• TABLE OF CONTENTS
HIDE
 Title Page
 Credits
 Table of Contents
 Introduction
 Anthracnose
 Wilt
 Downy mildew
 Gummy-stem blight
 Stem-end rot
 Southern blight
 Blossom-end rot
 Powdery mildew
 Cereospora leaf spot
 Macrosporium leaf spot
 Soil rot
 Speckle
 Mosaic
 Minor diseases not found in...
 Cold, wind and sand injury
 Handling
 Summary














Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; no. 459
Title: Diseases of watermelons in Florida
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027381/00001
 Material Information
Title: Diseases of watermelons in Florida
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 46 p. : ill. ; 23 cm.
Language: English
Creator: Walker, M. N ( Marion Newman ), 1900-
Weber, George F ( George Frederick ), b. 1894
Parris, G. K ( George Keith ), 1908-
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1949
 Subjects
Subject: Watermelons -- Diseases and pests -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by M.N. Walker and George F. Weber ; rev. by G.K. Parris.
General Note: Cover title.
General Note: "A revision of Bulletin 225"--T.p.
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00027381
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000925540
oclc - 18254220
notis - AEN6193

Table of Contents
    Title Page
        Page 1
    Credits
        Page 2
        Page 3
    Table of Contents
        Page 4
    Introduction
        Page 5
    Anthracnose
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Wilt
        Page 12
        Page 13
        Page 14
        Page 15
    Downy mildew
        Page 16
        Page 17
        Page 18
    Gummy-stem blight
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Stem-end rot
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
    Southern blight
        Page 30
    Blossom-end rot
        Page 31
        Page 32
        Page 33
        Page 34
    Powdery mildew
        Page 35
    Cereospora leaf spot
        Page 35
        Page 36
    Macrosporium leaf spot
        Page 37
    Soil rot
        Page 37
    Speckle
        Page 38
    Mosaic
        Page 38
        Page 39
    Minor diseases not found in Florida
        Page 40
    Cold, wind and sand injury
        Page 41
        Page 42
    Handling
        Page 43
    Summary
        Page 44
        Page 45
        Page 46
Full Text


Bulletin 459


(A Revision of Bulletin 225)

UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
HAROLD MOWRY, Director
GAINESVILLE, FLORIDA








Diseases of Watermelons

in Florida

By
M. N. WALKER and GEORGE F. WEBER
Revised by G. K. PARRIS


Fig. 1.-Watermelon showing anthracnose.


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


May, 1949








BOARD OF CONTROL

J. Thos. Gurney, Chairman, Orlando
N. B. Jordan, Quincy
Thos. W. Bryant, Lakeland
J. Henson Markham, Jacksonville
Hollis Rinehart, Miami
W. F. Powers, Secretary, Tallahassee


EXECUTIVE STAFF

J. Hillis Miller, Ph.D., President of the
University3
H. Harold Hume, D.Sc., Provost for Agr.'
Harold Mowry, M.S.A., Director
L. O. Gratz, Ph.D., Asst. Dir., Research
W. M. Fifield, M.S., Asst. Dir., Admin.
3. Francis Cooper, M.S.A., Editors
Clyde Beale, A.B.J., Associate Editors
W. H. Mosher, Assistant Editor
Ida Keeling Cresap, Librarian
Ruby Newhall, Administrative Managers
Geo. F. Baughman, M.A., Business Managers
Claranelle Alderman, Accountants


MAIN STATION, GAINESVILLE

AGRICULTURAL ENGINEERING
Frazier Rogers, M.S.A., Agr. Engineers
J. M. Johnson, B.S.A.E., Asso. Agr. Engineers
J. M. Myers, B.S., Asso. Agr. Engineer
R. E. Choate, B.S.A.E., Asst. Agr. Engineers
A. M. Pettis, B.S.A.E., Asst. Agr. Engineer2 8

AGRONOMY
Fred H. Hull, Ph.D., Agronomist'
G. E. Ritchey, M.S., Agronomists
G. B. Killinger, Ph.D., Agronomists
H. C. Harris, Ph.D., Agronomists
R. W. Bledsoe, Ph.D., Agronomist
S. C. Litzenberger, Ph.D., Associate
W. A. Carver, Ph.D., Associate
Fred A. Clark, B.S., Assistant
M. N. Gist, Collaborator'

ANIMAL INDUSTRY
A. L. Shealy, D.V.M., An. Industrialist' 3
R. B. Becker, Ph.D., Dairy Husbandman3
E. L. Fouts, Ph.D., Dairy Technologists
D. A. Sanders, D.V.M., Veterinarian
M. W. Emmel, D.V.M. Veterinarians
L. E. Swanson, D.V.M., Parasitologist
N. R. Mehrhof, M.Agr., Poultry Husb.3
G. K. Davis, Ph.D., Animal Nutritionists
R. S. Glasscock, Ph.D., An. Husbandman3
P. T. Dix Arnold, M.S.A., Asst. Dairy Husb.S
L. E. Mull, M.S., Asst. in Dairy Tech.
Katherine Boney, B.S., Asst. Chem.
J. C. Driggers, B.S.A., Asst. Poultry Husb.3
Glenn Van Ness, D.V.M., Asso. Poultry
Pathologist
S. John Folks, B.S.A., Asst. An. Husb.3
W A. Krienke, M.S., Asso. in Dairy Mfs.3
S P. Marshall, Ph.D., Asso. Dairy Husb.3
u. F. Simpson, D.V.M., Asso. Veterinarian
C. F. Winchester, Ph.D., Asso. Biochemist3


ECONOMICS, AGRICULTURAL
C. V. Noble, Ph.D., Agri. Economist'
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., Associate
R. E. L. Greene, Ph.D., Agri. Economist
H. W. Little, M.S., Assistant
Tallmadge Bergen, B.S., Asst.
Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. Agr. Economist
J. C. Townsend, Jr., B.S.A., Agr. Statistician'
J. B. Owens, B.S.A., Agr. Statisticians
J. F. Steffens, Jr., B.S.A., Agr. Statistician'


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

ENTOMOLOGY
A. N. Tissot, Ph.D., Entomologistx
L. C. Kuitert, Ph.D., Assistant
H. E. Bratley, M.S.A., Assistant

HORTICULTURE
G. H. Blackmon, M.S.A., Horticulturist'
F. S. Jamison, Ph.D., Horticulturist3
H. M. Reed, B.S., Chem., Veg. Processing
Byron E. Janes, Ph.D., Asso. Hort.
R. A. Dennison, Ph.D., Asso. Hort.
R. K. Showalter, M.S., Asso. Hort.
Albert P. Lorz, Ph.D., Asso. Hort.
R. H. Sharpe, M.S., Asso. Hort.
R. J. Wilmot, M.S.A., Asst. Hort.
R. D. Dickey, M.S.A., Asst. Hort.
Victor F. Nettles, M.S.A., Asst. Hort.4
F. S. Lagasse, Ph.D., Asso. Hort.2
L. H. Halsey, B.S.A., Asst. Hort.
Forrest E. Myers, B.S.A., Asst. Hort.

PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist's
Phares Decker, Ph.D., Plant Path.
Erdman West, M.S., Mycologist and Botanist
Howard N. Miller, Ph.D., Asso. Plant Path.
Lillian E. Arnold, M.S., Asst. Botanist

SOILS
F. B. Smith, Ph.D., Microbiologist's
Gaylord M. Volk, Ph.D., Chemist
J. R. Henderson, M.S.A., Soil Technologista
J. R. Neller, Ph.D., Soils Chemist
Nathan Gammon, Jr., Ph.D., Soils Chemist
C. E. Bell, Ph.D., Associate Chemist
R. A. Carrigan, Ph.D'., Asso. Biochemists
H. W. Winsor, B.S.A., Assistant Chemist
Geo. D. Thornton, Ph.D., Asso. Microbiologists
R. E. Caldwell, M.S.A., Asst. Chemists
J. B. Cromartie, B.S.A., Soil Surveyor
Ralph G. Leighty, B.S., Asso. Soil Surveyor
V. W. Cyzycki, B.S., Asst. Soil Surveyor
R. B. Forbes, M.S., Asst. Soils Chemist
W. L. Pritchett, M.S., Asst. Chemist
Jean Beem, B.S.A., Asst. Soil Surveyor

1Head of Department.
'In cooperation with U. S.
SCooperative, other divisions, U. of F.
4On leave.









BRANCH STATIONS

NORTH FLORIDA STATION, QUINCY
J. D. Warner, M.S., Vice-Director in Charge
R. R. Kincaid, Ph.D., Plant Pathologist
W. H. Chapman, M.S., Asso. Agron.
L. G. Thompson, Ph.D., Soils Chemist
Frank S. Baker, Jr., B.S., Asst. An. Husb.4
W. C. Rhoads, M.S., Entomologist

Mobile Unit, Monticello
R. W. Wallace, B.S., Associate Agronomist

Mobile Unit, Marianna
R. W. Lipscomb, M.S., Associate Agronomist

Mobile Unit, Chipley
J. B. White, B.S.A., Associate Agronomist

Mobile Unit, DeFuniak Springs
R. L. Smith, M.S., Associate Agronomist


CITRUS STATION, LAKE ALFRED

A. F. Camp, Ph.D., Vice-Director in Charge
W. L. Thompson, B.S., Entomologist
J. T. Griffiths, Ph.D., Asso. Entomologist
R. F. Suit, Ph.D., Plant Pathologist
E. P. Ducharme, M.S., Plant Pathologist'
R. K. Voorhees, Ph.D., Asso. Horticulturist
C. R. Stearns, Jr., B.S.A., Asso. Chemist
J. W. Sites, M.S.A., Horticulturist
H. 0. Sterling, B.S., Asst. Horticulturist
J. A. Granger, B.S.A., Asst. Horticulturist
H. J. Reitz, M.S., Asso. Horticulturist
Francine Fisher, M.S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
A. E. Willson, B.S.A., Asso. Biochemist
J. W. Kesterson, M.S., Asso. Chemist
R. N. Hendrickson, B.S., Asst. Chemist
Joe P. Barnett, B.S.A., Asst. Horticulturist
J. C. Bowers, B.S., Asst. Chemist
D. S. Prosser, Jr., B.S., Asst. Horticulturist
R. W. Olsen, B.S., Biochemist
F. W. Wenzel, Jr., Ph.D., Supervisory Chem.
Alvin H. Rouse, M.S., Asso. Chemist
L. W. Fayville, Ph.D., Asst. Chemist


EVERGLADES STATION, BELLE GLADE

R. V. Allison, Ph.D., Vice-Director in Charge
F. D. Stevens, B.S., Sugarcane Agronomist
Thomas Bregger, Ph.D., Sugarcane
Physiologist
J. W. Randolph, M.S., Agricultural Engineer
W. T. Forsee, Jr., Ph.D., Chemist
R. W. Kidder, M.S., Asso. Animal Husb.
T. C. Erwin, Assistant Chemist
Roy A. Bair, Ph.D., Agronomist
C. C. Seale, Asso. Agronomist
N. C. Hayslip, B.S.A., Asso. Entomologist
E. H. Wolf, Ph.D., Asst. Horticulturist
W. H. Thames, M.S., Asst. Entomologist
C. B. Savage, M.S.A., Asst. Horticulturist
D. L. Stoddard, Ph.D., Asso. Plant Path.


SUB-TROPICAL STATION, HOMESTEAD

Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
II. 0. Wolfenbarger, Ph.D., Entomologist
Francis B. Lincoln, Ph.D., Horticulturist
Robt. A. Conover, Ph.D., Asso. Plant Path.
R. W. Harkness, Ph.D., Asst. Chemist
Milton Cobin, B.S., Asso. Horticulturist


W. CENT. FLA. STATION, BROOKSVILLE

William Jackson, B.S.A., Animal Husband-
man in Charge2


RANGE CATTLE STATION, ONA

W. G. Kirk, Ph.D., Vice-Director in Charge
E. M. Hodges, Ph.D., Associate Agronomist
D. W. Jones, B.S., Asst. Soil Technologist


CENTRAL FLORIDA STATION, SANFORD

R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
J. W. Wilsori, Sc.D., Entomologist
Ben F. Whitner, Jr., B.S.A., Asst. Hort.


WEST FLORIDA STATION, MILTON

H. W. Lundy, B.S.A., Associate Agronomist



FIELD STATIONS

Leesburg
G. K. Parris, Ph.D., Plant Path. in Charge

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


Hastings
A. H. Eddins, Ph.D., Plant Path. in Charge
E. N. McCubbin, Ph.D., Horticulturist

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


Bradenton
J. R. Beckenbach, Ph.D., Hort. in Charge
E. G. Kelsheimer, Ph.D., Entomologist
David G. Kelbert, Asso. Horticulturist
E. L. Spencer, Ph.D., Soils Chemist
Robert O. Magie, Ph.D., Gladioli Hort.
J. M. Walter, Ph.D., Plant Pathologist
Donald S. Burgis, M.S.A., Asst. Hort.


Lakeland
Warren O. Johnson, B.S., Meteorologist2

1Head of Department.
SIn cooperation with U. S.
3 Cooperative, other divisions, U. of F.
4 On leave.















Contents


Page


INTRODUCTION .... ....................


- .............. ..... ..........- 5


ANTHRACNOSE .........................



W ILT ............ .. ........... .. -. ..... ..



DOWNY MILDEW ................. -----.. -- --



GUMMY-STEM BLIGHT ................ .......... ... ...



STEM-END ROT ....................... .................



SOUTHERN BLIGHT ................ -- ................ .. ..



BLOSSOM-END ROT .....................................



POWDERY MILDEW .......... -----......- ..... -------



CERCOSPORA LEAF SPOT -............... .....--



MACROSPORIUM LEAF SPOT ............... -.



SOIL R OT .................. ... ..........- ...



SPECKLE ............... .........



M OSAIC --.... --.- ..... -- ..... .... ....- --



MINOR DISEASES NOT FOUND IN FLORIDA .............



COLD, WIND AND SAND INJURY ..........................



HANDLING .-----.-----.-------- .....- -



SUMMARY ......... --..... ..............-


....--. ...........-------.----...... 5



..... .. .. ..... 12



...................-...... .... ........... 16
-- - ---- ------------- ----- 12





----------------- 19
.. .......................------.... 19



.................................... .. .- 24



...-. .....- .........--- -...-----. -- 30



...... -......... ---.......... ...... 31



............... -...... -.---...... ..... 35



.......---.........--..--........ 35



..... ...............-.. .....- ---- 37



. ...........- ............-----.. ...... 37



...........-...-...-..... ........ ...- 38



........................... ----..... 38



...-------------............ -- 40



....................... 41


.... 44







Diseases of Watermelons in Florida

By M. N. WALKER and GEORGE F. WEBER 1
Revised by G. K. PARRIS

Introduction
Watermelons are grown in commercial quantities in almost
every county in Florida, but the bulk of the crop is produced
in comparatively few of them. Between 25,000 and 45,000
acres are planted to the crop every year, and approximately
9,000 to 12,000 carloads, about 15 percent of the watermelon
crop of the United States, are shipped. The returns to growers
amount to from $2,000,000 to $6,000,000 a year, depending on
production per acre and prices obtained for the crop.
It is impossible to give an accurate estimate of the financial
loss incident to watermelon diseases, but they are often an im-
portant factor in determining the success or failure of the crop.
Certain of the diseases under conditions favorable for their
development may destroy the crop entirely, and few are the
melon fields in which one or more diseases of watermelons are
not doing some damage.
The area planted to watermelons each year is dependent
largely on the financial success of the preceding melon crop.
Although there are a number of important factors besides dis-
eases which determine the success of the crop, it is the purpose
of this bulletin to discuss only the diseases, to give descriptions
of them, and to outline means for their prevention and control.

Anthracnose
Anthracnose, caused by the fungus Colletotrichum lagenarium
(Pass.) Ell. & Hals., is the most destructive disease of water-
melons in the United States, and is found everywhere that
melons are grown with the possible exception of California.
The seriousness of anthracnose on watermelons may be realized
from the annual losses of from 20 to 30 percent of the crop
in some states. It is especially severe in the Southern states,
and in Florida it causes more loss than all the other diseases
of watermelons combined. Seldom a season passes without this
disease being a controlling factor in production, especially near
the end of the season when high temperatures and heavy rainfall
make it difficult to control. Anthracnose has been found on
1 Formerly plant pathologists, Florida Agricultural Experiment Stations.







Diseases of Watermelons in Florida

By M. N. WALKER and GEORGE F. WEBER 1
Revised by G. K. PARRIS

Introduction
Watermelons are grown in commercial quantities in almost
every county in Florida, but the bulk of the crop is produced
in comparatively few of them. Between 25,000 and 45,000
acres are planted to the crop every year, and approximately
9,000 to 12,000 carloads, about 15 percent of the watermelon
crop of the United States, are shipped. The returns to growers
amount to from $2,000,000 to $6,000,000 a year, depending on
production per acre and prices obtained for the crop.
It is impossible to give an accurate estimate of the financial
loss incident to watermelon diseases, but they are often an im-
portant factor in determining the success or failure of the crop.
Certain of the diseases under conditions favorable for their
development may destroy the crop entirely, and few are the
melon fields in which one or more diseases of watermelons are
not doing some damage.
The area planted to watermelons each year is dependent
largely on the financial success of the preceding melon crop.
Although there are a number of important factors besides dis-
eases which determine the success of the crop, it is the purpose
of this bulletin to discuss only the diseases, to give descriptions
of them, and to outline means for their prevention and control.

Anthracnose
Anthracnose, caused by the fungus Colletotrichum lagenarium
(Pass.) Ell. & Hals., is the most destructive disease of water-
melons in the United States, and is found everywhere that
melons are grown with the possible exception of California.
The seriousness of anthracnose on watermelons may be realized
from the annual losses of from 20 to 30 percent of the crop
in some states. It is especially severe in the Southern states,
and in Florida it causes more loss than all the other diseases
of watermelons combined. Seldom a season passes without this
disease being a controlling factor in production, especially near
the end of the season when high temperatures and heavy rainfall
make it difficult to control. Anthracnose has been found on
1 Formerly plant pathologists, Florida Agricultural Experiment Stations.





Florida Agricultural Experiment Stations


cucumbers, cantaloupes, and a number of other plants related
to watermelon.
The losses caused by this disease can be divided into those
occurring in the field and those occurring in transit; if it is
controlled in the field it should not occur in transit. Anthrac-
nose can cause defoliation of the plants, which is a direct cause
of melons failing to mature. Infected melons may be refused
by inspectors at loading time or rot while in transit to Northern
markets if shipped. The spots or lesions on the melons caused
by the parasite are a common and severe form of the disease.
These lesions vary considerably in size, depth and number, and
a few small spots on a melon missed by inspectors may cause
decay and loss in transit. Transportation loss from anthracnose
is second only to that caused by stem-end rot.

Description
The anthracnose fungus can attack all parts of watermelon
plants above ground in all stages of their development, but usually
the disease is first noticed on the oldest leaves of plants that have
attained some size (Fig. 2). The leaves show small black spots
(Fig. 3) which may enlarge until the whole leaf becomes black
and shriveled. During periods of weather favorable to the
disease an entire field may show these blackened leaves in a


Fig. 2.-Watermelon leaves around the center of the hill killed by
anthracnose. Arrow indicates base of the plant.






Diseases of Watermelons in Florida


few days, and is described by the grower as having been "burned
over" (Fig. 4). Heavy defoliation caused by attacks of anthrac-
nose results in the occurrence of many immature melons that
usually sunburn. Often, under less favorable conditions for the
disease, only the leaves at the center of the plant are killed,
leaving the stem and a portion of the runners bare.


Fig 3.-Anthracnose of watermelon showing typical lesions on leaf blade.


t *






Florida Agricultural Experiment Stations


Fig. 4.-Watermelon plant showing most of the leaves killed by
anthracnose. (Courtesy USDA.)

During wet weather the spots on the leaves show small,
orange-pink, oily, "heaped up" masses of the spores of the
fungus; in dry weather the spore masses are grayish and less
conspicuous. These spores spread the fungus in wet weather.
The stems and runners also may be attacked and killed. The
lesions on the stems are rather long and narrow in the direction
of the stem, and in the early stages of infection appear as small,
water-soaked areas which later become sunken and tan to black
in color. The spore masses also are found in these lesions.
Both leaf and stem lesions serve as sources of infection for the
melons that develop later.
When young melons are infected black spots appear similar
to those on the leaves on the young fruits and the melons can
become malformed. On older melons the disease causes small,
water-soaked spots with greasy, yellowish centers, which become
somewhat elevated, giving a bumpy appearance to the surface of
the melon. These raised areas later become sunken (Fig. 1)
and pitted, and of a creamy to black color. They are covered
with the pink spore masses of the fungus (Fig. 5). The lesions
enlarge slowly, but finally may attain an inch or more in diameter
and one-eighth to one-quarter inch in depth, and by coalescence
a large part of the surface of the melon may be involved.
Melons that show this pimply, bumpy surface when loaded
rot in transit, both from the continued growth of the anthrac-






Diseases of Watermelons in Florida


alam


I0


^ *, I 0 L,










Fig. 5.-Anthracnose of watermelon, slightly enlarged to show
characteristic lesions and masses of spores.

nose fungus and from other rot-producing fungi that enter
through the anthracnose lesions.
The anthracnose fungus is carried through winter as spores
on the surface of melon seeds, and on other cultivated host
plants such as cantaloupe and cucumber. The ability of the
fungus to survive in Florida soil in the absence of the melon
crop is not known. The spores are easily and widely spread by
wind, rain, cultural implements, animals and laborers. It is
often observed that an outbreak of anthracnose occurs soon
after the first picking, due to labor walking among wet and
diseased vines. The cotyledons, or seed leaves, become infected
from the spores on the seed coat, and from there the anthrac-
nose spreads to the first true leaves, which at later periods, when
the vines are running, are considered the oldest leaves. Symp-
toms of anthracnose on the cotyledons are very similar to those
due to gummy-stem blight (Fig. 10), and the grower often will
confuse the two. Both diseases are seed-borne. Under average
conditions it takes about 10 days from the germination of the
fungus spore and its infection of the plant to the production of
mature spores on the diseased spots. During dry, cool periods






Florida Agricultural Experiment Stations


(below 600 F.), this time may be longer, but on the other hand,
several wet, warm days may reduce it to six or seven days. From
these facts it can be understood why the disease early in the
season develops slowly, and why, with the advent of warmer
weather whole fields may become diseased in less than a week
if conditions are right.

Control of Anthracnose
To control anthracnose, it is imperative that the seed be
treated before planting. Treatment is simple and cheap, using
one of the newer organic fungicides, semesan, spergon or arasan,
all of which seem to do the job of destroying the spores of the
fungus present on the seed coat. In practice, a can with tight-
fitting cover is half-filled with seed, the fungicide added to the
seed at the rate of 0.3 percent by weight, that is, one-third of
a pound of fungicide to every 100 pounds of seed, the cover is
placed on the can, and can and contents are vigorously shaken
until all seeds are well coated with the chemical. Shaking for
two to five minutes will suffice. Treated seed can be planted im-
mediately or stored without harm to germination. If melon seeds
are to be stored in Florida and their vitality preserved they
should be placed in cold storage. The combination of high tem-
perature and high humidity quickly destroys the power of ger-
mination. The presence of a fungicide on the seed will have no
effect, by itself, on the vitality of watermelon seed.
It is not recommended that growers sprout melon seeds that
have been treated with semesan, spergon or arasan, as possible
chemical injury may follow, due to an accumulation of the chemi-
cal at a toxic concentration. Therefore, growers who wish to
rid their melon seed of the anthracnose fungus and also to sprout
the seed should dip the seed before sprouting in 1:1,000 corrosive
sublimate mercuricc chloride) solution for 10 minutes in a
wooden or crock container and then very thoroughly wash them
in running water or several changes of water. Corrosive sub-
limate is a deadly poison to man, to animals and also to melon
seed, so be sure to use it with caution and make sure that none
of the chemical remains on the seed after washing. Do not
store the treated seed in old bags unless they, too, have been
dipped in corrosive sublimate solution and then washed.
Of the three dry (dust) treatments, semesan is the most
poisonous, for its active ingredient is mercury. Arasan is the
least poisonous, and spergon, while not called "non-poisonous,"






Diseases of Watermelons in Florida


is practically so. Where labor is employed to plant melon seed
and there is danger of transferring the chemical from their
hands to their mouth, it might be best to avoid semesan and
use either spergon or arasan. From the standpoint of actual
control of anthracnose, all three give good results, but semesan-
treated melon seed has been found to germinate slightly better
than when other materials are used, which it is doubtful a grower
ever considers, since he plants five to eight seeds per hill.
Later development of anthracnose, originating from fields of
untreated seed or possibly from the soil of former melon plant-
ings, can be checked by applying a fungicide such as dithane,
parzate, or possibly other materials, at rates recommended
by the manufacturers, either as a spray or as a dust. A spray
sticks better than a dust, but spraying watermelons seems,
to this author at least, to be less practical than dusting, par-
ticularly if the dust is applied by airplane. Dusting by plane,
fixed wing or helicopter, is rapid and efficient. The fungicide
is put on early in the day, when wind is at a minimum, often
when dew is on the foliage, and coverage usually is good to ex-
cellent, depending on the operator. Dusting young, and there-
fore small, vines by plane is probably more costly than necessary,
approximately 83.00 per acre, but plane application does get the
job done and over with.
It is not known when the first application of fungicide should
be made. If a grower can watch his fields closely, it is believed
that the fungicide should not be put on until the anthracnose
has made its initial appearance. Therefore, it will vary from
season to season and consequently from crop to crop. With the
adoption of seed treatment by most Central Florida growers
during the last four years, anthracnose does not appear in melon
plantings on new land as early as it did in former years. On
old land it will appear on the melon vines as soon as the soil,
if infested, is splashed on to the leaves. Subsequent applications
can be made at 7- to 10-day intervals as deemed necessary. A
disease forecasting service, similar to services available to apple,
cucumber, tomato and potato growers in other parts of the
nation, lends itself to watermelon disease control in Florida. Such
a service would tell growers what diseases threatened the melon
crop and whether application of a fungicide is advised. The cost
to spray or dust one acre of watermelons ranges from $2.50 to
$3.00. Most growers apply a fungicide at least once, some twice,
a few three or more times. Dusting or spraying for aphids is






Florida Agricultural Experiment Stations


always practiced, and the fungicide could be applied simul-
taneously. The insecticide is applied when it is known that
the insect is present; this cannot be said of the fungicide. The
savings to growers in fungicide costs by intelligent timing would
more than pay for employing personnel to staff and direct such
a forecasting service.
Some growers still spray their melon vines with 4-4-50 bor-
deaux, but research has shown that this material, while an ex-
cellent fungicide, injures the melon vine through hardening
the foliage and without doubt reduces the set. All of the copper
fungicides tried at Leesburg-copper compound A, COCS, copper-
zinc-lime, copper-lime and tri-basic copper sulfate-cause copper
burning of the melon leaf, which is expressed as a loss of green
color of the margin of the leaf, the green being replaced by, or
transformed to, a bright yellow. Neither dithane nor parzate
causes this injury and since they are good fungicides against
anthracnose they are recommended over anything else hereto-
fore mentioned.
Much anthracnose infection can be avoided by keeping persons
out of the melon field when plants are wet, for the spores of the
fungus are easily spread by people walking through the vines.
The variety Black Kleckley shows a certain degree of toler-
ance to anthracnose, and the Watermelon Labortory at Leesburg
is breeding for resistance to the disease.

Wilt
The wilt disease of watermelons, caused by the soil-inhabiting
fungus Fusarium oxysporum (E. F. S.) f. niveum Synder and
Hansen, has been recognized as a serious disease for many years.
Growers have found by experience that it is inadvisable to grow
susceptible varieties on the same ground without an 8- to 10-
year interval between crops. The disease is known in every
melon-growing area of the United States, but it is on the lighter,
sandier soils that wilt does most damage. When a field is in-
fested heavily a total loss of the crop may result. Ordinarily,
in commercial practice where the same ground is rarely planted
to watermelons two years in succession, the disease is not
especially serious, but in escaping the disease by rotation there
is the additional expense of changing to new land every year.
In small home plantings, or in new fields located close to older
fields that have shown the presence of the disease, wilt can
cause heavy loss.






Diseases of Watermelons in Florida


The fungus causing the wilt disease can live in the soil in the
absence of a watermelon crop for as long as 16 years on decay-
ing organic matter, though it gradually becomes less abundant
if melons are not planted. It is spread in a number of ways
and may be introduced into new areas on the feet of men or
animals, by cultivation implements, drainage water, infested
manure, wind-blown spores, soil, or plant debris. It is a common
practice to turn cattle into an abandoned field, and this usually
spreads the disease to the surrounding territory. The disease
apparently is limited in its attack to watermelon, not attacking
the closely related cucumber, squash, cantaloupe and muskmelon.

Description
The name wilt accurately describes the appearance of dis-
eased plants, as wilting is the most noticeable symptom of the
disease (Fig. 6). Wilt can attack watermelon plants in any
stage of development, though the symptoms are most spectac-
ular after the plants have attained some size. The disease may
occur as a general rot of germinating seed, or as a damping-off
of seedlings after they are well out of the ground. This latter
type of injury is preceded by a loss of green color of the coty-
ledons and small leaves which soon droop and become completely
dry and withered after a day or so. The stems of such plants
when pulled up are found to be girdled by a soft rot just at or
below the soil level. Often the stems appear to be water-soaked


4.-u
Ar
'i -

IA
^^.^l~f
^ ^~~.-iflVR


ESAIL t


w


e '%* 1-.7 p


Fig. .-Watermelon plants in the field killed by Fsarium wilt.
Fig. 6.-Watermelon plants in the field killed by Fusarium wilt.


~IP~pir~'s~
~ Ph~,-~~~_'99~-~Gi~,







Florida Agricultural Experiment Stations


Fig. 7.-Longitudinal sections of watermelon stems
showing darkened areas caused by Fusarium wilt. A
healthy plant is shown on right.






Diseases of Watermelons in Florida


for some distance above the rotted area. After the plants are
killed the fungus grows out over the surface and produces spores
in great numbers. Stunting is another type of injury caused
by the wilt organism on seedling plants not immediately killed.
Wilt is observed most commonly in older plants. Their leaves
wilt and shrivel, starting at the tips of the runners. Plants
may appear healthy in the morning, wilted by noon and healthy
next morning. This alternate wilting and recovery may con-
tinue for several days, but plants never recover permanently
after they are attacked and eventually they die. Melon plants
in the later stages of the disease often show a light colored
cottony growth, indicating the presence of the fungus which
bears large number of spores. The water-carrying vessels of
wilted plants are yellow or brown, or a large part of the stem
will be browned (Fig. 7).
The wilt fungus grows best at a temperature around 800 F.,
which explains the appearance of the disease in the field late in
the season. Even under favorable conditions there appears to
be considerable variation in the susceptibility of different strains
and varieties of watermelons to the disease.

Control of Wilt
Where wilt occurs, about the only sure way to avoid the dis-
ease is not to plant watermelons on land that has produced a
watermelon crop before. It is known that the fungus can live
for 16 years in the soil, but in general eight to 10 years between
melon crops will reduce the amount of the fungus in the soil
to a point where land can be used again for planting susceptible
varieties. There is always danger of wilt occurring on new land
where drainage water from a diseased field has flowed over the
new field, or where cattle have had access to both fields.
The most hopeful means of combating wilt is by using re-
sistant varieties. However, local investigations have shown
that it pays to wait at least two years between crops of water-
melons on the same land when wilt-resistant varieties are grown.
This laboratory has developed the wilt-resistant varieties Lees-
burg (1936) and Blacklee (1944), but neither has found favor
with the Florida melon grower, who is desirous of growing an
early melon that does not sunburn, such as the wilt-susceptible
Cannon Ball, Florida Giant, Black Diamond or Clara Lee, as it
is variously called. In other parts of the nation the high quality
Blacklee has been tried and is well liked. Other wilt-resistant






Florida Agricultural Experiment Stations


varieties available are the Klondike of California, Miles of Ten-
nessee, Black Kleckley, Kleckley No. 6, Dixie Queen of Iowa,
and the Georgia Wilt-Resistant of that state. Several unnamed
strains developed by the USDA Regional Vegetable Breeding
Laboratory at Charleston, South Carolina, and the Brownlee and
the Improved Leesburg, developed at Leesburg but not released,
are also wilt-resistant. None of these has been tried commer-
cially to any extent in Florida. In 1948 much wilt appeared in
the Florida plantings of Cannon Ball and it appears that unless
a wilt-resistant strain of this variety can be obtained by breed-
ing, the variety is on its way out or will not be grown to any
extent until the wilt fungus is reduced by rotation. Work to
develop a wilt-resistant Cannon Ball is the object of research
at the Watermelon Laboratory

Downy Mildew
Downy mildew, caused by the parasitic fungus Peronoplas-
mopara cubensis (B. & C.) Rostow, has been found in most
Gulf and Atlantic states and in a few of the interior ones that
produce watermelons. It is common year after year, is wide-
spread in Florida and as a disease threat must be considered
to be of almost equal rank with anthracnose. The fungus has
been collected on most of the cucurbits, such as cucumber, canta-
loupe, squash, pumpkin and gourd. It is the worst disease of
cucumbers in the State and, since cucumbers are widely grown
during most of the year, there is an abundant source of inoculum
for watermelons. The disease usually does not become of seri-
ous consequence until after the middle of the growing season.
It attacks only the leaf blades of the watermelon, where it causes
lesions which eventually kill the foliage. The spores are pro-
duced on the diseased spots, most plentifully on the lower sur-
faces, and are easily detached and spread by rain and wind.
These fruiting structures are difficult to detect except in the
early morning before the dew has disappeared. Consequently
the spots caused by the fungus generally are mistaken for
anthracnose.
Description
The first symptom of infection by the downy mildew fungus
is the appearance of a slightly yellowish spot on the blade of the
leaf. The yellowing becomes more pronounced and about two
days later the fruiting fungus can be observed. These yellow






Diseases of Watermelons in Florida


spots are circular or oval in outline and blend gradually into
the green color of the leaf (Fig. 8). Later, however, the tissue
is killed and turns brown or blackish. The spots now are an-
gular in outline and are easy to confuse with anthracnose (Fig.
3) and gummy-stem blight. They may be few or many on a
single leaf, depending on the abundance of primary infection,


Fig. 8.-Spotting of citron leaf caused by downy mildew.






Florida Agricultural Experiment Stations


and may coalesce when in close proximity and thus rapidly in-
volve the entire leaf blade which then turns black, dries and
disintegrates. They vary in size from one-eighth to one-half
inch or more in diameter. Downy mildew can produce the same
effect in a field of almost mature watermelons as can anthrac-
nose, except that
it takes place in
late April or early
May. Almost
over night the
foliage is blasted
and dying, and
only by a care-
ful microscopic
examination can
the causal organ-
ism be determined
by means of its
spores (Fig. 9).
Much leaf de-
struction thought
Sto be caused by
anthracnose in
Florida in the
past has been due
to downy mildew.
If lesions are
Fig. 9.-Branched conidiophore of downy mildew found d on the
fungus and spores that grow upon its branches s o
(highly magnified).tems t
melon plants at
the same time as they appear on the leaves, then it may safely
be said that anthracnose and not downy mildew is implicated,
but not always does the former fungus attack the stems of the
melon vine.
Control of Downy Mildew
Downy mildew can be controlled by using the same materials
recommended to control anthracnose, namely dithane or parzate,
while tri-basic copper sulfate also is excellent. All the materials
listed under anthracnose, as well as zerlate and fermate, do a
fair job of controlling mildew. Generally, both diseases have
to be controlled, so it seems wise to use materials which will
control both, and these materials are dithane and parzate. As






Diseases of Watermelons in Florida


with anthracnose, a disease forecasting service for melon grow-
ers would be desirable for downy mildew. A grower must know
not only when to apply but also when not to apply a fungicide
in order to save his money.

Giummyi-Stem Blight
Gummy-stem blight, caused by the fungus Mycosphaerella
cucumis (Fautr. and Roum.) Chiu and J. C. Walker, is widely
distributed over the eastern and central United States and has
been reported as far west a Arizona. The disease can cause con-
siderable losses by killing the emerging seedling and through de-
foliation and killing of runners when weather conditions are
favorable. Though prevalent in Florida, the disease is ordi-
narily of secondary importance. Its wide distribution can be
accounted for by its ability to live for several years on decaying
plant material in the soil from which it attacks cotyledons (Fig.
10), leaves and runners as they develop. Later the fungus forms
great quantities of spores on the attacked parts, which serve for
its further spread by wind and water or other agencies such as
cultural implements and animals.
















Fig. 10.-Spots of gummy-stem blight on cotyledons of watermelon plants.

Description
The circular, sunken, blackish and wrinkled spots on the
cotyledons (Fig. 10) and primary stems of young plants are
often the first symptoms of gummy-stem blight. As mentioned
previously, symptoms of anthracnose on the cotyledons are







20 Florida Agricultural Experiment Stations






























\. 4 ,


Fig. 11-Gummy-stem disease on blade and petiole of watermelon leaf.
Fig. 11.-Gummy-stem disease on blade and petiole of watermelon leaf.





Diseases of Watermelons in Florida 21















P7W




























Colletotrichimt laflenarizm, and Mycosphaerella evenmis.
Colletotrichll,, lagenuari~c,z and Mylcosph2e7c~le a l c~lcrnis..





Florida Agricultural Experiment Stations


identical with those of gummy-stem, except for the pycnidia or
fruiting structures containing spores which are produced in
abundance on spots caused by gummy-stem. If these spots are
located on the portion of the cotyledon close to the petiole, the
whole blade can be killed (Fig. 11), and the axillary bud or the
whole growing tip may be destroyed by the enlargement of the
primary lesion. The first true leaves are infected by spores
from the spots on the cotyledons, and girdling and death of the
growing tip can take place in the same manner as described for
the cotyledon infections. The disease can also attack and girdle
the stem below the cotyledons. Gummy-stem blight spreads
from the center of the hill outward just as anthracnose does
(Figs. 2 and 4) as the season advances, attacking leaves and


Fig. 13.-Gummy-stem blight affecting crown of melon plant. The point
of attack is indicated by point of knife.






Diseases of Watermelons in Florida


stems. Sometimes more than one disease can occur simultane-
ously and it is not uncommon to find gummy-stem blight, an-
thracnose and downy mildew on the same leaf (Fig. 12).
On the leaves the disease is characterized by light brown spots,
in the centers of which the minute, black fruiting bodies-
pycnidia-of the fungus develop. On the stems the disease ap-
pears as elongated, water-soaked areas that later become light
brown to whitish (Fig. 13). The fruiting bodies, in which are
formed great quantities of spores, appear abundantly in these
cankered areas, sometimes in numbers sufficient to give the
lesion a black appearance. The cankers often crack open and
exude a reddish-amber gum, and this characteristic has given
the disease its name. But anthracnose likewise will cause
exudation of a similar gum, so once again we must use a hand


















Fig. 14-Typical lesions on watermelon stem caused by gummy-stem blight.

lens or microscope to determine which disease is present. If
small black dots, the pycnidia, are present on the lesions then
it can be said with sureness that the disease is gummy-stem
blight. The lesions on the stems or runners persist until the
end of the season if the plant is not killed and, late in the season
they may become continuous and the stem and all runners ap-
pear bleached, often cracked (Fig. 14) and sometimes blackened
with the dried gum and the masses of fruiting bodies of the
fungus. In some instances the cankered stem enlarges to two
or three times its normal size, as shown in Fig. 14. The gummy-





Florida Agricultural Experiment Stations


stem blight fungus also occurs on the melon fruit, though to
no great extent.
Control of Gummy-Stem Blight
Seed treatment, as given for anthracnose control, will do much
to reduce losses from this disease, but control is not too perfect,
as 1948 field observations showed. Apparently the gummy-
stem blight fungus, enclosed in its thick-walled pycnidium, which
is not present in the anthracnose fungus, is more difficult to
penetrate with a fungicide than is the open type fruiting body,
the acervulus of the genus Colletotrichum. Semesan, spergon
and arasan reduce gummy-stem blight considerably and are
recommended until something better is developed.
Spraying or dusting as recommended for anthracnose should
control this disease on the growing plants.













B c
Fig. 15.-Photomicrographs of pycnidiospores of Diplodia sp., the imper-
fect stage of Physalospora rhodina that causes stem-end rot of watermelon.
A-Diplodia frumenti; B-Diplodia gossypina; C-Diplodia tubericola.

Stem-End Rot
Stem-end rot of watermelons is primarily a transit disease.
It is caused by the fungus Physalospora rhodina (Berk. & Curt.)
Cooke. This organism also causes diseases of sweet potato,
ear and stalk rot of corn, boll rot of cotton and gumming of
citrus. It is widely distributed throughout the tropics, grow-
ing as a wound parasite or secondary organism. The imperfect
stage lies in the genus Diplodia, members of which produce
spores, called pycnidiospores because they are borne in a
pycnidium, which often are indistinguishable from one another
(Fig. 15).






Diseases of Watermelons in Florida


The disease is common and destructive in most of the water-
melon-growing regions of the United States and is especially
prevalent in the Southern states, because of the long time the
fruit is in transit to Northern markets. In Florida the disease
is almost wholly a transportation problem. The melons are
loaded at the local shipping points in a healthy, sound condition
as far as can be determined and when they arrive at their


Fig. 16.-Interior of railroad car at destination after sound melons
were removed. Loss caused principally by stem-end rot and anthracnose.
(Courtesy USDA.)





Florida Agricultural Experiment Stations


destination, from four to eight days later, decay is evident,
usually about 10 percent (Fig. 16).
The exact source of the inoculum is not definitely known, but
since it has been proved that the organisms affecting citrus,
sweet potatoes, corn and cotton will also cause the disease, it
can be readily understood where some of the fungus spores
originate. Records of collections in Florida show that Diplodia
sp. producing spores very much like those found on diseased
watermelons have been found infecting more than 40 different
kinds of plants.
















Fig. 17.-Stem-end rot of watermelon caused by Physalospora rhodina.

The disease can cause serious loss to watermelon shippers
in all parts of this State during the shipping season. Reports
of inspectors at destination have shown as high as 40 percent
stem-end rot. In every instance where more than 12 to 15
percent decay occurred, the stems had not been treated. The
average of several hundred reports was 8 to 10 percent. Such
losses are entirely too high when the disease can be so easily
controlled.
The uninjured melon on the vine is resistant to the disease.
When it is injured or cut from the vine these unprotected areas
are exposed to infection. Where the skin is broken or the stem
is cut, a watery exudate appears and persists for considerable
time. This makes a very suitable medium for the germination
of the spores and growth of the fungus, which later advances
into the melon and causes decay. The percent of decayed melons
increases with the length of exposure of these injured places.






Diseases of Watermnelons in Florida


Melons should be handled carefully and removed from the field
to loading points as soon as possible. The spores germinate
quickly and in less than 12 hours may infect the cut stem and
later grow into the fruit, causing the rot typical of the disease.
Development of the disease in transit is favored by high tem-
peratures, high humidity and lack of ventilation in the cars,
along with constant jarring while traveling. All commercial
varieties of melons are subject to the disease to about the same
extent.

Description of Stem-End Rot

The first symptom of the disease is the browning and shrivel-
ing of the stem, which may be observed before the melon itself
shows infection.
The first decay of
the fruit takes place
around the stem,
where the rind be-
comes slightly dark-
ened and then
water-soaked, later
followed by a light
tan or brown color
(Fig. 17). After the
decay first shows on
the rind the advance
of the line of de-
marcation between
invaded and sound
tissue is rapid and
can be observed
readily from day to
day. After one-
third or more of' the
melon has been in-
vaded the stem-end Fig. 18.-Stem-end view of watermelon show-
vaded the stem-end ing development of stem-end rot.
portion becomes
dark colored and wrinkled and gradually shrinks as evaporation
continues (Fig. 18). The outer rind becomes overgrown with
a dense greenish or grayish-black mold, or under certain condi-
tions the mold may be light gray whitish, speckled with black.
The spores of the fungus are produced in abundance on the





28 Florida Agricultural Experiment Stations

older decayed areas. An indication of decay can often be de-
tected before any discoloration appears by the softness of the
rind around the stem end as determined by light pressure of
the thumb.

Control of Stem-End Rot
Control of this disease should begin in the field at harvest
time, and instructions should be given labor to guard against
injury to the fruit by rough and careless handling. The stems
should be clipped close to the vine rather than close to the melon,
so as to permit a second clipping after the melons are loaded in
the railroad car. The truck bodies used to collect melons in the
field should be free from gravel, sand, splinters, nails, etc., and
should be lined with burlap. Laborers should not be permitted

Fig. 19.-Clipping stems of tier of watermelons after loading in railroad
car and preparatory to treating to prevent stem-end rot.






Diseases of Watermelons in Florida 29

to ride on top of a load of melons. The melons should be loaded
carefully a tier at a time in alternate ends of the car so that
the stems can be clipped a second time and the cut ends dis-
infected with copper sulfate paste in one end of the car while
untreated melons are being loaded in the opposite end. The
stems can be cut off with an ordinary knife (Fig. 19), but thin-
bladed, sharp clippers are preferred. Immediately following
clipping, the stem should be painted. The first cutting in the
field should have left the stems about 2 to 3 inches long and
when the melons are loaded the stems should be cut to about
an inch long. A reliable workman should do this job, making
certain that there are no bruises on the stem when it is recut.
If bruised, the stem should be recut closer to the melon. The
clipped off stems should be collected and removed from the car.

Fig. 20.-Painting the clipped stem ends with copper sulfate paste for
the prevention of stem-end rot.






Florida Agricultural Experiment Stations


An additional precaution would be an occasional disinfection of
the clippers. The paste used to paint the clipped stems should
be about as thick as ordinary paint. It is easily applied with a
long-handled paint brush (Fig. 20) from a container that will
not easily tip. The disinfecting paste can be bought ready made
or can be made up according to the following formula: Place
31/2 quarts of water in an enamelware kettle and add 8 ounces of
copper sulfate or bluestone and bring to a boil. As soon as the
bluestone is dissolved and while boiling, add a starch mixture
made by mixing 4 ounces of either laundry or corn starch with
a pint of cold water, stirring until a milky mixture is obtained.
Continue the boiling and stirring until the mixture thickens to an
even paste, but the boiling should last only one or two minutes
after the starch is added, as the paste must not be too thick
to be easily applied with a brush. This paste serves as a dis-
infectant and kills the germinating spores, if they are present,
and treated melons arrive in the market without stem-end decay.

Southern Blight
Southern blight caused by the fungus Corticium rolfsii (Sacc.)
Curzi, is common in the southeastern and south central portions
of the United States, the northern limit approximating the Ohio
River. This area also coincides with the great watermelon pro-
ducing area of this country. This fungus has been found on
more than 180 species of plants. Effects from attacks of C.
rolfsii on various hosts are primarily the same and result in a
wilting and dying of the plant, because of the girdling of the
main stem at or near the soil line. On watermelons this disease
has not been of much importance except in occasional fields
where melons followed a crop of sweet potatoes or peanuts which
are highly susceptible. The fungus lives in the soil from season
to season as sclerotia, which are hard, brown, round structures
of fungus growth about the size of mustard seed (Fig. 21).
These sclerotia develop in large numbers on dying plant parts,
from which they are scattered by wind, water and cultivation,
and remain in the soil until the next crop is developing. When
warm, wet periods prevail, the sclerotia germinate and produce
the fungus mycelia which attack the stems of the plants in their
immediate vicinity. After the stems are girdled and killed,
numerous sclerotia are again produced.






Diseases of Watermelons in Florida


Description
When the fungus has attacked the main stem of the melon
plant at the soil line, the first indication of disease to the casual
observer is a slight lack of turgidity or wilting of some of the
younger leaves near the grow-
ing tips of the runners. The
disease seldom has been found
attacking melon vines before
runners have started. This
wilting gradually becomes more
pronounced and involves more
and more of the plant until
complete collapse takes place
and the plant quickly dies.
Often the fungus will attack
only a single runner at some **
distance from the main root
and in such instance only the -
runner is killed.,
The fungus also attacks the
melons themselves (Fig. 22)
where the lower surface is in
contact with the soil. The
fungus hyphae penetrate the
rind, causing it to turn brown.
The watery contents of the cells
in this area escape through the -
rind and collect on the surface Fig. 21.-Corticium rolfsii on a
col s d Te girdled and killed watermelon plant
in colorless droplets. The fun- (after 72 hours in moist chamber).
gus rapidly overgrows the at-
tacked areas, producing an abundance of white mycelium until
the melon collapses, shrivels and dries, leaving the innumerable
newly-developed sclerotia.

Control of Southern Blight
Rotation and sanitation are of most importance. All infected
melons should be removed from the field or buried at least a
foot deep.
Blossom-End Rot
Blossom-end rot is the name applied to a group of abnormali-
ties, either parasitic or physiological, which affect the end of
the melon opposite the stem. All the causes have not been





Florida Agricultural Experiment Stations


Fig. 22.-Ycung melon killed by Southern blight. The fungus is fruiting
on one side of it.
definitely decided upon by investigators. Some attribute the
cause to deranged nutrition, closely associated with moisture
supply and high temperatures. Others contend that parasitic
organisms, principally Pythium debaryanum Hesse and P. apha-
nidermatum (Eds.) Fitz., are the cause of the decay, or at least
start the infection (Fig. 23). A large number of organisms,
both fungi and bacteria, either saprophytic or parasitic, have
been isolated from diseased melons. Those who favor the physio-
logical theory consider this influx of organisms to be a natural
result of the breaking down of the tissues and the destruction
of any vestige of protective resistance. This can apply to melons
attacked by parasitic fungi such as Pythium spp., which break
down the protection or resistance of the host by their invasion,
leaving the tissue subject to the inroads of the multitude of
secondary invaders. Pythium debaryanum has been definitely
determined to be the cause of blossom-end rot of citrons. Other
organisms found associated with blossom-end rot are Myco-
sphaerella cueumis (Fautr. and Roum.) Chiu and J. C. Walker
(gummy-stem blight), Colletotrichum lagenarium (Pass.) E. &
H. anthracnosee), Cladosporium sp., Fusarium sp., Alternaria
sp. and Diplodia spp.






Diseases of Watermelons in Florida


Fig. 23.-Blossom-end rot of citron caused by Pythium debaryanum.
The fungus has advanced from the blossom-end toward the stem-end and
caused a decay of all the melon except the light colored area around the
stem.

Blossom-end rot is common in melon fields throughout the
country, especially in the South. In Florida it can be found in
almost any field after the first fruits set. The disease has been
found on fruits of all sizes and ages, but appears to be most
common on melons approximately one-fourth grown, or melons
measuring six to 10 inches by four to six inches. The affected
ones are conspicuous at this stage of development because of
the contrasting black color of the diseased area and because
a large percent of the melons are also crook-necked or mal-
formed. Whether the "crooks" are a result of invasion by a
parasite or of mechanical injury which permits the entrance of
fungi is a matter of opinion.






Florida Agricultural Experiment Stations


Description
The first indication of blossom-end rot is the water-soaked-
appearing tissue at the blossom end, which gradually becomes
darker in color. As the spot enlarges and involves more tissue,
the center changes from green to a tannish brown and becomes
soft. It is at this stage of development of the spot, which may
be one to three inches in diameter, that secondary invasion is
most common and the spots become almost black (Fig. 24).
Often there is no secondary invasion and the whole melon be-
comes involved in the decay. Other instances occur where the
progress of the rot is arrested and only a portion of the fruit
decays, shrinks and becomes wrinkled and black, while the re-
mainder of the melon is of normal green color.



1















Fig. 24.-Blossom-end rot of melon caused by the gummy-stem
blight organism.
Control
No control methods are known, although the "crooks" and mal-
formed fruits should be removed from the vines and field to
prevent the development of parasitic organisms on them which
may possibly infect other fruits and portions of the vine. These
malformed melons have no sales value and are a drain on the
vine which could be producing normal fruits.






Diseases of Watermelons in Florida


Powdery Mildew
The fungus Erysiphe cichoracearum DC. has been found at-
tacking watermelon leaves and fruits, causing the disease known
as powdery mildew. This disease has been reported from various
foreign countries and the watermelon-growing sections of the
United States. In Florida it is common on the leaves but sel-
dom is serious, as it develops most rapidly in warm, moist
weather which occurs usually in Florida toward the end of the
growing season. Powdery mildew has been found on canta-
loupe, cucumber, squash, gourd and pumpkin. The early symp-
toms appear on the leaf surfaces as small, superficial, circular
spots of a white, powdery nature which is the vegetative growth
of the fungus. The spots enlarge and the white coating becomes
more dense as spores are produced in increasingly large numbers
on both surfaces of the leaves, but are more plentiful on the
upper surface; they serve to spread the mildew. The fungus
seldom kills the leaves quickly, but overgrows them without
causing much loss of turgidity until they appear grey or whitish.
When this stage is reached brownish spots begin to develop,
which gradually involve the whole leaf, causing it to dry and die.

Control
Sulfur dust is specific for control of the powdery mildews but
sulfur injures cucurbits, so the regular spray schedule followed
for the control of other melon diseases is recommended to hold
this disease in check.

Cercospora Leaf Spot
This characteristic spot of watermelon leaves is caused by
Cercospora citrullina Cke. The disease has been reported from
most of the watermelon-growing sections of the United States.
In Florida it has been found widespread, but is not common or
of economic importance until toward the end of the season.
The disease usually is first observed on the leaves around the
center of the hill, but as the season advances it involves all of
the leaves toward the growing tip of the runners. The spotted
leaves turn yellow, wilt and die.

Description
The first symptom of the disease is the appearance of small,
water-soaked spots scattered over the surface of the leaf. These
spots enlarge up to several millimeters in diameter, become






Diseases of Watermelons in Florida


Powdery Mildew
The fungus Erysiphe cichoracearum DC. has been found at-
tacking watermelon leaves and fruits, causing the disease known
as powdery mildew. This disease has been reported from various
foreign countries and the watermelon-growing sections of the
United States. In Florida it is common on the leaves but sel-
dom is serious, as it develops most rapidly in warm, moist
weather which occurs usually in Florida toward the end of the
growing season. Powdery mildew has been found on canta-
loupe, cucumber, squash, gourd and pumpkin. The early symp-
toms appear on the leaf surfaces as small, superficial, circular
spots of a white, powdery nature which is the vegetative growth
of the fungus. The spots enlarge and the white coating becomes
more dense as spores are produced in increasingly large numbers
on both surfaces of the leaves, but are more plentiful on the
upper surface; they serve to spread the mildew. The fungus
seldom kills the leaves quickly, but overgrows them without
causing much loss of turgidity until they appear grey or whitish.
When this stage is reached brownish spots begin to develop,
which gradually involve the whole leaf, causing it to dry and die.

Control
Sulfur dust is specific for control of the powdery mildews but
sulfur injures cucurbits, so the regular spray schedule followed
for the control of other melon diseases is recommended to hold
this disease in check.

Cercospora Leaf Spot
This characteristic spot of watermelon leaves is caused by
Cercospora citrullina Cke. The disease has been reported from
most of the watermelon-growing sections of the United States.
In Florida it has been found widespread, but is not common or
of economic importance until toward the end of the season.
The disease usually is first observed on the leaves around the
center of the hill, but as the season advances it involves all of
the leaves toward the growing tip of the runners. The spotted
leaves turn yellow, wilt and die.

Description
The first symptom of the disease is the appearance of small,
water-soaked spots scattered over the surface of the leaf. These
spots enlarge up to several millimeters in diameter, become






36 Florida Agricultural Experiment Stations

sunken and dry out in the center (Fig. 25). The tissue in the
center of the spots changes from green to light tan and finally
to a dull white. The whitish centers are separated from the green
tissue by a dark brown to black ring which is very characteristic.
Often these spots are so close together that they coalesce, form-
ing larger brown areas that may include several of the individ-
ual spots. The spots are often invaded by other parasitic fungi,
such as Colletotrichum and Alternaria, which hasten the death
of the leaf. The fungus may be detected with a hand lens on


4




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.


A


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Jliw q."


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U


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'A lm
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9,


Fig. 25.-Cercospora leaf spot of watermelon.






Diseases of Watermelons in Florida


either surface of the leaf, but is usually more conspicuous on
the lower surface where the spores occur in the form of dark,
hairy specks. They are long and thin and are easily detached
and distributed by wind or water.

Control
Cercospora leaf spot is not important enough to warrant
specific control measures. The fungicides recommended for the
control of other leaf diseases should control this spot.

Macrosporium Leaf Spot
A leaf spot caused by Macrosporium cucumerinum E. & E. is a
very widely distributed disease of watermelons and related
plants, especially cantaloupe. It usually causes little damage
and is seldom observed, except during warm, wet seasons which
favor development of the fungus. The disease attacks the leaves
around the center of the hill and causes brown, concentrically
ringed spots to develop, on which the spores are borne in black
tufts. These spots may enlarge, and when numerous they
coalesce to involve the whole leaf and cause it to shrivel and die.
Occasionally in warm, moist weather the disease may cause con-
siderable defoliation. The disease is often confused with anthrac-
nose, but the lighter colored and concentrically zoned spots serve
to distinguished it from anthracnose spots, which are black.
The application of fungicides recommended for anthracnose also
serves to reduce the amount of leaf spot present.

Soil Rot
Soil rot, caused by Corticium vagum B. & C., has not been
of much importance in Florida or the United States as a whole
up to the present. Occasionally a watermelon will show lesions
on the side in contact with the soil, but these usually are small
and insignificant. The spots at first appear almost superficial,
and are slightly tan colored in contrast to the surrounding green.
In the more advanced stages the spots are sunken and the brown
color may cover an area several inches in diameter. This dis-
ease, most troublesome during wet seasons or when the melons
rest on wet soil, may occur in any field. The causal organism
is present in practically all Florida soils and is capable of caus-
ing infection whenever favorable conditions develop.






Diseases of Watermelons in Florida


either surface of the leaf, but is usually more conspicuous on
the lower surface where the spores occur in the form of dark,
hairy specks. They are long and thin and are easily detached
and distributed by wind or water.

Control
Cercospora leaf spot is not important enough to warrant
specific control measures. The fungicides recommended for the
control of other leaf diseases should control this spot.

Macrosporium Leaf Spot
A leaf spot caused by Macrosporium cucumerinum E. & E. is a
very widely distributed disease of watermelons and related
plants, especially cantaloupe. It usually causes little damage
and is seldom observed, except during warm, wet seasons which
favor development of the fungus. The disease attacks the leaves
around the center of the hill and causes brown, concentrically
ringed spots to develop, on which the spores are borne in black
tufts. These spots may enlarge, and when numerous they
coalesce to involve the whole leaf and cause it to shrivel and die.
Occasionally in warm, moist weather the disease may cause con-
siderable defoliation. The disease is often confused with anthrac-
nose, but the lighter colored and concentrically zoned spots serve
to distinguished it from anthracnose spots, which are black.
The application of fungicides recommended for anthracnose also
serves to reduce the amount of leaf spot present.

Soil Rot
Soil rot, caused by Corticium vagum B. & C., has not been
of much importance in Florida or the United States as a whole
up to the present. Occasionally a watermelon will show lesions
on the side in contact with the soil, but these usually are small
and insignificant. The spots at first appear almost superficial,
and are slightly tan colored in contrast to the surrounding green.
In the more advanced stages the spots are sunken and the brown
color may cover an area several inches in diameter. This dis-
ease, most troublesome during wet seasons or when the melons
rest on wet soil, may occur in any field. The causal organism
is present in practically all Florida soils and is capable of caus-
ing infection whenever favorable conditions develop.






Florida Agricultural Experiment Stations


Speckle
Speckle is an abnormal condition of the rind of watermelons,
the cause of which is not known. The disease is characterized
by the appearance of numerous yellow or whitish spots scattered
over the surface of the melon, principally on the upper half (Fig.
26). The spots usually are more or less circular in shape and
vary in size from those barely visible to those almost a centi-
meter in diameter. The surface of the melon is smooth and the
epidermis appears to be normal except in color. The speckled
melons show no effects other than their poor appearance. The
condition apparently is not parasitic in nature and is due to
some abnormality in the plant or its environment.


Fig. 26.-Speckle of watermelon (cause unknown).

Mosaic
Watermelon mosaic was first observed in Florida in Polk
County, near Fort Meade, in April 1932. This is the first record
of its natural occurrence in the United States. The disease,
while serious on other cucurbits, causes little damage to water-
melon or citron when they are artificially inoculated. No further
occurrence of mosaic has been noted in Florida since 1932.

Description
Diseased vines are conspicuous because the tips of the runners
and a proliferation of shoots from around the crowns protrude






Florida Agricultural Experiment Stations


Speckle
Speckle is an abnormal condition of the rind of watermelons,
the cause of which is not known. The disease is characterized
by the appearance of numerous yellow or whitish spots scattered
over the surface of the melon, principally on the upper half (Fig.
26). The spots usually are more or less circular in shape and
vary in size from those barely visible to those almost a centi-
meter in diameter. The surface of the melon is smooth and the
epidermis appears to be normal except in color. The speckled
melons show no effects other than their poor appearance. The
condition apparently is not parasitic in nature and is due to
some abnormality in the plant or its environment.


Fig. 26.-Speckle of watermelon (cause unknown).

Mosaic
Watermelon mosaic was first observed in Florida in Polk
County, near Fort Meade, in April 1932. This is the first record
of its natural occurrence in the United States. The disease,
while serious on other cucurbits, causes little damage to water-
melon or citron when they are artificially inoculated. No further
occurrence of mosaic has been noted in Florida since 1932.

Description
Diseased vines are conspicuous because the tips of the runners
and a proliferation of shoots from around the crowns protrude






Diseases of Watermelons in Florida


stiffly above the general level of the vines, giving a "petunia-like"
appearance. The tips and shoots have shorter than normal
internodes which produces a crowding of the young leaves which
are stunted and rolled. Mottling may or may not be present,
marked or diffuse (Fig. 27), consisting of irregular yellow areas
only slightly lighter than normal green of the young melon
leaves. Flowers on severely infected plants show abnormalities
of the petals which are of unequal size and of a greenish color.
Stamens are distorted and unevenly developed and the flowers
may fall prematurely. Melons produced on diseased vines are
mottled (Fig. 28) and also sometimes misshapen (Fig. 29).
Diseased vines bear few melons.
The disease, due to a virus, is transmitted by the aphid, Aphis
gossypii, which is common on melons every year in Florida.

Control
Since this disease is uncommon, no special measures for its
control seem to be in order here. Control of the aphid carrier
would seem to be important if the disease should appear again.
This insect is well known for its ability to stunt and injure
watermelons and nicotine sulfate ("black-leaf 40") or isotox
is recommended to control it.


Fig. 27.-Effect of mosaic on watermelon leaves.


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CL' i~.dgili~
J






Florida Agricultural Experiment Stations


Fig. 28.-Mottling of surface of watermelon due to mosaic.


Fig. 29.-Misshapen melon diseased with mosaic.


Minor Diseases Not Found in Florida
Bacterial wilt, caused by Erwinia tracheiphila (Erw. Smith)
Holland, has been reported on watermelons but a few times,
and watermelons are considered as practically immune to the
disease, although other cucurbits are susceptible in the following
order: squash, cantaloupe and cucumber.
Bacterial leaf spot, caused by Xanthomonas cucurbitae
(Bryan) Dowson, has been found on squash in South Carolina






Diseases of Watermelons in Florida


and Georgia, but there are no authentic reports of its natural
occurrence on watermelons, although artificial inoculations have
shown them to be susceptible.
Black root rot, caused by Thielavia basicola (B. & D.) Zopf.,
has been reported on watermelons in the northwestern part of the
United States on only two occasions. Rather serious losses were
reported in one of these cases, however.
Watery soft rot, caused by Sclerotinia sclerotiorum (Lib.)
Mass., has been reported as causing damage to melons in transit.
Other parasites reported on watermelons are Phytophthora
citrophthora (Sm. and Sm.) Leonian, Corticium centrifugum
(Lev.) Bres., and Pestalotia torulosa B. & C., and the virus-
produced curly top disease of sugar beets.

Cold, Wind and Sand Injury
During the early part of the watermelon-growing season in
Florida, January through February, the young plants often are
exposed to temperatures considerably below the optimum for
the growth and development of the crop. Freezing results in
immediate death of plants, but temperatures below 40 F. which
do not kill can cause severe damage by stunting young plants
to such an extent that further growth is slow. Plants turn
yellow, oftentimes with the tips and margins of the cotyledons
browned and shriveled. This browning, however, is of a lighter
color than that caused by the attacks of various fungi, and can
be easily distinguished on most specimens. The older leaves,
which are even more sensitive than the cotyledons, assume a
bronzed, glazed appearance when subjected to very cool weather,
particularly on the higher portions of the leaf surface (Fig.
30), and feel hard and brittle. Growth is almost entirely stop-
ped, and when further growth occurs it is often in an irregular
manner, causing a curling of the leaf. Plants or leaves showing
cold injury are more susceptible to the attacks of various
fungi than those in a more normal condition of growth, and
often are killed by them.
Strong winds, particularly in March, often whip and tear the
leaves severely. Such leaves dry out on the torn edges, become
hard and brittle, and are susceptible to the attacks of fungi such
as Macrosporium and Colletotrichum. The most serious type of
wind injury, however, occurs during fruit setting by whipping
off blossoms and young melons.






Florida Agricultural Experiment Stations


I9 i. -. _J
Fig. 30.-Cold injury to watermelon leaf.

High wind, particularly during dry weather, often causes
sand burn, which is characterized by the almost white, rough
and brittle areas that appear on leaves and stems. Wind-blown
sand injures the epidermis and cortex of the main stems and






Diseases of Watermelons in Florida


runners, causing the formation of thick calluses over the injured
areas.
Handling
The profits in watermelon growing may be greatly reduced,
if not lost, by growers who consider their work finished when
the melon is cut from the vine. Melons, although they have
thick rinds, have thin skins and are tender. They should be
handled with this in mind so as to prevent abrasions, bruises,
cuts, gouges or cracks. Any blemish of a melon that breaks
the skin opens a way for the invasion by any of a large number
of organisms that cause it to rot while in transit. Labor used
in the harvest of melons should be carefully and thoroughly in-
structed before they are sent into the fields. The cutting and
windrowing should be done with care.
As mentioned previously in the section on stem-end rot, the
rack or box of the wagon or truck used for transporting melons
from the field should be lined with several layers of burlap or
some similar material. Too much speed in handling and hauling
is often a detriment.
Strict attention should be given the railroad car into which
the melons are loaded, being sure first that it is in good order.
See that a good, solid false lining is present. Clean the car
carefully, removing all traces of foreign material, especially fer-
tilizers, which have been found to burn the melons and thus
allow rot fungi to enter (Fig. 31). Smooth out all obstructions
such as splinters and nails. After the car has been cleaned a
washing with formaldehyde is beneficial, but the car should be





-J,
~~ z/


Fig. 31.-Injury of watermelon caused by contact with chemicals or
fertilizer on floor of uncleaned railroad cars.






Florida Agricultural Experiment Stations


aired thoroughly afterward. Unless diseased melons have been
in the car this treatment may be dispensed with.
The material used for bedding should be according to law
(in certain counties local materials such as hay, straw, moss
and pine straw cannot be used on account of tick eradication
regulations). Any bedding used should be perfectly dry, as
moist conditions are especially favorable to diseases. Excelsior
is being used more and more, and is very satisfactory, as it is
clean, soft and cheap. It should be carefully pulled apart as
it is put into place.
The melons should not be walked upon, even with bare feet,
during any of the loading operations; the weight causes the
melons to crack internally and deteriorate much faster than
sound melons. They should be handed from the truck to helpers
in the car who place them gently in the tiers. While melons
may be pitched from one worker to another, they should not be
tossed or too roughly forced into place in packing, though no
spaces should be left. The melons should be placed with stems
toward the middle of the car in rows and tiers, alternating be-
tween the two ends of the car, in order that the stems can be
cut and treated in one end while the other is being loaded.

Summary
Diseases of watermelons are responsible for losses to Florida
growers amounting to many thousands of dollars annually. The
area in Florida planted to watermelons each year is dependent
largely on the financial success of the preceding melon crop.
Although there are a number of strictly horticultural factors
besides diseases which determine crop success or failure, melon
diseases and their control loom large in the mind of the average
grower. This bulletin contains the latest and best information
available on this subject.
Anthracnose, the worst disease of melons in the United States,
caused by Colletotrichum lagenarium (Pass.) Ell. & Hals., is best
controlled by preplanting seed treatment with semesan, spergon
or arasan (0.3 percent by weight), by staying out of melon fields
while the foliage is wet with rain or dew, and by timely applica-
tions of a fungicide such as dithane or parzate. The time of
first fungicide application is uncertain; to save money and at
the same time protect melon vines from defoliation and melon
fruits from spotting, the plants should be carefully watched
and the fungicide applied as soon as the disease makes its first






Diseases of Watermelons in Florida


appearance. Subsequent fungicide applications, at 7- to 10-day
intervals, may be needed, but their application is determined by
the weather and by disease conditions in the field. A watermelon
disease forecasting service for Florida melon growers is dis-
cussed and advocated. Such a service would tell growers when
to apply, and more important, when not to apply, fungicides.
Copper fungicides as a rule burn the watermelon foliage and
may injure the young fruits, thereby reducing the set. The
variety Black Kleckley shows some tolerance to anthracnose
and the Leesburg Watermelon Laboratory is breeding for re-
sistance to this disease.
The best way to avoid losses from Fusarium wilt, caused by
Fusarium oxysporum (E.F.S.) f. niveum Synder and Hansen,
is to plant wilt-resistant varieties on land that has been out of
melons for two to three years. Such varieties are Blacklee,
Black Kleckley, wilt-resistant Dixie Queen and others but none,
so far, has found acceptance with Florida growers. In general,
the wilt-resistant varieties are later to mature than the wilt-
susceptible variety Cannon Ball. The Leesburg Watermelon
Laboratory is undertaking the development of wilt-resistant
strains of this variety. In the absence of desirable wilt-resistant
varieties, an 8- to 10-year interval between watermelon crops
is a necessary rotation; even so, wilt may be serious enough to
reduce yields, and a 15-year rotation would be less risky.
Downy mildew, caused by Peronoplasmopara cubensis (B. &
C.) Rost., often is confused with anthracnose. Only by using
a microscope can the observer report with accuracy which fungus
is concerned. No varieties are known to be resistant to downy
mildew. This disease is controlled with the same materials
recommended to control anthracnose, but other materials such
as fermate, zerlate and copper-lime also will give fairly good
control of downy mildew. The disease forecasting service men-
tioned above could include downy mildew in its coverage.
Gummy-stem blight, caused by the fungus Mycosphaerella
cucumis (Fautr. and Roum.) Chiu and J. C. Walker, can be
easily confused with both anthracnose and downy mildew. It
can be controlled in part by seed treatment with the same ma-
terials recommended for anthracnose control but better materials
are needed to give complete protection against this organism.
Fungicides recommended for control of anthracnose by dusting
or spraying will also control gummy-stem blight. No varieties
are known to possess resistance to gummy-stem blight.






46 Florida Agricultural Experiment Stations

The stem-end rot disease, due to the fungus Physalospora
rhodina (Berk. & Curt.) Cooke, can be controlled with little
difficulty by proper clipping and disinfecting of the stems of
harvested watermelons. Improper usage of proven methods
and materials is all too often the cause of unnecessary losses
from this disease.
Other diseases of less importance, which are discussed and
pictured, are Southern blight (Corticium rolfsii (Sacc.) Curzi),
blossom end-rot, powdery mildew (Erysiphe cichoracearum DC.),
Cercospora leaf spot (Cercospora citrullina Cke.), Macro-
sporum leaf spot (Macrosporium cucumerinum E. &. E.), soil
rot (Corticium vagum B. & C.), and mosaic. A list of water-
melon diseases not known to occur in Florida is included.
The effects of cold, wind and sand injuries on melon foliage
are discussed; often, these are mistaken for disease by growers.
Proper handling of harvested melons is discussed and em-
phasized.




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