• TABLE OF CONTENTS
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 Title Page
 Table of Contents
 Summary
 Introduction
 Preliminary experiments
 Experiments during 1933
 Experiments during 1934
 Applications of lime-sulfur for...
 Spray injury
 Seasons for spraying
 Acknowledgments and litterature...






Group Title: Bulletin - University of Florida Agricultural Experiment Station - 282
Title: Lime-sulfur sprays for the combined control of purple scale and rust mites
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00026715/00001
 Material Information
Title: Lime-sulfur sprays for the combined control of purple scale and rust mites
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Alternate Title: Lime sulfur sprays for the combined control of purple scale and rust mites
Physical Description: 38 p. : ; 23 cm.
Language: English
Creator: Thompson, W. L
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1935
 Subjects
Subject: Purple scale -- Control -- Florida   ( lcsh )
Plant mites -- Control -- Florida   ( lcsh )
Spraying and dusting in agriculture -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 38.
Statement of Responsibility: by W.L. Thompson.
General Note: Cover title.
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00026715
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: aleph - 000924357
oclc - 18213121
notis - AEN4975

Table of Contents
    Title Page
        Page 1
        Page 2
    Table of Contents
        Page 3
    Summary
        Page 4
    Introduction
        Page 5
    Preliminary experiments
        Page 5
        Page 6
        Page 7
    Experiments during 1933
        Page 8
        Purple scale control with rust mite control incidental
            Page 9
            Page 10
        Rust mite control with purple scale control incidental
            Page 11
            Page 12
            Page 13
            Page 14
            Page 15
        Melanose and purple scale experiment
            Page 16
    Experiments during 1934
        Page 17
        Melanose and purple scale experiment, Babson Park, Florida
            Page 17
            Page 18
        Scab and scale-insect experiment
            Page 19
            Page 20
            Page 21
            Page 22
            Page 23
            Page 24
        Purple scale and rust mite experiment, Lake Alfred, Florida, 1934
            Page 25
            Page 26
            Page 27
            Page 28
            Page 29
            Page 30
    Applications of lime-sulfur for purple scale and whitefly control
        Page 31
    Spray injury
        Page 32
        Page 33
        Page 34
        Page 35
    Seasons for spraying
        Page 36
        Page 37
    Acknowledgments and litterature cited
        Page 38
Full Text


Bulletin 282


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









LIME-SULFUR SPRAYS FOR THE

COMBINED CONTROL OF

PURPLE SCALE AND RUST MITES




By W. L. THOMPSON













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


July, 1935









EXECUTIVE STAFF

John J. Tigert, M.A., LL.D., President of the
University
Wilmon Newell, D.Sc., Director
H. Harold Hume, M.S., Asst. Dir., Research
Harold Mowry, M.S.A., Asst. Dir., Adm.
J. Francis Cooper, M.S.A., Editor
Jefferson Thomas, Assistant EJitor
Clyde Beale, A.B.J., Assistant Editor
Ida Keeling Cresap, Librarian
Ruby Newhall, Administrative Manager
K. H. Graham, Business Manager
Rachel McQuarrie, Accountant

MAIN STATION, GAINESVILLE
AGRONOMY
W. E. Stokes, M.S., Agronomist**
W. A. Leukel, Ph.D., Agronomist
G. E. Ritchey, M.S.A., Associate*
Fred H. Hull, Ph.D., Associate
W. A. Carver, Ph.D., Associate
John P. Camp, M.S., Assistant

ANIMAL HUSBANDRY
*A. L. Shealy, D.V.M., Animal Husbandman**
R. B. Becker, Ph.D., Dairy Husbandman
W. M. Neal, Ph.D., Asso. in An. Nutrition
D. A. Sanders, D.V.M., Veterinarian
M. W. Emmel, D.V.M., Asst. Veterinarian
N. R. Mehrhof, M.Agr., Poultry Husbandman
W. W. Henley, B.S.A., Asst. An. Husbandman
Bradford Knapp, Jr., M.S., Asst. An. Husb.
P. T. Dix Arnold, B.S.A., Assistant Dairy
Husbandman
L. L. Rusoff, M.S. Laboratory Assistant
Jeanette Shaw, M.S., Laboratory Technician

CHEMISTRY AND SOILS
R. W. Ruprecht, Ph.D., Chemist**
R. M. Barnette, Ph.D., Chemist
C. E. Bell, Ph.D., Associate
R. B. French, Ph.D., Associate
H. W. Winsor, B.S.A., Assistant

ECONOMICS, AGRICULTURAL
C. V. Noble, Ph.D., Agricultural Economist**
Bruce McKinley, A.B., B.S.A., Associate
Zach Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Assistant

ECONOMICS, HOME
Ouida Davis Abbott, Ph.D., Specialist**
L. W. Gaddum, Ph.D., Biochemist
C. F. Ahmann, Ph.D., Physiologist
L. H. Rogers, M.A., Spectroscopic Analyst

ENTOMOLOGY
J. R. Watson, A.M., Entomologist**
A. N. Tissot, Ph.D., Associate
H. E. Bratley, M.S.A., Assistant
J. W. Kea, B.S.A., Assistant

HORTICULTURE
A. F. Camp, Ph.D., Horticulturist**
G. H. Blackmon, M.S.A., Horticulturist
A. L. Stahl, Ph.D., Associate
F. S. Jamison, Ph.D., Truck Horticulturist
R. J. Wilmot, M.S.A., Specialist, Fumigation
Research
R. D. Dickey, B.S.A., Assistant Horticulturist

PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist**
George F. Weber, Ph.D., Plant Pathologist
R. K. Voorhees, M.S., Assistant
Erdman West, M.S., Mycologist
Lillian E. Arnold, M.S., Assistant Botanist


BOARD OF CONTROL
Geo. H. Baldwin, Chairman, Jacksonville
A. H. Blanding, Bartow
A. H. Wagg, West Palm Beach
Oliver J. Semmes, Pensacola
Harry C. Duncan, Tavares
J. T. Diamond, Secretary, Tallahassee

BRANCH STATIONS
NORTH FLORIDA STATION, QUINCY
L. O. Gratz, Ph.D., Plant Pathologist in
Charge
R. R. Kincaid, Ph.D., Asso. Plant Pathologist
J. D. Warner, M.S., Agronomist
R. M. Crown, B.S.A.. Asst. Agronomist
Jesse Reeves, Farm Superintendent
CITRUS STATION, LAKE ALFRED
John H. Jefferies, Superintendent
Geo. D. Ruehle, Ph.D., Associate Plant
Pathologist
W. A. Kuntz, A.M., Assoc. Plant Pathologist
B. R. Fudge, Ph.D., Associate Chemist
W. L. Thompson, B.S., Asst. Entomologist
EVERGLADES STATION, BELLE GLADE
A. Daane. Ph.D., Agronomist in Charge
R. N. Lobdell, M.S., Entomologist
F. D. Stevens, B.S., Sugarcane Agronomist
Thomas Bregger, Ph.D., Sugarcane Physiologist
G. R. Townsend, Ph.D.. Assistant Plant
Pathologist
J. R. Neller, Ph.D., Biochemist
R. W. Kidder, B.S., Assistant Animal
Husbandman
Ross E. Robertson, B.S., Assistant Chemist
SUB-TROPICAL STATION, HOMESTEAD
H. S. Wolfe, Ph.D., Horticulturist in Charge
W. M. Fifield, M.S., Asst. Horticulturist
Stacy 0. Hawkins, M.A., Assistant Plant
Pathologist
W. CENTRAL FLA. STA., BROOKSVILLE
W. F. Ward, M.S.A., Asst. An. Husbandman
in Charge*

FIELD STATIONS
Leesburg
M. N. Walker, Ph.D., Plant Pathologist in
Charge
W. B. Shippy, Ph.D,. Asso. Plant Pathologist
K. W. Loucks, M.S., Asst. Plant Pathologist
J. W. Wilson, Ph.D., Associate Entomologist
C. C. Goff, M.S., Assistant Entomologist
Plant City
A. N. Brooks, Ph.D., Plant Pathologist
R. E. Nolen, M.S.A., Asst. Plan, Pathologist
Cocoa
A. S. Rhoads, Ph.D., Plant Pathologist
Hastings
A. H. Eddins, Ph.D., Plant Pathologist
Monticello
G. B. Fairchild, M.S., Assistant Entomologist
Bradenton
David G. Kelbert, Asst. Plant Pathologist
Sanford
E. R. Purvis, Ph.D., Assistant Chemist,
Celery Investigations
Lakeland
E. S. Ellison, Ph.D., Meteorologist*
In cooperation with U.S.D.A.
** Head of Department.

















CONTENTS


Page
Sum m ary................... ..... ....... ...... .. ...... ......... ...... 3

Introduction .......................... ..... ..................-- -- 5

Prelim inary Experim ents........................ ............. .............. ... 5

Experiments During 1933........................................ .... .... 8

Purple Scale Control with Rust Mite Control Incidental....................... 9

Rust Mite Control with Purple Scale Control Incidental........................ 11

Melanose and Purple Scale Experiment..........-----........ ........... 16

Experiments During 1934............... ........ ......... ....... 17

Melanose and Purple Scale Experiment........---------............... 17

Scab and Scale-Insect Experim ent................................. ............ .... ....... 19

Purple Scale and Rust Mite Experiment..............-........- ........... 25

Applications of Lime-Sulfur for Purple Scale and Whitefly Control.......... 31

Spray Injury......................... ........ .. .... .. .... ... ...... 32

Seasons for Spraying.................. ....... .............. ... 36

A cknowledgm ents...................................... .. ............. ..... 38

Literature Cited................................................ .... 38















SUMMARY
Three lime-sulfur applications made at intervals of six weeks
or longer reduced purple scale infestations and controlled rust
mites for a period of seven to ten months.
Purple scale infestations were held in check or reduced by three
lime-sulfur sprays following a Bordeaux mixture spray. Rust
mites were controlled from the time of application to December
1st with less than 2 percent russets and golden fruit.
Two lime-sulfur applications at an interval of two weeks gave
results comparable with one oil emulsion application in control
of purple scale when applied after Bordeaux mixture.
Experimental results of one year showed that a greater reduc-
tion of purple scale was obtained when lime-sulfur or oil emulsion
followed basic copper sulfate spray than when it followed Bor-
deaux mixture.
The percent of increase of purple scale was greater following
an application of Bordeaux 3-3-50 than when following Bordeaux
11/2-11/2-50.
The effectiveness of liquid lime-sulfur and dry lime-sulfur
against purple scale and rust mite was increased by the addition
of either wettable sulfur or bentonite sulfur.
A greater reduction in numbers of purple scale was obtained
when the first lime-sulfur application was made during the first
half of April rather than the first half of May.








LIME-SULFUR SPRAYS FOR THE COMBINED CONTROL
OF PURPLE SCALE AND RUST MITES

By W. L. THOMPSON

INTRODUCTION
This publication is a progress report, based mainly upon experi-
mental work with lime-sulfur as a means of control of purple
scale, rust mites, purple mites, and whitefly.
It has long been known that lime-sulfur solution is toxic to
young scale-insects (3)1, and that one application was not as
effective as one of an oil emulsion. For that reason scale-insects
and whitefly have been controlled largely with oil emulsions, and
rust mites with dusting sulfur and, to some extent, lime-sulfur
spray. During the past few years spray machinery has been
greatly improved so that a greater volume of spray material can
be applied in a much shorter time than formerly, thereby cutting
the item of labor per unit, and making more applications eco-
nomically possible. Since no experimental work had been pub-
lished in Florida concerning the practicability of a lime-sulfur
program, various experiments have been conducted along those
lines during the past five years.
The citrus insect problem in Florida is closely associated with
two of the most common citrus diseases; namely, melanose and
citrus scab, in that the recommended control for these diseases
is Bordeaux mixture or some other copper compound. Scale-
insects and mites are more difficult to control after the use of
Bordeaux, a fact so well known to practically all citrus growers
that many hesitate to apply this fungicide, which results in a
large percentage of second grade fruit being shipped to market
or carried to the canning plants and cull piles. During the past
two years, therefore, some lime-sulfur experiments followed
applications of Bordeaux. For the same reason the writer co-
operated with the Plant Pathology Department, checking the
scale-insect infestation in their melanose and scab experiments.
PRELIMINARY EXPERIMENTS
In 1930 near Fort Meade some purple scale counts were made
in a grove where calcium cyanide had been applied as a scalecide.
On a few plots the calcium cyanide and lime-sulfur were com-

1Figures in parentheses (Italic) refer to "Literature Cited" in the back
of this bulletin.








LIME-SULFUR SPRAYS FOR THE COMBINED CONTROL
OF PURPLE SCALE AND RUST MITES

By W. L. THOMPSON

INTRODUCTION
This publication is a progress report, based mainly upon experi-
mental work with lime-sulfur as a means of control of purple
scale, rust mites, purple mites, and whitefly.
It has long been known that lime-sulfur solution is toxic to
young scale-insects (3)1, and that one application was not as
effective as one of an oil emulsion. For that reason scale-insects
and whitefly have been controlled largely with oil emulsions, and
rust mites with dusting sulfur and, to some extent, lime-sulfur
spray. During the past few years spray machinery has been
greatly improved so that a greater volume of spray material can
be applied in a much shorter time than formerly, thereby cutting
the item of labor per unit, and making more applications eco-
nomically possible. Since no experimental work had been pub-
lished in Florida concerning the practicability of a lime-sulfur
program, various experiments have been conducted along those
lines during the past five years.
The citrus insect problem in Florida is closely associated with
two of the most common citrus diseases; namely, melanose and
citrus scab, in that the recommended control for these diseases
is Bordeaux mixture or some other copper compound. Scale-
insects and mites are more difficult to control after the use of
Bordeaux, a fact so well known to practically all citrus growers
that many hesitate to apply this fungicide, which results in a
large percentage of second grade fruit being shipped to market
or carried to the canning plants and cull piles. During the past
two years, therefore, some lime-sulfur experiments followed
applications of Bordeaux. For the same reason the writer co-
operated with the Plant Pathology Department, checking the
scale-insect infestation in their melanose and scab experiments.
PRELIMINARY EXPERIMENTS
In 1930 near Fort Meade some purple scale counts were made
in a grove where calcium cyanide had been applied as a scalecide.
On a few plots the calcium cyanide and lime-sulfur were com-

1Figures in parentheses (Italic) refer to "Literature Cited" in the back
of this bulletin.






Florida Agricultural Experiment Station


bined, and in these plots a noticeable reduction in scale crawlers
was observed.
During 1931 a lime-sulfur experiment was carried on in the
same grove by the grower with the advice of Professor J. R.
Watson* in outlining the program, the results on the scale-
insects being checked by the writer. It was again demonstrated
that where lime-sulfur was used there was a noticeable reduction
in scale-insects as compared with the plots that received no treat-
ment or received hydrated lime in the form of a spray. One plot
was sprayed with 10 pounds and another with 20 pounds of
hydrated lime per 100 gallons of water. The purple and Florida
red scales increased very noticeably in these two plots compared
with unsprayed plots. Three applications of a 1 to 40 lime-
sulfur, plus calcium caseinate or hydrated lime as a spreader,
applied May 8, June 8, and July 8, gave about the same results as
four applications at three-week intervals starting with May 8
and ending July 10. In all cases where three applications of
lime-sulfur were made, there was less scale than on the check
plots.
During 1932 a lime-sulfur experiment was carried on at Lake
Alfred in a small block of citrus trees about 18 years old, com-
posed of two rows of orange, one of tangerine, and the remain-
ing seven of late grapefruit trees. The block of trees was
divided into five plots of two rows each with from 16 to 18 trees
per plot. Plot 1, which consisted of one row of tangerines and
one row of Valencia oranges, received a 1 to 40 lime-sulfur spray;
Plot 2, consisting of one row of Valencia oranges and one row of
grapefruit, received 1 to 40 lime-sulfur plus 5 pounds of hydrated
lime per 100 gallons; Plot 3, all grapefruit, received 1 to 40 lime-
sulfur plus 3/8 of 1 percent of a highly sulfonated light oil; Plot
4, all grapefruit, received 1 to 40 lime-sulfur plus iron sulfate, 3
pounds per 100 gallons of water. The remainder of the block
was used as a check plot. The spray material was applied at
approximately 350 pounds pressure. Each tree received an
average of approximately 17.5 to 18 gallons of spray per appli-
cation. Each treated plot was divided so that one half received
three and the other half four applications. The materials were
applied May 12, June 21, and August 4; the half of each plot re-
ceiving four applications was sprayed September 30.
At the time the first spray was applied, a count of scale-insects
showed that 15.5 percent were in the crawler stage and 44.9 per-

*Entomologist, Florida Agricultural Experiment Station.







Lime-Sulfur Sprays for Scale and Rust Mites


cent of the living females were depositing eggs. Twenty-six
days after the first application, a count of young scale-insects
and crawlers showed a reduction of from 1.5 to 3.5 percent in
living scale insects in second stage, and from 47 to 52 percent
of live crawlers.
TABLE 1.-COMPARISON OF PURPLE SCALE INFESTATION ON CURRENT YEAR'S
LEAVES AND OLDER LEAVES, LAKE ALFRED, FLORIDA, DECEMBER, 1932.


PlotI
No. I


Materials Used


1 Lime-sulfur 1-40

2 Same as on Plot 1

3 Lime-sulfur 1-40.
Hydrated Lime 5
lbs. per 100
gallons

4 1 Same as on Plot 3

5 Lime-sulfur 1-40
Highly sulfonat-
ed oil % of one
percent


Number of
Applica-
tions

4


Per cent
Scaly
Leaves of
Current
Year's
Growth

22.5


3 32.4


4 22.3


3 25.1


4


25.6


Difference in
Per cent Percent of
Scaly Current
Leaves of Year's
Old Growth and
Growth Old Growth

89.2 66.7


84.3


80.0


78.5


97.5


6 Same as on Plot 5 3 27.1 95.6 68.5

7 Lime-sulfur 1-40
Iron sulfate 3 4 20.3 95.3 75.0
lbs. per 100
gallons

8 Same as on Plot 7 3 9.6 85.0 75.4

9 Check I 89.2 79.5 -9.7
Twenty leaves were picked at random from each tree in the plot, ten
leaves from the outside and ten from the inside of the tree.

Counts made in late October showed a reduction of scale-
insects in all sprayed plots and an increase in the check. The
value of the fourth application is somewhat questionable, since
plots receiving four applications showed little or no difference
in numbers of living scale-insects per leaf as compared with those
receiving three applications of the spray. However, there was a
lower percentage of infested leaves in each of the half plots that
received the fourth application. As shown in Table 1 there was
a marked difference in the percent of infested leaves on the


-


.






Florida Agricultural Experiment Station


growth of the current year in the sprayed plots as compared with
the check. There was not enough difference in any of the
sprayed plots to justify recommending any one combination over
the other for scale-insect control.
Rust mites were present at the time of the first application
but at no time during the summer were they numerous enough
to necessitate control measures, although it was necessary to
dust the check plot six times. Portions of the plots receiving the
last application in August were dusted with sulfur the first part
of December, but the portions receiving a fourth application
September 30 had no further treatment. The grapefruit was
not picked until the first part of April and at that time no russet
fruits were observed.
The numbers of cloudywinged whiteflies (Dialeurodes citri-
folii) were reduced in the sprayed plots. There was consider-
ably less sooty mold on trees sprayed with lime-sulfur solutions
than on the check. At the time of the last application, Septem-
ber 30, the last brood of whitefly adults was about at its peak.
Ten days after the application, counts were made from leaves
that had had a good coverage of spray material and also from
leaves collected from the check plot. A count of 3,000 eggs was
made from each lot of leaves. In Table 2 are shown the results
of the count.
TABLE 2.-EFFECT OF LIME-SULFUR SPRAY ON WHITEFLY LARVAE.
No. of Dead
and Living Percent Percent
Materials Larvae per Dead Living
3,000 eggs Larvae Larvae
Lime-sulfur 1-40
Hydrated lime, 5 pounds per 435 54.5 45.5
one hundred gallons. __
Unsprayed plot 982 6.2 93.8

EXPERIMENTS DURING 1933
During 1933 three different experiments were carried on;
first, different combinations of lime-sulfur for the control of
purple scale with the control of rust mites incidental; second,
combinations of sulfur applied in liquid and dust forms for rust
mite control with the control of purple scale incidental; third,
to determine the increase or decrease of purple scale where the
materials were applied for melanose control. The last experi-
ment was conducted by the Plant Pathology Department, the
writer observing only the purple scale activity.







Lime-Sulfur Sprays for Scale and Rust Mites


PURPLE SCALE WITH RUST MITE CONTROL INCIDENTAL
The experiment was conducted at Lake Alfred, in the same
grove and in much the same way as in 1932. The plots were
again divided so that three applications of the materials were
made on one half of each plot and four on the other half. Date
of first application was moved up from May 12 to April 1, be-
cause the peak of scale crawlers usually occurs in early April.
The amount of spray solution applied to each tree was reduced
from 17.5 gallons, the amount used in 1932, to approximately
'14.7 gallons per tree. The height of the average tree was 16.5
feet, with a limb spread of 23 feet.
TABLE 3.-PURPLE SCALE EXPERIMENT, LAKE ALFRED, FLORIDA, 1933.

Av. No. Living Percent
Dates of Scale per Leaf Increase or
Plot Applica- Before After Decrease of
No. Materials Used tions Treatment Treatment Living Scale
April 5
1 Lime-sulfur 1-40 May 11
July 7 2.9 .23 -92.1
SAug. 16
May 11
la Lime-sulfur 1-40 July 7 4.4 1.25 -71.6
SAug. 16
2 Lime-sulfur 1-40 Hy- April 5
drated lime 5 lbs. May 11 6.6 1.11 -83.0
per 100 gallons. July 7
Aug. 16
2a Lime-sulfur 1-40 Hy- May 11
drated lime 5 lbs. July 7 7.9 3.46 -56.2
per 100 gallons. Aug. 16
3 Bentonite sulfur April 5
(70% sulfur) 72 May 11 6.9 4.87 -29.4
lbs. 100 gallons. July 7
Aug. 16
3a Bentonite sulfur May 11
7/2 lbs. per 100 July 7 8.8 8.16 7.3
gallons. Aug. 16
4 *Lime-sulfur 1-50 April 18
Lim e-sulfur 1-50, May 11 7.6 2.13 -72.0
Wettable sulfur 5 July 7
lbs. per 100 gals. Aug. 16
SCheck Dusted with
sulfur for rust 12.9 12.90 00.0
mite control _
*The first application of lime-sulfur 1-50 was made by the caretaker.

The different materials used, dates of applications, and results
of the experiment are shown in Table 3. Data for only part of
the original experiment are presented here, as a portion of the
grove was damaged by the hurricane in September of that year.






Florida Agricultural Experiment Station


At the time the first spray was applied, 25 percent of the
females were depositing eggs and 15 percent of the living scale-
insects were in the crawler stage. In each plot receiving four
applications there was a greater decrease in scale-insects than
in plots receiving three applications. From the results of 1932
it would seem to be more beneficial to apply the first spray in
April than early in May. Greatest reduction in scale-insects re-
sulted from the use of straight lime-sulfur (average of Plots 1
and la) on tangerine and orange tree. The other plots con-
tained grapefruit trees, except Plots 2 and 2a, which were half-
orange and half grapefruit trees. The poorest results were ob-
tained with the bentonite sulfur, which would indicate that a
non-caustic sulfur was not as effective as lime-sulfur, although
there was approximately the same amount of sulfur in both solu-
tions. Unfortunately the caretaker sprayed Plot 4 with lime-
sulfur 1-50 on April 18, more for the control of rust mite than
scale-insects, as a very low percentage of the under sides of the
leaves was sprayed. Nevertheless the reduction in numbers of
scale-insects with three applications of lime-sulfur plus wettable
sulfur was very satisfactory in this plot.
TABLE 4.-COUNTS OF SECOND STAGE PURPLE SCALE AND CRAWLERS
LAKE ALFRED, FLORIDA, MAY 25, 1933.*
| Young Scale Crawlers
Plot Dates of (Second Stage) (First Stage)
No. Materials Used Applica- Percent Percent Percent I Percent
S tion Dead Alive Dead Alive
la Dry lime-sulfur 5 lbs. May 11 89 11 92 8
per 100 gals. _
2 Lime-sulfur 1-40 April 5
| ____ May 11 93 7 95 5
3 Lime-sulfur 1-40 April 5
Hydrated lime 5 May 11 91 9 95 5
lbs. per 100 gals. __ __
4 Bentonite (70% April 5
__ sulfur) May 11 80 20 76 24
5 Lime-sulfur 1-50 April 18
Lime-sulfur 1-40
plus wettable sul- May 11 88 12 91 9
fur 5 lbs. per 100
gals.
6 Lime-sulfur 1-40 plus
Iron sulfate 2 lbs. May 11 96 4 94 6
per 100 gals. __
10 | Check I 79 | 21 1 63 37
*1,000 living scale insects counted from each plot.

In Table 4 are shown results of counts of second stage scale-
insects and crawlers 14 days after the second application of







Lime-Sulfur Sprays for Scale and Rust Mites


sprays. There was a reduction of from 28 to 32 percent of living
crawlers on the plots receiving the lime-sulfur combinations com-
pared with the unsprayed plot, but only 13 percent on the plot
receiving bentonite sulfur. The lime-sulfur plots also showed
some reduction in young scale-insects but none was evident
where bentonite sulfur was used alone.
The reduction of living scale-insects per leaf in all plots can-
not be credited altogether to the sprays applied, as the hurricane
knocked many leaves off the trees, carrying the scale-insects
with them. This also may be the reason the check plot showed
no increase in scale-insects.
Except at the time of the first application, rust mites were
never numerous enough during the summer to make spraying
necessary. One application of sulfur dust was necessary on all
the plots in late December. Plot 5, receiving lime-sulfur plus
wettable sulfur, showed the longest protection from rust mites.
A count made in August, a month after an application of lime-
sulfur alone, showed a range of .17 to .59 mites per field* on all
sprayed plots. In Plot 5, the lime-sulfur plus wettable sulfur
plot, not a mite was observed. The plot was rechecked with the
same results. During the period between the last application
and the making of the count, 7.48 inches of rain fell.
No counts of whitefly were made but there was much less
sooty mold on trees in the plots receiving a lime-sulfur combina-
tion than on trees in the unsprayed plot and on the one receiving
bentonite sulfur.
RUST MITE CONTROL WITH PURPLE SCALE CONTROL INCIDENTAL
In this experiment the materials were applied when rust mite
control was necessary. The scale-insect infestation was very
light. Three plots were dusted and seven sprayed. To lessen
the chance of dust drifting into the sprayed plots, two of the
three dust plots were at the ends of the grove. The plots ad-
jacent to the dusted ones included six or seven rows of trees and
the counts were taken from the rows farthest away from the
dusted ones.
A 10-year-old grapefruit grove was used for this experiment.
The average tree was 12 feet high, with a limb spread of 14 feet.
The sprays were applied under 500 pounds pressure from a spray
machine with a capacity of 300 gallons. Two four-nozzle mist
spray guns were used to apply the material. Both the dusting
machine and the sprayer were pulled by a tractor. Each appli-
*The area seen at one time under a lens magnifying 10 times.










TABLE 5.-RUST MITE EXPERIMENT, LAKE ALFRED, FLORIDA, 1933.
Av. No. Mites Av. No. Mites Percent
Percent of per Field on per Field of Range of of Trees
Plot Fruit Fruits all Fruits Mites per with Mites
No. Materials Used Infested Infested Inspected Field on Fruit

1 Bentonite sulfur dust, 70% sulfur...................................... 28.0 2.92 .82 1 to 20 85.0

2 Dry lime-sulfur, 4 lbs. per 100 gallons--................................. -10.0 1.6 .16 1 to 4 30.0

3 Dry lime-sulfur, 6 lbs. per 100 gallons---.................................-- 9.0 1.55 .14 1 to 6 35.0

4 Bentonite sulfur, 30% sulfur, 6 lbs. per 100 gallons..-......... 8.0 1.75 .14 1 to 3 30.0

5 Bentonite sulfur dust, 70% sulfur-- ......... ......------------ 20.0 2.4 .48 1 to 10 70.0

6 Lime-sulfur 1-50 plus Iron sulfate, 2 lbs. per 100 gallons.... 12.0 2.16 .26 1 to 10 45.0

7 Lime-sulfur 1-50 ----------............................... .... 15.0 2.46 .37 1 to 14 55.0

8 Check...........................------------.------ 85.0 16.78 14.72 1 to 110 100.0

9 Bentonite sulfur, 30% sulfur, 12 lbs. per 100 gallons.......... 27.0 2.33 .63 1 to 10 75.0

10 i Sulfur dust, 95% sulfur .................................. 41.0 2.65 1.00 1 to 30 90.0


number of rust mites from three


Counts made July 24, 25 and 26.
Materials applied May 8.
Method of taking data; Counts made of 5 fruits from 20 trees in each plot-The average
fields on each fruit were recorded. The field was 1% centimeters in diameter.






Lime-Sulfur Sprays for Scale and Rust Mites


cation averaged 3.6 gallons of spray or three-fourths pound of
dust per tree.
Counts of both scale-insects and rust mites were made before
the first application and counts of mites were made throughout
the summer and winter. Another count of scale-insects was
made approximately six weeks after the last application.
Various sulfur sprays were used in the experiment, such as
liquid lime-sulfur, dry lime-sulfur, bentonite sulfur as a spray
and as a dust, and also combined materials as shown in Tables
5 and 6. Table 5 shows the method used in taking rust mite
records and also the degree of infestation just before the second
application of materials. There was a period of 78 days between
the first and second applications and during that period 17.35
inches of rain fell-4.65 inches in May, 6.82 inches in June, and
5.88 inches up to July 25. Thirteen weeks elapsed between the
second and third applications, but under more normal weather
conditions the period of protection from rust mites probably
would not have been as long, since the hurricane in September
materially reduced the rust mite population. A count of mites
made in the check plot about two weeks before the hurricane
showed 50 percent and two weeks after the hurricane only 20
percent infested fields.
On October 30 all plots received the third application. The
mites increased in Plots 1 and 5 bentonitee sulfur dust) and a
fourth dust was applied November 21. By January 25 a few
mites were showing up in all plots, but they were much more
numerous in the dusted ones. Due to lack of time, close inspec-
tions could not be continued so the whole grove was sprayed the
fourth time. At that time, only from 2 to 14 percent of the
fields were infested in the sprayed plots and from 16 to 68 per-
cent in the dusted ones.
In Table 6 are shown the condensed results of the experiment.
Although one dusted plot received the same number of applica-
tions as the sprayed ones, it yielded a much higher percentage
of golden and russet fruit, while in the sprayed plots no russets
and not more than 2 percent of golden fruits were observed.
There was no outstanding difference in results produced by
various liquid materials used for rust mite control. Obtaining
a good coverage and applying the first sprays before the mites
had increased to any extent was probably a big factor in keeping
the mites down to a minimum.
In Table 6 also are shown the results of the purple scale count.
In each plot where a lime-sulfur was applied, there was a reduc-










TABLE 6.-RUST MITE AND PURPLE SCALE EXPERIMENT, LAKE ALFRED, FLORIDA, 1933.


Materials


Bentonite sulfur



Dry lime-sulfur,


dust (70% sulfur) ..............



4 lbs. per 100 gallons...........


Dates
of
Applica-
tions

5/8
7/28
10/30
11/21
5/8
7/28
10/30


Purple Scale Results

Percent
Increase
Av. No. Living or
Scale per Leaf Decrease
of
Living
Before After Scale
Treatment Treatment

1.75 2.95 +68.5


1.23


- 3.9


Rust Mite Results
Percent Infested Fields
0 0




28 25 16* 23.0

28 25 16* 23.0


12.0


5/8
3 Dry lime-sulfur, 6 lbs. per 100 gallons ..... ....... 7/28 2.49 1.25 -49.7 9 15 11 11.6
-10/30____

4 Bentonite sulfur (30% sulfur) 6 lbs. per 5/8
100 gallons.................... ............................. 7/28 1.80 2.23 +23.8 8 17 23 16.0
___ 10/30
5/8
5 Bentonite sulfur dust (70% sulfur)................... 7/28 1.19 1.75 +32.0 20 20 24* 21.3
10/30
11/21

6 Liquid lime-sulfur 1-50 plus Iron sulfate 2 lbs. 5/8
per 100 gallons..................................................... 7/28 1.27 .92 -27.5 12 9 3 8.0
10/30 ]


Plot
No.




1



2


0




3.







0
CT
rr
a+
b



-
rr
CT>
3.
Kl


i


:--:-








TABLE 6.-RUST MITES AND PURPLE SCALE EXPERIMENT, LAKE ALFRED, FLORIDA,


Purple Scale Results | Rust Mite Results
Percent Infested Fields
Percent
Increase 4 ;4
Plot Dates Av. No. Living or A
No. Materials of Scale per Leaf Decrease c
Applica- of t4
tions Living B
Before After Scale ,_ e
___ _______Treatment Treatment ,o C 1
5/8
7 Liquid lime-sulfur 1-50............................................ 7/28 1.69 .55 -67.4 15 15 14 14.6
_____e ._________________________________.. 10/30 ____________________ ___

**8 Dry lime-sulfur 5 lbs. per 100 gals. plus 7/28
bentonite sulfur 2 lbs. per 100 gals................... 10/30 2.11 .90 -57.3 19 2 10.5

5/8
100 gallons.............................................................. 10/30 1.43 1.91 +33.5 27 12 11 16.6

5/8 +58.0 41 19 32 30.3
10 Sulfur dust (95% sulfur) .......................... 7/28 2.41 3.81 +58.0 41 19 2 30.3
S________10/30 ____
***11 Check........................... ................................ 1.28 2.42 +89.0 85 54 68 69.0

*Eight weeks after fourth application.
**Original checks for rust mites.
***Used as check after second application.


1933-Continued.







Florida Agricultural Experiment Station


tion in scale-insects, compared with an increase in each plot
where sulfur dust or bentonite sulfur as a spray was used. Two
applications of a spray composed of dry lime-sulfur plus benton-
ite sulfur gave a marked reduction in numbers of scale-insects.
Dry lime-sulfur, 6 pounds per 100 gallons of water, was much
more effective than 4 pounds per 100 gallons.
MELANOSE AND PURPLE SCALE EXPERIMENT
The primary purpose of the experiment was to compare the
results obtained from various sulfur and copper materials used
for the control of melanose. The program was planned and the
materials were applied under the supervision of Wm. A. Kuntz
and George D. Ruehle of the Department of Plant Pathology, the
writer observing the resulting control of the scale-insects.
The experiment was carried on in a 15-year-old grapefruit
grove near Babson Park. Each plot consisted of two rows of
trees, 26 trees to the row. For the scale-insect counts, 10 leaves
were picked at random from the inside and outside of each tree.
The various materials used, dilutions, approximate dates of
applications, and the results of scale counts are shown in Table
7.
TABLE 7.-MELANOSE AND PURPLE SCALE EXPERIMENT,
BABSON PARK, FLORIDA, 1933.
Percent
Increase
Dates of Av. No. Living (+) or
Plot Applica- Scale per Leaf* Decrease
No. Materials Used tions Before After (-) of Living
I Treatment Treatment Scale
IColloidal copper April 6
1 Lime-sulfur 1-40 April 20 3.6 .73 -79.7
May 4
Bordeaux 1V2-2-50 April 6
2 Lime-sulfur 1-40 April 20 3.0 1.00 -66.6
_____ ________ May 4 __
April 6
Colloidal sulfur, 1 April 20 2.9 .68 -76.5
3 gal. per 100 gals. May 4 __
April 6
Colloidal sulfur, 2 April 20 3.7 .98 -73.5
4 gals. per 100 gals. May 4
Lime-sulfur 1-40, April 6
5 Bentonite sulfur 4 April 20 4.2 .30 -92.8
lbs. per 100 gals. May 4_
April 6
April 20 5.1 .31 -93.9
6 Lime-sulfur 1-40 May 4 _______

7 Check _2.2 .81 -61.8
*Wm. A. Kuntz and G. D. Ruehle assisted in making these counts.







Lime-Sulfur Sprays for Scale and Rust Mites


Although all plots, including the check, showed a reduction of
scale-insects, there was a decided decrease in Plots 5 and 6 which
received three applications of lime-sulfur 1-40 plus bentonite
sulfur, and straight lime-sulfur 1-40, respectively. In Plots 1
and 2 where one copper spray was followed by two lime-sulfur
the reduction in scale-insects was smaller, but greater than in
the check. A greater reduction of scale-insects was obtained
where lime-sulfur followed a colloidal copper than where it
followed a Bordeaux 11/2-2-50 spray. Plots 3 and 4, which re-
ceived a colloidal sulfur, had the least average reduction of scale-
insects of any of the sprayed plots.

EXPERIMENTS DURING 1934
During the past four years results with lime-sulfur sprays
have shown rather definitely that light to medium infestations
of purple scale can be reduced or held in check. The experiments
in 1934 were so planned that the majority of the sulfur sprays
followed applications of Bordeaux mixture for control of
melanose or scab. The Departments of Plant Pathology and
Entomology cooperated in some of the tests in 1934.
MELANOSE AND PURPLE SCALE EXPERIMENT, BABSON PARK,
FLORIDA
The melanose and purple scale experiment was conducted in
the same grove and in much the same manner as in 1933, except
that more combinations of spray materials were used. The plots
consisted of two rows of grapefruit trees with 26 trees per plot.
The experiment was arranged so that in some cases two plots
received the same strength copper spray but one plot received oil
and the other lime-sulfur as follow-up sprays.
Four plots received a delayed dormant application of spray
February 6, and eight plots received the first application April 9
and 10.
Counts of scale-insects were made in February before the de-
layed dormant sprays were applied but another count from all
plots was not made until November. The object of waiting until
November to make the count was to determine whether two to
three sprays applied at close intervals were effective until the
cool months. Ten leaves were picked at random from each tree
in the plot for counts of scale-insects. Five hundred living scale
insects were counted from each plot, or if 500 were not present,
the total from the 260 leaves collected was taken. The leaves
were put in paper bags and kept in the refrigerator until







Lime-Sulfur Sprays for Scale and Rust Mites


Although all plots, including the check, showed a reduction of
scale-insects, there was a decided decrease in Plots 5 and 6 which
received three applications of lime-sulfur 1-40 plus bentonite
sulfur, and straight lime-sulfur 1-40, respectively. In Plots 1
and 2 where one copper spray was followed by two lime-sulfur
the reduction in scale-insects was smaller, but greater than in
the check. A greater reduction of scale-insects was obtained
where lime-sulfur followed a colloidal copper than where it
followed a Bordeaux 11/2-2-50 spray. Plots 3 and 4, which re-
ceived a colloidal sulfur, had the least average reduction of scale-
insects of any of the sprayed plots.

EXPERIMENTS DURING 1934
During the past four years results with lime-sulfur sprays
have shown rather definitely that light to medium infestations
of purple scale can be reduced or held in check. The experiments
in 1934 were so planned that the majority of the sulfur sprays
followed applications of Bordeaux mixture for control of
melanose or scab. The Departments of Plant Pathology and
Entomology cooperated in some of the tests in 1934.
MELANOSE AND PURPLE SCALE EXPERIMENT, BABSON PARK,
FLORIDA
The melanose and purple scale experiment was conducted in
the same grove and in much the same manner as in 1933, except
that more combinations of spray materials were used. The plots
consisted of two rows of grapefruit trees with 26 trees per plot.
The experiment was arranged so that in some cases two plots
received the same strength copper spray but one plot received oil
and the other lime-sulfur as follow-up sprays.
Four plots received a delayed dormant application of spray
February 6, and eight plots received the first application April 9
and 10.
Counts of scale-insects were made in February before the de-
layed dormant sprays were applied but another count from all
plots was not made until November. The object of waiting until
November to make the count was to determine whether two to
three sprays applied at close intervals were effective until the
cool months. Ten leaves were picked at random from each tree
in the plot for counts of scale-insects. Five hundred living scale
insects were counted from each plot, or if 500 were not present,
the total from the 260 leaves collected was taken. The leaves
were put in paper bags and kept in the refrigerator until







Florida Agricultural Experiment Station


counted. Before being counted, the leaves were mixed gently
and put back into the bag and taken out at random for counts.
All the 1934 counts of scale-insects were made in that manner.
Various materials and dilutions, dates of applications, and re-
sults of counts are shown in Table 8.

TABLE 8.-PURPLE SCALE EXPERIMENT, BABSON PARK, FLORIDA, 1934.

Dates of Av. No. Living Percent
Plot Applica- Scale per Leaf Increase or
No. Materials Used tions Before After Decrease of
T___reatment Treatment Living Scale
Bordeaux 1%-2-50 plus April 9
1 calcium caseinate
Liquid lime-sulfur April 24 4.89 9.25 +89.1
1-40 May 7
Bordeaux 1%-2-50 plus
2 calcium caseinate April 9
Oil emulsion (1% oil) June 1 4.68 8.76 +87.1
Bordeaux 3-4-50 plus
3 1% oil Feb. 6
Liquid lime sulfur April 24 2.58 2.98 +15.5
1-40 May 7
Bordeaux 3-4-50 plus
4 1% oil Feb. 6
Oil emulsion (1% oil) June 1 5.00 6.66 +33.2
Lime-sulfur 1-40, April 10
5 Bentonite sulfur 4 Ibs. April 24 2.45 2.14 -12.8
per 100 gals. May 7
April 10
6 Lime-sulfur 1-40 April 24 2.17 5.43 +150.2
May 7 ___
7 *Ethyl Mercury Feb. 6
1Oleate No. 2 April 9 1.54 3.37 +118.8
8 *Ethyl Mercury Feb. 6 1.35 4.71 +248.8
I Oleate No. 2___
Basic cop. sulfate plus
9 Calcium caseinate April 9
Lime-sulfur 1-40 April 24 I 5.86 4.16 -29.0
SMay7 I
Basic copper sulfate
plus 1% oil plus Cal- April 10
10 cium caseinate
IOil emulsion (1% oil) June 1 6.30 1.85 -70.6
SProprietary Bordeaux-
11 oil plus calcium April 10
caseinate
Oil emulsion (1% oil) June 1 7.11 2.32 -67.3
Bordeaux 3-4-50 plus April 10
12 calcium caseinate
Oil emulsion (1% oil) June 1 8.26 14.70 +77.9
13 Check I 7.81 | 9.34 +19.7
*Ethyl Mercury Oleate in oil emulsion, 60% oil in stock emulsion.
A heavy shower of rain fell before the spray material (oil emulsion) was
dry on some of the trees in Plot 12, which may account for the increase
of scale-insects in that plot.






Lime-Sulfur Sprays for Scale and Rust Mites


There was practically, no difference in degree of control of
scale-insects between plots receiving 11/2-2-50 Bordeaux followed
by two applications of lime-sulfur 1-40, in one plot and a 1 per-
cent oil emulsion in another (Plots 1 and 2). The same was
more or less true where these same materials followed a delayed
dormant Bordeaux 3-4-50 plus 1 percent oil, except that lime-
sulfur showed less increase of scale-insects (Plots 3 and 4).
Lime-sulfur appeared to be much more effective when used as a
follow-up spray after basic copper sulfate than after Bordeaux
(Plot 9). Basic copper sulfate plus oil emulsion, applied as a
delayed dormant spray and followed by an oil emulsion in June,
gave a decided decrease in scale-insects as compared with a
dormant Bordeaux plus oil emulsion followed by oil emulsion
(Plots 10 and 4). Three applications of liquid lime-sulfur 1-40
plus bentonite sulfur gave much better results than liquid lime-
sulfur used alone (Plots 5 and 6). Plot 6 has been the only
exception in the experiments of the last three years when liquid
lime-sulfur did not result in a decrease in scale-insects when not
following Bordeaux. A proprietary oil and copper mixture
followed by an oil gave very good control of scale-insects (Plot
11). A proprietary organic mercury in oil, applied twice in one
plot and once in another, gave unsatisfactory results, especially
in the plot receiving only one application (Plots 7 and 8).
SCAB AND SCALE-INSECT EXPERIMENT*, BRADENTON, FLORIDA
The purpose of the experiment was to compare results obtained
from the use of various materials in a combined program for the
control of citrus scab, purple scale, Florida red scale, and, to some
extent, melanose. Unfortunately the block of trees used for
this experiment did not set a crop of fruit, so no results were
obtained for scab, melanose or rust mite control.
In the Bradenton district Florida red scale is as much or more
of a problem than purple scale and for that reason both species
were considered in this experiment. The experiment was
carried on in a grapefruit grove. Each plot consisted of one
row of 20 trees. The spray was applied from a 200 gallon spray
machine at a pressure of approximately 500 pounds.
A 3-4-50 Bordeaux, applied during the dormant season, is
recommended for scab control (1). An oil emulsion is usually
added as a spreader and scalecide. Eight of the plots received a
dormant application of Bordeaux, 3-4-50, plus 1 percent oil emul-

*Cooperative experiment with Dr. G. D. Ruehle, Department of Plant
Pathology.









TABLE 9.-PURPLE SCALE COUNTS IN THE SCAB AND PURPLE SCALE EXPERIMENT, BRADENTON, FLORIDA, 1934.

Dates Av. No. Living Percent
Dates Scale per Leaf Percent
No. IMaterials Used of Scale per Leaf Increase or
Plot Applica- Before After Decrease of
Itions Treatment Treatment Living Scale

1 Check 1.4 7.1 +407.0
Jan. 18 1.02 1.7 +66.6
2 Organic mercury CS-2-F, 1-60 April 11

3 Bordeaux 3-4-50, Oil emulsion (1% oil) Jan. 18 .54 2.8 +418.5
I Oil emulsion (1% oil) June 26
Bordeaux 3-4-50, Oil emulsion (1% oil) Jan. 18
4 Lime-sulfur 1-40 May 11 .61 2.6 +326.2
Lime-sulfur 1-50 June 25
Lime-sulfur 1-60 plus Bentonite sulfur 3 lbs. per 100 gals. Aug. 6

Bordeaux 3-4-50, Oil emulsion (1% oil) Jan. 18
5 Lime-sulfur 1-40 April 11 1.16 1.5 +29.3
Lime-sulfur 1-40 May 11
Lime-sulfur 1-50 June 25

Bordeaux 3-4-50, Oil emulsion (1% oil) Jan. 19
6 Lime-sulfur 1-40 April 11 1.2 1.2 0.0
Lime-sulfur 1-50, Wettable sulfur 4 lbs. per 100 gals. May 11
Lime-sulfur 1-60, Wettable sulfur 4 lbs. per 100 gals. June 25

Bordeaux 3-4-50, Oil emulsion (1% oil) Jan. 19
7 Lime-sulfur 1-40, Bentonite sulfur 4 lbs. per 100 gals. April 11 .86 1.7 +97.6
Lime-sulfur 1-40, Bentonite sulfur 4 lbs. per 100 gals. May 11 I
| Lime-sulfur 1-50, Bentonite sulfur 4 lbs. per 100 gals. June 25 _









TABLE 9.-PURPLE SCALE COUNTS IN THE SCAB AND PURPLE SCALE EXPERIMENT, BRADENTON, FLORIDA, 1934.-(Continued).

Plot Dates Ave. No. Living Percent
No. Materials Used of Scale per Leaf Increase or
Applica- Before After Decrease of
tions Treatment Treatment Living Scale

SBordeaux 3-4-50, Oil emulsion (1% oil) Jan. 19
8 Bordeaux 1%-2-50 plus Calcium caseinate April 11 1.25 2.9 +132.0
Oil emulsion (1% oil) June 26

Bordeaux 3-4-50, Oil emulsion (1% oil) Jan. 19
Bordeaux 1%-2-50 plus Calcium caseinate April 11
9 Lime-sulfur 1-40 May 11 .95 2.0 +110.5
Lime-sulfur 1-50 June 25
Lime-sulfur 1-60 Aug. 6 _

10 Bordeaux 3-4-50 plus Calcium caseinate Jan. 19 .47 2.2 +368.0
Oil emulsion (1% oil) June 26 _______

Bordeaux 3-4-50 plus Calcium caseinate Jan. 19
11 Lime-sulfur 1-40 April 11 .45 1.5 +334.4
Lime-sulfur 1-50 June 25
SLime-sulfur 1-60 Aug. 6 _________

Bordeaux 3-4-50, Oil emulsion (1% oil) Jan. 19
12 Dry lime-sulfur 5 lbs. Bentonite sulfur 2 lbs. per 100 gals. April 11 .82 .76 -7.5
Dry lime-sulfur 5 lbs. Bentonite sulfur 2 lbs. per 100 gals. May 11
IDry lime-sulfur 5 lbs. Bentonite sulfur 2 lbs. per 100 gals. June 25
*Ethyl Mercury Oleate in oil emulsion, 60% oil in stock solution.






Florida Agricultural Experiment Station


sion; two plots received a dormant Bordeaux, 3-4-50, plus a cal-
cium caseinate spreader; and one plot received a dormant appli-
cation of a proprietary organic mercury in an oil. Some of the
plots received a petal-fall spray April 11 (Plots 5, 6, 7, 9, 11 and
12). All sprays applied after the petal-fall were for control of
scale-insects.
Materials used, dates of applications, and results obtained for
purple scale and Florida red scale control are given in Tables 9
and 10.
There was a very light infestation of purple scale when the
experiment was started. When the counts were made during
October the infestation was still considered light but there was
an increase in all but two plots. The scale-insects increased less
in the plots that received three applications of some form of lime-
sulfur than in those receiving one application of an oil emulsion.
There was also less increase in plots that received the first lime-
sulfur application April 11 as compared with the ones receiving
the first application May 11.
Plots 4 and 5 give a good comparison as they were both sprayed
with the straight lime-sulfur. It should, of course, be noted
that Plot 5 received two lime-sulfurs, 1-40 and 1-50, while Plot 4
received applications of 1-40, 1-50 and 1-60. Plots receiving
lime-sulfur plus wettable sulfur and dry lime-sulfur plus benton-
ite sulfur, respectively, gave better results than straight lime-
sulfur or lime-sulfur plus bentonite sulfur. Two applications of
an ethyl mercury oleate in oil emulsion gave better results than
Bordeaux-oil followed by an oil and also better results than some
of the lime-sulfur sprays (Plot 2).
The same manner of counting was followed with Florida red
scale as with the purple scale. The results were such that it is
doubtful if any conclusions can be drawn of the comparative
value of the various materials used. In Table 10 are shown the
results of the count. There was a very light infestation at the
time the first count was made. With the exception of Plot 3
there was little increase in living scale per leaf when the count
was made in October, but from general observations it was
evident that the population of scale-insects had increased dur-
ing the summer to a marked degree. By October some natural
agency, other than fungi, had caused a high mortality. The de-
crease in the percent of living scale-insects was greater in the
check than in any of the other plots. Emergence holes of para-
sites were observed in many of the scale armours but a large
proportion of the immature scale-insects were dead, although








TABLE 10.-SCAB AND FLORIDA RED SCALE EXPERIMENT, BRADENTON, FLORIDA, 1934.


Plot
No.


Materials Used


1 I Check

2 Organic Mercury 1-60


3 Bordeaux 3-4-50, Oil emulsion 1%
__ Oil emulsion 1%

Bordeaux 3-4-50, Oil emulsion 1%
4 Lime-sulfur 1-40
Lime-sulfur 1-50
Lime-sulfur 1-60 plus bentonite sulfur 3 Ibs. per 100 gals.


Dates
of
Applica-
tions


1/18
4/11

1/18
6/26

1/18
5/11
6/25
8/6


Av. No. Living Percent
Scale per Leaf Increase or
Before After Decrease of
Treatment Treatment Living Scale

.32 I .06 -81.2

.69 .25 -63.7


.02 1.47 +7250.0


.59


+1.7


Bordeaux 3-4-50, Oil emulsion 1% 1/18
5 Lime-sulfur 1-40 4/11 1.87 .55 -70.5
Lime-sulfur 1-40 5/11
Lime-sulfur 1-50 6/25

Bordeaux 3-4-50, Oil emulsion 1% 1/19
6 Lime-sulfur 1-40 4/11 .48 .61 +27.0
Lime-sulfur 1-50, wettable sulfur 4 lbs. per 100 gals. 5/11
Lime-sulfur 1-60, wettable sulfur 4 lbs. per 100 gals. 6/25 ____

Bordeaux 3-4-50, Oil emulsion 1% 1/19
7 Lime-sulfur 1-40, bentonite sulfur 4 lbs. per 100 gals. 4/11 .38 .92 +142.1
Lime-sulfur 1-40, bentonite sulfur 4 Ibs. per 100 gals. 5/11
Lime-sulfur 1-50, bentonite sulfur 4 lbs. per 100 gals. 6/25


t/ri
c.



re
CI




41
i








co
C3
~C-
a
so
sa.

rr


---











TABLE 10.-SCAB AND FLORIDA RED SCALE EXPERIMENT, BRADENTON, FLORIDA, 1934.-(Continued).

Dates Av. No. Living Percent
Dates Ppnr Tft
Plot of Scale per Leaf Increase or
No. Materials Used Ap'plica- Before After Decrease of
__tions Treatment Treatment Living Scale
SBordeaux 3-4-50, Oil emulsion 1% 1/19
8 Bordeaux 1%-2-50 plus caseinate 4/11 1.03 .75 -27.1
SOil emulsion 1% 6/26

Bordeaux 3-4-50, Oil emulsion 1% 1/19
Bordeaux 11/2-2-50 plus spreader 4/11
9 Lime-sulfur 1-40 5/11 .61 .55 -9.8
Lime-sulfur 1-50 6/25
Lime-sulfur 1-60 8/6

10 Bordeaux 3-4-50 plus caseinate 1/19 .18 .16 -11.1
Oil emulsion 1% 6/26

Bordeaux 3-4-50 plus caseinate 1/19
11 Lime-sulfur 1-40 4/11 .54 .19 -64.8
Lime-sulfur 1-50 6/25
Lime-sulfur 1-60 8/6

Bordeaux 3-4-50, Oil emulsion 1% 1/19
12 Dry lime-sulfur 5 lbs. bentonite sulfur 2 lbs. per 100 gals. 4/11 1.14 .53 -53.5
Dry lime-sulfur 5 lbs. bentonite sulfur 2 lbs. per 100 gals. 5/11
IDry lime-sulfur 5 lbs. bentonite sulfur 2 lbs. per 100 gals. 6/25







Lime-Sulfur Sprays for Scale and Rust Mites


there were no emergence holes of the parasites visible. Further
studies of the problem are to be made.
PURPLE SCALE AND RUST MITE EXPERIMENT, LAKE ALFRED,
FLORIDA, 1934
The purpose of this experiment was to test various sulfur
sprays for the control of purple scale and rust mites after an
application of Bordeaux for control of melanose.
A grapefruit grove approximately 18 years old located in
Lake Alfred was used for these tests. The trees averaged 16
feet in height and the average spread of the lower limbs was 22
feet. Each plot was five rows wide and nine rows long. All
except two plots were sprayed with Bordeaux. In the Bordeaux
plots, five rows were sprayed with Bordeaux 1-11/-50 and
four rows with Bordeaux 3-3-50. One plot received no Bordeaux
but was sprayed with dry lime-sulfur plus bentonite sulfur at
the time the Bordeaux mixture was applied. This plot received
the same kind of application as did the other plots when they
were sprayed later in the season. The check plot received no
control treatment of any kind.
Practically all the counts of scale-insects and rust mites were
taken from the center rows of each plot. Counts of scale-insects
were made in the same way as in other experiments conducted
during the year. The various materials used, dates of applica-
tions, and results obtained are shown in Tables 11 and 12.
In Table 11 are shown the results where various materials
were used as scalecides after an application of Bordeaux 11/2-
11/2-50 and Bordeaux 3-3-50.
With the exception of Plot 11, which received an oil emulsion,
there was a larger number of living scale-insects per leaf where
Bordeaux 3-3-50 was used than where Bordeaux 11/-11/2-50 was
used. Comparing the plots that received sulfur sprays, Plot 5
and 5a, which received lime-sulfur plus wettable sulfur, showed
the largest percent decrease in living scale insects per leaf and
straight lime-sulfur (Plot 4 and 4a) the greatest increase. In
Plot 1 straight dry lime-sulfur showed up well but it is doubtful
if it would consistently show as good results as dry lime-sulfur
plus bentonite sulfur. Dry lime-sulfur plus bentonite sulfur
showed better results than liquid lime-sulfur plus bentonite sul-
fur. Plot 11 and lla, which received one oil emulsion, showed
very good scale-insect control but there was a rather large per-
cent of rust mite injury even with five applications of sulfur dust
up to December 1. Plot 12 and 12a, receiving only the Bordeaux










TABLE 11.-COMPARISON OF PURPLE SCALE CONTROL BY LIME-SULFUR FOLLOWING FULL-STRENGTH AND HALF-STRENGTH
BORDEAUX MIXTURE, LAKE ALFRED, FLORIDA, 1934.

Dates Av. No. Living Percent
Plot of Scale per Leaf Increase (+) or
No. Materials Used Applica- Before After Decrease (-) of
Stions Treatment Treatment Living Scale

Bordeaux 1%-1%-50 April 9
1 Dry lime-sulfur, 5 lbs. per 100 gals. April 30 18.7 9.2 -50.8
Dry lime-sulfur, 5 lbs. per 100 gals. June 8
SDry lime-sulfur, 5 lbs. per 100 gals. Aug. 6
la Bordeaux 3-3-50
Lime-sulfur treatment as on Plot 1 April 9 18.7 22.2 +18.6
Bordeaux 1%-1%-50 April 9
2 Dry lime-sulfur, 5 lbs., Bentonite sulfur 2 lbs. per 100 gals. April 30 15.4 12.5 -18.8
Dry lime-sulfur, 5 lbs., Bentonite sulfur 2 lbs. per 100 gals. June 8
SDry lime-sulfur, 5 lbs., Bentonite sulfur 2 lbs. per 100 gals. Aug. 6
2a Bordeaux 3-3-50
Lime-sulfur treatment as on Plot 2 April 9 15.4 18.5 +20.1
Bordeaux 1%-1%-50 April 9
3 Liquid lime-sulfur 1-40 April 30 13.6 18.5 +36.0
Liquid lime-sulfur 1-50 June 8
Liquid lime-sulfur 1-60 Ag __ Aug. 6
3a Bordeaux 3-3-50
Lime-sulfur treatment as on Plot 3 April 9 13.6 23.8 +75.0
Bordeaux 1%-1-50 April 9
4 Liquid lime-sulfur 1-40 plus Bentonite sulfur 2 lbs. per 100 gals. April 30 10.7 9.2 -14.0
Liquid lime-sulfur 1-50 plus Bentonite sulfur 3 lbs. per 100 gals. June 8
Liquid lime-sulfur 1-60 plus Bentonite sulfur 4 lbs. per 100 gals. Aug. 6
4a Bordeaux 1%-1%-50
Lime-sulfur treatment as on Plot 4 April 9 10.7 13.1 +28.0









TABLE 11.-COMPARISON OF PURPLE SCALE CONTROL BY LIME-SULFUR FOLLOWING FULL-STRENGTH AND HALF-STRENGTH
BORDEAUX MIXTURE, LAKE ALFRED, FLORIDA, 1934.-Continued.

Dates Av. No. Living Percent
Plot of Scale per Leaf Increase (+) or
No. Materials Used Applica- Before After Decrease (-) of
tions Treatment Treatment Living Scale
Bordeaux 1-11/2-50 April 9
5 Liquid lime-sulfur 1-40, plus Wettable sulfur 2 lbs. per 100 gals. April 30 15.0 6.3 -58.0
Liquid lime-sulfur 1-50, plus Wettable sulfur 3 lbs. per 100 gals. June 8
Liquid lime-sulfur 1-60, plus Wettable sulfur 4 lbs. per 100 gals. Aug. 6
5a Bordeaux 3-3-50
Lime-sulfur treatments as on Plot 5 April 9 15.0 10.8 -28.0
Dry lime-sulfur 5 lbs., plus Bentonite sulfur 2 lbs. per 100 gals. April 9
8 Dry lime-sulfur 5 lbs., plus Bentonite sulfur 2 lbs. per 100 gals. April 30 7.7 3.7 -51.9
Dry lime-sulfur 5 lbs., plus Bentonite sulfur 2 lbs. per 100 gals. June 8
Dry lime-sulfur 5 lbs., plus Bentonite sulfur 2 lbs. per 100 gals. Aug. 6
Bordeaux 1%-1y2-50 April 9 6.9 5.2 -24.6
11 Oil emulsion (1% oil) June 8
Five applications of sulfur dust
lla Bordeaux 3-3-50
SLater treatments as on Plot 11 April 9 6.9 4.4 -36.2
12 Bordeaux 11/2--1/250
I Six applications of sulfur dust. I April 9 5.5 9.2 +67.2
12a Bordeaux 3-3-50 I
Later treatments as on Plot 12 April 9 5.5 I 14.7 L +167.1

13 1 Check I 5.2 8.1 +55.7






Florida Agricultural Experiment Station


sprays and seven applications of dust, had the greatest increase
of scale-insects, exceeding that of the check.
In Table 12 are shown the combined counts of all the plots.
Plot 8, which received no Bordeaux but four applications of dry
lime-sulfur plus bentonite sulfur, showed the greatest decrease in
scale-insects; but liquid lime-sulfur plus wettable sulfur follow-
ing Bordeaux was almost as good. On the average, dry lime-
sulfur plus bentonite sulfur showed up well in the control of
scale-insects, Plots 2 and 10. Plot 10 received only two applica-
tions of spray and two of sulfur dust. Although soluble sulfur
showed a decrease in scale-insects (Plot 6), the first application
was followed by a very heavy leaf drop (Table 13) and some fruit
drop. The rust mite control was very poor.
In the majority of sprayed plots better rust mite control was
obtained where lime-sulfur, liquid or dry, was supplemented by
either wettable sulfur or bentonite sulfur than where the lime-
sulfur alone was used. The results are shown in Table 12. Lime-
sulfur plus wettable sulfur had a lower percent of infested fields
than any other combination. Comparing dry lime-sulfur plus
bentonite sulfur and liquid lime-sulfur plus bentonite sulfur, the
results show that these two combinations were about equal for
rust mite control. All three of those combinations gave results
so similar that it should be a matter of using the combination
which is most economical (Plots 2, 4 and 5). Soluble sulfur plus
bentonite sulfur showed results comparable to the dusted plots,
with a rather high percentage of fruit damaged by mites (Plots
6 and 9). A comparison of rust mite control by an oil emulsion
and by lime-sulfur can be made by comparing Plot 11 with Plots
1 to 5, inclusive. Plot 11 received an oil emulsion June 8, the
same date the other plots were sprayed with their respective
sulfur combinations. On July 17 none of the plots sprayed with
lime-sulfur except 6, 9 and 10 showed any mites, while Plot 11
showed 12 percent infested fields. By July 25, Plot 11, the oil
emulsion plot, showed 45 percent infested fields and Plots 1 to 5,
the straight lime-sulfur and lime-sulfurs plus wettable sulfurs
plots, showed only from 1 to 2 percent infested fields. Although
Plot 11 received one application of oil emulsion and five applica-
tions of 95 percent sulfur dust, the average percent of infestation
for the season was higher than Plot 12, which received six appli-
cations of bentonite sulfur (70 percent sulfur). The results would
indicate that if rust mites are controlled with sulfur dust, in a
year of heavy rainfall the bentonite sulfur would give better con-
trol than ordinary sulfur.









TABLE 12.-PURPLE SCALE AND RUST MITE CONTROL, LAKE ALFRED, FLORIDA, 1934.


| Purple Scale ] Rust Mites


5 rows of each plot sprayed with Bordeaux 3-3-5
Plot 4 rows of each plot sprayed with Bordeaux 1%-1/2-5
No. The respective sprays and dusts follow

Dry lime-sulfur 5 lbs. per 100 gals.
1 Dry lime-sulfur 5 lbs. per 100 gals.
SDry lime-sulfur 5 lbs. per 100 gals.
Dry lime-sulfur 5 lbs., Bentonite sulfur 2 lbs. per 100 gals.
2 Dry lime-sulfur 5 lbs., Bentonite sulfur 2 lbs. per 100 gals.
SDry lime-sulfur 5 lbs., Bentonite sulfur 2 lbs. per 100 gals.
SLiquid lime-sulfur 1-40
3 Liquid lime-sulfur 1-50
Liquid lime-sulfur 1-60
SLiquid lime-sulfur 1-40, plus Bentonite sulfur 2 lbs. per 100
4 Liquid lime-sulfur 1-50, plus Bentonite sulfur 3 lbs. per 100
Liquid lime-sulfur 1-60, plus Bentonite sulfur 4 lbs. per 100
I Liquid lime-sulfur 1-40, plus Wettable sulfur 2 lbs. per 100
5 Liquid lime-sulfur 1-50, plus Wettable sulfur 3 lbs. per 100
SLiquid lime-sulfur 1-60, plus Wettable sulfur 4 lbs. per 100
Soluble sulfur 3 lbs., plus Bentonite sulfur 3 lbs. per 100 gi
6 Soluble sulfur 5 lbs., plus Bentonite sulfur 3 Ibs. per 100 gi
Soluble sulfur 3 lbs., plus Bentonite sulfur 3 lbs. per 100 g:
Dusted with Bentonite sulfur
Dry lime-sulfur 5 lbs., plus Bentonite sulfur 2 lbs. per 100
8 Dry lime-sulfur 5 lbs., plus Bentonite sulfur 2 lbs. per 100
Dry lime-sulfur 5 lbs., plus Bentonite sulfur 2 lbs. per 100
Dry lime-sulfur 5 lbs.. plus Bentonite sulfur 2 lbs. per 100


0i
iO


Dates
of
Applica-
tions
April 30
June 8
Aug. 7


April 30
June 8
Aug. 7


April 30
June 8
Aug. 7


Perce
(+)o
(-)
Scal
Dec


nt Increase
r Decrease Av. I
of Living Inf
e per Leaf Fields
member 1 Expe

-19.2 1


-16.7


+52.9


Percent
ested
During
riment

.0.5


5.6


7.1


-'.


April 30
June 8 + .9 5.8
Aug. 7
April 30
June 8 -46.6 3.6
Aug. 7
April 30
June 8 -24.2 22.4
Aug. 7
Oct. 20
April 9
April 30 -51.9 9.3
June 8
Aug. 7


-i-


I


I


I


,


- v :---


'


,


_











TABLE 12.-PURPLE SCALE AND RUST MITE CONTROL, LAKE ALFRED, FLORIDA, 1934.-Continued.
SI Purple Scale Rust Mites
Percent Increase
I 5 rows of each plot sprayed with Bordeaux 3-3-50 Dates (+) or Decrease Av. Percent
Plot 4 rows of each plot sprayed with Bordeaux 11/2-1%-50 of (-) of Living Infested
No. The respective sprays and dusts follow Applica- Scale per Leaf Fields During
tions December 1 Experiment
Soluble sulfur 3 lbs., Bentonite sulfur 3 lbs. per 100 gals. April 30
9 Soluble sulfur 3 lbs., Bentonite sulfur 3 lbs. per 100 gals. June 8 + 3.6 35.0
Dry lime-sulfur 4 lbs., Bentonite sulfur 6 lbs. per 100 gals. Aug. 7
Dry lime-sulfur 5 lbs., Bentonite sulfur 2 lbs. per 100 gals. April 30
10 Dry lime-sulfur 5 lbs., Bentonite sulfur 2 lbs. per 100 gals. June 8 +29.3 12.7
Dusting sulfur (95% sulfur) Aug. 7
Dusting sulfur (95% sulfur) Sept. 25
Oil emulsion (1% oil) June 6
Dusting sulfur (95% sulfur) May 5
11 Dusting sulfur (95% sulfur) May 25 -31.8 29.8
Dusting sulfur (95% sulfur) July 27
Dusting sulfur (95% sulfur) Sept. 25
Dusting sulfur (95% sulfur) Dec. 1
Dusted with Bentonite sulfur (70% sulfur) May 5
Dusted with Bentonite sulfur (70% sulfur) May 25
12 Dusted with Bentonite sulfur (70% sulfur) June 8 +105.4 20.2
Dusted with Bentonite sulfur (70% sulfur) July 27
Dusted with Bentonite sulfur (70% sulfur) Sept. 25
Dusted with Bentonite sulfur (70% sulfur) Dec. 1
13 Check I ~ +55.7 59.0
*No Bordeaux applied to Plot 8.







Lime-Sulfur Sprays for Scale and Rust Mites


It was not possible to grade the fruit according to plots in the
packinghouse for rust mite damage, so only an estimate was
made. It is doubtful if 60 percent of the fruit would be classed
as bright in Plots 11 and 12, which received sulfur dust. In Plots
2, 3, 4, 5, 7 and 8, all lime-sulfur plots, no russets were observed
and not more than 1 percent would be classed as golden. Plot 10,
which received two sulfur sprays and three sulfur dusts, had
more golden fruit than any of the other sprayed plots except
Plots 6 and 9, the soluble sulfur plots. Plot 11, having rather
heavy infestations several times during the season, may be partly
responsible for more marked fruit in Plot 10. The last complete
rust mite records were taken November 18. As shown in Table
12, the mites were increasing. The whole grove was dusted
December 1 and the fruit was picked in early January.

APPLICATIONS OF LIME-SULFUR FOR PURPLE SCALE
AND WHITEFLY CONTROL
If scale-insects and whitefly are to be controlled with lime-
sulfur, a good coverage must be obtained, especially for the first
and second applications. Both purple scale and whitefly are
much more abundant on the lower sides of the leaves than on the
upper sides, and contact of the insecticide with the insects is
necessary to cause death, especially if the insects have become
anchored. During the winter months and up to the first of May,
many of the rust mites are found on the under sides of the
leaves, making it very important that the first spring spray of
lime-sulfur be thoroughly applied. It has been observed that
very few of the first brood of scale-insects infest the spring
flush of growth until July, so to get a maximum kill the older
leaves should have a good coverage. By making it a point to
cover the older growth, the current year's leaves will be well
covered.
If the trees have a dense covering of foliage and the limbs are
near the ground, a surprisingly greater number of them are hit
on the under side if the spray gun or rod is given several turns in
the inside of the tree than if all the spray is applied entirely from
the outside. Even though a high pressure is used, poor cover-
age is obtained on the inside leaves if the spray is forced through
the outer growth.
The practice of spray riding, that is, the continual movement
of the spray machine while the application is being made, will
not give satisfactory results where the trees are large and the






Florida Agricultural Experiment Station


foliage is quite dense. The writer has made repeated observa-
tions in groves where the crew rode the spray machine. These
observations show that too many leaves, especially the under
sides, were not covered by the spray material. As shown in the
preceding paragraph, the successful control of these insects is
predicated upon a good coverage of the leaves by the spray
material.
The amount of spray material applied per tree, of course, de-
pends to some extent on the denseness of the foliage. In some
experimental plots at Lake Alfred, the trees averaged 16 feet in
height and the lower limbs had an average spread of 22 feet.
Although the tree averages were the same in height and limb
spread in the various plots, the trees were in a more vigorous con-
dition at the north end of the grove than at the south end. To
obtain approximately the same coverage on the trees in all plots,
more material was needed where the foliage was more dense.
The trees on the north end of the grove received an average of
11 gallons per tree, and the trees on the south end received an
average of 9.5 gallons per tree. Had all the trees been sprayed
by men riding on the sprayer, the percent of leaf area covered
with spray would have been lower on the trees with dense foliage
than on those with sparse foliage, although the height and spread
were the same.
SPRAY INJURY
The cause of injury from the use of various spray materials
appears to be more or less unknown. Injury sometimes develops
from the use of lime-sulfur when least expected and at other
times does not develop when most expected. Others (5) reports
spraying citrus trees with a lime-sulfur 1-25 during the months
of May, June, and August without burn developing, and in an-
other case a lime-sulfur solution of the same strength was applied
in June with the temperature at 95 degrees F. and no injury
developed. He also cites cases when slight to severe injury did
develop. During two successive years the writer sprayed the
same block of trees-oranges, grapefruits and tangerines-dur-
ing the months of May, June, August, and late September of one
year and April, May, June and August of the following year, with
a lime-sulfur solution 1-40 and no injury developed on the fruit
and only a slight injury showed on succulent foliage after one
application with the temperature at 92 degrees F. The addition
of five pounds of hydrated lime per 100 gallons to the lime-sulfur
did not decrease the amount of injury. In a few instances injury





TABLE 13.-INJURY DEVELOPING ON FRUIT AFTER LIME-SULFUR APPLICATION, OCTOBER 10, 1935.
Dates of Observations
Varieties of Oranges
and October 19 I| October 26 I1 November 2
Dilutions of Sprays Degree of No Slight Deep No. Fruit No Slight Deep No. Fruit
Injury Burn Burn Burn Examined Burn IBurn Burn Examined
VALENCIA ORANGES % % % % % %

Lime-sulfur 1-40.................................... Trace 93.75 6.25 0.0 80 74.24 12.12 13.64 66
Lime sulfur 1-40 plus wettable sulfur 97.
5 lbs. per 100 gals............................. No burn 97.14 1.43 1.43 70 97.06 1.471 1.47 68
Lime-sulfur 1-50...................................... No burn 11 100.0 0.0 | 0.0 1 66 11 96.921 3.081 0.0 1 65
Lime-sulfur 1-60 .................................I No burn I]100.0 1 0.0 I 0.0 1 81 11100.0 | 0.0 I 0.0 1 80
PINEAPPLE ORANGES
Lime-sulfur 1-40................................. Slight burn 95.88 2.62 1.50 267 90.50 5.32 4.82 263
Lime-sulfur 1-40 plus wettable sulfur
5 lbs. per 100 gals............................... No burn II 97.82 2.18 0.0 138 I 96.10I 2.34 1.56 128
Lime-sulfur 1-50...................................... No burn I| 100.0 | 0.0 I 0.0 1 17 11 88.241 5.881 5.88 1 17
Lime-sulfur 1-60 .................................... No burn | 100.0 1 0.0 I 0.0 1 25 | 100.0 | 0.0 1 0.0 1 27
HAMLIN ORANGES
Lime-sulfur 1-40.----.............................. Severe burn 56.16 16.44 27.40 73 60.32 15.87 23.81* 63
Lime-sulfur 1-40 plus wettable sulfur I I 1 6
5 lbs. per 100 gals............................... Slight burn 77.61 7.46 14.93 67 80.65 6.4512.90* 62
Lime-sulfur 1-50............................ Slight burn 1I 66.661 16.661 16.66 6 11 66.661 16.66 16.66 | 6
Lime-sulfur 1-60...................................... Slight burn IL 54.55 1 9.09 36.361 11 11 54.551 9.09 136.36 11
Checks of above varieties...................... No burn 11100.0 I 0.0 1 0.0 1 200 1 100.0 1 0.0 1 0.0 200
*Some of the injured fruit had dropped.






Florida Agricultural Experiment Station


has developed on fruit after an application of lime-sulfur 1-50
and 1-60, respectively, with a temperature ranging from 80 to
85 degrees F.
The condition of the fruit on trees may be one of the factors
determining whether or not injury develops. On October 20,
1934, two different plots of Valencia oranges were sprayed with
the lime-sulfur 1-50 plus wettable sulfur, 3 pounds per 100 gal-
lons. The temperature ranged between 83 and 85 degrees F.
during the time the spray was being applied. One plot had re-
ceived no commercial fertilizer during the past year; the other
had received the normal applications of fertilizer and the trees
were in good condition. Some of the trees in the fertilized plot
were sprayed with part of the same tank load of material that
was sprayed on the unfertilized plot. Rather severe injury
developed on some of the fruit on trees in the unfertilized plot
but no appreciable amount of injury was observed on fruit in the
fertilized plot. Injured fruits were found on all sides of the
trees.
The variety of orange is probably a factor also, especially if
the fruit is near maturity when sprayed. During the season of
1934 a few trees of several varieties of oranges were sprayed
with different dilutions of lime-sulfur as follows: lime-sulfur
1-40, lime-sulfur 1-40 plus 5 pounds of wettable sulfur per 100
gallons, lime-sulfur 1-50 and 1-60. The sprays were applied May
21, July 20 and October 10. No injury developed on any of the
varieties after the first two applications. After the October
spray severe damage developed on Hamlin oranges and, to some
extent, on Pineapples and Valencias. The temperature ranged
between 84 and 86 degrees F. during the time the applications
were made in October. Less injury developed on fruit sprayed
with lime-sulfur plus wettable sulfur than when sprayed with
straight lime-sulfur. Although the most severe burn developed
after lime-sulfur 1-40, burn also developed on Hamlin oranges
after lime-sulfur 1-60. Unfortunately there were only a few
fruits on the trees receiving the weaker solution but five out of
11 were injured. Pineapple oranges showed less injury than
Hamlin, and Valencias the least injury of any of the three
varieties. In Table 13 is shown the degree of injury that
developed on the different varieties.
Slight injury developed on succulent foliage of Valencia
oranges after an application of lime-sulfur in July, 1934. Three
plots received liquid lime-sulfur 1-50, liquid lime-sulfur 1-50 plus
three pounds of bentonite sulfur per 100 gallons, and liquid lime-






TABLE 14.-LEAF DROP DATA, PURPLE SCALE EXPERIMENT, ATTI GROVE, LAKE ALFRED, FLORIDA.


Plot Materials Applied Three Weeks
No. After Bordeaux Spray


1 Dry lime-sulfur 5 lbs. per 100 gal. water


Dry lime-sulfur 5 lbs. ~er 100 gal, water


Dry lime-sulfur 5 lbs. per 100 gal. water
Bentonite sulfur 2 lbs. per 100 gal. water

Liquid lime-sulfur 1-40


4 Liquid lime-sulfur 1-40 plus
Bentonite sulfur 2 lbs. per 100 gal.

5 Liquid lime-sulfur 1-40

6 Soluble sulfur 5 lbs. per 100 gal.
I Bentonite sulfur 3 lbs. per 100 gal.

8 Dry lime-sulfur 5 lbs. per 100 gal.
SBentonite sulfur 2 lbs. per 100 gal.

9 Soluble sulfur 2 lbs. per 100 gal.
SBentonite sulfur 3 lbs. per 100 gal.

13 1 Check


Bordeaux
11/2-1V2-50
Leaf Fruit
Drop Drop


68 no
record


Bordeaux
3-3-50
Leaf Fruit
Drop Drop

84 no
I record


80 41 51 54


207


360

799


68


46

37


437 86


297 29

745 57





no no
record record


Dry Lime-
sulfur plus
Bentonite
Sulfur
Leaf I Fruit
Drop I Drop


84


Totals
Leaf F
Drop D

152
re

131


380

424


657

1544


84


874


78


Leaves collected May 8. Sulfur sprays applied April 30 and May 2.
Leaves and fruit collected from an area of one square yard under each of four trees, per plot, at approximately the same
distance from the trunk and the same side of each tree.
*Leaves picked from only two trees, figures in total column doubled to show comparative results.


.


Fruit -
)rop

no
record

95 -


108

140


75

94


78


172


80


I


I


,










Florida Agricultural Experiment Station


sulfur 1-50 plus three pounds of wettable sulfur per 100 gallons
of spray. The amount of foliage injury was about the same in
all three plots. Four other plots received 5 pounds of dry lime-
sulfur and 2 pounds of bentonite sulfur per 100 gallons of
water, and one plot received 5 pounds of dry lime-sulfur per 100
gallons without the bentonite sulfur. No injury was observed
on any of those trees sprayed with dry lime-sulfur.
It has been observed that a rather heavy leaf drop often occurs
when lime-sulfur follows within several weeks after an applica-
tion of Bordeaux. In the experiments during 1934 at Lake Alfred
the first sulfur sprays were applied three weeks after Bordeaux.
A week later a count of dropped leaves was made. Only leaves
that had recently dropped were considered. In Table 14 are
shown the results of the count. The dry lime-sulfur plots
showed the least drop and the soluble sulfur plots the greatest.
Plots 3, 4, and 5, all receiving a lime-sulfur 1-40, showed a de-
cidedly heavier leaf drop than plots receiving dry lime-sulfur
(Plots 1 and 2). A comparison of Plots 2 and 8 shows little more
of a leaf drop when dry lime-sulfur plus bentonite sulfur followed
Bordeaux than where dry lime-sulfur alone was applied.
SEASONS FOR SPRAYING
In the control of citrus insects an attempt usually is made to
apply the insecticides at the time when the insects are easiest to
kill. Since citrus trees are covered with foliage during the whole
year, it is not safe to apply a very concentrated spray material
as can be done with deciduous trees when they are dormant and
bare of foliage and fruit.
The easiest times to kill scale-insects is when they are in the
first (crawler) stage and the second stage. Although all the
different stages of purple scale may be found at any time of the
year, there are three rather definite periods when crawlers are
more abundant. These are in late March or early April, from
the latter half of June to early July, and September and October.
Whiteflies are also more easily killed in the crawler stage and
the first nymphal stage. A chart by Yothers (4) shows the
peaks of adult cloudywing whitefly at Orlando to be approximate-
ly April 1 to 15, July 1 to 15, and October 7 to 21. The citrus
whitefly peaks are March 7 to 25, June 1 to 15, and August 10 to
24. A chart by Watson (2) shows very similar dates for white-
fly adult peaks. The peaks of cloudywinged whitely at Lake
Alfred correspond very closely with the peaks referred to above.







Lime-Sulfur Sprays for Scale and Rust Mites


The peaks of the adults are considered because the eggs are be-
ing deposited at that time and control measures should be taken
soon after.
In the average year an application of lime-sulfur 1-40, made
during the first half of April, should materially reduce the
population of scale-insects, whitefly, and mites. If Bordeaux
mixture is to be applied for melanose control on the fruit, the
lime-sulfur application can be delayed for two to three weeks and
still be quite effective. If a thorough application of lime-sulfur
has been made, rust mites should not appear before the middle
of June or later. If Bordeaux mixture has been applied in the
spring a second application of lime-sulfur should be made in
June, even though there are not enough rust mites to warrant
spraying. If scale-insects are materially increasing, a summer
oil emulsion can be substituted for lime-sulfur.
If two good applications of lime-sulfur have been made, the
third application may be made when needed for rust mite con-
trol. If the first two applications of lime-sulfur give rust mite
protection well through the summer, a sulfur dust may be sub-
stituted for the third lime-sulfur application, especially if the
fruit is of an early variety and scale-insects are not increasing.
During four successive years three applications of lime-sulfur,
either alone or with added wettable sulfurs, gave rust mite pro-
tection from April to periods ranging from December 1 to
March 1.
If Bordeaux is not applied during the year and scale-insects
are not abundant, a good practice is to apply a thorough lime-
sulfur spray during the first half of April, or, if a large acreage
is to be covered, start the spray applications in late March. The
later applications may then be made when rust mite control is
necessary. During the season of 1934, nine plots of Valencia
oranges were sprayed with various combinations of sulfur with
lime-sulfur. Applications were made April 30, July 7, and Octo-
ber 20. At the time of the last inspection, February 20, 1935,
only 29 percent of the fields were infested. Fifty fruits and 50
leaves from each plot were examined, each being placed once
under the lens. This gave a total of 900 fields for the nine plots.
Counts of scale-insects were not made from those plots but the
general appearance of the trees indicated that the scale-insects
had not increased during the year. The trees averaged 15 feet
in height, with a limb spread of 16 feet. The average tree re-
ceived six gallons per application.







Florida Agricultural Experiment Station


ACKNOWLEDGMENTS

The writer wishes to acknowledge the valuable advice and help
of Professor J. R. Watson in formulating the preliminary spray
programs and his constructive criticisms of this publication.
The author is indebted also to Doctor G. D. Ruehle and W. A.
Kuntz of the Department of Plant Pathology for permission to
cooperate in some of their experiments and for their assistance
in some of the counts of scale-insects. Mr. W. W. Lawless also
assisted in some of the counts of scale-insects and rust mites.
Appreciation is expressed to the several citrus growers who co-
operated in allowing the experiments to be conducted in their
groves.

LITERATURE CITED
1. RHOADS, A. S. and E. F. DEBUSK. Diseases of Citrus in Florida. Fla.
Agri. Exp. Sta. Bul. 229. 1931.
2. WATSON, J. R. and E. W. BERGER. Citrus Insects and their Control.
Fla. Agri. Ext. Serv. Bul. 67. 1932.
3. YOTHERS, W. W. Spraying for the Control of Insects and Mites
Attacking Citrus Trees in Florida. U. S. D. A. Farmers Bul. 933.
1918.
4. Spraying for the Control of Insects and Mites Attacking
Citrus Trees in Florida. U. S. D. A. Farmers Bul. 933. 1922.
5. The Citrus Rust Mite and Its Control. U. S. D. A.
Technical Bul. 176. 1930.




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