Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Spraying and dusting cucumbers for control of downy mildew from 1925 to 1930
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Permanent Link: http://ufdc.ufl.edu/UF00026450/00001
 Material Information
Title: Spraying and dusting cucumbers for control of downy mildew from 1925 to 1930
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 58 p. : ; 23 cm.
Language: English
Creator: Weber, George F ( George Frederick ), b. 1894
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1931
Copyright Date: 1931
 Subjects
Subject: Downy mildew diseases -- Florida   ( lcsh )
Cucumbers -- Diseases and pests -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 54-58).
Statement of Responsibility: by George F. Weber.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00026450
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AEN4681
oclc - 18176411
alephbibnum - 000924077

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HISTORIC NOTE



The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida






Bulletin 230 June, 1931


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
Wilmon Newell, Director




SPRAYING AND DUSTING

CUCUMBERS

FOR CONTROL OF DOWNY MILDEW

FROM 1925 TO 1930

By GEORGE F. WEBER















Fig. 1.-Portion of experimental plot showing sprayed plants on left and
unsprayed (check) plants on right.




TECHNICAL BULLETIN

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







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

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

MAIN STATION-DEPARTMENTS AND INVESTIGATORS
AGRONOMY ECONOMICS, AGRICULTURAL
W. E. STOKES, M.S., Agronomist C. V. NOBLE, Ph.D., Agricultural Economist
W. A. LEUKEL, Ph.D., Associate BRUCE McKINLEY, A.B., B.S.A., Associate
G. E. RITCHEY, M.S.A., Assistant* M. A. BROOKER, Ph.D., Assistant
FRED H. HULL, M.S., Assistant
J. D. WARNER, M.S., Assistant ECONOMICS, HOME
JOHN P. CAMP, M.S.A., Assistant OUIDA DAVIS ABBOTT, Ph.D., Head
L. W. GADDUM, Ph.D., Biochemist
ANIMAL HUSBANDRY C. F. AHMANN, Ph.D., Physiologist
A. L. SHEALY, D.V.M., Veterinarian in
Charge ENTOMOLOGY
E. F. THOMAS, D.V.M., Asst. Veterinarian J R. WATSON, A. M., Entomologist
R. B. BECKER, Ph.D., Associate in Dair A. N. TISSOT, M.S., Assistant
Husbandry. H. E. BRATLEY, M.S.A., Assistant
W. M. NEAL, Ph.D., Assistant in Animal W. ZIEGLER, B.S., Assistant
Nutrition L.W. ZIEGLER, BS., Assistant
C. R. DAWSON, B.S.A., Assistant Dairy HORTICULTURE
Investigations
Investigation A. F. CAMP, Ph.D., Horticulturist
CHEMISTRY HAROLD MOWRY, B.S.A., Associate
R. W. RUPRECHT, Ph.D., Chemist M. R. ENSIGN, M.S., Assistant
R. M. BARNETTE, Ph.D., Associate A. L. STAHL, Ph.D., Assistant
C. E. BELL, M.S., Assistant G. H. BLACKMON, M.S.A., Pecan Culturist
J. M. COLEMAN, B.S., Assistant C. B. VAN CLEEF, M.S.A., Greenhouse
H. W. WINSOR, B.S.A., Assistant Foreman
H. W. JONES, B.S., Assistant PLANT PATHOLOGY
COTTON INVESTIGATIONS W. B. TISDALE, Ph.D., Plant Pathologist
E. F. GROSSMAN, M.A., Assistant G. F. WEBER, Ph.D., Associate
P. W. CALHOUN, B.S., Assistant A. H. EDDINS, Ph.D., Assistant
K. W. LOUCKS, M.S., Assistant
ERDMAN WEST, M.S., Mycologist
BRANCH STATION AND FIELD WORKERS
L. 0. GRATZ, Ph.D., Asso. Plant Pathologist in charge, Tobacco Exp. Sta. (Quincy)
R. R. KINCAID, M.S., Assistant Plant Pathologist (Quincy)
W. A. CARVER, Ph.D., Assistant, Cotton Investigations (Quincy)
RAYMOND M. CROWN, B.S.A., Field Asst., Cotton Investigations (Quincy)
JESSE REEVES, Farm Superintendent, Tobacco Experiment Station (Quincy)
J. H. JEFFERIES, Superintendent, Citrus Experiment Station (Lake Alfred)
GEO. D. RUEHLE, Ph.D., Assistant Plant Pathologist (Lake Alfred)
W. A. KUNTZ, A.M., Assistant Plant Pathologist (Lake Alfred)
B. R. FUDGE, Ph.D., Assistant Chemist (Lake Alfred)
W. L. THOMPSON, B.S., Assistant Entomologist (Lake Alfred)
R. V. ALLISON, Ph.D., Soils Specialist in charge Everglades Experiment Sta. (Belle Glade)
R. W. KIDDER, B.S., Foreman, Everglades Experiment Station (Belle Glade)
R. N. LOBDELL, M.S., Assistant Entomologist (Belle Glade)
F. D. STEVENS, B.S., Sugarcane Agronomist (Belle Glade)
H. H. WEDGEWORTH, M.S., Associate Plant Pathologist (Belle Glade)
B. A. BOURNE, M.S., Associate Plant Physiologist (Belle Glade)
J. R. NELLER, Ph.D., Associate Biochemist (Belle Glade)
A. DAANE, Ph.D., Associate Agronomist (Belle Glade)
FRED YOUNT, Office Assistant (Belle Glade)
M. R. BEDSOLE, M.S.A., Assistant Chemist (Belle Glade)
A. N. BROOKS, Ph.D., Associate Plant Pathologist (Plant City)
R. E. NOLEN, M.S.A., Field Assistant in Plant Pathology (Plant City)
A. S. RHOADS, Ph.D., Associate Plant Pathologist (Cocoa)
C. M. TUCKER, Ph.D., Associate Plant Pathologist (Hastings)
H. S. WOLFE, Ph.D., Associate Horticulturist (Homestead)
L. R. TOY, B.S.A., Assistant Horticulturist (Homestead)
STACY O. HAWKINS, M.A., Field Assistant in Plant Pathology (Homestead)
D. G. A. KELBERT, Field Assistant in Plant Pathology (Bradenton)
FRED W. WALKER, Assistant Entomologist (Monticello)
D. A. SANDERS, D.V.M., Associate Veterinarian (West Palm Beach)
M. N. WALKER, Ph.D., Associate Plant Pathologist (Leesburg)
W. B. SHIPPY, Ph.D., Assistant Plant Pathologist (Leesburg)
C. C. GOFF, M.S., Assistant Entomologist (Leesburg)
J. W. WILSON, Ph.D., Assistant Entomologist (Pierson)
*In cooperation with U. S. Department of Agriculture.
















TABLE OF CONTENTS

PAGE

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

THE DISEASE .... .............................................. 5
Geographical Distribution ........... .- .... ..--- ..------. ....-- ....-- ... 5
Host Range .................... ......------ --. -........... ... .......- ..-- 6
Economic Importance ....-..............-..- -........ .... .............. .. 7

CONTROL MEASURES ........-------............---.........-- --..........--.........-..... 8
M ethods and M materials .......................-.........--- -.................... 10
Experiments Conducted During 1925 ....................... --........-....... 14
Summary for 1925 ....... -..---.......---....--................. 18
Experiments Conducted During 1926 .................... .................... 20
Summary for 1926 .................... ............----- -- .................. .. 25
Experiments Conducted During 1927 ..................... ....... .............- 26
Summary for 1927 .........-...----.......----.....-................ 30
Experiments Conducted During 1928 ........................ ..................... 31
Summary for 1928 .--. -------..-...........-... -...... ................ 37
Experiments Conducted During 1929 ................... .--.... .......--.... 38
Summary for 1929 -...--..--...------.............---- -.................... 43
Experiments Conducted During 1930 --.......---..........----................. 44
Summary for 1930 .......--..............-................................. 449
Discussion and Summary ........---...--...........--.......... ............ 50

CONCLUSIONS --------...- -- ----------...................... .. ... ... ...................- 53

LITERATURE CITED ....................-----.......... ......... .......-------......- 54











SPRAYING AND DUSTING
CUCUMBERS
FOR CONTROL OF DOWNY MILDEW
FROM 1925 TO 1930
By GEORGE F. WEBER
INTRODUCTION

The Florida cucumber growers' yields are reduced annually by
the premature destruction of the foliage of the vines by the com-
mon disease known as downy mildew (blight or rust) which is
caused by the parasitic fungus Peronoplasmopara cubensis (B.
& C.) Clint. (12).1 The disease as it occurs in Florida has been
fully described (84) (85) and a repetition of the description in
this connection is unnecessary. Control measures, as used by
growers who have a limited period for marketing their crop of
fresh cucumbers, have proved more or less unsatisfactory. Dur-
ing some seasons the duration of the period in which cucumbers
can be marketed profitably is only two or three weeks and since
downy mildew does not become very prevalent until about the be-
ginning of the picking season, many growers contend that spray-
ing or dusting is an unprofitable investment. Consequently, there
has been great need for experimental information on the possi-
bilities for increasing the yield of cucumbers by the use of fungi-
cides under these conditions. Accordingly, spraying and dusting
experiments were begun in 1925 and continued each year
through 1930. This bulletin gives a review of the literature
concerning control of this disease and a report of the results
of the experiments conducted in Florida over the six-year period.
THE DISEASE
GEOGRAPHICAL DISTRIBUTION
According to Clinton (12), the fungus which causes downy
mildew of cucumbers was first collected in Cuba by Wright and
described by Berkley and Curtis in 1869. Farlow (19) recog-
nized it on specimens received from Japan in 1889. In the same
year Halsted (28) reported it from New Jersey, which was the
'Figures in parentheses (italic) refer to Literature Cited in the back
of this bulletin.






6 Florida Agricultural Experiment Station

first report from the United States. Galloway (22) reported it
from Florida and Texas during the same year. In 1890, Hum-
phrey (37) reported it from Massachusetts and Swingle (81) re-
ported it from Maryland. Since that time it has been reported
from Connecticut (3) (82), Rhode Island (73), New Hampshire
(43), Vermont (54), Maine (10), New York (54), Pennsylvania
(55), New Jersey (28) (29) (30) (31) (49), Delaware (48),
West Virginia (67), Virginia (24), Kentucky (23), Tennessee
(10), Ohio (62) (65), Illinois (60), Michigan (55), North Car-
olina (86), Wisconsin (15), South Carolina (46), Georgia (34),
Florida (5) (36) (68) (85), California (51), Alabama, Missis-
sippi, Louisiana, Indiana, Texas, Colorado, and Arizona (83).
Chupp (10) lists all the states east of the Mississippi River and
nine states west of it. In Florida the disease is more or less per-
petual, having occurred in some sections every year since its
discovery in 1889 with the possible exception of 1893 when Rolfs
(58) reports that cucumbers grew from February to July and
showed no disease. Hume (35) (36), Fawcett (20), Sherbakoff
(69), Burger (6) (7), and Weber (84) (85) have reported the
disease as occurring at practically all seasons of the year when
cucumbers are grown during the past 30 years. Outside of the
United -States the disease has been reported from the following
foreign countries: Bermuda (52), Porto Rico (83), Cuba (13),
Guam (27), Colombia (9), Ecuador (8), Brazil (1), Japan (42),
Russia (59), Germany (16) (18) (87), Austria (33) (41), Hun-
gary (44), England, Italy, Australia, Java, China, New Zealand
(39), East Africa and India (8). These reports show a world-
wide distribution of the disease outside the United States and a
distribution in this country in all but the arid mountainous
states.
HOST RANGE
The disease was first reported on an undetermined cucurbit
species. The other early reports (19) (22) (28) (50) (62) (75)
(81) (82) show that the disease has appeared annually on cu-
cumbers. At first it was most serious on greenhouse plants but
gradually involved cucumbers in the field. Later Halsted (31)
found it on watermelon and considered it responsible for fail-
ures of this crop. He also reported it on squash and pumpkin.
Cantaloupes are recorded as having suffered in the North At-
lantic and New England states probably as much as or more
than cucumbers (2) (32) (57) (78). Gourds and certain orna-
mentals are susceptible, according to Butler (8), Eriksson (18),







Bulletin 230, Spraying and Dusting Cucumbers 7

and Linhard (44). Selby (64) planted a variety plot containing
a large list of cucurbits and closely related plants for the pur-
pose of determining the host range of this fungus. He found
that the following plants were susceptible:
Bryonopsis laciniosa erythiocarpa Cucurbita pepo L.
Naud. Cucurbita verrucosa L.
Citrullus vulgaris Schr. Echinocystic lobata T. & G.
Cocinnia indica W. & A. Lagenaria vulgaris Ser.
Cucumis anguria L. Melothria scabra Naud.
Cucumis erinaceus Hort. Momordica balsamia L.
Cucumis melo L. Momordica charantia L.
Cucumis odoratissimus Moench. Mukia scabrella Am.
Cucumis sativus L. Sicyos angulatus L.
Cucurbita melopepo L. Trichasanthes colubrina Jacq.
Cucurbita moschata Duch.
In Florida the following cultivated hosts, including numer-
ous varieties of each, have been found affected by the disease:
Citrullus vulgaris Schr. Cucurbita maxima Duch.
Cucumis anguria L. Cucurbita moschata Duch.
Cucumis melo L. Cucurbita pepo L.
Cucumis sativus L. Lagenaria leucantha Rusb.
The possibility of a wild host in Florida which harbors the
disease during certain periods of the year has not been thor-
oughly investigated.

ECONOMIC IMPORTANCE
Downy mildew was not an economic factor in the United
States until 1889, though it had been of mycological interest for
the previous 20 years. Since the disease first came under obser-
vation, numerous reports have shown that its economic import-
ance varies in different states and countries and in the same
locality from year to year. It caused the first injury to green-
house cucumbers in New Jersey according to Halsted (28), and
after a careful study he predicted it would be a destructive dis-
ease in the future. Later it was found that the disease spread to
cucumbers in the field (31) after ruining the greenhouse crops
(30) and was the probable cause of a watermelon failure in Mas-
sachusetts (31). Halsted also noted (32) that it was erratic in its
occurrence; for instance, it was common and destructive in 1897
and was not found in 1898. Burger (6) stated that it was the cause
of short picking seasons in Florida, while Gilbert (25) reported
that no serious damage was caused by it in Indiana. Manns and
Adams (47) recorded a 40 percent loss in sections of Delaware
in 1924. Bennett (2) in Connecticut reported that cucumber






8 Florida Agricultural E., pr, i : in t Station

growers were driven from that state by the severity of this dis-
ease. Stone and Smith (77) (78) considered it common and of
general occurrence under glass in Massachusetts. Selby (65)
classified this disease as the most serious enemy of the cucum-
ber and stated (66) that epidemics were caused by favorable
weather conditions. Linhart (44) reported losses of 80 percent
of all cucurbits in certain sections of Hungary. Stewart (71)
(72) reported a 55 percent loss to cucumbers in certain sections
of New York and stated that it was destructive on Long Island.
Other reports in 1924 (83) include losses as follows: Dela\\are
2 percent, Maryland 1 percent, South Carolina 30 percent, Flor-
ida 30 percent, which are only a sample of reports each year
during the past 10 years. In Florida, Hume (35) reported the
first losses on cucumbers in 1889. Burger (5) stated that con-
siderable loss was caused in 1913-14. Sherbakoff (68) consid-
ered cucumbers badly affected in 1915-17. During the past 10
years this disease has caused annually from 10 to 70 percent
losses in this State. A very conservative estimate would be 15
percent loss annually. The annual farm value of cucumbers
shipped from Florida over this 10-year period averages approxi-
mately two and a quarter millions of dollars. Thus the loss
would amount to $337,500 annually to Florida growers.

CONTROL MEASURES
Stevens and Hall (74) stated that the use of fungicides for
the control of downy mildew was discovered in 1883 by Millardet
in France. Millardet experimented with it in 1884-85 and re-
ported on the results in 1885. He was attempting to secure the
control of the downy mildew of grape caused by a fungus closely
related to the one causing downy mildew of cucumber. Scribner
(61) conducted the first spraying experiments for the control of
downy mildew diseases in the United States in 1885 and 1886. In
these experiments Scribner used Gironde's mixture, now known
as bordeaux mixture, Andoynand's formula for eau celeste, our
ammoniacal copper carbonate, David's Powder, a form of evapo-
rated bordeaux mixture and sulfated sulfur. These fungicides
were first used to control mildew of grapes and late blight of
potatoes. Halsted (32) used the above mentioned fungicides on
cucumbers in New Jersey and considered bordeaux mixture the
best for the control of downy mildew, followed by copper sul-
fate, eau celeste, and potassium sulfide in the order named.
IHume (35) reported good control of this disease in Florida by






Bulletin 230, Spraying and Dusting Cucumbers 9

the use of 4-4-50 bordeaux mixture. Almost all of the investi-
gators (1) (2) (11) (14) (17) (34) (40) (46) (48) (56) (70)
(85) have recommended bordeaux at various strengths for the
control of this disease. Sayre (60) preferred copper-lime .dust
in Illinois while Brigs (4) used sulfur in Guam. Doran (17)
found that sulfur was toxic to cucumbers and consequently used
copper-lime dust. Garman (23) reported good results from the
use of liver of sulfur and seven applications of bordeaux. Hig-
gins (34) found copper acetate and colloidal copper to be of
value in controlling the disease in Georgia, but reported that
these materials burned the foliage. Sturgis (80) reported un-
satisfactory results from the use of bordeaux mixture in Con-
necticut. Stewart (71) and Geise (24) reported good results
with bordeaux mixture in years when the disease appeared, but
in years when there was no disease the sprayed plants showed a
reduced yield. Manns and Adams (47) consider that the control
of the disease is impossible when seasonal conditions favor the
development of the disease. Kock (40) reported that bordeaux
sprays reduced the yield in Austria.
Recommendations in regard to the time of the first applica-
tion, the number of applications and the manner of application
in different states are quite variable. This may be explained on
a basis of the differences in climatic conditions which occur in
different localities. It is generally agreed (14) (56) (69) (85)
that the first application should precede the appearance of the
disease without any reference to the stage of development of the
plant. Some investigators (12) (13) (27) (63) have considered
it necessary to make the first application before the vines begin
to run. Halsted (28) and Massee (50) urged the application of
fungicides to both surfaces of the leaves. Sherbakoff (69) and
Weber (85) recommended bordeaux mixture for the control of
the disease in Florida, the first application to be made as soon
as the true leaves appear and others at weekly intervals until
the end of the season. Since downy mildew has caused consid-
erable annual injury to cucumbers in Florida and since it usu-
ally appears early in the season, it is necessary to make the first
application of fungicides early to obtain the best control.
Kock and Kornauth (41) have reported that certain climbing
varieties of cucumbers have shown resistance to downy mildew.
Thirty-seven commercial varieties of cucumbers were tested
in a plot in Florida (84) but none of them showed any degree
of resistance.






10 Florida Agricultural Experiment Station

Without some means for controlling downy mildew the cul-
ture of cucumbers in Florida may result in a loss. Crop rota-
tion, host resistance, field sanitation, and other means of control-
ling.the disease have been attempted without success. The fun-
gus does not attack the plant through the parts in contact with
the soil. The only other logical means of controlling the disease
appeared to be by means of fungicides applied to the growing
plants in the field.
METHODS AND MATERIALS
It has been shown by investigators referred to previously that
downy mildew of cucumbers can be controlled in certain locali-
ties through the proper use of fungicides. The beneficial effects
of the fungicides are usually manifested by prolonging the life
of the vines, thereby increasing the yield of fruit. Under Flor-
ida conditions where cucumbers are sold for consumption fresh,
and the period during which they can be marketed at a profit is
short, it is often necessary to discontinue picking before the
vines cease to bear. On this account, there has been a demand
for information concerning the advisability of using fungicides,
even though downy mildew occurs every year and shortens the
bearing period of the vines.
Accordingly, the experiments have been planned and conducted
so as to obtain information concerning the effect of certain
fungicides on the control of downy mildew [Peronoplasmopara
cubensis (B. & C.) Clint.] under growing conditions in Florida.
These experiments were conducted in commercial fields owned
by certain well-known, capable growers in the immediate vicin-
ity of Gainesville, Florida. The experiments were divided into
plots, which were used as units in calculating the average re-
sults. The plots varied in size from one-fifteenth to one-third
acre, the largest number of them being one-eighth to one-sixth
acre. The size of some plots was limited by the number of plants
growing in each plot. Occasionally, because of a poor stand of
plants, the area was enlarged in order to reduce possible error
in calculations. The plots were located in fields or portions of
fields that showed wide variation in environmental conditions;
such as soil type, moisture relations, cold protection, air drain-
age, exposure, slope, and culture.
The soil types are probably more influential than other en-
vironmental factors. Consequently, a brief description of the
soil upon which each experiment was placed will be given. The







Bulletin 230, Spraying and Dusting Cucumbers 11

seasonal developments of all the crops were comparable, since
the planting seasons were uniform with very few extra early or
late plantings. The fertilizers applied were also very much the
same and the same kind of seed were planted in the different
experimental plots. There were some variations in the cultural
methods in the various experiments during any one season, and
also from season to season, due primarily to the different types
of soil and according to the cultural practices of the growers.
The cooperative agreement adhered to was to the effect that the
department of plant pathology furnished the fungicides, applied
them, and assisted in recording the yield, while the growers
cared for the experimental plots in the same manner as the re-
maining portion of the fields. The result of the agreement was
to the effect that the grower secured the protection of his plants
with fungicides with no cost to himself except the extra time
required for the detailed count and measuring of the yield of
the separate plots. He picked the fruit and measured the yield
of each plot at each picking in hampers. The plots were staked
and numbered so that the grower seldom knew the kind of fungi-.
cide applied to any specific plot. The yield was kept by plot
number by the grower and a very impartial aspect surrounded
the data accumulated thereby. This type of agreement worked
very satisfactorily for all concerned. In fact, growers were often
solicitous in the placing of the experiments.
The fungicides applied consisted of several kinds of commer-
cial products and the standard copper sprays and dusts. Rock
and hydrated lime were used in preparing bordeaux mixture, to
determine their relative merits. Commercial forms of calcium
caseinate, which functions as a spreader and sticker, were added
to certain sprays. The bordeaux mixture was made up from
stock solutions immediately before use, in lots of three gallons.
The stock solutions of copper and lime were measured carefully
and diluted before being mixed and in mixing the diluted copper
solution was poured into the diluted lime solution, which was
well stirred. The ingredients for the bordeaux mixture con-
sisted of granulated bluestone (copper sulfate) and rock lime
or the commercial builder's hydrated lime. These materials
were always of the best commercial grade obtainable. The dusts
were purchased in large lots and stored in air-tight containers.
The required portions were taken to the experimental plots for
application. Separate dusters were used for the different kinds
of dust so as to avoid mixtures in the separate plots. The dusts







12 Florida Agricultural Experiment Station

were applied in the early morning when the plants were wet
with dew. Upon drying, the dusts adhered very well to the
plants. The cloud of dust usually rose less than three feet above
the plants and settled rapidly, because there was seldom inter-
fering wind or air currents at this time of day. The sprays
were applied usually in the afternoons when the plants were dry
with a substantial hand sprayer of the knapsack type that held
about three gallons of spray. It was equipped with an extension
rod and a fine nozzle adjusted so as to spray both leaf surfaces
easily. The dust was applied with a ball bearing hand duster
of the latest type. It had a hopper of 10-pound capacity and an
adjustable outlet by means of which the quantity applied was
easily regulated. The spray was measured by the tank which
held three gallons and the amount of dust used was determined
by weighing the duster and its contents before and after the
respective plots were dusted. The total amounts of fungicides
used are given in the tables in gallons and pounds. In the fol-
lowing tables the column headed "costs" includes the cost of the
fungicides plus the cost of application. The cost of materials
was determined by the retail cost of them or the ingredients
necessary to prepare them. The cost of labor was determined
by the actual amount of time required to apply the fungicide.
The total time and total number of gallons or pounds were re-
corded for the season and then calculated as to cost of applica-
tions, which was 80 cents per acre per application for dust and
2 cents per gallon for liquid spray. The applications were made
at weekly intervals, amounting to a total of about five applica-
tions per season. The average labor cost for dusting as con-
tained in the tables summarizing each season's results was ob-
tained by averaging the number of applications in the different
plots during that year and multiplying by 80 cents, the labor
cost of dusting one acre. The materials, both sprays and dusts,
were applied during the entire experiment by the same assistant.
The fruit was picked usually every other day with the excep-
tion of longer intervals at the beginning and at the end of the
season. The yield per plot, as previously stated, was measured
in field hampers by the grower before the fruit was sorted and
graded. The grower was usually able to select the best fungi-
cide by the indication of the yield. When the yields were almost
the same, the grower always selected as best the plot producing
the most uniform dark green color of fruit. The degree of con-
trol of the disease by the various fungicides in the experiments






Bulletin 230, Spraying and Dusting Cucumbers 13

was determined by the yield obtained during the marketing sea-
son. Picking was discontinued when the market price dropped
too low to warrant further shipments. Consequently, the total
yield was greater in certain years than in others. The numerous
tables presenting the data are made up of two distinct parts, i. e.,
the first half contains the exact figures as originally taken, while
the second part consists of the averages of duplicates and repli-
cations and the whole calculated on the basis of one acre for
convenience in making comparisons.
Downy mildew is a severe disease of cucumbers and quickly
affects the yield of plants. The fungicides were applied to check
this disease and it was considered that the yield would be a di-
rect and definite measure of the value of the fungicide. In addi-
tion to the yield as a measure of the control of the disease the
plots in certain experiments have been compared as to the
amount of the disease that appeared on the foliage of the plants,
calculated by the apparent percentage of green, yellow, and dead
leaves.
A general field comparison of the plots was made by indicat-
ing the appearance of the healthiest plot at a high percent, such
as 90 percent, the figure being entirely arbitrary. The other
plots were compared with this plot and given a relative rank.
In this way a comparison was made which in most instances
almost corresponded with the comparison of the plots in the
various experiments as determined by the actual yield.
There are a large number of factors, that are influential in
production of fruit that may be of considerable importance in
determining the exact results. The most important of these
factors are moisture, temperature, and market conditions. The
disease may be commercially controlled but to no avail, if mar-
kets have slumped and the product cannot be sold profitably, or
the disease may be commercially controlled and the produce
sold at a good profit but the temperature may be so high or the
rainfall so scanty that production is materially reduced. There
are also factors to consider in the form of competition from
other trucking sections. This competition is detrimental to the
Gainesville section, especially during late or delayed seasons.
Late killing frosts dipping deep into northern Florida usually
cause a large area of the southern states to come into produc-
tion at the same time.






14 Florida Agricultural Experiment Station

These factors have been taken into consideration in planning
the experiments that have been conducted. An attempt has been
made to simulate the grower's situation in his endeavor to pro-
duce a crop profitably. The grower must fertilize, rotate, culti-
vate, pick, and market his crop. He must contend with fluctua-
tions in rainfall and moisture and temperature, seed purity, in-
sect and fungus damage, and labor, marketing and market con-
ditions, all of which are more or less inter-related. These fac-
tors are different on every farm. Since the experimental plots
have been placed on farms in different localities with different
growers, there naturally has been considerable variation in
methods, although fungicidal applications have been quite com-
parable. For this reason, there is a wide variation in the differ-
ent experiments during each season and from year to year. It
is known that bordeaux mixture or copper-lime dust will prolong
the life of plants when downy mildew is prevalent and produce
fruit in excess of untreated plants.
The purpose of these experiments was to determine, if pos-
sible, whether treatment of plants is profitable under existing
Florida conditions. Consequently, the experiments were con-
ducted under conditions confronting the farmer, except that
fungicides were applied to certain plants.
EXPERIMENTS CONDUCTED DURING 1925
Three experiments were planned for the season of 1925; one
was conducted in a field irrigated with an overhead sprinkler
system, another was on unirrigated high land, while the third
was on low land. Seed were planted during the last of February
and the plants developed slowly because of cool weather. The
first applications of the fungicides were made about the middle
of April when the seedlings averaged three or four true leaves.
The first report of the disease was April 20. The picking sea-
son began about May 1 and continued for about three weeks.
Experiment 1: This experiment was located on low, wet
sandy-loam soil bordered on one side by a small stream. The
field was divided into nine parts, of which three were sprayed,
three dusted, and three were left as checks. The first applica-
tions of the fungicides were made on April 9 and subsequent
applications were made April 18 and 27, respectively. The pick-
ing was started May 4 and continued through the 25th. The







Bulletin 230, Spraying and Dusting Cucumbers 15

data obtained from this experiment are shown in condensed form
in Table I.
TABLE I.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 1-1925.
Plot I Fungicide ] Cost i
o- Total I P INo. Yield
No. 1 Size Kind Amt. I Mat' Labor App. Hampers
I I
10 1/6 A 4-4-50 bordeaux 49 gal. $ .50 $1.00 3 69
11 copper-lime 13 lbs. 1.30 .40 3 73
12 check 66
13 4-4-50 bordeaux 49 gal. .50 1.00 3 69
14 copper-lime 13 lbs. 1.30 .40 3 60
15 check 35
16 4-4-50 bordeaux 1 49 gal. .50 1.00 3 33
17 copper-lime 13 lbs. 1.30 .40 3 29
18 check 1t5

Results calculated on basis of one acre.
Repl. 1
3 1 A 4-4-50 bordeaux 1294 gal. 3.00 6.00 3 342
3 copper-lime 78 bs. 7.80 2.40 3 324
3 check I 232


The results given in the above table show that the yield from
the sprayed plots was slightly greater than the yield from the
dusted plots, and each of the treated plots showed a consider-
ably higher yield than the check plots. The total cost per acre
of spraying and dusting was about the same.
Experiment 2:-This experiment was located on dark, sandy-
loam soil in a portion of an eight-acre field which was irrigated
by an overhead sprinkler system. The seed were planted early,
but the season was cool and the plants developed slowly. The
first applications of fungicides was made on April 10. Three
more applications were made, as follows, April 16, 29, and May
12. The first appearance of the disease was on April 20. Pick-
ing was started on the 29th day of April and continued until
the 27th of May. The data obtained from the plots in this ex-
periment are shown in condensed form in Table II.
The above data show that a heavy application of copper-lime
dust was more beneficial than a heavy application of 4-4-50 bor-
deux mixture. The liquid spray burned the plants in some cases
but the detrimental effects were offset by the beneficial ones
since the sprayed plot equalled the check plot in yield. However,







16 Florida Agricultural Experiment Station

the added cost of the spray places it in the unprofitable position
in comparison with the copper-lime dust which showed a 72-
hamper increase per acre at a cost of 41.6 cents per hamper.

TABLE II.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 2-1925.
Plot Fungicide Cost
]Total No. Yield
No. Size Kind I Amt. I Mat'l Labor Appl. Hampers
I- ----
56* 1/4A check 84
57 1/4 A 4-4-50 bordeaux 100 gal. $1.00 $2.00 4 74
58 1/4 A copper-lime 65 Ibs. 6.50 .80 4 92
59* 1/4 A check 64

Results calculated on basis of one acre.

Repl.
1 1 A copper-lime 260 lbs. 26.00 3.20 4 368
2 1 A checks 296
1 1A 4-4-50 bordeaux 400 gal. 4.00 8.00 4 296

*Average yield 74.
A very interesting feature of this experiment was that the
check plots yielded better during the first two weeks than the
plots to which fungicides were applied. The yield per week for
each plot for the season is shown in Table III.

TABLE III.-YIELD PER PLOT BY WEEKS IN FIELD HAMPERS FROM CUCUM-
BER PLOTS, WHICH WERE DUSTED, SPRAYED, AND UNTREATED IN EXPERI-
MENT 2-1925.
Plot ~ [ Yield in Hampers
Fungicide 1st 2nd 3rd 4th
No. Size I Week Week Week Week Total

56 1/4A Check 14 31 35 4 84
57 1/4 A 4-4-50 bordeaux 6 19 36 13 74
58 I 1/4 A copper-lime 11 27 39 15 92
59 1/4A check 10 22 29 3 64

Total ........ ...... 41 99 139 35 314


The average yield of the cheek plots for the first week was 50
percent higher than that of the sprayed plots and 9 percent
higher than that of the dusted plot, but during the second week
it was only 19 percent higher than the sprayed plot and was







Bulletin 230, Spraying and Dusting Cucumbers 17

out-yielded by the dusted plot. During the third week the re-
sults were reversed and the yields from the sprayed plot were
12 percent and from the dusted plot 19 percent greater than the
average yield of the checks. During the fourth week the in-
crease was still greater in favor of the sprayed and dusted plots,
namely 72 and 77 percent, respectively. The total yields calcu-
lated on a one-acre basis of the dusted, sprayed, and check plots
were 368, 296, and 296 hampers, respectively.
This variation in production is of considerable importance to
the grower when the influence of competition and fluctuating
market prices are considered.

TABLE IV.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 3-1925.
Plot Fungicide I Cost
I I Total I I No. Yield
No. 1_Size Kind Amt. Mat'l I Labor JAppl. Hampers
51 1/8 A check 38
52 1/8 A copper hydroxidel 51 gal. $ .75 1 $1.02 4 48
53 1/8 A 4-4-50 R.* bord. 48 gal. .48 .96 4 41
54 1/8 A 4-6-50 H.* bord. 1 47 gal. .47 .94 4 47
55 1/8 A Pyrox + kayso j 48 gal. 1.92 .96 4 46.5
56 1/8 A check 42
57 1/8 A 4-4-50 R. board.
+ kayso I 48 gal. .48 .96 4 45
58 1/8 A cop.-lime-arsen. 34 lbs. 3.40 .40 4 41.5
59 1/8 A copper hydrox-
ide + kayso 50 lbs. .75 1.00 4 43
60 1/8 A copper-lime 37 lbs. 3.70 .40 4 40
61 1/8 A Pyrox 47 gal. 1.82 .94 4 36.5
62 | 1/8 A 4-6-50 H. bord.
I + kayso 48 gal. .48 .96 4 42
63 1/8 A copper-lime-ar-
I senate 35 lbs. 3.50 .40 4 45
64 1/8 A Kilrust 54 gal. 2.16 1.04 4 21
65 1/8 A check : 32
66 1/8 A 4-4-50 R. bord. 48 gal. .48 .96 4 34

*R-rock lime. *H=hydrated lime.
Results calculated on basis of one acre.
Repl. I ] -
2e 1A copper hydrox. 1404 gal. $6.00 $8.16 4 364
5 1 A 4-4-50 bordeaux ) 384 gal. 3.84 7.78 4 334.4
3 [ 1 A cop.-lime-arsen. 282 lbs. 28.20 3.20 4 334.4
2 1 A Pyrox 380 gal. 15.20 7.60 4 332
3 I 1A check I 298.4
1 1 A Kilrust 432 gal. 17.28 8.64 4 168






18 Florida Agricultural Experiment Station

Experiment 3:-This experiment was located in the immedi-
ate vicinity of Gainesville on a low portion of a field without
irrigation facilities. The soil was a dark-colored, sandy-loam
that had been previously cultivated and planted to cucumbers
and other vegetable crops. The first application of the fungi-
cides was made April 11, when the plants were in the 4-6 leaf
stage, followed by three other applications on April 18, April
27, and May 9, respectively. Picking began May 4 and continued
until May 28. Table IV gives the information and data collected
from the various plots in this experiment.
It may be seen from Table IV that the plots to which copper
fungicides were applied gave larger yields as a group than the
non-copper sprays or the checks. The yields of the individual
plots treated with materials containing copper checked fairly
closely. Copper hydroxide proved to be a little better in regard
to yield, whereas bordeaux appeared to be better than the other
copper fungicides when yield and cost of treatment were taken
into consideration. The average yield for the copper fungicides
was 341.2 hampers per acre as compared with 298.4 for the
check plots and 168 for those sprayed with Kilrust. There ap-
peared to be no consistent advantage of slaked rock lime over
hydrated lime when additional amounts of the latter were used
in making bordeaux mixture. The use of a.spreader or sticker
in liquid sprays on cucumbers did not prove to be of consider-
able advantage.
TABLE V.-SUMMARY AND CONSOLIDATION OF THE DATA OBTAINED IN EX-
PERIMENTS CONDUCTED DURING THE SEASON OF 1925 RELATING TO THE
CONTROL OF DOWNY MILDEW OF CUCUMBERS.
Plot Fungicide_ Cost
S. .. Total Yield
Repl. Size Kind Amt. Mat'l Labor Hampers
2 1 A Cop. hydroxide 404 gal. $6.00 $8.16 364
7 1 A copper-lime (1) 191 lbs. 19.10 2.93 334.7
9 1 A 4-4-50 bordeaux 356 gal. 3.56 7.12 332.6
2 1A Pyrox 380 gal. 19.10 7.60 332
8 1 A check 272.9
1 1 A Kilrust 432 gal. 17.28 8.64 168

(1) average 3% applications.
Summary for Season 1925:-The experiments conducted dur-
ing the 1925 season yielded considerable data relative to the
value of fungicides for the control of downy mildew of cucum-
bers. The season was very favorable for the production of






Bulletin 230, Spraying and Dusting Cucumbers 19

cucumbers even though the mildew showed up in midseason.
The market prices held up well to the end of the season, which
insured profitable returns for late pickings which resulted from
the use of fungicides. The data for the 1925 season are sum-
marized in Table V.
The copper hydroxide sprayed plots showed the greatest yield,
while the Kilrust plot shows the lowest yield. These are indica-
tive of what might be expected but because of the limited repli-
cations the information they convey should not be considered
final. The other plots, however, were very uniform in yield and
were considerably better than the check plots. By considering
the increased yields in connection with the cost, bordeaux mix-
ture proved to be decidedly more economical than any of the
other fungicides. Comparisons were made of bordeaux mixture
prepared with hydrated lime and with slaked rock lime but the
differences were not consistent and definite enough to prove
that one form is better than the other. Consequently, the hy-
drated lime will probably be used in the future, since it is more
easily handled. A commercial form of calcium caseinate, Kayso,
was used in the liquid sprays as a spreader and sticker. The
season's results showed no marked and consistent difference
where it was used and its use will be discontinued in sprays ap-
plied to cucumbers in the future. Sulfur, which is one of the
active ingredients of Kilrust, was detrimental to the development
of cucumber plants and will be discontinued as a spray, although
further work should be conducted to determine the value of sul-
fur dusts of different compositions on cucumbers for the control
of downy mildew. The picking season of 1925 was continued
longer than usual on account of the continued good market
prices, and the prolonged fruiting period resulting from spray-
ing and dusting proved profitable. An increase in the total num-
ber of applications of the fungicides during the season would
possibly be more advantageous during such years.
During the season there was considerable evidence of copper
injury to sprayed plants. Some of the leaves showed yellow mar-
gins, while others appeared to be more or less hardened and
would make a distinct rustling when brushed with the hand.
In certain instances distinct burning of the leaves resulted from
the bordeaux spray. Consequently, the strength of the bordeaux
to be used in the future experiments will be prepared according
to a 2-4-50 formula instead of the 4-6-50 formula, using hydrated
lime.






20 Florida Agricultural Experiment Station

EXPERIMENTS CONDUCTED DURING 1926
During this season five experiments were planned and con-
ducted along lines similar to those of the previous season. These
experiments were distributed over the Micanopy-Gainesville-
LaCrosse cucumber-growing section. They were conducted in
cooperation with the commercial growers and the yield of the
different plots was taken as a direct measure of the control of
the disease.
Plantings were made in the latter part of February and the
early conditions were favorable for plant growth, resulting in
rapid development of the plants. The first application of the
fungicides was made April 19 when the plants averaged about
three true leaves and was repeated at weekly intervals until
five applications were made. The season continued quite favor-
able for the growth of the plants, except in certain fields where
the land was sandy the crop suffered from lack of moisture.
The experiments are discussed individually and the season's
data for all the experiments are averaged and summarized in
the following tables.
Experiment 1:-This experiment was located on a gently
sloping field, the north end of which was high, dry, and quite
sandy, while the south end was low, rich, and moist. The plots
were small, but produced fair yields, considering the fact that
the north end of all of the plots died prematurely, because of
lack of moisture. The data obtained from this experiment are
shown in Table VI.
TABLE VI.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 1-1926.
Plot I Fungicide I Cost
"I I Total I No. Yield
No. Size Kind Amt. Mat'l Labor Appl. Hampers
1 1/15 A 2-4-50 bordeaux 10 gal. $ .10 $ .20 5 11
2 1/15 A copper-lime 11 lbs. 1.10 .26 5 11.5
3 1/15 A check 10
4 1/12 A 2-4-50 bordeaux 15 gal. .15 .30 5 11
5 1/12A copper-lime 13 Ibs. 1.30 .33 5 6
6 1/12A check __6.5
Results calculated on basis of one acre.

Repl.
2 1 A 2-4-50 bordeaux 165 gal. $1.65 $3.30 5 148.5
2 1 A copper-lime 160 lbs. 16.50 4.00 5 122.2
2 1A check 114






Bulletin 280, Spraying and Dusting Cucumbers 21

The yields of these plots show that bordeaux mixture con-
trolled the disease better than copper-lime dust. These experi-
mental results indicate that the increased yield resulting from
the use of copper-lime dust cost $2.50 per hamper, making its
use undesirable, whereas the bordeaux spray produced an in-
crease of 341/2 hampers at a cost of 111/2 cents per hamper.
Experiment 2:-This experiment was located on fertile, sandy-
loam soil in a large, level field exposed on all but the north side.
The fungicides were applied first April 21 and at weekly inter-
vals thereafter until five applications were made. Picking was
begun May 13 and was continued to the end of the month and
stopped then because of low prices. The data obtained from
these plots are shown in Table VII.

TABLE VII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 2-1926.
Plot I Fungicide ( Cost
o - Total L No. Yield
No. Size Kind _Amt. Mat' L rAppl. Hampers
11 (1/19 A copper-lime 11.5 lbs. $1.15 $ .21 5 13.5
12 11/19 A check I12
13 11/19 A 2-4-50 bordeaux 12.5 gal. .13 .26 5 13
14 1/58 A check 4
15 1/6 A copper-lime 35.5 lbs. 3.55 .66 5 21
16 1/6 A 2-4-50 bordeaux 41 gal. .41 .82 5 41
17 1/6 A check 43
18 1/6 A copper-lime 35.5 lbs. 3.55 .66 5 37
19 1/6 A 2-4-50 bordeaux 41 gal. .41 .82 5 46

Results calculated on basis of one acre.

Repl. I
3 1 A 2-4-50 bordeaux 43.1 gal. $2.43 $4.86 5 256.3
3 1 A check 237.3
3 1A copper-lime 214.6 lbs. 21.46 4.00 5 219.7


The summary of the data in the above table shows that the
plots sprayed with bordeaux mixture produced a considerably
larger number of hampers of fruit than the plots dusted with
copper-lime dust, which, in turn produced better than the check
plots. The cost of the dust and its application was about twenty-
five dollars per acre in comparison with less than eight dollars
per acre for the cost and application of the bordeaux spray.
Experiment 3:-This experiment was located on a slightly-
sloping section of a 10-acre field supplied with an overhead







22 Florida Agricultural Experiment Station

sprinkler irrigation system. The soil was a black sandy-loam
well cultivated and fertilized. The application of the different
fungicides was made first on April 19 and was repeated at weekly
intervals until five applications were made. Table VIII contains
the data obtained from the experimental plot.

TABLE VIII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 3-1926.
Plot Fungicide I Cost
STotal I No. Yield
No. Size Kind Amt._ I Mat'l Labor Appl. Hampers
56 1/21 A 2-4-50 bordeaux 10 gal. $ .10 $ .20 5 18
57 1/21 A check 13
58 1/8 A copper stearate 9 lbs. 1.35 .50 5 44
59 1/7 A copper-lime 22 lbs. 2.20 .57 5 56
60 1/8 A check 44.5
71 1/7 A copper-lime 29 lbs. 2.90 .57 5 50.5
72 1/8 A copper-lime 20 lbs. 2.00 .50 5 36
73 1/7 A check 651
74 1/8 A copper-lime 25 lbs. 2.50 .50 5 60.5
75 1/7 A copper stearate 10 lbs. 1.50 .57 5 60
76 11/14 A 2-4-50 bordeaux 14 gal. .14 .28 5 25.5
77 1/14 A check 20

Results calculated on basis of one acre.

Repl.
2 1 A copper stearate 71 lbs. $10.65 $4.00 5 386
4 1 A copper-lime 194.2 lbs. 19.42 4.00 5 379.4
2 1 A 2-4-50 bordeaux 203 gal. 2.03 4.06 5 329
4 1 A check 316.5


In the above table it is noted that copper-lime and copper
stearate dusts both produced better yields of cucumbers than the
bordeaux sprays or h h the check plots. At the same time the bor-
deaux plots produced better than the check plots. There is an
added cost to the plots to which the fungicides were applied,
thus the increased yields cost 21 cents, 37 cents and 46 cents
per hamper, respectively, for the copper stearate, copper-lime,
and 2-4-50 bordeaux treatments.
This experiment shows that all three fungicides proved bene-
ficial. It also shows that the dusts were better in controlling
the disease than the liquid spray, as shown by the respective
yields which are taken as direct measures of the prevalence of
the disease. The check plots which were located at frequent
intervals in the experiment indicated the prevalence and severity







Bulletin 230, Spraying and Dusting Cucumbers 23

of the disease and the degree of control produced by the fungi-
cides.
Experiment 4:-This experiment was located on irrigated,
low sandy-loam soil in the vicinity of Gainesville and was planned
and conducted for the purpose of obtaining information on the
relative merits of copper-lime dust and liquid bordeaux mixture.
The first application of the fungicides was made April 24 when
the plants were in the three-leaf stage and three other applica-
tions were made at weekly intervals during the following month.
The data obtained from the experiment are presented in Table
IX.
TABLE IX.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 4-1926.
Plot Fungicide Cost
S. Total I No. Yield
No. Size Kind Amt. _Mat' Labor Appl. Hampers
21 1/8 A Copper-lime 23 lbs. I $2.30 $ .40 4 68.5
22 1/8 A 2-4-50 (H) bord. 27.5 gal.1 .28 .55 4 77
23 1/8A check 1 56
24 1/8 A copper-lime 23 lbs. 2.30 .40 4 66
25 1/8 A 2-4-50 (H) bord. 27.5 gal. .28 .55 4 67
26 1/8 A copper-lime 20.5 lbs. 2.05 .40 4 67
27 1/8 A 2-4-50 (R) bord. 27 gal. .27 .54 4 66
28 1/8 A check 68
29 1/8 A copper-lime 20.5 lbs. 2.05 .40 4 65
30 1/8 A 2-4-50 (R) board. 29 gal. .29 .58 4 91

Results calculated on basis of one acre.

Repl. 1
Rep2. i I gal. $2.22 $4.44 4 602
4 1 A 2-4-50 bordeaux 222 gal. $2.22 $4.44 4 602
4 1 A copper-lime 174 lbs. 17.40 3.20 4 526.4
2 1A check 496


The check plots showed 18 percent less yield than the plots
sprayed with bordeaux mixture. The yield from the plots dusted
with copper-lime was also considerably less than that from the
bordeaux plots.
Experiment 5:-This experiment was located on a gently slop-
ing portion of a sandy, irrigated field protected on the north
and west by trees. The local conditions were favorable for the
early development of the seedlings. The first application of
the fungicides was made April 27 when the plants were in the
three-leaf stage and others were made at weekly intervals. This







24 Florida Agricultural Experiment Station

experiment was planned and conducted so as to determine, if
possible, the number of applications of fungicides required to
control downy mildew of cucumber. The data obtained from
the experiment are shown in Table X.

TABLE X.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 5-1926.
Plot I Fungicide Cost
I Total No. Yield
No. I Size Kind Amt. I Mat'l Labor Appl. Hampers
38 1/12 A copper-lime 3 lbs. .30 .06 1 27
39 1/12 A copper-lime 6.5 lbs. .65 .13 2 29.5
40 1/10 A copper-lime 12 Ibs. 1.20 .24 3 35
41 1/10 A copper-lime 16.5 lbs. 1.65 .32 4 31
42 1/10 A copper-lime 16.5 lbs. 1.65 .32 4 31.5'
43 1/12 A check 32.5
44 1/10 A 2-4-50 bordeaux 20.5 gal. .21 .41 4 37
45 1/10 A 2-4-50 bordeaux 20.5 gal. .21 .41 4 34
46 1/10 A 2-4-50 bordeaux 16.5 gal. .17 .33 3 31
47 1/12 A 2-4-50 bordeaux 9 gal. .09 .18 2 26
48 1/12 A 2-4-50 bordeaux 5 gal. .05 .10 1 18.5

Results calculated on basis of one acre.

Repl.
38 1 A copper-lime 36 lbs. $3.60 $ .80 1 324
39 1 A copper-lime 78 lbs. 7.80 1.60 2 354
40 1 A copper-lime 120 lbs. 12.00 2.40 3 350
41 1 A copper-lime 165 lbs. 16.50 3.20 4 310
42 1 A copper-lime 165 Ibs. 16.50 3.20 4 315
43 1A check 390
44 1 A 2-4-50 bordeaux 205 gal. 2.05 4.10 4 370
45 1 A 2-4-50 bordeaux 205 gal. 2.05 4.10 4 340
46 1 A 2-4-50 bordeaux 165 gal. 1.65 3.30 3 310
47 1 A 2-4-50 bordeaux 108 gal. 1.08 2.16 2 312
48 1 A 2-4-50 bordeaux 60 gal. .60 1.20 1 223


There is but very little difference in the yields of the various
plots in relation to the number of applications of the fungicides.
This may be the result, however, of the fact that little or no dis-
ease appeared until late in the picking period. The plots sprayed
four times produced better than those sprayed or dusted only
once. The real difference manifests itself when the dusted and
sprayed plots are averaged and compared respectively with the
check plot. In this instance, the check plot produced more than
the average of either of the sprayed or dusted plots. The larger
yield from the check plot showed that the spraying and dusting
resulted in a loss not only in the cost of material and labor but







Bulletin 230, Spraying and Dusting Cucumbers 25

in reduced yield. The conclusion is that the fungicides were
detrimental to the plants in this experiment.
Summary for Season 1926:-The results of the five experi-
ments conducted during the 1926 season are summarized in
Table XI. The different experiments were located in cucumber
fields that varied considerably in soil type, moisture relations,
and cold protection. The mildew was prevalent in all fields dur-
ing the season and was the limiting factor in production in most
fields. The decrease in market prices toward the end of the
season was important in relation to the success of numerous
growers. Many fields were abandoned before the total yield was
obtained because of market conditions. Whenever this was done
the picking of the experimental plots was also concluded. In
certain instances this procedure perhaps did not show the max-
imum effect of the fungicides in controlling downy mildew.
TABLE XI. SUMMARY OF THE DATA OBTAINED IN EXPERIMENTS CON-
DUCTED DURING THE SEASON OF 1926 RELATING TO THE CONTROL OF
DOWNY MILDEW OF CUCUMBERS.
Plot Fungicides I Cost
I Total I L Yield
Repl. Size I Kind I Amt. I Mat'l I Labor Hampers
2 1 A Copper stearate' 71 lbs.I$10.65 $4.00 1 386
18 1 A copper-lime2 141.5 lbs. 14.15 2.88 323.5
16 1 A 2-4-50 bordeaux 171.4 gal. 1.71 3.42 317
12 1 A check 315.8

'5 applications. 2Average 3.6 applications.
The above table shows that the plots dusted with copper stear-
ate produced the largest yield. The yield was 70 hampers more
per acre than the check plots and the cost of the treatment was
only $14.65 per acre. However, with but two replications the
data are not so significant as they might at first appear. The plots
sprayed with 2-4-50 bordeaux mixture at an added cost of $6.00
over the check plots produced only two more hampers of cucum-
bers than the check plots, whereas the copper-lime dust at an
added cost of about $17.00 produced less than eight more hamp-
ers than the checks. Therefore, neither of these fungicides
was used profitably in the control of the disease. The plots
dusted with copper-lime dust produced more than the check plots
but costs of material and labor were too great. The general
conclusions drawn from the season's work are that copper stear-
ate dust controlled the downy mildew to such an extent that






26 Florida Agricultural Experiment Station

the increased yield cost 20 cents per hamper. On the other hand,
neither copper-lime dust nor 2-4-50 bordeaux mixture produced
sufficient increases in yield over the untreated plots.
EXPERIMENTS CONDUCTED DURING 1927
The experiments during this season were conducted along lines
similar to those of 1926. The plots were located so as to include
as wide a variation of conditions as possible.
Downy mildew was first observed May 6 and spread later over
the whole section. A cool, rainy period assisted materially in
the spread of the disease and destruction of the plants. The
first application of the fungicides was made about the middle of
April; the picking season began the latter part of April and con-
tinued until the middle of May.
Results of the experiments are given in detail below.
Experiment 1:-This experiment was located on the south
slope of a sandy field that was not irrigated. The seed were
planted in February and under the early favorable conditions
grew well. The fungicides applied consisted of four dusts and
two liquid sprays. There were also two check plots. The first
applications were made April 13 when the plants had developed
two true leaves and others followed at weekly intervals until six
applications were made. The first pickings were made the last
of April. The information obtained from this experiment is
shown in Table XII.
The above table shows that the check plots produced the high-
est yield, whereas the yield from the plots to which fungicides
were added, both spray and dust, varied considerably. It is
possible that the checks may have been slightly favored by bet-
ter locations in the field, especially in regard to moisture, since
the season turned out to be quite dry. It does not seem, from
past experiences, that the various fungicides should all prove
detrimental to fruit production, to such an extent as in this ex-
periment.
Downy mildew did not show up until the latter part of the
picking season and the actual influence of this disease on the
yield is debatable. Notes taken on the experiment show that on
the 6th of May all the plots were healthy and green with occa-
sional blossoms appearing. At this time the disease was appear-
ing in local areas in nearby fields. On May 16 all the plants in
the experiments were more or less yellow because of the disease;







Bulletin 230, Spraying and Dusting Cucumbers 27

the check plots showed the disease most conspicuously. About
this time most of the picking operations ceased because of low
market prices. On May 27 the sulfur and bordeaux plots were
the best in the experiment. They showed the least disease,
while the check plots were both entirely dead. Another im-
portant factor was that the marketing conditions during this
season were not satisfactory, consequently resulting in the early
abandoning of the fields. This situation can be discerned in the
low average yields of the various plots in this experiment.

TABLE XII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE CON-
TROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 1-1927.
Plot I Fungicides I Cost
STotal No. Yield
No. Size Kind Amt. Mat'l Labor Appl. Hampers
11 1/8 A Colloidal sulfur 35 lbs. $1.08 $ .60 6 10.5
12 1/8 A 2-4-50 bordeaux 18 gal. .18 .36 6 10.5
13 1/8 A check 12.5
14 1/8 A copper carbonate 21 lbs. 3.15 .60 6 13
15 1/8 A Pyrox 18 gal. 1.50 .36 6 13
16 1/8 A check 15
17 1/8 A copper-lime 31 lbs. 2.48 .60 6 12.75
18 1/8 A copper stearate 20 lbs. 3.00 .60 6 9

Results calculated on basis of one acre.

16&13 1A check 110
14 1 A copper carbonate 168 lbs. 25.20 4.80 6 104
15 1 A Pyrox 144 gal. 12.00 2.88 6 104
17 1 A copper-lime 248 lbs. 19.84 4.80 6- 102
12 1 A 2-4-50 bordeaux 144 gal. 1.44 2.88 6 84
11 1A sulfur 280 lbs. 8.64 4.80 6 84
18 1 A copper stearate 160 Ibs. 24.00 4.80 6 72


Experiment 2:-This experiment included a field of cucumbers
planted on sandy soil with a gentle northern slope and protected
on the north by native woods. The soil was of good quality and
not irrigated. This experiment was conducted to compare the
beneficial effects obtained from different numbers of applications
of the fungicides as determined by the yield of fruit. The plots
consisted of checks and those plots to which 1, 2, 3, and 4 appli-
cations of the fungicide, both spray and dust, were made, at
weekly intervals beginning April 14.







28 Florida Agricultural Experiment Station

TABLE XIII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OP DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 2-1927.
Plot 1 Fungicide I Cost o
I Total ( No. Yield
No. Size Kind IAmt. Mat'l Labor Appl. Hampers

20 1/8 A 2-4-50 bordeaux 5 gal. $ .05 $ .10 1 32
21 1/8 A 2-4-50 bordeaux 8 gal. .08 .16 2 30
22 1/8 A check ]29
23 1/8 A 2-4-50 bordeaux 12 gal. .12 .24 3 34
24 1/8 A 2-4-50 bordeaux 16 gal. .16 .32 4 33
25 1/8 A check 32
26 1/8 A copper-lime 18 lbs. 1.44 .40 4 26
27 1/8 A copper-lime 12 lbs. .96 .30 3 24
28 1/8 A check 21
29 1/8 A copper-lime 7 lbs. .56 .20 2 20
30 1/8 A copper-lime 4 lbs. .32 .10 1 17

Results calculated on basis of one acre.

20 1 A 2-4-50 bordeaux 40 gal. $ .40 $ .80 1 256
21 1 A 2-4-50 bordeaux 64 gal. .64 1.28 2 240
23 1 A 2-4-50 bordeaux 96 gal. .96 1.92 3 272
24 1 A 2-4-50 bordeaux 128 gal. 1.28 2.56 4 264
22-25-
28 1 A check 218.6
26 1 A copper-lime 144 lbs. 11.52 3.20 4 192
27 1 A copper-lime 96 lbs. 7.68 2.40 3 168
29 1 A copper-lime 56 lbs. 4.48 1.60 2 160
30 1 A copper-lime 32 lbs. 2.56 .80 1 136


The final averages of the above table show that the plants
sprayed with bordeaux mixture 2-4-50 produced the greatest
amount of fruit, while the plants dusted with copper-lime dust
produced considerably less fruit than the check plants. Close
examination shows that all of the sprayed plots produced more
fruit than any of the dusted plots and with one exception all
of the sprayed plots produced more fruit than any of the check
plots. Two of the check plots produced more than any dusted
plot,- No ex pla. ition can be given to account for these variations
in yield. The dusted plants show a gradual increase in produc-
tion of fruit in direct proportion to the number of applications
of the fungicide. Thus the plot dusted four times produced
the most fruit of any dusted plot. In considering the sprayed
plots, however, those sprayed once produced almost as much as
those sprayed four times. Since picking was discontinued be-
cause of a slump in the market price, the differences in yields are






Bulletin 230, Spraying and Dusting Cucumbers 29

not as large as they might have been if all of the later fruit had
been picked. Those plants growing in low places were green and
growing as compared with the wilted plants on high ground, but
were spotted somewhat with the disease. As far as the applica-
tions of spray were concerned, one was as good as four and
the operation was profitable. In respect to the applications of
dust, there is no other conclusion than that the dusts were detri-
mental to the plants and their production of fruit and, in addi-
tion, the expense of the fungicide and its application was a total
loss.
Experiment 3:-The plots in this experiment were located in
a portion of a six-acre field that had been planted to cucumbers
for a number of successive seasons. The soil was a rich sandy-
loam, almost level, which was irrigated with an overhead sprin-
kler system. The seed were planted early in March and a good
stand resulted. The fungicidal dusts were applied weekly be-
ginning April 13. Table XIV contains the information obtained
from the different plots in this experiment.
TABLE XIV.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 3-1927.
Plot Fungicides I Cost
o. iz K TTotal I No. Yield
No. Size Kind Amt. I Mat'I Labor Appl. Hampers
1 1/8 A colloidal sulfur 52 bs. $ 1.56 I$ .60 6 44.5
2 1/8 A copper carbonate 44 lbs. 6.60 .60 6 51
3 1/8 A check 59
4 1/8 A copper-lime 46 lbs. 3.68 .60 6 49

Results calculated on basis of one acre.

3 1A check 1 I 472,
2 1 A copper carbonate 352 lbs. $42.80 $4.80 6 408
4 1 A copper-lime 368 lbs. 29.44 4.80 6 392
1 1 A colloidal sulfur 416 lbs. 12.48 4.80 6 336


In this experiment the check plot yielded a much larger crop
than the dusted plots. This can partially be explained by the fact
that the check plot was growing on a little more fertile plot of
soil. The seedlings emerged first in this plot and all during the
season grew and produced better than the other plots. The
disease was not an important factor in this experiment until
the last week of the picking season. The picking was stopped






30 Florida Agricultural Experiment Station

because the market prices dropped too low to make further
picking, packing, and selling profitable. No detrimental effect
of the dusts on the plants could be detected, except a slight
hardening of the leaves and petioles of the plants dusted with
sulfur. The results of this experiment show that the application
of fungicides to these plants for the control of downy mildew did
not increase the yield.
Summary for Season 1927:-The early part of the season was
most favorable for the growth of cucumbers, but owing to the
lack of rainfall, later production was considerably reduced. The
following rainfall was recorded: March 2.33", April 1.46", and
May .46", which was much below normal for April and May.
Where irrigation was not practiced, the plants wilted in most
fields during the latter part of the picking season. Downy mil-
dew was first detected in this vicinity on May 6 and gradually
spread until all plants were killed. A few cool, rainy days about
May 12-14 favored the spread and development of the disease
which resulted in a rapid killing of the plants during the follow-
ing week. Usually the picking seasons have continued until the
vines are entirely dead, whereas the picking season of the cur-
rent year was concluded principally because of the low market
price.
The data obtained from the experiments conducted during the
season are averaged and summarized in Table XV.

TABLE XV.-SU-NMnaR OF THE DATA OBTAINED IN EXPERIMENTS CON-
DUCTED DURING THE SEASON OF 1927 IN RELATION TO THE CONTROL OF
THE DOWNY MILDEW OF CUCUMBERS.
Plot Fungicide I Cost
Total I Yield
Repl. Size Kind Amt. I Mat'l Labor Hampers
6 1 A check 266.8
2 1A cop. carbonated 239 lbs. $35.85 $4.80 256
6 1A copper-lime2 270 lbs. 21.60 3.52 219.3
2 1 A sulfur1 352 lbs. 10.56 4.80 210
5 1 A 2-4-50 bordeaux 145 gal. 1.45 2.90 167
1 1 A Pyrox 144 gal. 12.00 2.88 104
1 1 A copper stearate' 160 lbs. 24.00 4.80 72

'Average 6 applications. 2Average 4.4 applications.

The results listed in the above table show conclusively that
tiungicide.. did not increase the yields of cucumbers in the 1927
experiments. The check plots produced more fruit than the
plots of the same size to which fungicides were added in various






Bulletin 230, Spraying and Dusting Cucumbers 31

amounts and of different constituents. The cause for this can-
not be explained. In addition to the decreased yields of the
treated plots in comparison with the checks, the cost of material
and labor must be added to the loss suffered because of the re-
duced yield. Copper carbonate dust plots produced almost as
much as the checks, and the fruit was much better appearing
than that in the check plot, because of its darker, uniform green
color. However, the excessive costs of this fungicide did not
justify its use this season. The low yields obtained from the
plots treated with the other fungicides cannot be satisfactorily
explained.
EXPERIMENTS CONDUCTED DURING 1928
The general plan of the experiments conducted during the
1928 season was similar to that of the previous season. The
various plots were located in the immediate vicinity of Gaines-
ville, on farms of commercial growers.
The 1928 season opened very early. The seed were planted
in February and the plants developed rapidly until cool weather
early in March stopped their growth and froze large areas. Re-
plantings were made and by the middle of April the new plants
had developed several leaves and were large enough for the
first applications of fungicides. At this time none of the plants
in any of the plots had developed runners or had blossomed.
In fact the plants in one of the plots were barely past the coty-
ledon stage at this time. The first pickings were made the
second week in May, at which time the first signs of downy mil-
dew were noticeable. The picking season continued until the
first of June and during this time downy mildew gradually in-
volved more and more of the fields until most of the plants were
dead. At the end of the picking season the various plots in
the respective experiments were compared as to the amount of
healthy green plants, diseased plants, and dead plants.
Experiment 1:-This plot was on a portion of a six-acre field
that was irrigated with an overhead sprinkler system. The soil,
a light sandy loam, was almost flat. This field had been planted
to cucumbers for a series of years and the successive crops ap-
peared to be poorer and poorer. Previous to this year's plant-
ing stable manure had been applied to the whole field. The
field had always been carefully cared for and cultural methods
were above the average. At certain times in the spring, wind-
blown sand had caused some injury to seedlings. The field was






32 Florida Agricultural Experiment Station

planted early and because of the freezing temperatures it was
replanted. Continued cold weather caused the seedlings to be-
come stunted. In fact their growth was stopped for a consider-
able period during March and April. After the advent of warm
weather the plants still ceased to grow well and further examina-
tion showed that the plants in the whole field were badly in-
fested with root knot [Heterodera radicicola (Greef) Mueller].
The first application of fungicides was made April 17 before any
of the plants were blooming or putting out runners. The data
obtained from this plot during the season are shown in Table
XVI; it is also calculated on an acre basis.
TABLE XVI.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 1-1928.
Plot Fungicide I Cost
.- Total- I No. Yield
No. ISize Kind Amt. Mat' I Labor Applj Hampers
1 1/8 A copper-lime 26 lbs. $2.08 $ .60 6 7
2 1/8 A sulfur 37.5 lbs. 1.12 .60 6 13.3
3 1/8 A copper carbonate 27 lbs. 4.05 .60 6 11.75
4 1/8 A check 14.5

Results calculated on basis of one acre.

4 1A check 116
2 1A sulfur 300 lbs. $9.00 $ 4.80 6 106.4
3 1A copper carbonate 216 Ibs. 32.40 4.80 6 94
1 A copper-lime 208 lbs. 16.64 4.80 6 56


Beginning with the 17th of April the plants in these plots
made very little growth for three weeks. During this period
and afterward the check plot looked the best. A few plants de-
veloped but it was found that the root-knot was too bad to ex-
pect the plants to develop very much. The plants showed no
signs of downy mildew until close to the end of the season but
after it appeared, the plants in the check plot were killed almost
entirely before the plants in the other plots showed any injury.
The check plot had less nematode infestation than any of the
other plots which accounted, in part, for the larger yield. Under
these conditions no benefit was derived from spraying.
Experiment 2:-This experiment was located on newly cleared
land of a sandy-loam type, slightly rolling with a gradual slope
toward the south. The field, about eight acres in size, was well







Bulletin 230, Spraying and Dusting Cucumbers 33

protected on all sides by native woods except a small portion to
the northeast. It was irrigated by an overhead sprinkler sys-
tem; the water was pumped by engine from a nearby brook.
The first application of fungicides was made April 15 when the
plants had developed four leaves and the others followed at
weekly intervals. Six applications were made during the sea-
son. Picking was begun on May 12 and continued into the first
week of June. The data collected from these plots are included
in Table XVII.

TABLE XVII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 2-1928.
Plot Fungicide ] Cost j
Total I No. I Yield
No. Size Kind Amt. Mat'l Labor (Appl.1 Hampers
72 1/8 A copper stearate 20.5 lbs. $ 3.07 $ .60 6 42
73 1/8 A check I36
74 1/8 A sulfur 143 Ibs. 1.29 .60 6 32
75 1/8 A copper-lime 36 lbs. 2.88 .60 6 39
76 1/8 A check 43
77 1/8 A 2-4-50 bordeaux 35 gal. .35 .70 6 55
78 1/8 A copper carbonate 37 lbs. 5.55 .60 6 49

Results calculated on basis of one acre.

77 ) IA 2-4-50 bordeaux 280 gal. 1$ 2.80 $5.60 1 6 440
78 I 1 A copper carbonate 296 lbs. 44.40 4.80 1 6 392
72 1 A copper stearate 164 lbs. 24.60 4.80 6 336
73&761 1A check 1 316
75 1A copper-lime 288 lbs. 23.04 4.80 6 312
74 1 A sulfur 344 lbs. 10.32 4.80 6 256


The yields of the plots in this experiment as shown above in-
dicate that 2-4-50 bordeaux mixture gave the best control of the
disease and at an exceedingly low cost. The sulfur plot gave the
lowest yield and all during the season was rated as the poorest
in the experiment in regard to growth, color, and the amount of
the disease present. The check plot developed the diseases more
rapidly than the sulfur plot but previous to the advent of the dis-
ease, the check plot developed much better than the plants
covered with sulfur. Both the copper carbonate and the copper
stearate plots produced more than the check plots, thus show-
ing a partial control of the disease. However, when the costs
are considered, neither of these two fungicidal dusts proved to
be profitable. The former showed an increase of 76 field hampers






34 Florida Agricultural Experiment Station

at a cost of slightly over $50, or 65 cents per hamper for the in-
creased yield, whereas the bordeaux plot showed an increase of
120 field hampers at an increased cost of $8.40 or 7 cents per
hamper for the increased yield. The copper-lime plot yielded
about the same as the check. The quality of fruit was the best
on the copper stearate plot, especially in respect to the color,
which was a much darker uniform green, very desirable for the
market. At the end of the picking season the plots were ex-
amined and compared with each other in relation to general ap-
pearances. At this time the check plots which were the poorest
showed 100 percent infection and from 50 to 80 percent of the
plants were dead. The plants in the copper carbonate plot were
all green and showed only 30 percent infection. They were of
a good color, except that the margins of some leaves were slightly
yellowish, probably caused by the copper. The other plots to
which fungicides were applied were quite uniform in appear-
ance with the exception of the sulfur plot which was yellowish
(not because of the color of the sulfur), in contrast to a dark
green color of the plots dusted with copper. The plants dusted
with sulfur were smaller and seemed to be more rigid than those
of other plots. However, the sulfur plot showed less disease
than the check plots.
Experiment 3:-This experiment was located in a sandy, six-
acre field with a considerable eastern slope and had previously
been a cowpen. The soil was not the thirsty type and no irriga-
tion was provided. A fine stand of seedlings was obtained and
they grew rapidly. The first fungicides were applied April 15
when the plants were in the four-leaf stage, and the other ap-
plications followed at weekly intervals. The first picking was
made May 18. The experiment contained seven plots, the data
from which are contained in Table XVIII.
In this experiment the copper stearate plot gave the largest
yield, followed closely by the plot sprayed with bordeaux. The
plot dusted with copper stearate not only produced the most
fruit, but the vines looked best during the entire season and the
fruits were of a desirable uniform dark green color. In each of
these plots less than 10 percent of the plants were infected when
picking was discontinued on account of market conditions. The
check plots produced better than either the sulfur or copper-lime
plots. This advantage was gained early in the season before the
disease developed. The check plots were the first attacked by the







Bulletin 230, Spraying and Dusting Cucumbers 35

TABLE XVIII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 3-1928.
Plot Fungicide ______ ____Cost
i Total INo. Yield
No. Size Kind Amt. Mat' Labor Appl. Hampers

50 1/8 A copper stearate 18 Ibs. $ 2.70 $ .60 6 28
51 1/8 A check 18.5
52 1/8 A sulfur 49.5 Ibs. 1.48 .60 6 19
53 1/8 A copper carbonate 35.5 lbs. 5.32 .60 6 22.5
54 1/8 A 2-4-50 bordeaux 45 gal. .45 .90 6 25
55 1/8 A check 19.5
56 1/8 A copper-lime 32 lbs. 2.56 .60 6 18.5

Results calculated on basis of one acre.

50 1 A copper stearate 144 lbs. $21.60 $4.80 6 224
54 1 A 2-4-50 bordeaux 360 gal. 3.60 7.20 6 200
53 1 A copper carbonate 284 lbs. 42.50 4.80 6 180
51&55 1A check I 152
52 1 A sulfur 396 lbs. 11.84 4.80 6 152
56 1 A copper-lime 256 lbs. 20.48 4.80 6 148


disease and they showed 100 percent infection, were badly yel-
lowed, and numbers of plants were killed when picking was dis-
continued. Most of the other plots showed from 10 to 30 percent
infection. The copper stearate and copper carbonate produced
increased yields at a cost of 36 cents and $1.68 cents per hamper,
respectively. The bordeaux plot showed an increase in yield of
48 hampers per acre at an added cost of only $10.80 or 221/2
cents per hamper for the increase.
Experiment 4:-This experiment was located on a piece of
sandy soil that sloped northward to a wooded stream. The soil
was rich but not irrigated. The plantings were made early
and a good stand of plants was obtained earlier than on any other
fields in the immediate vicinity. The first application of fungi-
cides was made April 17, when the plants were in the four-leaf
stage, at which time half of the plot was sprayed with 2-4-50
bordeaux mixture and the other half dusted with 20-80 copper-
lime dust, with the exception of the checks. Other applications
followed at weekly intervals for four applications. Two plots
were left untreated for checks, while others received one appli-
cation, two applications, three applications, and four applications
at successive weekly intervals. It was considered best to make
the applications at the beginning of the season where only one







36 Florida Agricultural Experiment Station

treatment was to be made. The first pickings were made May 7
and the season continued until June 1. The data obtained from
the plots in this experiment are shown in Table XIX.

TABLE XIX.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 4-1928.
Plot Fungicide Cost
STotal i No. Yield
No. Size Kind Amt. Mat'l Labor Appl. Hampers

5 1/6 A copper-lime 28.5 lbs. $ 2.28 $ .53 4 40
6 1/6 A 2-4-50 bordeaux 30 gal. .30 .60 4 48
7 1/6 A copper-lime 17.5 lbs. 1.40 .40 3 34.5
8 1/12 A check 19
9 1/6 A 2-4-50 bordeaux 21 gal. .21 .42 3 81
10 1/6 A copper-lime 9 lbs. .72 .26 2 30.2
11 1/12 A check 15
12 1/6 A 2-4-50 bordeaux 14 gal. .14 .28 2 23
13 1/6 A copper-lime 3 lbs. .24 .13 1 24.3
14 1/6 A 2-4-50 bordeaux- 6 gal. .06 .12 1 21.5

Results calculated on basis of one acre.

5 1 A copper-lime 1171 lbs. $13.68 $3.20 4 240
6 1 A 2-4-50 bordeaux 180 gal. 1.80 3.60 4 288
7 1 A copper-lime 105 lbs. 8.40 2.40 3 207
9 1 A 2-4-50 bordeaux 126 gal. 1.26 2.52 3 186
8&11 1A check 204
10 1A copper-lime 54 lbs. 4.32 1.60 2 181.2
12 1 A 2-4-50 bordeaux i 84 gal. .84 1.68 2 138
13 1 A copper-lime 18 lbs. 1.44 .80 1 145.8
14 1 A 2-4-50 bordeaux 36 gal. .36 .72 1 129


The data in the above table show that the yield of plots re-
ceiving four applications of the fungicide was almost double that
of the plots receiving but a single application. The yields, which
are taken as indirect measures of the amount of disease present,
show a gradual increase with each successive application of
fungicide. It is of interest to note, however, that only the plots
to which four applications were made produced more cucumbers
than the average of the check plots. On account of the high cost
of the copper-lime dust there is some question as to the advis-
ability of its use. However, the increase in yield of the sprayed
plot over the dusted plot to which four applications were made
and the lower cost of the spray places it in a very favorable
position for recommendation.
It is also evident that one, two, or even three applications were






Bulletin 230, Spraying and Dusting Cucumbers 37

of little value. In fact none of these plots so treated exceeded
the check plots in production. One and two treatments were ex-
ceedingly detrimental as indicated by the results. It might be
added however that this part of the plot became a little dry dur-
ing the end of the season and some reduction in yield may be ac-
counted for in this way. The check plots showed signs of in-
fection first and the disease spread over them very rapidly. The
disease spread gradually to the plots to which the fewer ap-
plications of fungicides were made, then successively to the
others in rotation depending on the number of applications they
received. When the check plants were dead the plants which
were sprayed and dusted four times showed from 20 to 40 per-
cent infection and were not suffering materially from the dis-
ease. Picking was discontinued abruptly because the fruit could
not be marketed profitably, thus preventing a greater possible
difference between checks and treated plants.
Summary for Season 1928:-The season was favorable for the
growth of cucumber plants in most sections of central Florida in
spite of several cold periods and occasional replanted fields. The
experiments were planned and conducted along lines similar to
those of the previous season. They were located with experi-
enced growers in different localities and under various conditions.
The different experiments have already been described in detail.
The results obtained from all four experiments are averaged,
calculated on an acre basis, and shown in Table XX.
TABLE XX.-SUMMARY OF THE DATA OBTAINED IN EXPERIMENTS CON-
DUCTED DURING THE SEASON OF 1928 IN RELATION TO THE CONTROL OF
THE DOWNY MILDEW OF CUCUMBERS.
Plot | Fungicides_ Cost
STotal I Y ield
Repl. Size Kind Amt. Mat'1 Labor Hampers
2 1A copper stearate 116 lbs. $23.10 $4.80 280
4 1A 2-4-50 bordeaux 219.2 gal. 2.19 4.39 275
3 1A cop. carbonate 265 lbs. 39.78 4.80 222
7 1A check 195
4 1 A copper-lime 255.5 lbs. 16.78 3.20 177.4
3 1A sulfur 313 Ibs. 10.39 4.80 171.5
__

It may be seen from Table XX that the copper stearate plots
produced the greatest yield, which is interpreted as resulting
in the best control of the disease. This fungicide was applied as
a dust to the cucumber plants in the early mornings when they






38 Florida Agricultural Experiment Station

were still wet with dew. These plots averaged 85 field hampers
of fruit to the acre more than the check plot at an additional
cost of $27.90. The cost amounted to approximately 32 cents
per hamper for the increase in yield and would possibly raise the
production cost too high. The total cost of the increase in yield
of the plots sprayed with 2-4-50 bordeaux was $6.58 or 8.2 cents
per hamper for the increase in yield. The increase in yield was
produced at a cost of 8.2 cents per hamper, as compared with
32 cents per hamper for the increase in yield resulting from the
use of copper stearate. Although the plots sprayed with bor-
deaux did not produce the highest yield, the production costs
were enough less to place the operation in a favorable light with
the grower. The copper carbonate plots yielded better than the
checks, but the high cost of the increased yield per hamper,
which was $1.65, made its use prohibitive. The other dusts,
sulfur and copper-lime, did not produce as much as the check
plots.
EXPERIMENTS CONDUCTED DURING 1929
The experiments were planned and conducted in 1929 about
the same way as they were the previous season. The different
plots were distributed over the cucumber section in the im-
mediate vicinity of Gainesville.
The season was considered early and the seedlings developed
rapidly from early plantings due to favorable temperatures and
adequate rainfall. Because of the earliness of the season and
the rapid growth of the seedlings early in the season, it was
thought possible that they might escape downy mildew. Care-
ful observations were made daily for the first appearance of the
disease. On March 30 the first diseased leaves were found and
the first applications of fungicides were made on that day. At
this time the more advanced plants had developed short runners
and were in blossom. The fungicides were applied thoroughly
with hand machinery and the treatments were repeated once a
week until the close of the picking season. The first pickings
were made April 22 and by May 12 the season was over because
the disease had killed the plants.
Experiment 1:-This plot was located on light hammock soil
and was a portion of a 12-acre field that had been cleared the
previous season. The whole field sloped gently and was sup-
plied with an overhead sprinkling system of irrigation.
The first application of fungicides was made on the 30th of






Bulletin 230, Spraying and Dusting Cucumbers 39

March, at which time the cucumber plants had begun to develop
runners, were showing about a dozen leaves and an occasional
blossom. Other applications were made at weekly intervals for
five weeks.
The data obtained from the experimental plots are shown in
Table XXI.

TABLE XXI.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 1-1929.
Plot Fungicides I Cost
I I Total I 1 No. Yield
No. Size Kind Amt. Mat'l Labor Appl.1 Hampers
1 1/16 A sulfur 12.5 lbs. $ .38 $ .25 5 15.7
2 1/8 A 2-4-50 bordeaux 17 gal. .17 .34 5 45.5
3 1/16 A check 18.2
4 1/8 A copper-lime 12.5 lbs. 1.00 .25 5 53.5
5 1/8 A copper stearate 6.7 lbs. 1.01 .25 5 52
6 1/16 A check 22.7
7 1/8 A 2-4-50 bordeaux 17 gal. .17 .34 5 62
8 1/8 A cop. carbonate 11 lbs. 1.65 .25 5 57
9 1/16 A sulfur 12.5 lbs. .38 .25 5 25
10 1/8 A 2-4-50 bordeaux 17 gal. .17 .34 5 47.5
11 11/16 A check 22.7
12 1/8 A copper-lime 12.5 lbs. 1.00 .25 5 53.7
13 1/8 A copper stearate 7 lbs. 1.05 .25 5 60.5
14 1/16 A check 23.7
15 1/8 A 2-4-50 bordeaux 17 gal. .17 .34 5 54
16 1/8 A cop. carbonate 11 lbs. 1.72 .25 5 43.5

Results calculated on basis of one acre.

Repl. I
2 1 A copper stearate 1 55 lbs. $ 8.25 $4.00 5 450
2 1A copper-lime I100 lbs. 8.00 4.00 5 429
4 1 A 2-4-50 bordeaux 1136 gal. 1.36 2.72 5 417.5
2 1A cop. carbonate 90 lbs. 13.50 4.00 5 402
4 1A check I 350
2 1 A sulfur [200 lbs. 6.00 4.00 5 326.5


In these experiments the extent of control of the disease ob-
tained by the applications of fungicides was determined by the
yield of fruit from the respective plots as was done in preceding
years. The results show that copper stearate dust produced the
greatest beneficial effect upon the yield. The other fungicides
are listed in the order of their relative merits on this standard.
All of the fungicides of which copper was the base apparently
controlled the disease better than those which contained no
copper. They did not, as far as could be determined, prove to be






40 Florida Agricultural Experiment Station

detrimental in any way. The plants dusted with sulfur were,
slightly lighter green in color, grew less rapidly and extensively.
than the checks, and they were killed by the disease about the
same time as the checks.
Experiment 2:-A portion of a 10-acre field of cucumbers was
laid out for this experiment. It was located on the brow of a
low bluff along a running stream and was surrounded on three
and a half sides by native woods. This piece of land was of the
sandy-loam, high hammock type that had been planted to cu-
cumbers the previous season. The field was irrigated by an over-
head sprinkler system. The seed were planted early and the
plants grew rapidly under favorable conditions. The first ap-
plication of fungicides was made March 31, when the plants were
large, showing an average of a dozen leaves and an occasional
blossom.
Table XXII contains the classified data obtained from this
experiment.
TABLE XXII. EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 2-1929.
Plot Fungicide Cost
SI Total No. Yield
No. Size I Kind Amt. Mat'1 Labor App. Hampers
1 1/8 A sulfur 18 lbs. $ .54 $ .50 5 35.2
2 1/8A check 34.5
3 1/8 A copper stearate 8.2 lbs. 1.23 .50 5 32.3
4 1/8 A 2-4-50 bordeaux 23 gal. .23 .46 5 37.2
5 1/8 A copper-lime 11.5 lbs. .92 .50 5 43.7

Results calculated on basis of one acre.

1 1 A sulfur 144 lbs. $4.32 $4.00 5 282
2 1 A check 276
3 1 A copper stearate 66 lbs. 9.90 4.00 5 258
4 1 A [2-4-50 bordeaux 184 gal. 1.84 3.68 5 298
5 1 A copper-lime 92 lbs. 7.36 4.00 5 350


The disease showed up first in the check plot close to the edge.
of the woods. This plot contained the largest, most rapidly
growing plants, probably as a result of protection by the woods
on the north. The copper-lime and bordeaux plots produced the
most fruit while the plot dusted with copper stearate produced
the lightest yield. This low production may be due to consider-






Bulletin 230, Spraying and Dusting Cucumbers 41

able mosaic that developed in one end of the plot, as the vines
remained green two weeks after the check plots were dead.
Experiment 3:-This experiment was located in a field of dark
sandy-loam soil. At the time the first application of fungicides
was made the plants were in blossom and downy mildew was evi-
dent on a few plants in the field. The field was selected because
it was in about the same condition that most fields are in when
the owners put on their first application, i.e. the disease must be
in the field and plainly evident before the grower recognizes the
need of a fungicide. Three applications were made before the
plants were killed by the disease. There is one less application
on the plots in this experiment than any of the others conducted
during 1929. Table XXIII includes the data obtained from the
experiment.
TABLE XXIII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 3-1929.
Plot I Fungicide I Cost
~--- -- ~-`-_ _^^_^ -ie-
I Total I No. I Yield
No. Size Kind Amt. Mat'l Labor JAppl. Hampers
1 1/8 A copper-lime 14 lbs. $ 1.12 $ .30 3 45
2 1/8 A check 28
3 1/8 A sulfur 16 lbs. .48 .30 3 22
4 1/8 A check 30
5 1/8 A cop. carbonate 12 lbs. 1.80 .30 3 36
6 1/8 A check 25
7 1/8 A copper stearate 6.5 lbs. .97 .30 3 22

Results calculated on basis of one acre.

1 1 A copper-lime 112 lbs. 8.96 $2.40 I 3 360
2 1A cop. carbonate 96 lbs. 14.40 2.40 1 3 288
3 1A check I 222
4 1 A copper stearate 1 52 lbs. 7.80 2.40 3 176
5 1 A sulfur 128 lbs. 3.84 2.40 3 176


Because of the delay in making the first applications the whole
field became infected. The fungicides aided materially in holding
the disease in check but did not prevent the plants from being
killed. The untreated plants died only a few days before the
treated ones, and the plants in the whole plot died two weeks
before those in Experiment 1. Two copper dusts showed up
much better, however, than the check, which in turn was better
than the plots dusted with sulfur and copper stearate.






42 Florida Agricultural Experiment Station

Experiment 4:-This experiment was located on a relatively
level piece of low, non-irrigated, dark, sandy-loam soil. An area
of slightly more than an acre was divided into three portions,
one was used as a check, one was sprayed with bordeaux, and
the third was dusted with copper-lime dust. The fungicides
were applied late, when the plants were in blossom. The disease
was evident in the field at the time of the first application.
TABLE XXIV. EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 4-1929.
Plot I Fungicide Cost
Total I No. Yield
No. Size Kind Amt. I Mat'l LaborAppl. Hampers
1 3/7 A copper-lime 32 lbs. $2.64 $1.36 4 83.5
2 1/6 A check 23
3 3/7 A 2-4-50 bordeaux 60 gal. .60 1.20 4 110.5
I I I
Results calculated on basis of one acre.

1 1 A 2-4-50 bordeaux 140 gal. $1.40 $2.80 4 257.8
2 1A copper-lime 77 lbs. 6.16 3.17 4 194.8
3 1A check 138


The disease, which was evident on the plants at the time of the
first application of fungicides, was only slightly checked in its
advance. The check plants were killed rapidly and the others
soon followed. The plot sprayed with bordeaux far out-yielded
the dusted plot and both exceeded the yield of the checks. The
bordeaux plot remained green and vigorous for some time after
the dusted plot was entirely dead because of the disease. In this
experiment the fungicides were exceedingly profitable regardless
of the lateness of their application.
Experiment 5:-This experiment was conducted on about a
half-acre of a six-acre field that had grown cucumbers for a
number of years. The soil was of a sandy-loam type and irri-
gated with an overhead sprinkler system. The plants were well
advanced, being in blossom when the first applications of fungi-
cides were made. There were four plots in the experiment;
three were dusted with fungicides and the fourth was a check
plot. The relatively light applications were made in order to
determine their value in comparison to heavier applications.
The disease was evident in this plot at the time the first ap-
plications were made and steadily spread until the plants were






Bulletin 230, Spraying and Dusting Cucumbers 43

killed. The fungicides checked the disease somewhat, as is
shown by the yields of the plots. The yield of all the dusted
plots exceeded that of the check plot. This is due to the check-
ing of the disease during picking time and partly due to pro-
longing the life of the plants and picking season after the check
plots were dead.

TABLE XXV.- EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 5-1929.
Plot Fungicide I Cost
STotal I I No. Yield
No. ISize Kind Amt. Mat'l Labor Appl.- Hampers

1 1/8 A check 9.5
2 1/8 A copper-lime 6.7 lbs. $ .54 $ .40 4 13
3 1/8 A sulfur I 8.5 lbs. .26 .40 4 11.5
4 1/8 A cop. carbonate I 6 lbs. .90 .40 4 19

Results calculated on basis of one acre.

1 1A cop. carbonate 148 lbs. $7.20 $3.20 4 152
2 1 A copper-lime 54 lbs. 4.32 3.20 4 104
3 1A sulfur 68 lbs. 2.04 3.20 4 92
4 1A check 76


Summary for Season 1929:-To make the data more easily
understood, the information accumulated from- all five of the
experiments conducted during the season, have been averaged
under the different headings in Table XXVI. The replications
vary somewhat depending on the duplications in the respective
experiments. The cost item can be deduced at a glance by add-
ing material and labor costs.

TABLE XXVI.-SUMMARY OF THE DATA OBTAINED IN EXPERIMENTS CON-
DUCTED DURING THE SEASON OF 1929 IN RELATION TO THE CONTROL OF
DOWNY MILDEW OF CUCUMBERS.
Plot Fungicide Cost
I Total ( Yield
Repl. Size Kind Amt. Mat'l 1 Labor Hampers
6 1 A 2-4-50 bordeaux 144.6 gal. $ 1.44 $2.88 372.1
5 1A copper-lime 96 lbs. 7.60 3.68 352.5
4 1 A copper stearate 57 lbs. 8.55 3.68 333.5
4 1A cop. carbonate 81 lbs. 10.40 3.68 311
10 1A check 255.6
6 1A sulfur 148 lbs. 4.44 3.68 240.6
I_ I I I






44 Florida Agricultural Experiment Station

The replications vary because all of the fungicides were not
used in all of the experiments and others were used more than
once in the same experiment. The plots sprayed with 2-4-50
bordeaux mixture show a much better yield than the plots treat-
ed with any of the other fungicides and all treated plots pro-
duced a greater yield than the check plots with the exception of
the sulfur plots. The liquid spray was also less expensive than
any of the other fungicides. In comparing the yields of treated
plots with the check, it will be found that the additional cost of
the fungicide and its application was more than justified in
every case except sulfur. The plots to which sulfur was applied
produced a lower yield of fruit than the check plots for the
season's average.
The bordeaux spray showed less detrimental effect on the
plants this year than ever before. There was no burning of the
leaves, the blossoms set fruit from the beginning of the season,
and the bordeaux plots developed as rapidly as the checks
throughout the season. The plants dusted with sulfur were not
so dark green as the plants that were dusted or sprayed with
copper fungicides and their leaves appeared to be somewhat
dryer and abnormal. During the latter part of the season pow-
dery mildew began to develop in the experimental plots and it
was noted that it remained entirely absent from the sulfur plots.
As a whole, the season was successful from the experimental
standpoint. It was concluded that the grower can expect the dis-
ease annually and that the plants should be sprayed or dusted as
soon as possible after they are up, for the best control of the dis-
ease. It is not desirable to delay the applications after the first
true leaf appears on the plants. The early applications prevent
the primary infections and thus delay the secondary or general
infection that usually is responsible for the death of the plants
in this section. Copper-lime dust was the best dry fungicide;
no detrimental effects were noted and on the other hand the
plants remained free from the disease and of a healthy green
color through the picking season.
EXPERIMENTS CONDUCTED DURING 1930
The general plan of the experiments for 1930 was similar to
that of the previous season. Four individual experiments were
placed on a cooperative basis at various points in the immediate
vicinity of Gainesville. In addition to the yield as a measure of
control, the general conditions of the plants in the various plots






Bulletin 230, Spraying and Dusting Cucumbers 45

were compared and given rank according to the amount of green,
yellow, and dead leaves on the plants in the plots.
Because of results of previous experiments only the fungicides
which contain copper and sulfur were used in these experiments.
The locations of the four experiments were carefully selected
so as to include as wide a range of conditions as possible. The
high lands are usually considered quite dry and crops growing
on them often suffer during drouth. The low lands, on the other
hand, are often wet and cold and seldom become dry enough to
injure the plants growing upon them.
This season proved to be one of extremes as far as these plots
were concerned. The seed were planted during a cold, rainy
period and in most instances failed to germinate. A second
planting was necessary and in some instances a third was re-
quired to obtain a good stand of plants. Late frosts were also
instrumental in delaying the growth. About the time the seed-
lings were in the cotyledon stage in a majority of the fields the
rainy period closed but cool weather continued for several weeks.
The advent of warm weather resulted in rapid development of
the plants. However, the lack of precipitation resulted almost
immediately in drouth conditions that gradually became worse,
which caused considerable injury to the plants in unirrigated
fields. The earliest plantings were made in the latter part of
February and other plantings continued until the middle of
March. The first diseased leaves were collected April 1 on plants
in the vicinity of Gainesville from the early planting, although
the disease had been prevalent and destructive in other nearby
sections of the state for several weeks. The first application
of fungicides was made on April 18 when the plants in the ex-
perimental plots averaged two true leaves.
Experiment 1:-The plots in this experiment consisted of a
portion of a 15-acre field which was cleared during the previous
season but was not cultivated that year. The soil was a sandy
loam and sloped very little. The whole field was irrigated by an
overhead sprinkler system supplied with water from a small
creek by engine and force pump.
The first application of fungicides was made on April 18 when
the cucumber seedlings were developing the second and third
true leaves. The applications of fungicides were made a week
apart for six weeks. The comparative rank of the plots in the
field in relation to appearance was determined before any other
data were compiled. This relative rank represented the gen-






46 Florida Agricultural Experiment Station

eral appearance of the plots at the end of the picking season, the
plot showing the least disease was given the arbitrary rank of
90 percent and the others were given a proportionate rating,
depending on their condition.

TABLE XXVII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 1-1930.
Plot Fungicide Cost
Total 1 No. Yield
No. Size Kind Amt. I Mat'I LaborAppl. Hampers Rank
81 1/12 A cop. carb. 21.5 lbs. $3.22 $ .40 6 32.7 80
82 1/12 A cop. stearate 9.5 lbs. 1.42 .40 6 46 70
83 1/12 A 2-4-50 board. 29 gal. .29 .58 6 44.5 60
84 1/12 A cop. carb. 21 lbs. 3.15 .40 6 38.2 70
85 1/12 A sulfur 19 lbs. .57 .40 6 32 50
86 1/24 A check 17.2 30
87 1/12 A cop. stearate 12 lbs. 1.85 .40 6 43 85
88 1/12 A copper-lime 20.5 Ibs. 1.64 .40 6 36.5 90
89 1/12 A 2-4-50 bord. 28 gal. .28 .56 6 32.7 80
90 1/12 A sulfur 17.5 lbs. .52 .40 6 26 50
91 1/12 A cop. stearate 13 lbs. 1.85 .40 6 43.2 60
92 1/12 A copper-lime 20 lbs. 1.60 .40 6 44.7 70

Results calculated on basis of one acre.

3 1 A cop. stearate 138 Ibs. 21.21 4.80 6 528 70 +
2 1 A copper-lime 243 lbs. 19.44 4.80 6 487.5 80
2 1 A 2-4-50 bord. 342 gal. 3.42 6.84 6 463.5 70
2 1 A cop. carb. 255 lbs. 38.22 4.80 6 426 75
1 1A check I 414 30
2 1A sulfur 219 lbs. 6.54 4.80 6 348 50


The data given in Table XXVII show that copper stearate
dust was most effective in controlling the disease (because of the
greatest yield), followed closely by copper-lime dust, 2-4-50 bor-
deaux spray, and copper carbonate dust. The check plots pro-
duced well and even exceeded the sulfur-dusted plots. The sulfur
seemed to harden the plants to a considerable extent, thus slow-
ing down the growth and showing no beneficial effect in control
of the disease. During previous seasons it was observed that
4-4-50 bordeaux injured the plants to some extent but no sim-
ilar injury was observed this season when 2-4-50 bordeaux was
used. The copper-lime and copper stearate dusts, which gave
very nearly the same results in plot yields, also cost about the
same. The bordeaux spray cost less than half as much, while
the copper carbonate dust costs were twice as much.







Bulletin 230, Spraying and Dusting Cucumbers 47

Experiment 2:-This experiment was located in a 10-acre field
on high, sandy, unirrigated land. Because of the exceptionally
dry season, the yields were low. Up to the end of the picking
season the downy mildew disease was not common. A large
number of plants were infected (a single spot on a single leaf)
but the actual loss because of the disease was less than 1 per-
cent. The general procedure for taking data was similar to
that in the preceding experiment. Table XXVIII gives the data
accumulated from the various plots.
TABLE XXVIII.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 2-1930.
Plot Fungicide Cost
I Total No. Yield
No. Size_ Kind Amt. Mat'l Labor ppl. Hampers

81 1/6 A copper stearate 14.5 lbs. $ 2.17 $ .80 6 10.7
82 1/6 A copper-lime 22.2 lbs. 1.78 .80 6 10.2
83 1/6A check 10.2
84 1/6 A cop. carbonate 18.5 lbs. 2.77 .80 6 9.3
85 1/6 A sulfur 19 lbs. .57 .80 6 7.5
86 1/6 A 2-4-50 bordeaux 32 gal. .32 .64 6 6

Results calculated on basis f f one acre.

81 1 A copper stearate 87 lbs. $13.02 $4.80 6 64.5
82 1 A copper-lime 133.5 lbs. 10.68 4.80 6 61.5
83 1 A check 61.5
84 1 A cop. carbonate 111 lbs. 16.62 4.80 6 56
85 1 A sulfur 114 lbs. 3.42 4.80 6 45
86 1 A 2-4-50 bordeaux 192 gal. 1.92 3.84 6 36


These data show that the check plots produced more fruit than
the plots sprayed with bordeaux mixture or dusted with copper
carbonate or sulfur. Since the disease was not common in the
field with the exception of a few leaf spots on the plants in the
check plot, the difference in yield must be attributed to other
factors.
Experiment 3:-This experimental plot was located in a por-
tion of a small field on black, sandy loam which was relatively
low and ordinarily wet land. Considerable difficulty was ex-
perienced in obtaining a good stand of plants because of the ex-
cessive moisture at planting time. The disease appeared late
in this field which was abandoned early on account of growth of
weeds. The disease probably had very little effect on yield be-
cause of its late occurrence.







48 Florida Agricultural Experiment Station

TABLE XXIX.-EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 3-1930.
Plot Fungicides I Cost
STotal No. Yield
No. Size Kind .Amt. Mat'l Labor Appl. Hampers

75 1/5 A copper stearate 14 lbs. $ 2.10 $.80 5 19.5
76 1/5 A cop. carbonate 21.5 lbs. 3.22 .80 5 16.7
77 1/5 A check 21.7
78 1/5 A 2-4-50 bordeaux 39 gal. .39 .78 .5 25.5
79 1/5 A sulfur 21.7 lbs. .65 .80 5 28.1
80 1/5 A copper-lime 21 lbs. 1.68 .80 5 34.2

Results calculated on basis of one acre.

80 1 A copper-lime 105 lbs. $ 8.40 $4.00 5 171.2
79 1 A sulfur 108.7 lbs. 3.25 4.00 5 140.4
78 1 A 2-4-50 bordeaux 195 gal. 1.95 3.90 5 127.5
77 1A check 108.7
75 1A copper stearate 70 lbs. 10.50 4.00 5 97.5
76 1A cop. carbonate 107.5 lbs. 16.10 4.00 5 83.7


These data show very little other than that sulfur and pos-
sibly bordeaux did not show detrimental effects on production.
The copper stearate and copper-lime plots remained green longer
than the others, although the yield from the former plot was
less than the check.

TABLE XXX. EFFECT OF SPRAYING AND DUSTING CUCUMBERS FOR THE
CONTROL OF DOWNY MILDEW% AS DETERMINED BY THE INCREASE IN YIELD.
EXPERIMENT 4.-1930.
Plot Fungicide I Cost
STotal No. Yield
No. Size Kind Amt. Mat'I Labor Appl. Hampers

62 1/5 A copper-lime 22 Ibs. $ 1.76 $ .80 5 14
63 1/5 A sulfur 22.5 lbs. .67 .80 5 8.5
64 1/5 A check 9.5
65 1/5 A copper stearate 15.5 lbs. 2.32 .80 5 13
66 1/5 A 2-4-50 bordeaux 35 gal. .35 .70 5 9
67 1/5 A cop. carbonate 21 lbs. 3.15 .80 5 13.5

Results calculated on basis of one acre.

62 1 A copper-lime 110 lbs. $ 8.80 $4.00 5 70
67 1 A cop. carbonate 105 lbs. 15.75 -1.0 .5 67.5
65 1 A copper stearate 77.5 lbs. 11.60 4.00 5 65
64 1 A check 49.5
61 1 A 2-4-50 bordeaux 175 gal. 1.75 3.50 5 45
63 1A sulfur 112.5 lbs. 3.35 4.00 5 42.5







Bulletin 230, Spraying and Dusting Cucumbers 49

Experiment 4:-This experiment was located on a relatively
level piece of low unirrigated, sandy-loam soil. The early plant-
ing was injured by frost but the second planting developed quite
uniformly. As previously stated, the first application of fungi-
cide was made when the plants were in the 2-3 leaf stage. The
disease appeared on the check rows about the time picking was
begun and spread rapidly. By the end of the season they were
entirely dead and the other plants in the field were more or less
spotted regardless of the fungicidal applications.
The plots treated with copper fungicides, except bordeaux
mixture, produced better than the check plot and they showed
relatively less of the disease. The sulfur plot was not as good
as the check plot in yield or in general appearance. This dif-
ference in yield does not indicate the great difference in the con-
dition of the leaves and vines that was apparent. The plants in
the plot sprayed with bordeaux showed the best green color of
any plants of the various plots, although the yield was much
lower than the check plot. In comparison the plants in the
check plot at this time were almost completely dead.
Summary for Season 1930: -Because of the variation in the
results obtained from the different plots the data have been
summarized in Table XXXI. The results from the four ex-
periments have been averaged in a short table where the in-
formation obtained with different treatments can be easily com-
pared, since all the averages are calculated on a one-acre basis.
TABLE XXXI.-SUMMARY AND CONSOLIDATION OF THE DATA OBTAINED IN
EXPERIMENTS CONDUCTED DURING THE SEASON OF 1930 IN RELATION TO
THE CONTROL OF THE DOWNY MILDEW OF CUCUMBERS.
Plot I Fungicide _Cost
I I I Total 1 Yield
Mat'l Labor Hampers^ .e
Repl. I Size I Kind IAmt. Mat'1 Labor Hampers
6 1A copper stearate 108 lbs. $16.20 $4.53 301.8
5 1 A copper-lime 170 lbs. 13.60 4.53 255.5
5 1A 2-4-50 bordeaux 249 gal. 2.49 4.98 227.1
5 1 A cop. carbonate 166.7 lbs. 25.00 4.53 207.8
5 1 A sulfur 154.6 lbs. 4.63 4.53 I 184.8
4 1 A checkI 158.4


It may be observed from the above table that the plots dusted
with copper stearate dust produced the most fruit, which is taken
as direct evidence of the best control of the disease. The other
fungicides are arranged in descending order according to yield.
Sulfur appears to produce a general detrimental effect to cu-






50 Florida Agricultural Experiment Station

cumber plants in spite of slight fungicidal value. This con-
dition was very consistent throughout the season and especially
where downy mildew was present. In the above table the com-
parative yields show that the plots dusted with sulfur averaged
only slightly more fruit than the check plots to which no fungi-
cide was applied.
The yields of all plots this year were below the average, except
the irrigated fields, because of the lack of rain during picking
season. The costs of material and labor appear to be insignifi-
cant at first sight. However, certain of the fungicides cost so
much that the added increase in yield does not cover the cost of
the fungicide. This is especially true with copper carbonate
in which the increase in yield cost 60 cents per hamper. Copper
stearate costs as much per pound as copper carbonate but it is
a much lighter dust and less is required per application. The
increased yield resulting from its use cost 161/ cents per hamp-
er. Copper-lime dust costs less than half as much as copper
stearate or copper carbonate per pound and showed a high yield
among the fungicides used during the season, the cost per
hamper for the increased yield being 181/2 cents. Thus, con-
sidering both cost and control, it gave the best control of downy
mildew.
DISCUSSION AND SUMMARY
During the period from 1925 to 1930 inclusive, downy mildew
was an important factor in the production of cucumbers in the
vicinity of Gainesville, Florida. The first applications of the
fungicides were usually made during the first half of April. At
the time of the first application the plants were usually small,
generally showing only two or three true leaves. The application
of the fungicides was delayed during one of the seasons, until
the plants showed their first blossoms and it was found that
the treated plots showed almost as much disease as the check
plots with little or no increase in yield and with additional ex-
pense of the fungicides and their application. The indications
are that the first applications of the fungicides should be made
as soon as the first true leaves develop and should be frequent
enough thereafter to keep the plant well covered. A series of
experiments were conducted in which the number of applications
was varied, the single applications being made early. The data
show that in general the greater the number of applications of
the fungicide the better the yield.
In all experimental plots during the six years the disease ap-






Bulletin 230, Spraying and Dusting Cucumbers 51

peared in the check plots first and gradually spread to the others.
Only under conditions favorable for the development of the
fungus was it difficult to obtain a satisfactory commercial con-
trol of the disease.
The disease may appear in cucumber fields at any time after
true leaves have developed, averaging usually three to four weeks
later, however. During the extremely early season of 1929 in
which the plants were at least two weeks ahead of the average
seasons, the disease first appeared March 30, approximately a
month earlier than it appeared during the late season of 1927.
The appearance of the disease has occurred usually during the
first half of April, at which time the first applications of fungi-
cides were made. The disease appears first on the oldest, fur-
thest developed plants and, if the plants in a field are all the
same age, the disease most often appears first on the most vig-
orous growing plants. In certain fields during different seasons
these thrifty plants may be in wet or dry places or on the south-
ern exposure of hills or in places protected on the north by
woods. There has been no consistency in the first appearance of
the disease in a definite place or field year after year.
There are other factors of importance that should be men-
tioned in relation to the successful growing of cucumbers, such
as crop competition with other cucumber-growing sections and
the direct effect of a fluctuating market. Indirectly, these agen-
cies are more or less connected and have a direct bearing on total
production in this section because the fruits are not picked
when they cannot be sold profitably. During ordinary seasons,
when only the disease is a factor in production, the picking sea-
son continues for about a month. When crop competition and
market prices are to be considered, the picking season may be
limited to a week or 10 days. Late killing frosts are probably
more responsible for crop competition that affects this section
than any other single factor or condition.
The experiments concerning the possible control of the dis-
ease have been conducted over a period of six years during which
time a number of fungicides have been used. Some of the fungi-
cides were discontinued after a season or more because they
proved to be no better than the more common ones and their
use by the growers was considered impractical since they were
too expensive and the advantage negligible or that they were
detrimental to the development of the plant that was not affected
by the disease.






52 Florida Agricultural Experiment Station

The seasons vary considerably in relation to earliness, grow-
ing conditions, appearance and prevalence of the disease, com-
petition and market prices, length of season, and total yield.
These factors have been taken into consideration wherever pos-
sible and the data collected and herein summarized have been
accumulated under these conditions. Table XXXII shows a
summary of the final tables of each of the six seasons, all of
which have been computed on an acre basis for comparison.
The table contains the number of replications over the entire
period, also the kinds of fungicides used, with average amounts
and costs and the average yields in hampers.
TABLE XXXII.-SUMMARY OF THE DATA OBTAINED IN EXPERIMENTS CON-
DUCTED DURING THE SUCCESSIVE SEASONS FROM 1925-1930 INCLUSIVE IN
RELATION TO THE CONTROL OF DOWNY MILDEW OF CUCUMBERS.
Plot Fungicide Cost
Total Yield
Repl. Size Kind Amt. Mat'l Labor Hampers
15 1 A copper stearate 94 lbs. $14.86 $4.28 303.2
45 1 A 2-4-50 bordeaux 223.1 gal. 2.14 4.29 297
45 1 A copper-lime 176.8 lbs. 15.36 3.27 294.7
47 1A check 258
14 1 A cop. carbonate 173.6 lbs. 27.69 4.38 247.2
16 1 A sulfur 206.5 lbs. 6.38 3.71 206.3


The yield of the different plots in each experiment was taken
as a unit of measure of the effectiveness of the fungicides in the
control of the disease, the premise being that the more preva-
lent and severe the disease the more the yield is reduced. The
most effective fungicide was copper stearate dust. The cost per
hamper of the increased yield resulting from the use of copper
stearate was 42 cents. Bordeaux mixture, 2-4-50, prepared
with hydrated lime, gave almost as good control as copper stear-
ate at a cost per hamper of 161/2 cents for the increased yield.
The data in this table are the average of 45 replications over the
six-year period. It was found that hydrated lime used in place
of rock lime in the preparation of bordeaux mixture gave as good
results and was cheaper, more available, and easier to handle
and store. Calcium caseinate was used in the sprays for cucum-
bers one season but was discontinued because no advantage was
discovered. In comparison with the check plots, of which there
were 47 replications during the period, the data show that the
plots sprayed with bordeaux produced 14 percent more fruit.
The plots treated with copper-lime dust ranked second in yield,






Bulletin 230, Spraying and Dusting Cucumbers 53

averaging 13 percent more fruit than the check plots. It may
also be seen that the yield of plots sprayed with bordeaux was
only 1 percent greater than that from plots treated with copper-
lime dust, when the average of the same number of replications
is considered.
It should be noted that the average cost of material and labor
for the applications of copper-lime dust amounted to $18.63 per
acre, or 502/3 cents per hamper for the increase in yield, while
the added cost of the bordeaux spray was only $6.43 per acre or
161/2 cents per hamper for the increased yield. Thus, both bor-
deaux spray and copper-lime dust proved to be profitable when
the increased yield is considered with added costs. The other
fungicides listed in the table were not profitable and do not
warrant further discussion.

CONCLUSIONS

1. The first applications of fungicides to cucumber plants
should be made as soon as the true leaves appear.
2. Five applications of fungicide controlled downy mildew bet-
ter than fewer applications.
3. The disease usually appeared first on the oldest and most
developed plants.
4. Hydrated lime proved to be a good substitute for rock lime
in preparing bordeaux mixture; the amount used was increased
one-half by weight.
5. Calcium caseinate, a commercial form of which is sold as
Kayso, did not prove beneficial in bordeaux mixture applied to
cucumber plants.
6. Cucumber plants sprayed with bordeaux mixture produced
14 percent more fruit during the picking season over a six-year
period than non-sprayed plants.
7. Cucumber plants dusted with copper-lime dust produced 13
percent more fruit during the picking season over a six-year
period than non-dusted plants.
8. Sulfur in various forms used was detrimental to the de-
velopment of cucumber plants.
9. Bordeaux mixture (2-4-50) was the cheapest and, except
for copper carbonate and copper stearate, most beneficial of the
fungicides used.






54 Florida Agricultural Experiment Station

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Bulletin 230, Spraying and Dusting Cucumbers 57

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