oval or irregularly shaped and vary from small dots to areas
two inches or more in diameter. Spots sometimes enlarge,
coalesce and cover the entire leaf. Many spots are marked by
a series of dark brown concentric areas alternating with light


Fig. 3.-Alternaria spots on sections of cabbage leaves.







Diseases, Deficiencies and Injuries of Cabbage


brown zones which is a distinguishing characteristic of the dis-
ease. Fig. 3. Sooty masses of spores of the fungus are produced
over the surface of large spots during rainy weather, or when
the plants remain wet with dew until midmorning. Few spores
are produced during dry periods and these are formed in small
brown to black areas scattered over the spot. Leaf tissues
killed by the fungus crack when dry and dead parts fall out,
giving the leaf a ragged appearance. Old, severely-affected
leaves turn yellow and are shed and new leaves become infected
successively as they appear. Healthy plants may become in-
fected after they are transplanted, and the disease never dis-
appears from an affected plant.
Numerous spots on the wrapper and head leaves of cabbage
ruin the appearance and salability of the heads, Fig. 4. During


Fig. 4.-Cabbage head severely affected with Alternaria spot.







Florida Agricultural Experiment Stations


wet weather the fungus grows into the underlying leaves and
produces a soft rot of the head. Furthermore, soft rot bacteria
may enter the spots and hasten decay of the head.
Symptoms of the disease on other crucifers are similar to
those on cabbage. The disease appears on cauliflower leaves
and curds as water-soaked spots which turn dark brown to
black as they grow older, Fig. 5. The spots enlarge slowly in
dry weather and remain dry and firm. In wet weather they
increase rapidly in size and become wet and soft. Broccoli heads
are ruined when the causal fungus produces numerous small,
black, sunken spots on the flower clusters.





it-



.


.3% ^.. .d*f







Fig. 5.-Alternaria spots on cauliflower leaf and head.

Control.-Hot-water-treatment of seeds as recommended for
control of black rot will kill Alternaria spores on the seeds.
Treated seed also should be dusted before planting with thiram
or Semesan as recommended for control of seed decay and pre-
emergence damping-off of seedlings due to Alternaria fungi and
other organisms (19).
Alternaria-affected plants should not be transplanted, as the
disease will continue to develop in them after they are set in
the field and spread to healthy ones.
Ferbam, ziram and copper-containing fungicides may be used
to control Alternaria spot but they give poor control of downy







Diseases, Deficiencies and Injuries of Cabbage


mildew. Since mildew is usually present it is more economical
to control both diseases with a single fungicide. Fortunately,
Spergon spray, Spergon dust and nabam spray are very effective
against both diseases and one of these should be used as directed
in the section on downy mildew. Fungicides are needed to
control Alternaria spot in warm, wet seasons which favor
growth of the fungus and development and spread of the dis-
ease. It is not necessary to spray or dust a crop during dry
periods when only a trace of the disease is present on a few
plants.
Alternaria-affected cabbage, cauliflower and broccoli heads
should be left in the field or discarded at the packing station as
they are likely to decay in transit or after they reach the
market.
Cauliflower curds from diseased crops which are free from
Alternaria spot at the loading station may become infected
while in transit and be spotted and decayed on arrival at the
market. Since low temperatures check growth of the causal
organisms and development of the disease, packaged heads should
be precooled at the loading station and shipped in refrigerator
cars or trucks held at temperatures of 40' to 450 F. during transit
(28).
Left-over plants and crucifer refuse in old plant beds and
harvested fields should be plowed under to prevent Alternaria
spores on diseased plants, dead leaves and stubble from being
blown into nearby fields and infecting healthy plants.

BACTERIAL SOFT ROT -
Bacterial soft rot is a destructive field, transit and storage
disease of vegetables including cabbage, cauliflower and other
crucifers. It is caused by a group of soft rot bacteria typified
by Erwinia carotovora (L. R. Jones) Holland (15). The disease
is secondary in nature. The bacteria are universally present
and their relative abundance depends on the supply of moisture
and of dead plant material. Temperatures ranging between 690
and 77C F. are most favorable for development of soft rot; little
development occurs above 910 F. and below 46 F. (15). The
causal organisms invade dead, senescent and injured tissues only
when they are wet. They enter plants through injuries caused
by freezing, farm machinery and insects and lesions of other
diseases. Bruises which occur when crops are harvested and
packed also provide openings for the bacteria. The disease







Florida Agricultural Experiment Stations


may cause serious losses in cabbage and cauliflower fields during
extremely wet periods and also in poorly refrigerated shipments
which are cut, packed and loaded during rainy weather.


Fig. 6.-Cabbage head blackened and decayed by bacterial soft rot.

Symptoms.-Affected parts of a plant appear water-soaked at
first. This is followed by a soft, mushy, sticky decay and a bad
odor. An affected plant stem decays rapidly during warm, wet
weather and the plant wilts, collapses and dies. Affected cab-
bage and cauliflower heads rot rapidly and turn brown to black,







Diseases, Deficiencies and Injuries of Cabbage 13



































Fig. 7.-Discolored and decayed spots on cauliflower stem and curd
caused by bacterial soft rot.

Figs. 6 and 7. The disease is attended by foul, nauseating
odors caused mostly by secondary organisms. It spreads by
contact from decayed to healthy heads that are packed or piled
together.
Control.-An adequate spraying and dusting program should
be followed during the last weeks of the growing period to pro-
tect heads from Alternaria leaf spot and downy mildew, as
lesions caused by these diseases provide openings for soft rot
bacteria.







Florida Agricultural Experiment Stations


Proper handling of the crop during harvest to avoid all un-
necessary wounds and bruises is important.
Crops should not be harvested on rainy days, as wet, rainy
weather favors the disease by disseminating and bringing about
an increase in the number of soft rot bacteria and by moistening
injured tissues and lesions caused by other diseases, making
them more susceptible to infection by the bacteria.
Heads affected with other diseases, particularly yellows and
black rot, and those already affected with soft rot should be
rejected for shipment.
Precooling and shipment of the load at 40 to 45 F. in prop-
erly ventilated refrigerator cars and trucks check development
of the disease in transit (15).

BLACK ROT
Black rot is the most common and destructive bacterial disease
of cabbage, cauliflower and other crucifers in Florida. The
causal bacterium is Xanthomonas campestris (Pam.) Dows. The
disease is present in Florida throughout the year; collards carry
it through the summer months. Damage from the disease varies
from slight to total loss of the crop, depending upon the source
of infection and weather conditions. If the disease is present
in the planting stock and favorable weather prevails it may
destroy a large percentage of cabbage and cauliflower plants
before they produce marketable heads and the remainder of the
crop may be made unsafe for shipment.
The causal bacteria may be carried in and on the seed. When
diseased seed are planted and germinate the bacteria multiply
in the liquid in the stem of the seedling and move through the
conducting vessels and infect the leaves. Secondary infection
occurs when bacteria from the soil or from diseased plants enter
water pores and wounds in leaves.
The bacteria are scattered by wind, farm machinery, insects
and animals, but spattering rain and water from sprinklers are
the chief agents of dissemination, especially in plant beds.
Since most infected leaves drop off young plants when they are
pulled and carried to the field, black rot may not be detected in
diseased plants when they are being transplanted. Under such
conditions several weeks may elapse before the disease develops
enough to be seen in affected plants after they are set in the
field.







Diseases, Deficiencies and Injuries of Cabbage


The causal bacteria grow best at about 86 F.; the lower
limit for growth is 400 F. and the upper 102 F. (15). The dis-
ease develops and spreads rapidly during the fall and spring
when there are heavy dews and frequent showers and the days
are warm and the nights cool. Its appearance during the first
few weeks after plants are set in the field indicates infection
and spread in the plant bed. An outbreak during the heading
period is due mostly to infection and spread after transplanting.
Observations at Hastings during the last three years indicate
that non-treated, diseased seed and affected transplants im-
ported from other states are the principal sources of black rot




'A





-7





.- -AO


Fig. 8.-Cabbage leaf tissues discolored and veins blackened by
black rot bacteria.







Florida Agricultural Experiment Stations


-AI


Fig. 9.-Section of a cauliflower leaf showing discoloration, cracking,
drying and loss of parts of leaf tissue caused by black rot.

infection. The disease also has appeared in plants grown in soil
infested with the causal bacteria. However, a trace to less than
5 percent of the disease has been observed in most commercial
fields set with black rot-free plants. In a test at Hastings only
8 percent of the cabbage plants originating from hot-water-
treated seed were affected with black rot in 1949 when grown
in soil in which all of the plants were affected with the disease
in 1948. None of the cauliflower plants originating from hot-







Diseases, Deficiencies and Injuries of Cabbage


water-treated seed showed any symptoms of black rot when
grown in this soil in 1950.
Symptoms.-Patches of yellow and light brown with a network
of black veins appear in leaves of affected plants. Symptoms
of systemic infection in a cabbage leaf are shown in Fig. 8 and
secondary infection at the margin of a leaf is illustrated in Fig.
1. Symptoms in cauliflower leaves are similar to those in cab-
bage leaves but sometimes differ, as is shown in Fig. 9. Some
plants infected in the seedling stage are killed in the plant bed
or soon after they are transplanted while others are stunted,
curl to one side and produce deformed heads.
Most plants infected late in the growing season produce heads
of normal size, but those with discolored tissues are not salable.


I it
Fig. 10.-Black rot of cabbage. Sections of stems with black water
vessels (left) and a head with black decayed tissue in the stem and in-
terior leaves.


ti







Florida Agricultural Experiment Stations


Some typical symptoms of the disease in a cabbage stem and
head are shown in Fig. 10. Discolored leaves are shed from the
bottom of the plant upward; all may be shed if the disease
develops rapidly and the plant is not destroyed by soft rot
bacteria. In leaves infected in their margins the yellow spots
are mostly wedge-shaped with the tip of the wedge pointed
toward the midrib. An offensive odor is produced when soft
rot organisms enter an affected plant.
Control.-Treatment of seed is of great importance in control
of black rot, as the disease develops in plants grown from infected
and contaminated seed (3). The causal bacteria in or on cabbage
and brussels sprouts seeds are killed by treating the seeds for
25 minutes in water held at 1220 F. Broccoli, cauliflower, col-
lards, kale, kohlrabi, rutabaga and turnip seeds should be soaked
only 18 minutes in hot water, as their germination may be re-
duced by longer treatment. The treatment will reduce germina-
tion unless it is made properly. Old, weak seed will not survive
hot-water treatment. Consequently, seed should be tested before
treatment and stocks germinating less than 85 percent discarded.
The seed should be immersed in cold water immediately after
treatment, drained for about five minutes and then spread on
trays and dried. One or more central seed-treating stations run
by trained operators are recommended for each cabbage-growing
area.
Most of the seeds used in the production of cabbage and
cauliflower crops at Hastings during the last three years were
treated with hot water at two central stations at a cost of 25 to
50 cents a pound to the grower, depending on the quantity
treated. Results have been good, as black rot has caused little
or no loss in crops grown from treated seed. On the other hand
10 to 50 percent or more of the plants have been affected with
black rot and part of the crop has been destroyed by the disease
in fields set with plants grown locally from non-treated diseased
seed and also in fields set with affected plants imported from
other states.
Crucifer seeds grown in the Puget Sound area of Washington
are free from black rot and can be used without treatment (23).
However, most cabbage, cauliflower, broccoli and other crucifer
seeds require treatment as they come from areas where the dis-
ease occurs.
Crucifer seeds should be planted in new land or in old land in
which cabbage and other crucifers were not grown the previous







Diseases, Deficiencies and Injuries of Cabbage


year, as soils in such locations usually are free from black rot
bacteria. Observations indicate that it is not necessary to
rotate cabbage fields for control of black rot at Hastings if crops
are set with black rot-free plants, as losses have been negligible
in crops grown from such plants in fields where the disease
caused severe losses the previous year.
Cabbage heads which are not severely affected with black rot
at harvest may be salvaged for market by removing the wrapper
leaves which show infection near their margins. However, heads
with discolored, overlapping leaves and blackened water vessels
in their stems may decay in transit and should be left in the
field or discarded at the packing station.

DAMPING-OFF
Damping-off of cabbage and other plant seedlings is caused by
soil-inhabiting organisms. Principal ones associated with the
disease in Florida are Pythium sp. and other fungi, including
those which cause rhizoctoniose, downy mildew, sclerotiniose and
Alternaria leaf spot. Damping-off develops most rapidly at mod-
erate to high temperatures in wet soils following heavy rains or
over-irrigation. A few cloudy, rainy days in the summer and
fall months when temperatures are above 750 F. are likely to
cause serious outbreaks of the disease (21).
Symptoms.-Wilting at tips of leaves of seedlings is an early
symptom of damping-off. The appearance of a water-soaked,
collapsed area in a stem of a plant below or near the soil line is
a distinguishing characteristic. In final stages the shrunken and
browned or blackened stem is no longer able to hold the seedling
erect, the top wilts completely and the plant falls over on the
soil and dies. Damped-off plants appear in more or less circular
areas in broadcasted seedbeds. If the seedlings are in rows the
disease spreads in both directions from the place it originated.
Damped-off areas may be several inches long but each one is
usually confined to a single row. Under moist conditions white
mycelia of some of the causal fungi may be seen on dead plants
and the surrounding soil (27).
Control.-Since soils used for seedbeds year after year are
likely to become severely infested with damping-off fungi, it is
best to plant seeds in new land or rotate seedbeds in old land as
recommended for control of black rot.
As most damping-off fungi thrive in a wet soil, the best
location for a seedbed is on land that can be drained rapidly







Florida Agricultural Experiment Stations


after heavy rains. It is necessary to use narrow, raised beds,
12 to 18 inches wide on top and 8 to 10 inches high for growing
plants on flatwoods soils at Hastings and other places where
natural drainage is poor. On better drained soils plants are
grown successfully on the level or in beds 3 to 5 feet wide and
4 to 6 inches high.
Shallow cultivation of the soil between rows of plants and
plowing out the alleys between beds after heavy rains will
aerate the soil and lower the water table and thus reduce losses
from damping-off.
Dust treatment of crucifer seeds with thiram (1' teaspoonful
per lb. or 4 ozs. per 100 lbs. of seeds) or Semesan (14 teaspoonful
per lb. or 6 ozs. per 100 Ibs. of seeds) is recommended for pre-
venting seed decay and pre-emergence damping-off of seedlings
(19). Spergon wettable spray and dust and nabam spray used
for control of downy mildew and Alternaria leaf spot reduce
losses from post-emergence damping-off.

DOWNY MILDEW
Downy mildew of crucifers is caused by the fungus Peronos-
pora parasitica (Pers.) ex Fr. The cabbage race of P. parasitica
is parasitic on cabbage, cauliflower, collards, Chinese cabbage,
brussels sprouts, broccoli, kale and kohlrabi. It is the most de-
structive seedling disease of cabbage, cauliflower and broccoli in
Florida. In non-protected plant beds in the Hastings area 50
percent or more of the plants may be stunted or killed by the
disease during periods of cool, moist weather. Losses also occur
when head leaves of cabbage are spotted by mildew.
The disease may be initiated by resting spores of the fungus
which live over the summer in the soil. Primary infection de-
velops when a resting spore in contact with the hypocotyl or
stem of a young cabbage seedling germinates and attacks it (9).
From this point the fungus grows into the seedling and produces
spores on the surface of the seed leaves and stem. Spores are
scattered mostly by wind and rain. Those which come in con-
tact with leaves germinate in drops of rain or dew and infect
the leaves. Spores which are blown into new plant beds from
diseased plants in old nearby beds and fields are common sources
of the disease.
The disease is most destructive during cool, damp weather
and may be present on susceptible host plants in Florida from
September to the following May. The fungus grows best and







Diseases, Deficiencies and Injuries of Cabbage


the disease develops rapidly when night temperatures range
between 500 and 600 F. for four or more nights in succession
and the plants remain wet until 10 to 11 o'clock in the mornings.
Little growth of the fun-
gus occurs below 400 F.

heavy dews occur on
several successive nights
and the days are dry and
sunny the disease may
kill plants in the seed-
leaf stage and retard the '. -
growth of others (5, 7).
Symptoms. Downy
mildew first appears on
the seed leaves if the
seedlings emerge when
conditions are favorable
for the disease. It can
be recognized in the
morning, when the plants
are wet with dew, by the
presence of a white mold
consisting of mycelium, Fig. 11.-Downy mildew on the lower
spore-bearing structures side of a seedling cabbage leaf (x3).
and masses of spores of
the fungus on the lower sides of infected seed leaves and some-
times on their upper surfaces, Fig. 11. The mold also may
appear on petioles and stems of young seedlings. After the dew
disappears from the leaves during the day the fungus withers
and cannot be seen distinctly with the unaided eye. A diseased
leaf fades to a pale green and yellow and finally turns brown as
it dies. Young seedlings perish when their seed-leaves are
killed before they have formed true leaves.
First symptoms on true leaves consist of scattered pale green
spots about 1/32 inch in diameter. The causal fungus appears
as a white mold on the under side of the leaf. New spots appear
each day and the old ones grow larger, turn yellow and then
brown until most of the leaf is involved, Fig. 12. New leaves
become infected as they appear and the old ones which have
been killed by the disease are shed. Mildew spots which appear
on head leaves of cabbage impair the appearance and market







Florida Agricultural Experiment Stations


value of the head, Fig. 13. The fungus also may grow into the
inner leaves of the head and blacken the tissues invaded, Fig. 14.
Secondary rot-producing organisms which enter spotted heads
may cause decay in the
g- field during wet weather
or after the cabbage is
packed and shipped.
Control.-Soils u s e d
for growing cabbage and
other crucifers suscept-
ible to mildew become in-
fested with spores of the
causal fungus. Since
these spores are the
source of primary infec-
tions, plant beds should
be located on new land or
the seed sown in old land
which was not planted to
cruciferous crops the
previous year.
rOne or more spray and
dust formulations of var-
ious fungicides, including
Spergon, ferbam, nabam,
Phygon, thiram, zineb,
Fig. 12.-Downy mildew spots on a broccoli ziram, sulfur and copper
leaf. have been tested for con-
trol of downy mildew at Hastings during the last 10 years.
Spergon wettable spray, Spergon wettable dust and nabam spray
have given best control of mildew and good control of Alternaria
leaf spot. Formulas and application schedules recommended
for these fungicides at Hastings and in other areas of the state
where they have proved effective are given in Table 1. Quanti-
ties of spray or dust to use on small plants are listed in Table 2.
Spergon wettable spray and dust have usually proved superior
to nabam spray for control of mildew in plant beds and fields
(5). At present growers are advised to use nabam spray for
control of the disease in seeded, transplanted and thinned fields
in those areas of the State where it has proved effective, as it is
cheaper than Spergon wettable spray or dust.
A new form of Spergon known as stabilized Spergon wettable,







Diseases, Deficiencies and Injuries of Cabbage


containing 50 percent of the active ingredient, tetrachloro-para-
benzoquinone, applied at the rate of 2 pounds in 100 gallons of
water was as effective as 48 percent Spergon wettable (4 lbs. in
100 gals. water) in controlling mildew in a cabbage plant bed in
the fall of 1951 at Hastings. If stabilized Spergon wettable
continues to be effective in future tests it probably will replace
Spergon wettable for control of mildew, as the cost of a spray
made from the former should be about one-half that made from
the latter.
Fungicides are preventive and therefore give best control
when applied before plants are affected with mildew. Treat
seedlings three times each week with a one- to two-day interval


Fig. 13.-Downy mildew spots on the outer leaves of a cabbage head.


~'~''''
d~;.-:






~s"~
,c---






Florida Agricultural Experiment Stations


Fig. 14. -Black spots on inner leaves of a cabbage head caused
by downy mildew.

between treatments, except during cold weather when night
temperatures drop below 40 F., when two treatments per week
are sufficient. When plants are being treated with Spergon it
is advisable to spray or dust them after each rain or after irriga-
tion with sprinklers because water washes off the Spergon and
exposes the leaves to infection.
It is necessary to cover plants completely with the fungicide
to control mildew. Best control has been obtained with tractor-
drawn power sprayers and dusters equipped with four- to eight-
row drop booms and with enough nozzles to cover the plants with
spray or dust.
If seedbeds are too wide to be sprayed with a row-crop sprayer
use a power sprayer equipped with an agitator, a suitable length
of high pressure hose and an extension rod with a cutoff at one
end and nozzles mounted at the other end. Hand-operated
sprayers and dusters should be used only in gardens and other


.rt:


a








Diseases, Deficiencies and Injuries of Cabbage


places where plant beds are too small to permit use of larger
machines. Sprayer and auxiliary tanks should be calibrated and
the correct amount of fungicide and water used to make the re-
quired quantity of spray at the strength recommended in Table
1. Do not use more Spergon spray or dust on small plants than
is listed in Table 2, as heavier applications may injure or kill
them. Furthermore, excessive use of Spergon will not control
mildew any better and will increase cost of treatment. Spergon
spray and dust are more effective against mildew than nabam
spray, but there is less danger of injuring small plants by over-
treatment with nabam and growers are advised to use it in plant
beds if they are unable to apply Spergon as directed.
Fungicides are not needed to protect cauliflower curds against
mildew, but the plants should be sprayed when needed to protect
the curds from Alternaria spot.

TABLE 1.-FUNGICIDES RECOMMENDED FOR CONTROL OF DOWNY MILDEW
AND ALTERNARIA LEAF SPOT OF CABBAGE, CAULIFLOWER AND BROCCOLI IN
THE HASTINGS AREA.


Fungicides* i


Spergon
wettable


Nabam


Formula

4 lbs. 48% wet-
table in 100 gals.
water or a dust
containing 12% of
the active ingred-
ient in talc or
other suitable di-
luent.


2 qts. nabam plus
1 lb. zinc sulfate
in 100 gals. water


Application

Seedbed
Begin treatment before either disease is
present (usually within a week to 10
days after planting seed) and repeat 2
or 3 times each week until plants are
set in the field. Quantities of spray
and dust required for treating small
plants are given in Table 2.


Seeded Field
Use same application schedule and
quantities of spray as recommended for
treating seedbeds. Discontinue treat-
ment when plants are thinned to a stand.
Transplanted and Thinned Fields
Begin treatment of plants 2 weeks be-
fore harvest or prior to that time if
Alternaria leaf spot is developing and
spreading rapidly. Apply 100 to 150
gals. of spray per acre every 4 to 5 days,
depending on size of plants. Use a good
commercial spreader-sticker as recom-
mended on the manufacturer's label.

During cool, damp weather apply nabam
spray or Spergon wettable spray or dust
every two to three days to obtain best
control of mildew on heading cabbage.


Spergon wettable is compatible with TEPP, parathion, DDT and chlordane. Nabam
is compatible with DDT, chlordane, toxaphene, TEPP and parathion.







Florida Agricultural Experiment Stations


Discard cabbage heads severely spotted with mildew, as secon-
dary organisms may enter diseased tissues of the head leaves
and cause a soft decay of the heads while they are in transit to
market.
Plow under old plants and refuse in plant beds and fields
immediately after they are abandoned to prevent spread of
mildew from diseased plants and stubble to healthy plants in
nearby plant beds and fields.

TABLE 2.-APPROXIMATE QUANTITIES OF SPERGON WETTABLE AND NABAM
SPRAYS AND SPERGON DUST TO USE AT EACH APPLICATION FOR CONTROL
OF DOWNY MILDEW AND ALTERNARIA SPOT ON SMALL PLANTS.
Narrow 2- to 3-Row Beds,
40 to 42 Inches Apart Beds One Yard Wide
Plant Height I Spray Dust
Spray I Dust Gals. per 100 Lbs. per 100
Gals. per Acre I Lbs. per Acre Sq. Yds. Sq. Yds.
Less than 2
inches .-.. 80 to 100 15 to 20 4 to 5 3% to 1
2 to 4 inches .... 100 to 120 20 to 25 5 to 6 1 to 1/2
4 to 8 inches ... 120 to 150 25 to 35 6 to 7 1 to 2


RHIZOCTONIOSE
Rhizoctoniose is a common disease of vegetable crops including
cabbage, cauliflower and other crucifers. The sterile form of
the fungus is known as Rhizoctonia solani Kiihn. and the spore-
forming stage as Pellicularia filamentosa (Pat.) Rogers. The
disease is more important on cabbage than on other crucifers.
The causal organism is one of the principal seed-rotting and
damping-off fungi and it also attacks seedlings, causing their
stems to shrink, harden and become wirelike.
The fungus produces small black bodies or sclerotia which are
resistant to cold, heat and drought. The sclerotia can live in the
soil for many months. They germinate by forming mycelial
threads which spread through the soil and invade parts of
susceptible plants with which they come in contact. No soils in
Florida are known to be free of the fungus.
The cabbage strain of Rhizoctonia solani grows at tempera-
tures ranging between 48 and 910 F. Experiments have demon-
strated that optimum temperatures for infection of cabbage are
770 to 800 F., the minimum about 530 and the maximum 88 to
900 F. (15). The fungus invades the plant through non-injured







Diseases, Deficiencies and Injuries of Cabbage


tissues or through wounds, provided enough moisture is present
to permit it to grow on the tissues long enough to enter them.
Symptoms.-Several phases of the disease exist, depending
upon the plant part affected.
The damping-off phase is
described in another section
of this bulletin. Stems of
young plants infected after
they have begun to harden
may be severely stunted and
develop wire-stem. This is
the most common and de-
structive phase. Outer tis-
sues of the stem shrivel,
turn brown to black and the
affected part becomes tough
and woody, Fig. 15. In wet
soil decayed and discolored
tissues of the stem slough
off when the plant is pulled
from the soil. Roots of
severely-affected plants turn
brown to black as they decay
and the plant withers and
dies. Plants mildly affected
with wire-stem recover if
conditions are favorable for
growth. Bottom rot and
head rot develop in older
plants when the fungus
grows upward in the stem
and invades the leaves (27).
Control.-No thoroughly
effective method for control-
ling the disease is known. r
Dust treatment of seeds as
described in the section on Fig. 15.-Lower parts of cabbage
stems blackened by wire-stem. (Photo-
damping-off is recommended. graph by Dr. G. F. Weber.)
Seedbeds and fields should be
well-drained and the soil cultivated as soon as possible after
heavy rains to aerate and dry it and thus make conditions less
favorable for plant infection.







Florida Agricultural Experiment Stations


Plants with discolored stems and roots should be discarded at
transplanting time.
Avoid covering parts of leaves with soil when cultivating the
crop, as banking soil around plants creates conditions favorable
for development of stalk and head rot (27).

SCLEROTINIOSE
Sclerotiniose or watery rot is caused by the fungus Sclerotinia
sclerotiorum (Lib.) D By. Cabbage and other crucifers, most
vegetable crops, including beans, lettuce, tomatoes, celery and
potatoes, and many weeds are susceptible to the disease. It may
kill cabbage and cauliflower seedlings in plant beds and it has
destroyed about one-third of the cabbage plants in some Hastings
fields during prolonged cool, rainy weather. In an average
season, however, the number of cabbage plants affected with
sclerotiniose is less than 5 percent in most fields. Losses from
the disease also occur in transit in packages containing one or
more affected heads when loaded. The fungus has a wide tem-
perature range. It can grow and cause infection at 30 F.; the
optimum is between 700 and 78 F.; and there is little or no
growth above 88 F. (15). Moisture is a limiting factor in
development of sclerotiniose. Outbreaks occur during cool
weather when frequent rains, fogs and heavy dews keep plants
wet for long periods.
The fungus is dormant in Florida during the summer and at
other seasons when the weather is warm and dry. It survives
as sclerotia in old plant debris and in the soil. The sclerotia
germinate under favorable conditions and produce mycelial
threads which grow in or on the soil and infect plant parts with
which they come in contact. The sclerotia also form mushroom-
like structures or apothecia which contain special structures
known as asci in which spores are borne. The ascospores are
forcibly discharged from the asci and, when carried by air
currents and deposited on leaves and stems of plants, germinate
and infect these parts if conditions are suitable. Ascospore
infections of foliage can take place readily through dead areas
in a leaf or stem, whether these are caused by fungi, spray burn,
freezing injury or mechanical means, but the ascospore germ
tubes are unable to establish infection in healthy leaf tissue
under normal conditions. Once a mycelium is formed it can
readily infect all above-ground parts of the plant through con-
tact. Spores landing on organic matter also grow and produce







Diseases, Deficiencies and Injuries of Cabbage


mycelial threads, and if close enough the infection may spread
to the plant by contact. The effect of plant injury on develop-
ment of sclerotiniose was observed at Hastings during the 1950-


1951 season, as approximately a
plants in several fields injured
by freezes were later destroyed
by this disease.
Symptoms.-A small water-
soaked spot appears on the part
affected, followed by growth of
white mycelium of the fungus as
the spot enlarges, dies and turns
brown. The stem and leaves
nearest the ground usually be-
come infected first and the dis-
ease spreads upward and down-
ward, Fig. 16. A white mold
covers the surface of infected
parts during moist weather.
Plants with stems destroyed by
the disease wilt, collapse and
die. When the fungus grows up-
ward on a maturing plant it may
spread over the head, discolor
the leaves and convert the head
into a soft, watery mass, Fig. 17.
Presence of a cottony mold and
numerous irregularly-shaped
black sclerotia measuring 1/8 to
1 inch in length on dead and
dying parts of plants are dis-
tinguishing characteristics of
this disease.
Control.-Tests conducted in
Florida have demonstrated the
value of several methods of com-
batting sclerotiniose (12).
Treatment of muck soils with
cyanamid six to eight weeks be-
fore planting at rates of 800 to


third of the surviving cabbage







K \^"


/*f.
.4



a


Fig. 16.-Sclerotiniose. White
mold and black sclerotia of the
causal fungus on the decayed and
discolored part of a cabbage stem.


2,000 pounds per acre has controlled the disease on celery on the
West Coast of Florida. Applications of 500 to 750 pounds of







Florida Agricultural Experiment Stations


cyanamid also have reduced infection on potatoes grown in marl
soils. On the other hand, cyanamid has given poor control of
the disease on beans in sandy soils in preliminary tests on the
lower East Coast.
Keeping cultivated fields flooded during the summer for periods
of four to five weeks
.. has caused the scle-
rotia to soften and
rot in fields in the
Sarasota and Home-
stead areas.
Destruction of
numerous weed and
shrub hosts in the
vicinity of fields
treated with cyana-
mid or flooded is con-
sidered an essential
control measure. Ow-
ing to the life cycle
of the fungus, prob-
ably more benefit
would result from
eradication of weeds
u a from the seedbed
Area the season be-
fore use rather than
Fig. 17.-Sclerotiniose. Decaying cabbage head at the time the land
with moldy, discolored leaves.
is prepared for plant-
ing, as the spores are produced from sclerotia that were formed
the previous season.
Since all important vegetable crops are susceptible, it is im-
practical to try to control the disease by crop rotation, except
in sections where there is sufficient land to warrant growing a
highly-resistant crop such as corn for one or two seasons.
Cabbage and cauliflower plants should be examined when
pulled and sclerotiniose-affected ones discarded. Affected heads
should also be thrown away at harvest.
When shipments are precooled to 400 to 450 F. at the loading
station and those temperatures are maintained during transit
further development and spread of sclerotiniose are usually







Diseases, Deficiencies and Injuries of Cabbage


checked in affected packages of cabbages and cauliflower until
cars reach their destination.

YELLOWS
Yellows is a disease of cabbage and closely related crucifers
of similar ancestry. It is caused by the fungus Fusarium oxy-
sporum f. conglutinans (Wr.) Snyder and Hansen. Kohlrabi,
kale and varieties of cabbage, except those developed for yellows
resistance, are very susceptible to the disease (23). Cauliflower,
broccoli, brussels sprouts and collards are resistant.
Yellows was first observed in Florida at Bartow in 1936 and
was apparently introduced into that area on plants sent from
Wisconsin about 1920 (26). It was not known to be present
in any other section of the state until the fall of 1948, when it
was noted in the Hastings area. It was introduced into this area
in plants grown in Virginia and other states. It was found in
27 fields during the 1948-1949 season and destroyed 50 to 90
percent of the plants in 30 acres and a trace to 30 percent in
283 acres (6). About 1,000 acres of land in the Hastings area
have become severely infested with yellows during the last three
years. The disease probably will continue to spread and increase
in severity at Hastings, and it may be introduced into other
cabbage-growing sections of the State within a few years.
The causal organism is not carried on the seed and does not
spread from diseased to healthy plants, except through the soil.
It may be carried from field to field in infected plants and in
infested soil transported by surface drainage water, man,
animals, farming implements and the wind. The yellows organ-
ism lives in soils indefinitely, and it is unsafe to plant susceptible
varieties of cabbage in fields where the disease has once appeared.
The disease develops most rapidly at temperatures ranging
between 750 and 85 F. Little development occurs above 950
and below 600 F. (17, 23). It is most destructive in Florida
during the fall and spring, as temperatures are higher at those
seasons than during the winter. Low temperatures during the
winter months delay progress of the disease but usually they do
not prevail long enough to prevent its development. Yellows pro-
gresses rapidly during warm weather and affected plants may die
within two or three weeks; some may live through the season
but produce imperfect heads. During cool weather some plants
may show the disease in only one or two lower leaves which
eventually drop, and the plants may produce normal heads.







32 Florida Agricultural Experiment Stations

Symptoms.-When cabbage seed are planted in infested soil
signs of yellows usually become apparent at Hastings, Florida,
within one to four weeks after the plants emerge. During warm
weather the disease may stunt and kill many seedlings before
they grow large enough for transplanting. When healthy plants
are set in infested soil symptoms of yellows appear in two to
eight weeks, depending upon the temperature. The character-
istic yellowish-green color first appears in one or more of the
lowest leaves and it may progress upward to the top leaves.
Leaves and stem of a severely affected plant curl to one side,
giving it a distorted appearance, Fig. 18. In some plants the
yellowing is uniform on both sides of the midrib of the leaf and


L; .~i


Fig. 18.-Cabbage yellows. Plant with curled stem and curled
and discolored leaves.


t;t ~
;s~~L
~;ct~t;'"~







Diseases, Deficiencies and Injuries of Cabbage


Fig. 19.-Cabbage leaf affected with yellows, showing curved
central vein and discoloration on one side.

in most all leaves, but more often it is more intense on one side
of the leaves and stems than the other, Fig. 19. As the yellows
tissue ages it turns brown, dies and becomes brittle, and the
leaves shed prematurely, Fig. 20.
Yellows is a systemic disease; the fungus travels up the water
vessels from the roots and signs of the disease develop progres-
sively from the bottom to the top of the plant. When affected
stems and leaf petioles are cut lengthwise the water vessels show
as yellowish-brown streaks; in cross-sections they show dots of
that color. Soft rot bacteria may enter tissues killed by yellows
and hasten destruction of the plants and heads.







34 Florida Agricultural Experiment Stations



*. -






64'


tw
St t, t t









distinguishing characteristics. Both diseases are plant-borne;
but yellows, unlike black rot, is not carried in the seed. Leaves
b ig. 20.-yYellows-affected cabbage plants with bare heads
and stalks and shed leaves.

Yellows resembles black rot in many respects, but there are
distinguishing characteristics. Both diseases are plant-borne;
but yellows, unlike black rot, is not carried in the seed. Leaves
or parts of leaves affected with black rot usually are not as
bright yellow as the ones affected with yellows, and the veins in
the yellow portion of leaves are black rather than yellowish-
brown. Leaves may be infected by black rot bacteria at their
margins but there is no secondary infection from the yellows
fungus. Brittleness of affected leaves and stems is a character-
istic of yellows but not of black rot. Also, plants affected with
black rot do not lose their leaves as quickly as yellows-affected
ones.
Control.-Since the yellows organism persists indefinitely in
the soil the disease cannot be controlled by crop rotation.
It is not safe to plant Copenhagen Market, Glory of Enkhuizen
and other yellows-susceptible cabbage varieties on infested land.
Ninety-five to 100 percent of the plants of the best stocks of
yellows-resistant cabbage varieties should remain free of yellows
when grown in severely-infested soil. Early varieties which
produce marketable heads weighing two to three pounds each
within 60 to 85 days after the plants are set in the field and
midseason varieties which mature within 75 to 95 days meet







Diseases, Deficiencies and Injuries of Cabbage


present market requirements and are grown in the Hastings
area. Of 15 yellows-resistant varieties grown in yellows-sick
soil at Hastings during the last three years, Medium Copenhagen
Resistant (early) and Resistant Glory and Marion Market (mid-
season) proved best and are recommended for planting in in-
fested land at Hastings and in other areas of the State where they
are known to be adapted. Not all yellows-resistant varieties de-
veloped or introduced by different seed companies have been
tested at Hastings and some of these may be equal or superior
to the ones recommended. Furthermore, new yellows-resistant
varieties which are being developed by cabbage breeders may
excel the old ones in yield, market qualities and yellows re-
sistance. Testing of new as well as old yellows-resistant varie-
ties is being continued at Hastings and results will be reported
from year to year.
Medium Copenhagen Resistant is a new strain selected by
Ferry-Morse. It is a little later than the earliest strains and
yields about the same as most strains of Copenhagen Market.
It is very uniform and tested 92 percent resistance to yellows
in 1951.
Resistant Glory lacks uniformity but further selection is
being made and improvement in that character is expected. It
produced good yields and 98 percent of the plants were free of
yellows when it was grown in severely-infested soil at Hastings.
Marion Market has been grown extensively in Florida as a
midseason variety for many years. It lacks uniformity but is
one of the best substitutes for susceptible Glory of Enkhuizen.
Genuine stocks of Marion Market which test 95 to 100 percent
resistance to yellows should be used. Fourteen to 28 percent
of the plants of two non-authentic stocks of Marion Market
grown in infested soil at Hastings in 1951 were killed by yellows.
Late yellows-resistant cabbage varieties are not recommended
for production in the Hastings area, as they require a growing
period of 95 to 120 days to reach maturity and must be protected
against damage from diseases and insects for a longer period and
require more fertilizer to produce a crop than early and mid-
season varieties.
Cauliflower, collards, broccoli and brussels sprouts can be
grown safely on infested land during cool months. Collards
cannot be grown successfully in infested soil at high temper-
atures. This was demonstrated at Hastings in 1951 when 30







Florida Agricultural Experiment Stations


percent of the collard plants set in yellows-sick soil were de-
stroyed by the disease during the summer.
Imported cabbage and other cruciferous plants are not certified
as being free from yellows and it is not safe to use them. The
best transplants to use in setting fields free from the disease are
those grown locally in non-infested soil.

MINOR DISEASES

ANTHRACNOSE
Crucifers most susceptible to anthracnose are Chinese cabbage
and turnips. The causal fungus is Colletotrichum higginsianum
Sacc. The disease
may cause injury to
S turnip and Chinese
cabbage plants dur-
ing warm, humid
.. -. periods. Symptoms
k .consist of grayish to
light tan and circu-
.. lar to irregularly-
4,: '' I shaped spots on leaf
-blades, Fig. 21.
r .' -' Elongated, sunken,
S' brownn or gray spots
S' also appear on in-
-,fected leaf midribs
and petioles. Leaves
become ragged
S when the spots dry
and crack and dead
r tissues fall out.
Severely-affected
leaves turn yellow
and brown (23, 27).
Tops of turnips
G* / grown for greens
during the summer
months in Florida
Fig. 21.-Anthracnose of turnip. (Photograph are sometimes
by Dr. Howard N. Miller.)
ruined by anthrac-
nose. No control measures have been developed for this disease.







Diseases, Deficiencies and Injuries of Cabbage


BACTERIAL LEAF SPOT
Cauliflower is the principal crucifer attacked by bacterial leaf
spot or pepper spot caused by Pseudomonas maculicola (McCul.)
F. L. Stevens. The disease has been reported also on cabbage,
brussels sprouts and kale. Symptoms on cauliflower consist of
blotching and speckling of leaves on and between the veins.
Spots are small and circular at first and become elongated and
irregular as they grow together. Severely affected leaves be-
come ragged, turn yellow and shed prematurely. The disease
produces gray to black spots on cauliflower curds. It appears
most frequently on over-mature curds and those injured slightly
by freezing. Damp, moderately cool weather (650 to 80 F.)
favors the disease (15, 23). It is not important in Florida and
no control measures are suggested.

BLACKLEG
Blackleg is caused by the fungus Phoma lingam (Tode ex Fr.)
Desm. It produces a dry rot and blackening of the lower part
of the stem and roots. Other symptoms are round to irregularly-
shaped, ashen-gray spots with purple borders and minute black
fruiting bodies on the stem and leaves. Seriously-affected plants
are killed or stunted. The causal organism is carried in the seed
and lives on plant refuse for one to two years in Northern
cabbage-growing areas (23). The disease has been seen in only
a few cabbage and cauliflower fields in Florida in crops grown
from diseased seeds imported from Europe. It has not reap-
peared in cabbage crops grown at Hastings in the same fields
where it was present the preceding year. Hot-water-treatment
of seed as recommended for control of black rot is effective
against blackleg.

CERCOSPORA LEAF SPOT

Leaf spot caused by Cercospora sp. is sometimes found on
Chinese cabbage, mustard and turnips in Florida. Spots are
ashen gray, circular to irregular and may be 1 2 inch in diameter
(27). The disease is of little importance and control measures
are not necessary.

CLUBROOT
Clubroot, caused by the slime mold Plasmodiophora brassicae
Wor., is a destructive disease of cultivated crucifers and many







Florida Agricultural Experiment Stations


other cruciferous plants and weeds. The causal organism is
carried in infected plants from one part of the country to another
and will live in soil indefinitely (23).
Clubroot was not known to be present in Florida until August
1951, when it was found on Florida Broadleaf mustard and Sho-
goin turnip plants growing in a field in Marion County (18). Club-
root is classified as a minor disease in this bulletin but it might
soon become of major importance if introduced into one or more
of the leading commercial cabbage-growing areas of the State.
The clubroot organism is not seed-borne but, like the yellows
fungus, it is carried into clean fields in infected plants and in-
fested soil and crop refuse transported by surface drainage
water, man, animals, farming implements and the wind. It also
may be transmitted in soil clinging to the roots of transplants,
potato seed tubers and bulbs grown in infested fields. Manure
from livestock fed affected roots also carries the parasite.
Wellman (29) reported that clubroot developed in Wisconsin
soils kept moist enough for normal growth of cabbage and at
temperatures ranging from 53.60 to 80.6 F.; the optimum was
about 770 F. He found the disease serious in cabbage plants
growing in infested sandy, loam and clay soils with reactions
ranging from pH 5.0 to 7.8.
Symptoms.-The causal organism enters the plant through
root hairs and wounds and causes enlargement of the roots.
Passage of water and plant nutrients through the swollen roots
is retarded and wilting and stunting of the plant may follow.
Mildly-affected cabbage and cauliflower plants may form fair-
sized heads and the severely-affected ones may die before pro-
ducing heads. Effect of the disease on the root system varies
in different host plants. The main and lateral roots of cabbage
are affected and the clubs are shaped like spindles, Fig. 22.
Secondary roots of turnip, rutabaga and radish are the ones
usually clubbed, the fleshy roots also may be swollen and dis-
colored at points where the side roots emerge. Clubs on the
main and lateral roots of mustard are globose, cylindrical and
spindlelike in shape. The clubs are gray to yellow at first and
later turn dark, crack and become soft and flabby. They dis-
integrate into watery, foul-smelling masses when invaded by
secondary rot-producing organisms (23).
Control.-Clubroot is present in most cabbage-growing areas
of the United States. It is not known to be present in the







Diseases, Deficiencies and Injuries of Cabbage


leading cabbage-growing areas of Florida, and these areas can
be kept free from the disease by using transplants grown
locally in non-infested soil. It is not safe to use imported plants
and run the risk of introducing the disease.




























Fig. 22.-Clubroot of cabbage. (Photograph courtesy Dr. J. C. Walker.)

Adjusting reactions of infectious acid soils to pH 7.2 and
higher by treatment with hydrated lime is recommended for
control of the disease in Wisconsin (29). Other forms of lime
are not as effective as the hydrated. Limed soils must be kept
uniformly moist throughout the growing season to obtain good
control of clubroot (23).
With the exception of the alkaline marl soils on the lower
East Coast, soils planted to cabbage and other crucifers in
Florida generally have reactions ranging from pH 4.8 to 6.5







Florida Agricultural Experiment Stations


which are favorable for development of clubroot. However,
potatoes are grown in rotation with cabbage at Hastings and
in some of the other areas of the State, and it would be im-
practical to make the soils alkaline to control clubroot and
increase losses from common scab of potatoes which is some-
times very heavy in land testing as low as pH 6. Furthermore,
potatoes, crucifers and other vegetables cannot be grown suc-
cessfully in alkaline soils due to a deficiency of manganese unless
the soil or plants are treated with manganese sulfate as described
in another section of this bulletin.
No varieties of cabbage, cauliflower, kohlrabi and brussels
sprouts are known to possess any important resistance to club-
root (23). Snowball, Purple Top Milan and White Egg turnip
varieties and American Purple Top, Wilhelmsburger and Bang-
holm varieties of rutabaga are reported to be highly resistant
to the disease (15).

GRAY MOLD
Gray mold is caused by the fungus Botrytis cinerea Pers. It
occurs under conditions of high humidity at cool to moderate
temperatures on old foliage leaves and maturing cabbage and
cauliflower heads. Symptoms consist of water-soaked grayish-
green areas, and the appearance of a gray mycelium and clusters
of spores of the fungus on affected tissues (15). The disease
occurs mostly on vegetables in storage. It is not important in
the field.

MOSAIC AND VIRUS DISEASES
Mosaic diseases cause crinkling and the appearance of light
and dark green areas in cabbage leaves. Severely-affected plants
are stunted or killed. Symptoms of other virus diseases of
cabbage appear as brown to black necrotic spots and rings in
the outer leaves, sometimes extending throughout the entire
head. These diseases are caused by a single virus or a combina-
tion of viruses. They are spread mainly by aphids which trans-
mit the virus present in the sap of a diseased plant to a healthy
one. Cruciferous plants and weed hosts which live from one
season to the next harbor viruses (23). A few plants affected
with mosiac and virus diseases usually appear in cabbage and
cauliflower fields in Florida but losses are negligible.







Diseases, Deficiencies and Injuries of Cabbage


POWDERY MILDEW

Powdery mildew is caused by the fungus Erysiphe polygoni
DC. It occurs more frequently on rutabaga, mustard, turnips


and collards than
powdery spore mas-
ses and mycelium
of the fungus ap-
pear in spots or they
may completely
cover the upper sur-
faces of leaves and
stems of plants
(23), Fig. 23. The
disease usually is of
no economic import-
ance.

WHITE RUST
The causal fun-
gus, Albugo candida
(Pers. ex Chev.) O.
Kuntze, produces
white blisters on
leaves of mustard
and turnips. Other
cultivated crucifers
are seldom attacked.
leaves at Hastings in
yellow and are not


on cabbage and cauliflower.


Fig~. 23 mildew on a


Fig. 23.-Powdery mildew on a


White,


rutabaga leaf.


The disease has been observed on mustard
the spring. Severely-affected leaves turn
salable. Infection occurs during warm


weather when there is enough dew on leaves to enable spores of
the fungus to germinate and infect plants. The disease has not
been serious enough to warrant development of control meas-
ures.

WHITE SPOT
Leaves of turnips, mustard and Chinese cabbage are suscept-
ible to white spot which is caused by the fungus Cercosporella
brassicae (Fautr. and Roum.) HShn. Infection appears first as
small water-soaked spots on leaf blades. Spots are circular,
ashen-gray to white and may become one-fourth inch in diameter,
Fig. 24. Severely-spotted leaves turn yellow and shed. The







Florida Agricultural Experiment Stations


disease has not caused much damage in Florida (27). Control
measures have not been developed.

NUTRITIONAL DEFICIENCIES
Cruciferous crops are heavy users of the principal plant food
elements, nitrogen, phosphorus and potassium, and require small
amounts of boron,
S_.' '. V calcium, copper,
'^ P -,.'r iron, magnesium,
Smanganese, molyb-
denum, sulfur, iron
S and other elements.
Nutritional deficien-
bi .. cies observed by
4 the writer in cab-
V A L b a g e, cauliflower
A Z, and broccoli plants
Grown in Florida
S / are those due to a
: lack of nitrogen, po-
tassium, boron,
S. manganese and
V molybdenum.
S, BORON DEFICIENCY
Boron deficiency,
>, browning or bitter
brown rot, is a com-
mon malady of
.- cauliflower in Flor-
ida. Most culti-
Fig. 24.-Section of a turnip leaf affected with vated crucifers are
white spot. susceptible to the
deficiency but cauliflower, rutabaga and turnip are particularly
sensitive (24).
Symptoms.-Leaves of affected cauliflower plants become dull
green and greenish-yellow at their margins. They curl at the
edges and become thick and brittle. Blisters and cracks may
appear on midribs of leaves; and brown, necrotic areas develop
in the pith of stems. In advanced stages the discolored pith
shrinks and cracks and the stem becomes hollow, Fig. 25. Water-






Diseases, Deficiencies and Injuries of Cabbage


"2 .' ;'.
f "


- "__. .


rB -e
%IF

I- ..-^1
P ... .*


P ~


Fig. 25.-Symptoms of boron deficiency in a cauliflower stem and curd.
soaked irregularly-shaped spots appear in the curds. Spots
turn brown and disintegrate rapidly in wet weather; in dry
weather they dry and harden, Fig. 26. The discolored curd has
a bitter flavor (4).
Symptoms of boron deficiency or brown heart in rutabaga
and turnip are similar. Severely-affected plants are dwarfed
and have curled, rugose leaves. In advanced stages water-







Florida Agricultural Experiment Stations


soaked or brown spots and cracks appear in the interior of
roots (1).
Broccoli does not show symptoms of boron deficiency as early
as cauliflower or rutabaga. First symptoms consist of a curling,
rolling and discoloration of the leaves. Severely-affected plants
have cracked petioles, corky growths on the stem and petioles,
and brown buds in the heads or flower clusters. Discolored
flower buds are bitter and spotted heads are not salable.


Fig. 26.-Discoloration of a cauliflower curd due to boron deficiency.

The deficiency usually appears in cabbage in a mild form as
brown areas and cracks in the pith of stems similar to those
seen in affected cauliflower plants (24). In extreme cases
cabbage plants produce no heads if the deficiency occurs before
head formation begins or produce small, loose heads if it occurs
after head formation has started. If the head is fairly well


AdmY.. 'L







Diseases, Deficiencies and Injuries of Cabbage


developed when the deficiency occurs, leaves separate from the
stem and the head turns yellow (1).
Control.-In tests in New York browning or boron deficiency
of cauliflower was prevented by the application of 5 to 10 pounds
of borax per acre to the soil in the fertilizer (4). Application
of 20 pounds of borax per acre also was reported as giving very
good control of boron deficiency of cabbage and cauliflower
grown in a silty clay loam in Wisconsin (24). Purvis and
Ruprecht (14) controlled boron deficiency or cracked stem of
celery grown in sandy soil at Sanford, Florida, by applying
borax to the soil. The borax was effective when used in the
fertilizer at the rate of 10 pounds per acre and also when a weak
solution of borax (10 pounds in 100 gallons of water per acre)
was sprayed on the soil near the base of celery plants about two
weeks after they were set in the field.
Tests are being made to determine the effect of soil treatments
with different amounts of borax per acre in controlling boron
deficiency of cauliflower grown in sandy soil at Hastings,
Florida, and when sufficient data are obtained the results will
be reported.
MANGANESE DEFICIENCY
Yellowing of cabbage and other vegetable crops growing in
slightly acid to alkaline soils may be due to a deficiency of
available manganese. This element is essential for production
of chlorophyll. The trouble occurs where the soil solution is
not sufficiently acid to dissolve manganese compounds. It ap-
pears in crops grown in alkaline marl soils of Dade County and
in Everglades peat and muck which have been burned or mixed
with marl and have reactions above pH 6.0 (22). It also occurs
in plants growing in sandy soils which contain excessive amounts
of shell or other calcareous materials. It has been observed in
fields at Hastings in rows near highways and buildings where
limestone was mixed with the soil during construction.
Symptoms.-Manganese deficiency first appears in cabbage
and cauliflower plants as a light green color between veins of
leaves, Fig. 27. All leaves gradually lose their green color and
the entire plant turns yellow. Light brown, dead spots appear
in severely-affected leaves. Plants are stunted when the foliage
turns yellow and the leaves are shed from the bottom of the
plant upward. Severely affected plants die without producing
marketable heads.







Florida Agricultural Experiment Stations


Fig. 27.-Symptoms of manganese deficiency in a cauliflower leaf.

Control.-Manganese deficiency can be corrected by applying
manganese- to the soil, by treating soils with sulfur to increase
their acidity and by spraying plants with a solution of manganese
sulfate.
A fertilizer which supplies 50 to 100 pounds of manganese
sulfate per acre per year is required to correct manganese de-







Diseases, Deficiencies and Injuries of Cabbage


ficiency in marl soils on the lower East Coast (22). Fertilizers
containing 25 to 30 pounds of manganese sulfate per acre are
recommended for production of cabbage on the peat and muck
soils of the Everglades.
Fifty to 100 pounds of sulfur per acre applied in the row with
the fertilizer have been used successfully in some areas to in-
crease soil acidity and solubility of manganese compounds in
the fertilizer or naturally present in the soil. The change in soil
reaction is not permanent and the treatment must be repeated
with each crop. Sulfur treatment is not recommended for marl
soils on the lower East Coast (22).
Manganese sprays have been used successfully in southern
Florida to control manganese deficiency of beans grown in
manganese-deficient soils (22). Spraying each acre of cabbage
plants with 2 pounds of manganese sulfate (spray grade) dis-
solved in 100 gallons of water is recommended when the de-
ficiency develops in plants growing in peat and muck soils in
the Everglades. On some of the Parkwood soils in the Bradenton
area which have a high pH reaction manganese deficiency
appears in cabbage and it may be corrected by one or more ap-
plications of manganese sulfate added to the spray at the rate
of 2 pounds to 100 gallons. A spreader-sticker should be mixed
with sprays used on cabbage.

NITROGEN DEFICIENCY
Cabbage and other cruciferous plants which lack nitrogen
may turn pale green and yellow, become stunted and yield
poorly. With the exception of peat and muck, soils used for
production of cabbage and other vegetables in Florida contain
very little available nitrogen and must be fertilized heavily
with nitrogenous fertilizers to produce good crops. Tests made
by McCubbin (10) showed that commercial fertilizers and side-
dressing materials which supply 175 to 200 pounds of nitrogen
per acre are needed for producing maximum yields of cabbage
on sandy soils in the Hastings area.2

POTASH DEFICIENCY
Potash deficiency, also known as tipburn, may appear in cab-
bage planted in all types of soil. Symptoms consist of yellowing
of the leaves between veins, with most of the discoloration con-
fined to margins of outer leaves. Discolored leaves start dying
at their margins first and the affected tissues turn brown and







Florida Agricultural Experiment Stations


become brittle. Plants affected during early stages of growth
produce soft, loose, non-salable heads (23).
Fertilizers and side-dressing materials which supply 100 to
170 pounds of available potash per acre are used in the produc-
tion of cabbage in the Hastings area (10).2

WHIPTAIL OF CAULIFLOWER
Molybdenum is one of the elements essential for plant growth,
and whiptail in cauliflower and broccoli results from a deficiency
of this nutrient. Many crucifers are susceptible to the de-
ficiency but cauliflower and broccoli are particularly sensitive.
The amount of molybdenum required by a crop is very small.
The deficiency is affected by climate, and drought periods ac-
centuate the extent of symptoms. Soil acidity is conducive to
the occurrence of the deficiency. Molybdenum is present in acid
soils in an unavailable form and may be made available by
liming (13).
Whiptail is important on cauliflower in some parts of the
United States, particularly on the Atlantic Coast on highly acid
soils (23). In England it has appeared in crops growing in
soils with reactions of pH 4.5 to 5.6 (13). It has been observed
in Florida in cauliflower growing in sandy, acid soils and it has
been particularly troublesome in the Hastings area.
Symptoms in cauliflower consist of a general stunting of
growth, failure to curd, and the formation of unmarketable
heads. Affected plants are upright, branched or rosette. Leaves
are narrow, ruffled, and have irregular margins, Fig. 28. The
petioles and midribs tend to be longer than usual. Affected
plants may turn blue-green but in most cases leaf color is
normal. If the deficiency is present in plant bed soils some
seedlings may develop stubby growing points and others may
become completely blind. Development of adventitious buds
just above the fibrous roots is another symptom. Young plants
with mild symptoms and those with blind buds may recover
partly when transplanted to soils containing molybdenum in an
available form; adventitious buds on the blind plants may grow
and form suckers. Severely affected plants form loose, ricey

2 Kinds and amounts of fertilizers used in the production of cabbage in
other areas of the State differ from those used at Hastings, depending upon
the type and residual fertility of the soil and other conditions. Information
on nitrogen and potash requirements for cabbage in other areas of the
State can be obtained from the nearest Agricultural Experiment Station or
county agent.







Diseases, Deficiencies and Injuries of Cabbage


curds and deformed leaves in the curd, Fig. 29. Symptoms may
appear in the seedbed or after the plants are set in the field.
In England whiptail has been controlled experimentally by
adjusting acid soils to pH 5.2 and above with lime and by the
application of small amounts of sodium or ammonium molybdate


Fig. 28.-A cauliflower plant affected with whiptail.






Florida Agricultural Experiment Stations


to limed soils where the trouble has not disappeared. It also
was reported that whiptail plants recovered if sprayed early in
their development with a sodium molybdate solution (13).
In tests at Hastings by the writer in 1951, 88 percent of
Snowball A cauliflower plants developed whiptail when grown in
soil testing pH 4.4 to 4.6. The deficiency was almost eliminated
in plants grown in acid soil which had been adjusted to pH 5.2
with hydrated lime, and also by spraying the seedlings when one
inch in height with an ammonium molybdate solution (0.35 lb.
in 200 gals. water per acre). The tests were made with small
numbers of thinned plants grown in a seedbed but the results
agree with those reported by Plant in England (13). Until
results are obtained from more extensive tests, growers at
Hastings are advised to adjust extremely acid soils to pH 5.2
to 5.5 for control of whiptail. Soils, including those which are
to be used for plant beds, should be treated with the proper
quantity of liming materials in the spring or summer before they
are planted to cover crops. Sandy, acid soils of the Hastings
area require 100 pounds of hydrated lime or 200 pounds of
calcium or dolomitic limestone per acre to change the reaction
0.1 on the pH scale.
Treatment of plants and soils with molybdenum is not recom-
mended at present for control of whiptail in Florida, as plant
parts containing excessive amounts of the element are poisonous

Fig. 29.-Cauliflower curd affected with whiptail.



,% ^;~
I ""mg







Diseases, Deficiencies and Injuries of Cabbage


to man and animals. Tests will be continued at Hastings to
determine if small quantities of molybdenum can be used safely
in fertilizers and sprays to control the trouble in extremely acid
soils.
Snowball X or Snowdrift, Holland Erfurt, Snowball Y and
other varieties of cauliflower known to be resistant to whiptail
should be grown instead of susceptible ones such as Snowball A
or Super Snowball and Earliest Dwarf Erfurt.

INJURIES
Injuries of cabbage and other crucifers are due to various
causes. Some are of little significance and others, such as
torrential rains and hard freezes, may destroy crops. Injuries
due to insects and their control are described in other publica-
tions of the Florida Agricultural Experiment Station.

BOLTING
Bolting or premature seeding of cabbage plants sometimes
occurs in Florida. Cabbage is a biennial plant. It normally
requires two seasons or parts of two seasons in which to com-
plete its development from the seedling stage to the formation
of flowers and maturing of seeds. Seed are produced by plants
that have formed heads when they are given a rest period of
two months or longer and held at temperatures low enough to
stop growth temporarily but not cold enough to freeze the
tissues. The plants will then produce flower stalks, flowers and
seed when exposed to warm temperatures and good growing con-
ditions. Young cabbage plants behave in a similar manner if
exposed to conditions conducive to bolting. When young plants
with stems 3/16 to 1/4 inch or larger in diameter are exposed to
continuous temperatures of 400 F. or lower for two weeks or
longer many may form seed stalks or bolt during the first season
of growth, Fig. 30.
A survey made by Dr. E. N. McCubbin, horticulturist, Potato
Investigations Laboratory, showed that 2,500 acres of cabbage
bolted in Florida during the 1943-1944 season and the loss in
production costs alone was about $200,000. The Copenhagen
Market strain which bolted that year had been grown success-
fully in California for a number of years, but it bolted in Florida
when grown at lower temperatures than it had been exposed to
in California.
Ten percent or more of a few lots of cabbage plants grown in






Florida Agricultural Experiment Stations


"^i L., .
A




























Fig. 30.-A bolting cabbage plant.

North Carolina in the winter of 1951 also bolted after they were
set in fields in the Hastings, Florida, area. Apparently these
plants had been exposed to temperatures conducive to bolting
before they were pulled and shipped to Florida.
Standard strains of Copenhagen Market, Glory of Enkhuizen
and other cabbage varieties recommended by the Florida Agri-
cultural Experiment Station for production in different areas







Diseases, Deficiencies and Injuries of Cabbage


of the state have seldom produced more than a trace of bolting
plants. Consequently, bolting should not cause serious losses
in Florida if seed of standard strains of recommended varieties
are used and crops are produced from plants grown in Florida.

DROUGHT INJURY
Cabbage, cauliflower and broccoli seeds are usually planted
1/8 to 1/ inch deep in sand and marl and 1/2 to 3/ inch in muck.
Since the seed are planted shallow, it is necessary to irrigate
the seedbed during dry weather to promote germination and
growth of the plants, especially in sandy land. If the soil dries
out immediately after germination, roots of young seedlings
dry and the plants perish. Stems of older plants in crowded
seedbeds which have dried out become pithy and hollow and the
leaves lose their bright green color and turn yellow. When
transplanted, drought-injured plants grow slowly or die, depend-
ing upon the severity of the injury. Fields planted to cabbage
and other crucifers should be irrigated when needed to promote
growth of the plants during dry periods.

FERTILIZER INJURY AND SALT SICKNESS
Large amounts of commercial fertilizers containing plant food
in the form of soluble salts of nitrogen, potassium, phosphorus
and other elements are applied to soils for production of vege-
table crops in Florida. Plant injury may occur in soils which
have been fertilized too heavily and in those in which the ferti-
lizer has not been properly distributed or mixed (22). A similar
injury known as salt sickness also occurs in soils containing
high concentrations of salts derived from artesian well water.
Westgate (30) has reported that two to four tons of soluble
salts, over half of which are sodium chloride, may be added by
each acre-foot of artesian well water used for irrigation on some
farms in the Sanford area. Soluble salts are detrimental to
plant growth when present at high concentrations in the upper
layers of soil. Cabbage has a poor salt tolerance; 1,000 p.p.m.
of salt in the medium-textured soil may check growth of the
plants.
Capillary movement of water brings soluble salts to the sur-
face layers of soil, where they become concentrated when the
water evaporates. This is most likely to occur during warm, dry
weather, as evaporation is greatest at that time (22). Roots
and stems of cabbage seedlings growing in a soil containing a






Florida Agricultural Experiment Stations


high concentration of soluble salts are plasmolized; the cell sap
diffuses into the more concentrated soil solution and the stems
shrink. Severely-affected seedlings wilt, fall over on the soil
and die as though affected with damping-off. Older plants
injured by soluble salts recover if excessive salts are leached
from the soil in time; if not, they become chlorotic, stunted and
non-productive; tops of severely-affected ones wither and die
(30).
Injury from fertilizers can be prevented by applying them at
rates generally used in growing cabbage and other crucifers in
different parts of the state. If the fertilizer is distributed in
two bands in the row the plants should be set between the bands
so that the roots will not be in the fertilizer. Dry soils should
be irrigated after they are fertilized and before the seed are
sown or the plants are set out. If seedbeds and fields are irri-
gated as needed during the growing season and the soil kept
moist, plants are not likely to be injured by fertilizers or
succumb to salt sickness. Overhead irrigation of seedbeds is
one of the best ways to prevent seedlings from being injured
by an accumulation of toxic salts in the surface layers of soil.
Westgate (30) has found that it is not safe to use artesian well
water containing over 900 p.p.m. of chlorides or 1,260 p.p.m. of
sodium chloride for continuous irrigation in the Sanford area.
He recommends leaching of harmful quantities of soluble salts
from surface layers of the soil and also treating such soil with
liming materials.
FREEZING INJURY
Cabbage, cauliflower and other crucifers are hardy plants but
they may be injured or killed by freezing, depending upon age
of the plants when frozen, lowness of the temperature and length
of exposure. Cabbage tissue freezes at 31 F. (15). Young
plants are injured more severely by freezing than older ones.
Greatest damage from freezes in Florida has occurred in crops
grown in inland areas in the northern part of the State, par-
ticularly in muck and peat soils which are situated in low
locations.
Frozen cabbage leaves are stiff and brittle. Leaf tissues
tolerate formation of ice and thawing and recover without
injury, provided they are not frozen too hard and do not remain
frozen too long. Frozen areas become water-soaked when the
ice melts and water accumulates in the intercellular spaces. If
the cells are still alive some of the water will re-enter them and







Diseases, Deficiencies and Injuries of Cabbage


the tissues will appear wilted. If the cells are killed water
evaporates, causing the tissues to dry, or it remains and the
frozen parts become a soft, leaking mass (15). Tissues injured
but not killed by freezing turn pale green to white. Parts of
leaves between veins are sometimes killed and the dead tissues
dry and fall out, giving the leaves a ragged appearance, Fig. 31.
Leaves frozen to death wilt and appear water-soaked; later
they bleach and then turn brown as they die. Plants recover or
die from freezing injury, depending upon the degree of injury.
Small plants killed by a hard freeze wilt after thawing, fall over
on the soil and die. The pith of a stem of a severely frozen
plant which has survived becomes spongy and turns white.
Later the pith dries and shrinks and the stem becomes hollow;































Fig. 31.-A cabbage leaf in which frozen tissues have died and fallen out.







Florida Agricultural Experiment Stations


functional parts left are the outer tissues which include the
vascular bundles and epidermis. Most cabbage plants injured
in this manner in 1950 recovered and produced salable heads.
Common injury to heading cabbage consists of death and dis-
coloration of parts of the foliage leaves and the appearance of
discolored, wilted and soft spots on tops of the heads which
make them unsalable. Tissues killed by freezing serve as points
of entrance for soft rot bacteria and the fungus causing sclero-
tiniose. A third of the cabbage plants injured by freezes in
several fields at Hastings in 1950 were later attacked and de-
stroyed by sclerotiniose.

TABLE 3.-MINIMUM TEMPERATURES RECORDED AT THE POTATO INVESTIGA-
TIONS LABORATORY DURING THE PERIOD NOVEMBER 25-30, 1950 *
Mim.
Nov. Temp. Hours and Minutes When Temperatures Were At or Below
oF. j 2 31o 30 29 28 270 26 250
25 25.2 8:00 7:40 6:30 5:50 4:45 4:00 2:10 1:00
26 26.0 14:05 13:50 11:50 9:45 5:30 1:20 0:45
27 36.5
28 34.0
29 29.0 5:00 4:00 2:10 0:30
30 28.8 7:30 5:00 3:50 2:00

II
Total 34:35 30:30 24:20 18:05 10:15 5:20 2:55 1:00

Temperature records supplied by R. H. Dean, Meterologist, United States Weather
Bureau, Lakeland, Florida.

Losses due to freezing of cabbage, cauliflower and broccoli
plants in 1950 were the greatest ever recorded at Hastings. Ac-
cording to the United States Weather Bureau, minimum tempera-
tures for the last week in November 1950 are the lowest recorded
at Hastings for six consecutive November days during the last
25 years, Table 3. Most plants were young and tender and not
conditioned to withstand low temperatures when the freezes
occurred. Small cabbage plants subjected to a gradual lowering
of temperature in the fall in Northern states become resistant
to freezing and can withstand a temperature of 100 F. for short
periods. At Hastings 50 to 95 percent of the plants in many
plant beds were killed or seriously injured by the freezes in
1950. About 2,000 acres of cabbage, cauliflower and broccoli
plants of various stages of growth in the field also were damaged
by the freezes. Most broccoli and cauliflower plants which had
been transplanted were destroyed or severely stunted by the






Diseases, Deficiencies and Injuries of Cabbage


freezes, while most transplanted cabbage plants recovered and
produced salable heads. Cabbage, cauliflower and broccoli seed-
lings which were beginning to emerge from the soil when the
freezes occurred and older cabbage plants nearing maturity were
not seriously damaged. Likewise, plants situated in seedbeds
and fields in which the soil had been made wet by irrigation were
not damaged as severely as those growing in drier land. The
November freezes and cold weather in December delayed pro-
duction of the 1950-51 cabbage, cauliflower and broccoli crops
in the Hastings area about six weeks.

GROWTH CRACKS
Cabbage heads crack or burst if left in the field too long after
maturity. Most adapted varieties produce heads weighing two
to three pounds or more before much cracking occurs. Matur-
ing heads may crack after rains or irrigation when an abundance
of water and fertilizer causes the inner part of the head to grow
too rapidly. The outer leaves do not stretch or loosen and the
heads burst open.
OEDEMA
Oedema or intumesences are scattered, warty growths or
calluses the size of a pinhead or larger on leaves and stems of
cabbage, cauliflower and other crucifers. This condition is due
to excessive development or growth of cells (23). It develops
at points where leaves rub against each other and at places
where soil particles are blown against leaves and stems. It also
occurs when there is a loss of balance between intake and outgo
of water causing the tissues to become suffused with water (23).
The trouble is of little importance. Badly marred leaves can be
trimmed off.
ROOT-KNOT
Root-knot of many cultivated and wild plants is caused by
gall-forming nematodes belonging to the genus Meloidogyne.
The nematode causing root-knot of cabbage in the Hastings,
Florida, area has been identified as Meloidogyne incognita
(Kofoid and White) Chitwood.3 Soil temperatures near 80' F.
are most favorable for development and activity of root-knot
nematodes; they are relatively inactive at temperatures below

Identified by Dr. A. L. Taylor, Nematologist, Plant Industry Station,
United States Department of Agriculture, Beltsville, Maryland, in samples
of root-knot-affected cabbage roots sent to him from Hastings in November,
1951.






Florida Agricultural Experiment Stations


55 F. (20). Most of the damage from root-knot of cabbage in
Florida occurs during the fall when high temperatures favor
development of the trouble; low temperatures during the winter
and spring retard nematode activity, particularly in the northern
part of the state.
Root-knot nematode larvae migrate through the soil and bur-
row into roots of plants. They absorb nourishment from the
roots and secrete materials that cause the root cells to grow
abnormally large and form galls. Nematodes grow rapidly in
the roots. The female enlarges and becomes a pear-shaped,
pearly-white body about the size of a pin head. The full-grown
female produces several hundred eggs which hatch into larvae
that escape into the soil when the galls crack or decay.
Symptoms.-Root-knot is characterized by conspicuous swell-
ings or galls on roots of plants, Fig. 32. Infested roots cease
to function normally and produce very little new growth. Af-
fected plants are unable to obtain enough water and nutrients
and wilt in dry soil on a hot day. Severely affected cabbage
plants may be stunted or killed by a root-knot nematode, de-
pending upon the severity of infestation.









I-








.A.

\


Fig. 32.-Root-knot of cabbage.







Diseases, Deficiencies and Injuries of Cabbage


Root-knot may be mistaken for clubroot, but these troubles
differ, as is shown in Figures 22 and 32. Root-knot galls are
generally smaller than clubroot swellings. The entire root may
be enlarged if it is affected with clubroot and the clubs may be
globose, cylindrical or spindlelike in shape, depending upon the
host. Root-knot galls usually appear as knots arranged like a
string of beads on the lateral roots. The female nematode can
be found in a mature root-knot gall if it is broken open and
examined. The interior of a clubbed root is pinkish to brick
colored.
Control.-Cabbage plants free from root-knot usually grow
during cool weather and produce marketable heads, even when
set in nematode-infested land, if supplied with sufficient water
and fertilizer. Losses may occur during warm weather if root-
knot-affected plants are used for transplanting stock or if plants
become affected in seeded fields. If possible, the seedbed should
be located on soil free from root-knot nematodes. Pigweed, dog
fennel, careless weed and many other weeds are attacked by
nematodes and those growing in the area selected for a seedbed
should be examined for root-knot.
Soil fumigants have been tested for control of nematodes for
several years in Florida and some have given good results when
used in vegetable seedbeds at several places in the state.
Walter and Kelsheimer (25) found that in-the-row application
of Larvacide, D-D, and Soil Fume 80-20 (ethylene dibromide 20%
-mineral spirits 80%) reduced injury from root-knot and in-
creased yields of tomatoes at Bradenton, Florida. Clark and
Myers (2) also controlled nematodes and increased yields of
tobacco grown near Gainesville, Florida, in soil fumigated with
dichloropropane-dichloropropene (D-D) and ethylene dibromide
(EDB).
Soil fumigants are not recommended at present in the pro-
duction of cabbage in the Hastings, Florida, area, as they have
not been tested thoroughly and information is lacking on the
practicability of using them in cabbage seedbeds and fields.

SPRAY AND DUST INJURY
Plants may be injured or killed by treatment with excessive
amounts of fungicides and insecticides. Injury appears as a
discoloration, distortion and, in extreme cases, death of the
plant or plant parts affected, Fig. 33.
It is necessary to calibrate sprayer and auxiliary tanks and







Florida Agricultural Experiment Stations


Fig. 33.-Small cabbage leaves with discolored spots killed by spraying
with an excessive amount of Spergon spray.

add the correct amount of chemicals and other ingredients to
the water to make a spray of the proper strength. Labels on
most packages of insecticides and fungicides give directions
for making sprays of various strengths and precautions for
handling the materials to prevent injury to the operator and the
crop that is being treated. Dusts containing the proper per-
centage of the active ingredient are best prepared by the manu-
facturer or processor.
Size of plants determine the amount of spray or dust needed
to cover the foliage. Quantities that can be used safely on cab-
bage and other cruciferous plants are given in Tables 1 and 2 of
this bulletin. Special care should be taken to cover the foliage
completely with spray or dust. Power dusters and sprayers can
be adjusted to deliver the right amount of spray or dust more
easily than is the case with hand-operated equipment. A sprayer
or duster should be shut off when the tractor is stopped in the







Diseases, Deficiencies and Injuries of Cabbage


field and at the ends of rows to avoid injuring the plants by
treatment with excessive amounts of spray or dust.

VARIEGATED LEAVES
Variegated leaves may be found on a few plants in most cab-
bage, cauliflower and broccoli fields. Discolored parts are white
or yellow and limited to
the margin or appear in
various patterns in other
parts of the leaf, Fig. 34.
Discolorations of this na-
ture are due to the be-
havior of hereditary
characters which govern
the production of chloro- -
phyll or green coloring
matter in the leaf.

WATER INJURY
Plants growing in
poorly drained fields and
seedbeds are damaged by ,
rains which saturate and
erode the soil and leach
fertilizers from it. Fur-
thermore, soil organisms
which help maintain a
constant supply of plant
food do not function in a
wet soil and plants do not
obtain sufficient nitrogen
and other nutrients re-
quired for growth. Fig. 34.-A variegated cauliflower leaf.
Damping-off of seedlings occurs in water-logged soils, and
stems and roots of older plants are seriously injured or destroyed
by rot-producing organisms. Plants wilt permanently when the
soil remains saturated for several days. Wilted leaves appear
scalded at first, later turn light green, then yellow and finally
brown as they die. In locations where the water table has re-
mained a few inches below the surface of the soil for a few days
new roots may grow from uninjured parts of stems just below
the soil line, but plants which recover may be weak and non-
productive.







Florida Agricultural Experiment Stations


Protection against all but the heaviest rains can be secured
by using enough water furrows, drains, ditches, canals and
water pumps to drain flooded fields rapidly.
Cultivation of seedbeds and fields as soon as possible after
heavy rains to aerate and dry the soil will promote recovery of
plants which have not been damaged too severely. Side-dressing
with fertilizers containing nitrate nitrogen will provide needed
plant food and thus hasten recovery of the damaged plants.


ACKNOWLEDGMENTS
The author is indebted to Dr. E. N. McCubbin, horticulturist, Potato
Investigations Laboratory, Hastings, for assistance in preparing the section
dealing with nutritional deficiencies in this bulletin; to E. A. Wolf, assistant
horticulturist, Everglades Experiment Station, Belle Glade, for supplying
information on control of manganese deficiency of cabbage in the Everglades
area; and to Donald S. Burgis, assistant horticulturist, Gulf Coast Station,
Bradenton, for supplying information on control of manganese deficiency
of cabbage in the Bradenton area.


LITERATURE CITED

1. CHANDLER, FREDERICK B. Boron deficiency symptoms in some plants
of the cabbage family. Maine Agr. Exp. Sta. Bul. 402. 1940.
2. CLARK, FRED, and J. M. MYERS. Fumigation and equipment for nema-
tode control in soils for flue-cured tobacco. Fla. Agr. Exp. Sta. Cir.
S-27. 1951.
3. CLAYTON, E. E. Seed treatment for black-leg diseases of crucifers.
N. Y. Agr. Exp. Sta. Tech. Bul. 137. 1928.
4. DEARBORN, C. H. Boron nutrition of cauliflower in relation to browning.
Cornell Agr. Exp. Sta. Bul. 778. 1942.
5. EDDINS, A. H. Control downy mildew of cabbage with *pergon. Fla.
Agr. Exp. Sta. Press Bul. 633. 1947.
6. EDDINS, A. H., and W. B. TISDALE. Cabbage black rot and yellows and
their control. Fla. Agr. Exp. Sta. Cir. S-4. 1949.
7. FELTON, MATHIAS W., and J. C. WALKER. Environal factors affecting
downy mildew of cabbage. Jour. Agr. Res. 72: 69-81. 1946.
8. GROVEs, J. W., and A. J. SKOLKO. Notes on seed-borne fungi. Canadian
Jour. Res. 22: 217-234. 1944.
9. LEBEAU, F. J. Systemic invasion of cabbage seedlings by the downy
mildew fungus. Jour. Agr. Res. 71: 453-463. 1945.
10. McCUBBIN, E. N. Importance of fertilizer nitrogen for cabbage pro-
duction on sandy soils in northeast Florida. Proc. Fla. State Hort.
Soc. 58: 238-242. 1945.
11. MILBRATH, D. G. Alternaria from California. Bot. Gaz. 74: 320-324.
1922.







Florida Agricultural Experiment Stations


Protection against all but the heaviest rains can be secured
by using enough water furrows, drains, ditches, canals and
water pumps to drain flooded fields rapidly.
Cultivation of seedbeds and fields as soon as possible after
heavy rains to aerate and dry the soil will promote recovery of
plants which have not been damaged too severely. Side-dressing
with fertilizers containing nitrate nitrogen will provide needed
plant food and thus hasten recovery of the damaged plants.


ACKNOWLEDGMENTS
The author is indebted to Dr. E. N. McCubbin, horticulturist, Potato
Investigations Laboratory, Hastings, for assistance in preparing the section
dealing with nutritional deficiencies in this bulletin; to E. A. Wolf, assistant
horticulturist, Everglades Experiment Station, Belle Glade, for supplying
information on control of manganese deficiency of cabbage in the Everglades
area; and to Donald S. Burgis, assistant horticulturist, Gulf Coast Station,
Bradenton, for supplying information on control of manganese deficiency
of cabbage in the Bradenton area.


LITERATURE CITED

1. CHANDLER, FREDERICK B. Boron deficiency symptoms in some plants
of the cabbage family. Maine Agr. Exp. Sta. Bul. 402. 1940.
2. CLARK, FRED, and J. M. MYERS. Fumigation and equipment for nema-
tode control in soils for flue-cured tobacco. Fla. Agr. Exp. Sta. Cir.
S-27. 1951.
3. CLAYTON, E. E. Seed treatment for black-leg diseases of crucifers.
N. Y. Agr. Exp. Sta. Tech. Bul. 137. 1928.
4. DEARBORN, C. H. Boron nutrition of cauliflower in relation to browning.
Cornell Agr. Exp. Sta. Bul. 778. 1942.
5. EDDINS, A. H. Control downy mildew of cabbage with *pergon. Fla.
Agr. Exp. Sta. Press Bul. 633. 1947.
6. EDDINS, A. H., and W. B. TISDALE. Cabbage black rot and yellows and
their control. Fla. Agr. Exp. Sta. Cir. S-4. 1949.
7. FELTON, MATHIAS W., and J. C. WALKER. Environal factors affecting
downy mildew of cabbage. Jour. Agr. Res. 72: 69-81. 1946.
8. GROVEs, J. W., and A. J. SKOLKO. Notes on seed-borne fungi. Canadian
Jour. Res. 22: 217-234. 1944.
9. LEBEAU, F. J. Systemic invasion of cabbage seedlings by the downy
mildew fungus. Jour. Agr. Res. 71: 453-463. 1945.
10. McCUBBIN, E. N. Importance of fertilizer nitrogen for cabbage pro-
duction on sandy soils in northeast Florida. Proc. Fla. State Hort.
Soc. 58: 238-242. 1945.
11. MILBRATH, D. G. Alternaria from California. Bot. Gaz. 74: 320-324.
1922.







Diseases, Deficiencies and Injuries of Cabbage


12. MOORE, W. D., ROBERT A. CONOVER and DAVID L. STODDARD. The
sclerotiniose disease of vegetable crops in Florida. Fla. Agr. Exp.
Sta. Bul. 457. 1949.
13. PLANT, WILLIAM. The control of whiptail in broccoli and cauliflower.
Agriculture 57: 130-134. 1950.
14. PURVIS, E. R., and R. W. RUPRECHT. Cracked stem of celery. Fla.
Agr. Exp. Sta. Bul. 307. 1937.
15. RAMSEY, GLEN B., JAMES S. WIANT and GEORGE K. K. LINK. Market
diseases of fruits and vegetables: crucifers and cucurbits. U.S.D.A.
Mis. Pub. 292. 1938.
16. RANGEL, JEFFERSON F. Two Alternaria diseases of cruciferous plants.
Phytopath. 35: 1002-1007. 1945.
17. TISDALE, WILLIAM B. Influence of soil temperature and soil moisture
upon the Fusarium disease in cabbage seedlings. Jour. Agr. Res.
24: 55-86. 1923.
18. TISDALE, W. B. Clubroot of crucifers. U.S.D.A. Plant Dis. Rptr. 35:
509. 1951.
19. TISDALE, W. B., A. N. BROOKS and G. R. TOWNSEND. Dust treatments
for vegetable seed. Fla. Agr. Exp. Sta. Bul. 413. 1945.
20. TOWNSEND, G. R. Development of root-knot nematode on beans as
affected by soil temperature. Fla. Agr. Exp. Sta. Tech. Bul. 309.
1937.
21. ----------..................- Controlling damping-off and other losses in celery
seedbeds. Fla. Agr. Exp. Sta. Bul. 397. 1944.
22. TOWNSEND, G. R., and GEO. D. RUEHLE. Diseases of beans in southern
Florida. Fla. Agr. Exp. Sta. Bul. 439. 1947.
23. WALKER, J. C. Diseases of cabbage and related plants. U.S.D.A.
Farmers Bul. 1439. 1944.
24. WALKER, J. C., JOHN C. McLEAN and JAMES J. JOLINETTE. The boron
deficiency disease in cabbage. Jour. Agr. Res. 62: 573-587. 1941.
25. WALTER, J. M., and E. G. KELSHEIMER. In-the-row application of soil
fumigants for vegetables on sandy soils. Proc. Fla. State Hort. Soc.
62: 122-126. 1949.
26. WEBER, GEORGE F. Two new fungous diseases of vegetables in Florida.
U.S.D.A. Plant Dis. Rptr. 21: 282. 1937.
27. .........----.................... Some diseases of cabbage and other crucifers in
Florida. Fla. Agr. Exp. Sta. Bul. 256. 1932.
28. WEIMER, J. L. Alternaria leaf spot and brownrot of cauliflower. Jour.
Agr. Res. 29: 421-441. 1924.
29. WELLMAN, F. L. Clubroot of crucifers. U.S.D.A. Tech. Bul. 181. 1930.
30. WESTGATE, PHILIP J. Effects of soluble soil salts on vegetable pro-
duction at Sanford. Proc. Fla. State Hort. Soc. 63: 116-123. 1950.




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs