Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Spraying experiments for the control of certain grape diseases
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00026452/00001
 Material Information
Title: Spraying experiments for the control of certain grape diseases
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 15 p. : ; 23 cm.
Language: English
Creator: Loucks, Kenneth W ( Kenneth Wilfred )
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1936
Copyright Date: 1936
 Subjects
Subject: Grapes -- Diseases and pests -- Control -- Florida   ( lcsh )
Spraying and dusting in agriculture -- Florida   ( lcsh )
Black rot -- Control   ( lcsh )
Bitter-rot -- Control   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Kenneth W. Loucks.
 Record Information
Bibliographic ID: UF00026452
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 - AEN4990
oclc - 18212309
alephbibnum - 000924372

Full Text





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 294 April, 1936


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA
WILMON NEWELL, Director





SPRAYING EXPERIMENTS

FOR THE CONTROL OF

CERTAIN GRAPE DISEASES

By KENNETH W. LOUCKS


















Fig. 1.-Aerial view of experimental vineyard showing contrast in
amount of defoliation on sprayed and non-sprayed plots. The light colored
areas which appear as roadways are the unsprayed or check plots. (Photo-
graphed Sept. 1, 1933.)



Bulletins will be sent free to Florida residents upon application to
AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA










EXECUTIVE STAFF BOARD OF CONTROL
John J. Tigert, M.A., LL.D., President of Geo. H. Baldwin, Chairman, Jacksonville
the University Oliver J. Semmes, Pensacola
Wilmon Newell, D.Sc., Director Harry C. Duncan, Tavares
H. Harold Hume, M.S., Asst. Dir., Research Thomas W. Bryant. Lakeland
Harold Mowry, M.S.A., Asst. Dir., Adm. J. T. Diamond, Secretary, Tallahassee
J. Francis Cooper, M.S.A., Editor
Jefferson Thomas, Assistant Editor
Clyde Beale, A.B.J., Assistant Editor BRANCH STATIONS
Ida Keeling Cresap, Librarian'
Ruby Newhall, Administrative Manager NORTH FLORIDA STATION, QUINCY
K. H. Graham, Business Manager L. 0. Gratz, Ph.D., Plant Pathologist in
Rachel McQuarrie, Accountant Charge
R. R. Kincaid, Ph.D., Asso. Plant Pathologist
MAIN STATION, GAINESVILLE J. D. Warner, M.S., Agronomist
Jesse Reeves, Farm Superintendent
AGRONOMY CITRUS STATION, LAKE ALFRED
W. E. Stokes, M.S., Agronomist** A. F. Camp, Ph.D., Horticulturist in Charge
"W. A. Leukel, Ph.D., Agronomist John H. Jefferies, Superintendent
GF Ritchey, M.S.A., Associate W. A. Kuntz, A.M., Assoc. Plant Pathologist
Fred CHull, Ph.D., Associate B. R. Fudge, Ph.D., Associate Chemist
"J. A. Caver, Ph.D., Associate W. L. Thompson, B.S., Asst. Entomologist
John P. Camp, M.S., Assistant
ANIMAL HUSBANDRY EVERGLADES STATION, BELLE GLADE
A. L. Sheay, D ., A l H* A. Daane, Ph.D., Agronomist in Charge
A. L. Shealy, D.V.M., Animal Husbandman** R. N. Lobdell, M.S., Entomologist
R. B. Becker, Ph.D., Dairy Husbandman F. D. Stevens, B.S., Sugarcane Agronomist
W. M. Neal, Ph.D., Asso. in An. Nutrition Thomas Bregger, Ph.D., Sugarcane Physiologist
D. A. Sanders, D.V.M., Veterinarian G. R. Townsend, Ph.D., Assistant Plant
M. W. Emmel, D.VM, .M Veterinarian Pathologist
N. R. Mehrhof, M.Agr., Poultry Husbandman J. R. Neller, Ph.D., Biochemist
W. W. Henley, B.S.A., Asst. An. Husb.* R. W. Kidder, BS., Assistant Animal
W. Kirk, Ph.D., Asst. An. Husbandman Husbandman
R. M. Crown, M.S.A., Asst. An. Husbandman Ross E. Robertson, B:S., Assistant Chemist
P. T. Dix Arnold, B.S.A., Assistant Dairy B. S. Clayton, B.S.C.E., Drainage Engineer*
Husbandman
L. L. Rusoff, M.S., Laboratory Assistant SUB-TROPICAL STATION, HOMESTEAD
Jeanette Shaw, M.S., Laboratory Technician
Jeanette Shaw, M.S., Laboratory Technician H. S. Wolfe, Ph.D., Horticulturist in Charge
CHEMISTRY AND SOILS W. M. Fifield, M.S., Asst. Horticulturist
R W. Rpre Ph.D., Cmis** Geo. D. Ruehle, Ph.D., Associate Plant
R. W. Ruprecht, Ph.D., Chemist** Pathologist
R..M. Barnette, Ph.D., Chemist
C. E. Bell, Ph.D., Associate W. CENTRAL FLA. STA., BROOKSVILLE
R. B. French, Ph.D., Associate
H. W. Winsor, B.S.A., Assistant W. F. Ward, M.S.A., Asst. An. Husbandman
in Charge*
ECONOMICS, AGRICULTURAL
C. V. Noble, Ph.D., Agricultural Economist** FIELD STATIONS
Bruce McKinley, A.B., B.S.A., Associate
Zach Savage, M.S.A., Associate Leesburg
A. H. Spurlock, M.S.A., Assistant Leesbnr.
SH Spurlock, M.S.A., AssistanM. N. Walker, Ph.D., Plant Pathologist in
ECONOMICS, HOME Charge
O a D s Ab Ph.D., S t** W. B. Shippy, Ph.D., Asso. Plant Pathologist
Ouida Davis Abbott, Ph.D., Specialist* K. W. Loucks, M.S., Asst. Plant Pathologist
C. F. Ahmann, Ph.D., Physiologist J. W. Wilson, Ph.D., Associate Entomologist
ENTOMOLOGY Plant City
J. R. Watson, A.M., Entomologist** A. N. Brooks, Ph.D., Plant Pathologist
A, N. Tissot, Ph.D., Associate Cocoa
H. E. Bratley, M.S.A., Assistant A. S. Rhoads, Ph.D., Plant Pathologist
HORTICULTURE Hastings
A. F. Camp, Ph.D., Horticulturist** A. H. Eddins, Ph.D., Plant Pathologist
G. H. Blackmon, M.S.A., Horticulturist and Monticello
Associate Head of Department G. B. Fairchild, M.S., Asst. Entomologist***
A. L. Stahl, Ph.D., Associate
F. S. Jamison, Ph.D., Truck Horticulturist Bradenton
R. J. Wilmot, M.S.A., Specialist, Fumigation David G. Kelbert, Asst. Plant Pathologist
Research C. C. Goff, M.S., Assistant Entomologist
R. D. Dickey, B.S.A., Assistant Horticulturist Sanford
PLANT PATHOLOGY E. R. Purvis, Ph.D., Assistant Chemist,
W. B. Tisdale, Ph.D., Plant Pathologist** Celery Investigations
George F. Weber, Ph.D., Plant Pathologist Lakeland
R. K. Voorhees, M.S., Assistant*** E. S. Ellison, Ph.D., Meteorologist*
Erdman West, M.S., Mycologist B. H. Moore, A.B., Asst. Meteorologist*
Lillian E. Arnold, M.S., Assistant Botanist W. 0. Johnson, B.A., Asst. Meteorologist*
Stacy O. Hawkins, M.A., Assistant Plant R. T. Sherouse, Asst. Meteorologist*
Pathologist M. L. Blanc, Asst. Meteorologist*
SPECTROGRAPHIC LABORATORY
SPECTROGRAPHIC LABORATORY In cooperation with U.S.D.A.
L. W. Gaddum, Ph.D., Biochemist ** Head of Department.
L. H. Rogers, M.A., Spectroscopic Analyst *** On leave.










SPRAYING EXPERIMENTS FOR THE CONTROL OF
CERTAIN GRAPE DISEASES

By KENNETH W. LOUCKS

CONTENTS
Page Page
Methods and Materials............................... 4 Experiments of 1934.................................... .. 11
Experiments of 1932................................. 6 Carry-over Effects of Spraying.................. 14
Experiments of 1933.. ... .......... ...... .. 9 Discussion and Conclusions................. 15

The most prevalent fruit diseases of grapes encountered in
Florida are decays known as black rot, Guignardia bidwellii
(Ell.) V. & R., bitter rot, Melanconium fuligineum (Scrib. &
Viala) Cav., and ripe rot, Glomerella cingulata (Atk.) Spauld.
& von Schrenk. Anthracnose, Sphaceloma ampelinum DeBy.,
also is common on certain varieties but is rarely conspicuous
on the Beacon, the variety most widely grown in Florida. Al-
though some of the diseases also attack the blossoms, foliage
and young shoots, their presence on these parts is not so con-
spicuous and usually not so destructive as on the fruits. These
diseases occur every year and it has been observed that when
the season was characterized by frequent rains, the entire crop
of fruit in some vineyards was lost through decay. In vineyards
where the destruction of fruits was not so complete, the loss
was relatively high because only a small percentage of decayed
berries in the bunches was sufficient to place them in an in-
ferior grade and, if sold at all, they commanded a greatly
decreased price. Most growers have recognized the importance
of these diseases and have made attempts to control them. How-
ever, since many are unfamiliar with the different diseases and
the time when initial infection occurs, they have not obtained
any marked degree of success in controlling them. In their
attempts to control the rots, growers have used several different
materials according to different schedules with variable and
inconsistent results.
For the purpose of obtaining more definite information on
the kinds of materials to use and a schedule of applications,
spraying experiments were started in 1932. In these experi-
ments, effort has been directed toward a determination of the
minimum number of applications and the proper time to apply
them to obtain best control of the diseases.







4 Florida Agricultural Experiment Station

MATERIALS AND METHODS
Since bordeaux mixture is the material most commonly used
for the control of grape diseases in other sections of the United
States, it was used as a standard for comparison in these tests.
Inasmuch as it was necessary to conduct the experiments co-
operatively with growers, they could not be sufficiently exten-
sive to include a great variety of materials. In the beginning,
therefore, only bordeaux and three other materials were tested,
these being the ones used by some of the growers in the locality
where the experiments were conducted. They were copper
resinate suspended in soluble pine oil, a locally prepared mixture
(the composition of which was not revealed), and copper acetate.
Ten percent copper resinate was suspended in the pine oil and
four parts of this suspension were added to 100 parts of water.
Three spray schedules with bordeaux were employed to de-
termine the minimum number of applications necessary and
which of the applications were most essential to control the
diseases. In these schedules bordeaux was used with and with-
out spreaders. One schedule (A), which gave practically
complete coverage of vines and fruits throughout the entire
season, was used as a basis for comparison, and the other sched-
ules (B and C) omitted certain applications during the blooming
and fruit-setting periods. Copper acetate was used in a similar
manner, except that gelatin was used as a spreader instead of
tung oil emulsion. The proprietary material and copper resinate
were used in concentrations and according to schedules recom-
mended by the manufacturers.
The tung oil emulsion used in these tests was prepared with
the following materials and proportions: tung oil, 375 cc; oleic
acid, 50 cc; triethanolamine, 10 cc; and water, 370 cc. The
resulting mixture will amount to somewhat less than a quart.
The oleic acid, triethanolamine and 128 cc. of the oil were thor-
oughly mixed and then 150 cc. water was added slowly with
vigorous and constant stirring. By this procedure a thick
smooth emulsion was obtained. The remainder of the oil was
then added while stirring, followed by the water. Stirring was
discontinued as soon as the last of the water was evenly dis-
persed. The resulting emulsion is of the oil-in-water type, and
is a stable, creamy product which can be easily diluted further
with water. This emulsion was used at the rate of two quarts
to 100 gallons of spray solution.
Copper acetate was used in the concentration of two pounds








Spraying Experiments for Control of Grape Diseases 5

to 50 gallons water. The calcium caseinate was used in all in-
stances at the rate of two pounds to 100 gallons spray solution.
Gelatin was used at the rate of two ounces to 50 gallons spray
solution.
The vineyard procured for cooperative spraying was reported
to have suffered practically 100 percent loss of fruit from rots
during the seasons of 1930 and 1931. It was a square area con-
taining four acres, bounded on three sides by lakes. The ground
sloped gently from a point on the fourth side in three directions
toward the three lakes. The vines were five-year-old Beacons
on their own roots, and were as strong and vigorous as is usual
for vines of that age in that locality. For the purpose of these
experiments the vineyard was divided into plots in such manner
that each sprayed plot was large enough for 30 vines and adjoin-
ing each of these were check plots containing space for six
vines. Because of skips in the planting the actual number of
vines was not the same in all plots and this is so indicated in
the records. This was not an ideal arrangement but was the
best that could be obtained in a cooperative vineyard. All spray
treatments were run in duplicate the first year and subsequently
in triplicate or quadruplicate.
For the spray schedules which were intended to cover the
vines as completely as was practical, it was necessary to make
applications at intervals ranging from about one to three weeks,
the frequency depending upon the rate of growth of the vines.
During the first month or six weeks, when growth was rapid
and the fruit was setting, applications were required every six
to 10 days. Later in the season when growth was slower, a
maximum of three weeks elapsed between applications.
After the vines were pruned and while still dormant, they
were sprayed with a 4 percent copper sulfate solution to which
calcium caseinate was added as a sticker at the rate of two
pounds per 100 gallons. From the time growth started until
the fruit had reached nearly full size, or about a month before
the fruit would normally ripen, 4-4-50 bordeaux with and with-
out stickers was applied on certain plots and the other materials
indicated were used on the other plots. After this date and
until the fruit was harvested, a stainless spray of copper acetate
and gelatin was used on all plots.
The spray materials were applied under pressure of 175 to
200 pounds from a two-hose power spray outfit. One nozzle was
used on each hose and was manipulated by hand. The operators
walked through the vineyard and endeavored to apply spray








6 Florida Agricultural Experiment Station.

to all parts of the vines, especially covering the under side, of
the foliage and the interior of the fruit clusters.

EXPERIMENTS OF 1932

During the season of 1932 the following spray materials and
stickers in the combinations indicated were tested:
4-4-50 bordeaux alone
4-4-50 bordeaux + tung oil emulsion
4-4-50 bordeaux + calcium caseinate
Copper acetate alone
Copper acetate + calcium caseinate
Copper acetate + gelatin
Copper resinate
A proprietary mixture

The season of 1932 was not especially favorable for grapes.
The preceding fall and winter had been very dry and warm.
The vines had suffered from a long drought and did not become
completely dormant during the winter. Growth which started
in the spring of 1932 was very sparse and weak, and most of
it was killed by a frost about the middle of March. After that
time the vines were repruned in an effort to stimulate more
uniform growth. Some growers also repruned their vines and
obtained much better crops than those who did not reprune.
Only light rains fell during the remainder of the season and
the grape crop was estimated to have been only about 30 percent
normal. The dates on which the spray materials were applied
and the stage of growth on these dates are shown in Table 1.
TABLE 1.-SPRAY SCHEDULES USED IN 1932.
Date
of Stage of growth of Spray Schedules
ApplicationI appli- vines and fruit
_cation A B I C ID E F
1 Feb. 2 Dormant....... Dr ....- ----. * * *
2 Apr. 1...... New sprouts 2-6 in. long.... *
3 May 231... Flower buds separating........ *
4 June 1......I Bloom opening .......... *
5 June 7.... Full bloom .........................--- *
6 June 15.. Fruit set ...---.... --------- *
7 June 26... Fruit % full size........... *
8 July 7. Fruit full size...........--....-- *
1 On May 6 all of the current season's growth was removed to stimulate
a more uniform growth of the vines.

Because of the light crop, results obtained in the control of
diseases of the leaves appear more reliable than those recorded
for the fruit. However, the trend appears very definite. The
results are shown in terms of percentages of disease that were







Spraying Experiments for Control of Grape Diseases 7

controlled, which were obtained by determining the percentages
of diseased leaves and fruits in the sprayed plots-and adjacent
non-sprayed plots and dividing the difference between the two
by the percentage of diseases occurring in the non-sprayed plot.
Careful inspections were made of all plots from April 19 to
July 19 and all diseased fruits and leaves were removed and
counted at frequent intervals. During the early part of the
season diseased leaves and fruit were recorded, but when black
rot became prevalent on the fruit, only the infected fruits were
recorded. Because of the light crop the decayed fruits resulting
from all diseases were grouped together. However, observations
were made on the first and last appearances of each kind of rot.
As the season progressed, black rot ceased to develop and ripe
and bitter rots began to appear. It is possible that the removal
of the black rot-infected fruit from the vines may have re-
duced the total percentage of infection to some extent but
inoculation experiments made during 1934 and 1935 showed
that most black rot infection occurs during the period in which
the vines are blooming and setting fruit. In commercial vine-
yards where the diseased fruits were not removed, mummied
black rot fruit remained on the bunches throughout the sea-
son. For convenience in compiling the data in these tables
the number of berries is recorded in terms of their weight, as
calculated on the basis of the weight of ripe berries for that
current season. The spray materials used, schedules of applica-
tions and results obtained for 1932 are given in Table 2.
Results given in Table 2 show that bordeaux and copper acetate
were the most effective materials used for controlling grape
diseases in 1932 and were most effective when used according
to schedule A, the complete spray schedule (see Table 1). The
combination of copper acetate and calcium caseinate was very
ineffective but the cause of this was not apparent. The proprie-
tary mixture and copper resinate produced only slight control,
although this may have been due to the limited number of
applications.
Because of the comparatively high cost of copper acetate and
its lack of any special efficiency over bordeaux in disease con-
trol, no further tests were made with it alone. Because of its
non-staining properties, however, it was used each year in all
spray schedules for the last one or two applications. The
proprietary mixture was not used in any succeeding tests be-
cause nothing could be learned of its composition, and the copper
resinate soluble pine oil was omitted because of difficulty ex-










8 Florida Agricultural Experiment Station


TABLE 2.-COMPARATIVE EFFICIENCY OF CERTAIN FUNGICIDES AND SCHED-
ULES OF APPLICATION UPON THE CONTROL OF DISEASES OF GRAPES IN 1932.



Spray Materials 4| .



Bordeaux alone....................................................... A 7 96 8 98
Check ..... .... I ........ ....................................................... 170 187
Bordeaux alone........................................................... B 30 14 16.2 82
Check ............................................................................. 35 89
Bordeaux alone........................................................... 106 none 27.8 77
Check ............................................................................. 70 125
Bordeaux + tung oil.................................... .... A 15 68 24 41
Check .................................... .. .... ................................. 40 41
Bordeaux + tung oil.............................................. B 16 68 82.8 68
Check ............................................................................. 50 90
Bordeaux + tung oil.............................................. C 82 78 45 43
Check .................................... I .... .............................. 14 79
Bordeaux + calcium caseinate............................ A 2.5 99 7.6 97
Check .............................................................................. 190 258
Bordeaux + calcium caseinate............................ B 280 none 64.2 54
Check ........................................... ......... ............................ 75 188
Bordeaux + calcium caseinate....................... C 580 none 112.6 none
Check ......... ............................. 40 49
Copper acetate alone............................................. A 43 78 41.4 84
Check ............................................................................ 195 264
Copper acetate alone............................................... B 52 78 52.6 72
Check ..................................................... .............. 240 201
Copper acetate alone........................................ C 38 31 81.4 8
Check .......................... ....... ....... ......... 55 88
Copper acetate + gelatin...................................... A 15 57 2.4 98
Check .............................................................................. 35 125
Copper acetate + gelatin...................................... B 18 none 24.4 61
Check ............................................................... .... 15 62
Copper acetate + gelatin........................................ C 31 none 64 22
Check .............................................................................. 25 82
Copper acetate + calcium easeinate................ A 71 49 74.2 none
Check ............................................... ..................... .. 140 48
Copper acetate + calcium caseinate................... B 44 48 116.8 29
Check ................................ ....... .............. 85 164
Copper acetate + calcium caseinate............... C 58 80 147.8 16
Check .................... .......... ........ 75 176
Proprietary mixture ................................................ D 208 none 76.9 40
Check .................................. .............. 70 125
Proprietary mixture .................................................. E 58 60 62.7 20
Check ......................................................... ........... 145 79
Proprietary mixture ..... ..................................... F 374 none 11.7 75
Check ............................................ 40 49
Copper resinate + soluble pine oil.................... B 46 16 117.4 none
Check ......................................... ............................... 55 88
Copper resinate + soluble pine oil.................... C 41 none 84.5 none
Check ............................................................. .. 25 82
Copper resinate + soluble pine oil...................... G 56 25 189 none
Check ........................................ ..... ......... ................. 75 176
1Schedule G was the same as C except that 4 percent copper sulphate was used for the
dormant spray.








Spraying Experiments for Control of Grape Diseases 9

perienced in mixing. By omitting these materials from the
program, it was possible in the later trials to run most of the
treatments in triplicate and a few in quadruplicate.

EXPERIMENTS OF 1933
Experiments for 1933 and succeeding years were arranged
to determine whether or not certain wetting and sticking agents
improved the fungicidal properties of bordeaux and copper
acetate. For this purpose tung oil emulsion and calcium case-
inate were used with both of these fungicides and gelatin was
used with copper acetate only. Also, the schedules B and C
were changed so as to omit only one and two applications, respec-
tively. In other words, the plots which were sprayed according
to schedule A received all seven applications, those according to
schedule B received all except the third or early bloom applica-
tion, while schedule C omitted the early-bloom and full-bloom
sprays. The complete schedule is shown in Table 3.
TABLE 3.-THE SPRAY PROGRAM USED DURING THE SEASON OF 1933.
Spray
Appli- Date Schedules
cation Spray material applied Stage of growth A B C

1 4-50 copper sulfate. Mar. 9 Dormant ........................... *
2 4-4-50 bordeaux....... Mar.29 Blossom buds separating *
3 4-4-50 bordeaux........ Apr. 8 Bloom opening ................
4 4-4-50 bordeaux....... Apr. 18 Full bloom ................ *
5 4-4-50 bordeaux....... Apr. 28 Fruit set .............. *
6 4-4-50 bordeaux....... May 10 Fruit % grown .......... *
7 copper acetate.......... May 29 Fruit % grown ............... *


The season of 1933 was very favorable for the production of
grapes. A good crop was set and where careful spraying was
practiced, the harvest was good. During the harvest season
much rain fell and this increased the seriousness of late fruit
rots. Careful inspections were made in all plots at frequent
intervals from April 8 until the end of harvest on July 18. From
observations on the occurrence of the various fruit rots, it was
evident that two types of infection had to be considered. Black
rot was the first to make its appearance on the fruit and bitter
and ripe rots began to appear later in the season as the fruits
approached the ripening period. After the fruit had attained
about two-thirds size, no more black rot developed, but at that
time bitter rot and ripe rot became very prevalent.








10 Florida Agricultural Experiment Station

TABLE 4.-COMPARATIVE EFFICIENCY OF DIFFERENT SPRAY SCHEDULES WITH
BORDEAUX ON THE PRODUCTION OF MARKETABLE GRAPES IN 1933.



Spray Materials 0 0 a
0 01
g g " S p '"3 n s o* P
,_ Ql _l 1E
Bordeaux alone........................ A 3 32 400 435 147 2.9 2.7 93
Check ......................................... 8.5 11.5 35 55 17 3.2 2 64
Bordeaux alone.......................... B 8 21 324 348 87 4 3.7 93
Check....................................... 10 17 59 86 16 5.3 3.7 69
Bordeaux alone...................... C 8 40 152 200 107 1.9 1.4 76
Check......................................... 6 13 52 71 17 4.2 3 73
Bordeaux + tung oil.............. A 5 54 715 774 166 4.7 4.3 92
Check ........................................ 9 14 39 62 16 3.9 2.4 63
Bordeaux + tung oil.............. B 3 48 286 337 89 3.8 3.2 85
Check..................................... 11 24 74 109 18 6 4.1 68
Bordeaux + tung oil.............. C 15 50 228 293 113 2.6 2 78
Check....... .. ...... ................. 6 13 55 74 18 4.1 3 74
Bordeaux + cal. cas............ A 4 37 597 638 177 3.6 5.1 94
Check................. ..................... 13 23 56 92 17 5.4 3.3 61
Bordeaux + cal. cas............. B 4 52 340 396 87 4.6 3.9 86
Check........ ................... ......... 7 15 47 69 18 3.8 2.6 68
Bordeaux + cal. cas...... C 18 50 386 454 105 4.3 3.7 85
Check. ................................... 5 14 57 76 18 4.2. 3.2 75


These last two rots were so thoroughly mixed in the vineyard
that no attempt was made to record separately the extent of
infection caused by each. Therefore, because of the time of
their occurrence, the two kinds of rot have been considered
under the general designation of early and late rot. By so doing,
it was possible to calculate the amount of control obtained over
the two kinds of rot, as well as total disease control, as shown
in Table 4. The fruit set was considered as the total of the
diseased fruit and sound fruit occurring on the vines and its
weight was calculated on the basis of the weight of ripe fruit.
The data represent results from plots of the various sprays and
spray schedules. The sum of the results obtained from the
check plots was compared with those obtained from the sprayed
plots. From these results the average percentages of the early
and late rots in the corresponding plots were calculated, and the
actual percentage of the disease which was controlled by the
spray was calculated and is shown in Table 5.
Results shown in Tables 4 and 5 indicate that the stickers
were of no appreciable value in bordeaux mixture in controlling
either the early or the late rots and that in all instances efficiency
of the schedules ranked in the order A, B, and C. Field observa-








Spraying Experiments for Control of Grape Diseases 11

tions and inoculations made during the season indicate that
little or no black rot infection occurs after the fruits attain
appreciable size. On the other hand, bitter rot did not become
conspicuous until the fruit was approximately half normal size
and continued to develop until the end of harvest. The appear-
ance of bitter rot was preceded by rainfall and high relative
humidity, which persisted fairly consistently throughout the
remainder of the season. Ripe rot also appeared during this
period, but the percentage of decay caused by each disease was
not determined. As shown in Table 5, these diseases were less
effectively controlled than black rot.
TABLE 5.-COMPARATIVE EFFICIENCY OF DIFFERENT SPRAY SCHEDULES WITH
BORDEAUX IN THE CONTROL OF GRAPE ROTS IN 1933.
o ow 0, O w
Spray Materials B 2 t
0O c o rzc


Bordeaux alone --.................... A .09 7 7 99 68 81
Check ......................................... 15 22 37
Bordeaux alone ----------............--.. B 1 6 7 91 70 7
Check ........................-----. .......... 11 20 31
Bordeaux alone .......................------------ C 4 20 24 55 10 11
Check ..................................-- 9 18 27 1
Bordeaux + tung oil ................ A 06 7 7
Check ......................................... 14 23 37 1
Bordeaux + tung oil.....---......... B 1 14 15 90 36 53
Check .--------------......-......................-.... ------- 10 22 32 1
Bordeaux + tung oil-.......------- C 5 18 23 37 0 11
Check.---................... ------ 8 18 26
Bordeaux + cal. cas.---------------- A .5 7.5 8 97 70 80
Check ..........................-- ........--- ....... 14 25 39
Bordeaux + cal. cas................ B 1 13 14 90 41 56
Check .......................................... 10 22 32
Bordeaux + cal. cas.-----................ C 4 11 15 43 40 40
Check -------------........--................-- ...-- .. 7 18 25


EXPERIMENTS OF 1934

In the experiments for 1934, effort was made to duplicate
the experiments of 1933. Plots were laid out the same as for
the previous year but there were some differences in the number
of vines per plot because of re-arrangement of the plots. The








12 Florida Agricultural Experiment Station

same kinds of spray materials were used according to the three
schedules, but on account of different weather conditions and
consequent longer growing season, a greater total number of
applications was made. This program is shown in Table 6.
TABLE 6.-THE SPRAY PROGRAM USED DURING THE SEASON OF 1934.
Spray
Appli- Date Schedule
cation Spray materials applied Stage of growth

1 4-50 copper sulfate.. Mar. 16 Dormant ......................... *
2 4-4-50 bordeaux........ Apr. 6 Flower buds separate...... *
3 4-4-50 bordeaux........ Apr. 18 Early bloom ....................*
4 4-4-50 bordeaux........ Apr. 24 Full bloom ..................* *
5 4-4-50 bordeaux....... May 4 Fruit set ........................ *
6 4-4-50 bordeaux....... May 15 Fruit % size .................... *
7 4-4-50 bordeaux....... May 30 Fruit % size .................... *
8 copper acetate......... June 18 Fruit full size .... ...* *
9 copper acetate.......... July 2 Fruit full size .......... *


The early part of the 1934 growing season was characterized
by cool nights which retarded growth and flower development,
prolonging the growing season by several weeks. Careful in-
sp'ections were made at frequent intervals in all plots from April
24 to June 8 when the fruit was approximately two-thirds full
size. During this period black rot was the main disease present.
After that date and until June 24, it was found that the develop-
ment of black rot on the fruit decreased rapidly, but bitter rot
and ripe rot infection increased until July 10 when they were
the only diseases observed on the fruit. Results of these ex-
periments are shown in Table 7.
Because of the arrangement of the plots in these tests, it so
happened that the plots sprayed according to schedule B had
approximately twice as many check vines adjacent to them as
the other two schedules. There were also differences in the
numbers of vines occurring in the sprayed plots. However, re-
sults on the effectiveness of control were calculated in the same
manner as for the previous year.
An examination of the data in Tables 7 and 8 reveals that
during the season of 1934 there was again no advantage in the
addition of stickers and in all cases the efficiency of the sched-
ules was in descending order, A, B, and C.
The data also show that with all three schedules black rot
was controlled more effectively than bitter rot and ripe rot,
which occurred late in the season.









Spraying Experiments for Control of Grape Diseases 13

TABLE 7.-COMPARATIVE EFFICIENCY OF DIFFERENT SPRAY SCHEDULES WITH
BORDEAUX ON THE PRODUCTION OF MARKETABLE GRAPES IN 1934.



Spray Materials :. 0 0. 0g | 0 |s



Bordeaux alone.......................... A .75 6.25 1383 140 43 3.25 3 95
Check ....................................... 18 21.5 5 44.5 13 3.42 .4 11
Bordeaux alone ....................... B 8.75 64.8 778.75 852 90 9.46 8.61 91
Check ....................... ........ 41.5 74 6 121.5 34 3.57 .2 5
Bordeaux alone..............- C 10.25 51.5 479.25 541 54 10 9 88
Check....................................... 10 25.75 3.75 39.5 18 2.19 .2 10
Bordeaux + tung oil........... A 1.25 6 139175 147 34 4.32 4.11 95
Check....................... ......... 22.5 22.5 4.5 49.5 13 3.8 .35 8
Bordeaux + tung oil.............. B 8 70.5 586.5 665 86 7.73 6.82 88
Check ....... .... ........ 37.25 85 10.25 132.5 35 3.80 .29 8
Bordeaux + tung oil.............. C 16.5 74.5 499 590 53 11.1 9.4 85
Check .......... .. ... 12.75 37.5 5.75 56 18 3.1 .32 10
Bordeaux + cal. cas........ A 1 7.5 219.5 228 42 5.43 5.22 96
Check...................................... 32.5 32.5 1.75 66.75 14 4.77 .12 3
Bordeaux + cal. cas...... B 10.75 94.25 772 877 89 9.85 8.67 88
Check........ .. ...... ..... 48.5 70.5 5 124 33 3.75 .15 4
Bordeaux + cal. cas............... C 16.75 76.25 540 633 54 11.75 10 85
Check .................. ............ .... 16.5 32.25 2 50.75 16 3.17 .12 4


In all instances schedule B, in which the early bloom spray
was omitted, was less effective than schedule A, in which all
applications were used. Schedule C, in which both the early
bloom and full bloom sprays were omitted, was the least effective
of the three schedules. There appear no significant differences
between the efficiency of the stickers used with bordeaux, except
in the case of schedule C, from which the early bloom and full
bloom applications were omitted. In this schedule the calcium
caseinate seemed to be slightly better than the tung oil emulsion.
However, both of the stickers again showed evidence of decreas-
ing rather than increasing the efficiency of the bordeaux.
During this season the data which were taken on the occur-
rence of diseases in the check plots showed a direct correlation
between the percentage of black rot infection on the early foliage
and shoots before bloom and that on the fruit later in the season.
In other words, the plots which showed heaviest infection of
early leaves later showed heaviest infection of the fruit. This
emphasizes the importance of pre-bloom spraying to prevent the
early foliage from becoming a source of infection for the fruit.









14 Florida Agricultural Experiment Station

TABLE 8.-COMPARATIVE EFFICIENCY OF DIFFERENT SPRAY SCHEDULES WiTH
BORDEAUX UPON THE CONTROL OF ROTS IN GRAPES IN 1934.



Spray Material _3 '
'0 4)W g, 4 S 0- 4.-.
M 4)40 Ai )0 A 4 dHO iM0 W)

Bordeaux alone......- ........ A .4 4.3 4.7 9 9
Check .. --................ ........ ......... 52.3 40 92.3 90 95
Bordeaux alone............---- B 1 8 9
Check ........ ............. ...... 29.9 64 93.9 9
Bordeaux alone -.............. C 2.2 9.3 11.5 91 8 87
Check ................. .... .. ..... 24.4 66.7 91.1
Bordeaux + tung oil........- A 1.6 4.1 7 96 92 94
Check .....------.. .. ... 39.5 50.4 89.9
Bordeaux + tung oil---.......- B 1.3 11.2 12.5 95 83 85
Check ... ....... ...--. ...--. 26 65.9 91.9
Bordeaux + tung oil--........-. C 3.2 17.1 20.3 87 75 7
Check ............ ....... .....- 23.7 67.6 91.3 1
Bordeaux + cal. cas. ...... A .4 4.3 4.7 99 91 95
Check .................. ... 50.9 45.4 96.3 1
Bordeaux + cal. cas..--........... B 1.3 11.2 12.5 96 81
Check ..................36.2 57.8 94 96 81 87
Bordeaux + cal. cas ..... ... C 2.7 12.3 15 1
Check .............................. 28.7 65.8 94.5 91


CARRY-OVER EFFECTS OF SPRAYING

-As shown in the tables, no spraying was done after the fruit
was harvested until just before the end of the dormant season
the following spring. However, observations were made in the
experimental vineyard several times each summer and autumn
to check on the occurrence of foliage diseases. During this period
leaf blights and spots developed very rapidly, but the causes
were not. determined in all cases. The principal organisms as-
sociated with diseased leaves were Isariopsis clavispora (B. & C.)
Sacc., Alternaria sp. and Pestalozzia sp. These leaf diseases
developed most rapidly in the check plots, resulting in shedding
of the foliage several weeks in advance of that in the sprayed
plots (Fig. 1).
After having noted such conspicuous beneficial effects of
spraying on retention of foliage through the summer months,
certain plots were not sprayed the following year in order to








Spraying Experiments for Control of Grape Diseases 15

observe any differences which might be attributed to the effects
of spraying the previous year. For this purpose three plots in
which 99 percent of the early leaf diseases had been controlled
through spraying were compared with plots which were not
sprayed the previous year. The sprayed plots showed 56 percent
less early leaf infection and 15 percent less early fruit infection
than the non-sprayed plots. However, there was no significant
difference in the amount of late fruit infection on the two series
of plots. Thus, it appears that there is enough "carry-over"
of disease on the vines to initiate epidemics of diseases each
year and that it will be necessary to carry out a complete spray
program each year to hold the diseases in check.

DISCUSSION AND CONCLUSIONS

The principal object of these spraying experiments was to
determine a spray schedule that would enable the grape grower
to produce a crop of marketable fruit. Little attention was
given to the kinds of diseases that attack the canes and foliage.
However, during the course of the tests it was observed that
the sprayed vines retained the foliage much longer after the
fruit was harvested than did the non-sprayed ones. Further-
more, diseases appeared first the following year on the foliage
of vines which had not been sprayed the year before. By mid-
season, however, there was no apparent difference in the amount
of infection on non-sprayed and sprayed vines. The vines which
showed heaviest black rot infection on the early leaves also
showed heaviest black rot infection of fruit.
Results obtained from these experiments show that bordeaux
was most effective of the materials tested for the control of
grape rots. The addition of wetting and sticking agents did
not improve its effectiveness.
For best results it was necessary to apply spray during the
blooming and fruit setting period.
The total number of applications of spray that should be made
varies with seasonal conditions. When the rate of growth is
slow, resulting in a longer growing season, it is necessary to
make more applications than during a short growing season.
The main purpose should be to keep the foliage and fruit cov-
ered with the fungicide throughout the growing period.
Bitter and ripe rots are more difficult to control than black
rot. This is perhaps due to the more frequent rains during
the ripening period when bitter and ripe rots occur, making it








16 Florida Agricultural Experiment Station

more difficult to keep the fruits covered with a fungicide. It
is also possible that copper acetate is less effective against these
diseases than bordeaux. However, because of the residue left
by bordeaux it appears advisable to use a stainless spray as the
fruits approach the ripening stage. There is apparent need for
further experimentation to determine whether or not other stain-
less sprays are more effective than copper acetate in controlling
bitter and ripe rots.
Based upon results obtained from the three years' tests, the
following spray schedule is recommended for the control of
grape diseases in Florida:

SPRAY SCHEDULE RECOMMENDED FOR CONTROL OF
GRAPE DISEASES

Time of Application Purpose Materials to Use
'I. On dormant vines, as late Kill spores of fungi Copper sulfate, 4 lbs.
in the spring as possi- which cause diseases to 50 gal. water, with
ble before buds burst, on leaves, fruit and a good sticker.
vines.
II. One week to 10 days Prevent infection of 4-4-50 bordeaux with-
after buds burst, or leaves, also control out sticker. Add 1 to.
when the shoots are 8 leaf skeletonizers and 2 lbs. lead arsenate
to 18 inches. flea beetles. for chewing insects.
III. Bloom opening. Prevent infection of
leaves, blossoms and Same as above.
control insects listed
Above.
IV. Bloom open. Prevent infection of
leaves, f r u i t and Same as above.
control insects listed
above.
V. Fruit just set. Same as above. Same as above*.
VI. Fruit about % size. Same as above, also Same as above.
leaf folders.
VII. Fruit about full size. Same as above, also Copper acetate, 2 lbs.
sucking insects, such to 50 gal. water, with
as leaf hopper and 2 oz. gelatin as a
aphids. sticker. Add % pint
nicotine sulfate for
sucking insects.
VIII. Fruit full size. Same as above. Same as above, except
omit gelatin.
IX. As soon as fruit is Control Isariopsis 4-4-50 bordeaux with
harvested. and other leaf spots. sticker, arsenate if
needed for insects.
"** If chewing insects are numerous after the fruit is set when it is not
safe to use arsenate as a poison for them, pyrethrum and derris extracts
may be used effectively, especially against leaf skeletonizers.





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

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