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 Present status of blight contr...
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 Comparative cost of spraying and...
 Discussion of results obtained
 Conclusions and summary
 Reference














Title: Potato spraying and dusting experiments in Florida
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Title: Potato spraying and dusting experiments in Florida
Physical Description: Book
Creator: Gratz, L. O.
Publisher: University of Florida Agricultural Experiment Station
Publication Date: 1930
Copyright Date: 1930
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Volume ID: VID00001
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Table of Contents
    Title Page
        Page 1
        Page 2
    Table of Contents
        Page 3
        Page 4
    Introduction
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Present status of blight control
        Page 12
        Page 13
    Spraying and dusting experiments in Florida
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
    Comparative cost of spraying and dusting
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
    Discussion of results obtained
        Page 34
    Conclusions and summary
        Page 35
        Page 36
    Reference
        Page 37
        Page 38
        Page 39
Full Text



Bulletin 222 November, 1930
(Received for Publication August 30, 1930)
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION Y/
Wilmon Newell, Director / _
AA





POTATO SPRAYING AND DUSTING

EXPERIMENTS IN FLORIDA,

1924 TO 1929
By L. O. GRATZ








TECHNICAL BULLETIN












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








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

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

MAIN STATION-DEPARTMENTS AND INVESTIGATORS
AGRONOMY ECONOMICS, AGRICULTURAL
W. E. STOKES, M.S., Agronomist C. V. NOBLE, Ph.D., Agricultural Economist
W. A. LEUKEL, Ph.D., Associate BRUCE McKINLEY, A.B., B.S.A., Associate
G. E. RITCHEY, M.S.A., Assistant* M. A. BROOKER, M.S.A., Assistant
FRED H. HULL, M.S., Assistant JOHN L. WANN, B.S.A., Assistant
J. D. WARNER, M.S., Assistant ECONOMICS, HOME
JOHN P. CAMP, M.S.A., Assistant OUIDA DAVIS ABBOTT, Ph.D., Head
ANIMAL HUSBANDRY L. W. GADDUM, Ph.D., Biochemist
A. L. SHEALY, D.V.M., Veterinarian in C. F. AHMANN, Ph.D., Physiologist
Charge ENTOMOLOGY
E. F. THOMAS, D.V.M., Asst. Veterinarian J. R. WATSON, AM., Entomologist
R. B. BECKER, Ph.D., Associate in Dairy A. N. TISSOT, MS., Assistant
Husbandry A.N. TSSOT, M.S. Assistant
W. M. NEAL, Ph.D., Assistant in Animal H. E. BRATLEY. M.S.A., Assistant
Nutrition L. W. ZIEGLER, B.S., Assistant
C. R. DAWSON, B.S.A., Assistant Dairy HORTICULTURE
Investigations A. F. CAMP, Ph.D., Horticulturist
CHEMISTRY HAROLD MOWRY, B.S.A., Associate
R. W. RUPRECHT, Ph.D., Chemist M. R. ENSIGN, M.S., Assistant
R. M. BARNETTE, Ph.D., Associate A. L. STAHL, Ph.D., Assistant
C. E. BELL, M.S., Assistant G. H. BLACKMON, M.S.A., Pecan Culturist
J. M. COLEMAN, B.S., Assistant C. B. VAN CLEEF, M.S.A., Greenhouse
H. W. WINSOR, B.S.A., Assistant Foreman
H. W. JONES, B.S., Assistant PLANT PATHOLOGY
COTTON INVESTIGATIONS W. B. TISDALE, Ph.D., Plant Pathologist
W. A. CARVER, Ph.D., Assistant G. F. WEBER, Ph.D., Associate
E. F. GROSSMAN, M.A., Assistant A. H. EDDINS, Ph.D., Assistant
PAUL W. CALHOUN, B.S., Assistant K. W. LOUCKS, M.S., Assistant
RAYMOND CROWN, B.S.A., Field Assistant ERDMAN WEST. B.S., Mycologist

BRANCH STATION AND FIELD WORKERS
L. O. GRATZ, Ph.D., Asso. Plant Pathologist in charge. Tobacco Exp. Sta. (Quincy)
R. R. KINCAID. M.S., Assistant Plant Pathologist (Quincy)
JESSE REEVES, Farm Superintendent, Tobacco Experiment Station (Quincy)
J. H. JEFFERIES. Superintendent, Citrus Experiment Station (Lake Alfred)
GEO. D. RUEHLE, Ph.D., Assistant Plant Pathologist (Lake Alfred)
W. A. KUNTZ, A.M., Assistant Plant Pathologist (Lake Alfred)
B. R. FUDGE. Ph.D.. Assistant Chemist (Lake Alfred)
W. L. THOMPSON, B.S., Assistant Entomologist (Lake Alfred)
R. V. ALLISON, Ph.D.. Soils Specialist in charge Everglades Experiment Sfhtion (Belle Gladre
R. W. KIDDER, B.S., Foreman, Everglades Experiment Station (Belle Glade)
R. N. LOBDELL, M.S., Assistant Entomologist (Belle Glade)
F. D. STEVENS, B.S., Sugarcane Agronomist (Belle Glade)
H. H. WEDGWORTH, M.S., Associate Plant Pathologist (Belle Glade)
B. A. BOURNE, M.S., Associate Plant Physiologist (Belle Glade)
J. R. NELLER, Ph.D., Associate Biochemist (Belle Glade)
FRED YOUNT, Office Assistant (Belle Glade)
M. R. BEDSOLE, M.S.A., Assistant Chemist (Belle Glade)
A. N. BROOKS. Ph.D., Associate Plant Pathologist (Plant City)
R. E. NOLEN, M.S.A., Field Assistant in Plant Pathology (Plant City)
A. S. RHOADS, Ph.D., Associate Plant Pathologist (Cocoa)
C. M. TUCKER, Ph.D., Associate Plant Pathologist (Hastings)
H. S. WOLFE, Ph.D., Associate Horticulturist (Homestead)
L. R. TOY, B.S.A., Assistant Horticulturist (Homestead)
STAGY O. HAWKINS. M.A., Field Assistant in Plant Pathology (Homestead)
D. G. A. KELBERT, Field Assistant in Plant Pathology (Bradenton)
FRED W. WALKER, Assistant Entomologist (Monticello)
D. A. SANDERS, D.V.M., Associate Veterinarian (West Palm Beach)
M. N. WALKER. Ph.D., Associate Plant Pathologist (Leesburg)
"W. B. SHIPPY, Ph.D., Assistant Plant Pathologist (Leesburg)
C. C. GOFF, M.S., Assistant Entomologist (Leesburg)
J. W. WILSON, Ph.D., Assistant Entomologist (Pierson)
*In cooperatou with U. 8. Department of Agriculture.



















CONTENTS

PAGE
INTRODUCTION ......................................... ........ 5
Estimated Losses in the United States.......................... 5
Early History of Present-day Control Measures ................ 8

PRESENT STATUS OF BLIGHT CONTROL .............................. 12

SPRAYING AND DUSTING EXPERIMENTS IN FLORIDA .................... 14
The Scope of the Work................... ... .................. 14
The Experiments in 1924 .................................... 16
The Experiments in 1925 ................... ................... 16
The Experiments in 1926 ..................................... 20
The Experiments in 1927 .................................... 23
The Experiments in 1928 ..................................... 26
The Experiments in 1929 ...................................... 28

COMPARATIVE COST OF SPRAYING AND DUSTING ........................ 29

DISCUSSION OF RESULTS OBTAINED .................................. 34

CONCLUSIONS .................... .............. .... ........... 35

SUM M ARY ................ .......... ............................ 35

LITERATURE CITED ..................................................... 37











POTATO SPRAYING AND DUSTING

EXPERIMENTS IN FLORIDA,

1924 TO 1929
By L. O. GRATZ

INTRODUCTION
Late blight (Phytophthora infestans (Mont.) De Bary), early
blight (Alternaria solani (E. & M.) J. & G.), tip-burn and hopper-
burn (physiological or caused by Empoasca mali Le B.) are the
three foliage diseases of potatoes which, individually or collec-
tively, necessitate expensive spraying or dusting programs in
many of the potato sections of the United States.
ESTIMATED LOSSES IN THE UNITED STATES
According to calculated averages obtained from estimates given
in the Plant Disease Reporter of the Bureau of Plant Industry,
United States Department of Agriculture, late blight caused an-
nual losses during the 10-year period, 1918-1927, which varied
from 0.1 to almost 8 percent of the total crop produced in the entire
country. The average annual loss for this 10-year period was 3.58
percent, or almost 14,100,000 bushels (Table I). Late blight is














W LEUM STAIRS MIO I It UNlO IATE 5
STAWtS n K T
MAU+ = RACE


FLORtIA
Wmsr WilitiA _


Fig. 1.-Diagram showing the percentage losses of potatoes due to late blight
and its distribution in the United States.

















TABLE I.-ESTIMATED PRODUCTION OF POTATOES AND REDUCTION IN YIELD BY THE DIFFERENT DISEASES DURING THE 10-YEAR PERIOD
FROM 1918 TO 1927, AS REPORTED IN THE PLANT DISEASE REPORTER, BUREAU OF PLANT INDUSTRY, UNITED STATES DEPARTMENT
OF AGRICULTURE.
Percent Reduction in Yield caused by Total loss
Production i r l
Year in bushels Sum of
Mosaic Leaf roll ate Rho ois le wi t d hop tracesand es Percent Bushels
blight tonosis leg Wilt an hp blight no aa diseases
per- burn no data es

1918 400,106,000 2.3 1.3 1.8 2.2 0.4 2.3 4.9 1.1 0.06* .... 16.3 78,094,000 P
1919 357,901,000 2.5 1.7 4.7 2.0 0.5 1.6 3.7 1.9 .... 0.9 19.5 86,997,000
1920 430,458,000 1.6 2.0 7.9 2.0 0.4 1.6 1.4 0.7 .... 3.7 21.3 119,474,000 0
1921 346,823,000 1.9 1.4 0.5 2.7 0.3 1.7 6.5 2.5 .... 1.1 18.6 79,518,000
1922 451,185,000 2.8 3.5 2.0 2.9 0.6 1.1 4.3 0.6 .... 3.3 21.1 120,943,000 m
1923 414,472,000 3.4 2.8 0.1 2.6 0.5 0.8 2.3 0.3 1.1 2.3 16.2 80,125,000
1924 454,784,000 2.7 1.6 3.9 2.7 0.7 1.0 2.8 0.5 1.0 2.2 19.1 107,681,000
1925 323,243,000 2.9 1.9 3.5 2.8 1.1 0.2 3.5 0.4 1.3 3.4 21.0 86,020,000 2
1926 356,360,000 2.4 1.3 6.2 1.6 0.7 0.2 3.1 0.3 1.2 1.2 18.2 79,347,000 t
1927 402,149,000 2.4 1.6 5.2 2.4 1.1 0.8 4.3 0.2 ... 1.7 19.7 98,335,000 r
Average. 393,748,100 2.49 1.91 3.58 2.39 .63 1.13 3.68 0.85 0.93 1.98 19.10 93,653,400

*Estimated reduction by Verticillium wilt.
i.;









Bulletin 222, Potato Spraying and Dusting Experiments 7

TABLE II.-THE PREVALENCE OF LATE BLIGHT (Phytophthora infestans
(MONT.) DE BARY) OF POTATOES IN THE DIFFERENT STATES OF THE UNITED
STATES AS INDICATED BY THE PERCENT AND BUSHEL LOSSES REPORTED DUR-
ING THE 10-YEAR PERIOD FROM 1918 TO 1927 IN THE PLANT DISEASE
REPORTER, BUREAU OF PLANT INDUSTRY, UNITED STATES DEPARTMENT OF
AGRICULTURE.
Classification No. of Years Average Losses'
State according for available
to production' data Percent Bushels

Vermont ................ LD 7 11.1 595,857
Maine.................. MajLS 8 10.9 4,092,250
New York............... MajLS 10 10.4 5,549,200
Rhode Island ............ LD 5 9.6 48,000
Pennsylvania ........... MajLS 9 9.4 4,522,111
New Hampshire ......... LD 9 8.8 260,000
Massachusetts ........... LD 9 8.7 317,222
Florida.................. SE 5 7.2 164,500
West Virginia. ............ LD 10 5.7 423,200
Arkansas ............... SE 9 5.5 266,667
Connecticut ............ LD 10 5.2 150,900
Maryland............... LD 9 4.1 259,222
Wisconsin............... MajLS 10 3.6 1,254,000
Delaware ............... LD 7 2.7 27,857
New Jersey ............ MajLS 7 2.3 381,714
Ohio.................... LD 9 2.1 295,889
North Carolina........... SE 9 1.7 116,556
Oregon................. MiLS 10 1.1 80,900
Georgia ................ SE 9 1.0 16,333
Michigan................ MajLS 10 0.8 434,900
Tennessee .............. SE 9 0.5 15,667
South Carolina........... SE 6 0.5 17,500
Virginia................. SE 10 0.4 59,900
Minnesota .............. MajLS 10 0.2 1,254,000
Iowa ........ ....... ... LD 9 0.1 10,777
South Dakota ........... MiLS 9 0.06 3,000
Washington............. MiLS 10 t 4,100
California .............. MiLS 7 t 2,571
Kentucky ............. LD .9 t +
North Dakota.......... MajLS 10 0 0
Wyoming ............... MiLS 9 0 0
Nebraska............... MiLS 10 0 0
Nevada ................ MiLS 9 0 0
Idaho.................. MiLS 10 0 0
Utah................... MiLS 9 0 0
Colorado ............... MiLS 9 0 0
Montana .... .......... MiLS 10 0 0
Kansas.................. MiLS 9 0 0
Indiana. ................ LD 8 0 0
Illinois.................. LD 9 0 0
Missouri............... LD 9 0 0
Alabama................ SE 7 0 0
Mississippi .............. SE 9 0 0
Louisiana............... SE 10 0 0
Texas................... SE 10 0 0
Oklahoma ............... SE 10 0 0
New Mexico............. SE 9 0 0
Arizona ................ SE 10 0 0

United States. .... ...... ..... 10 3.58 17,653,700
1MiLS = Minor Late Surplus MajLS = Major Late Surplus
LD = Late Deficient SE = Southern Early
"2t = trace + = loss too small for actual estimate.








8 Florida Agricultural Experiment Station

usually considered the most destructive disease of potatoes, but
when the entire United States was considered, it was found that
tip-burn and hopper-burn produced losses which were fully as
great, while losses produced by early blight were comparatively
small (Table I).
Also it was noted that there is a difference in geographic distri-
bution of epidemics of these diseases. Late blight is most severe
in the northeastern portion of the United States, while most of the
central, southern, and western states are practically free from the
disease (Table II, Fig. 1). Although tip-burn and hopper-burn
occur throughout the United States, they are least severe in the
western states, very slight in Maine and in a few southern early
states and have not been reported from Florida (Table III, Fig. 2).














TIN LLAPUM STATES AMD THE UNMED SrATES ~ A\
AVERCtE i.SS MROR IS1-.17\
STATR HT5 PER CENT C
w+TrV.GA h OL 025 PER CENT
FigA showing the percentage losses of potatoes due to tip-burn





Fig. 2.-Diagram showing the percentage losses of potatoes due to tip-burn
and hopper-burn and their distribution in the United States.

Early blight is more or less generally distributed, except that it
has not been reported from Washington, Montana and Nevada
(Table IV, Fig. 3).
EARLY HISTORY OF PRESENT-DAY CONTROL MEASURES
Although late blight has been responsible for large reductions
in yield of potatoes in both hemispheres since about 1830 and for
a famine in Europe in 1845 which resulted in the death of a quarter









Bulletin 222, Potato Spraying and Dusting Experiments 9

TABLE III.-THE PREVALENCE OF TIP-BURN AND HOPPER-BURN OF POTATOES IN
THE DIFFERENT STATES OF THE UNITED STATES AS INDICATED BY THE PER-
CENT AND BUSHEL LOSSES REPORTED DURING THE 10-YEAR PERIOD FROM 1918
TO 1927 IN THE PLANT DISEASE REPORTER, BUREAU OF PLANT INDUSTRY,
UNITED STATES DEPARTMENT OF AGRICULTURE.

Classification No. of Years Average Losses2
State according to for available -
production' data Percent Bushels

West Virginia........... LD 10 14.4 939,700
Nebraska.... ........ MiLS 1 12.0 1,419
Michigan ............... MajLS 9 9.3 4,174,778
Iowa.......... .......... LD 6 9.1 1,020,167
New Mexico............. SE 3 8.0 17,667
Minnesota .............. MajLS 10 7.3 3,075,200
Delaware..... .... ... LD 7 6.9 62,429
Kentucky ... ........... LD 7 6.9 773,000
Ohio ................... LD 9 6.7 869,444
New Jersey ............. MajLS 6 6.3 703,000
South Dakota............ MajLS 8 5.4 367,500
Pennsylvania ............ MajLS 8 5.3 1,899,875
New York.. ............. MajLS 9 5.1 2,706,556
Indiana................. LD 7 4.3 210,429
Arkansas ............... SE 7 4.3 128,571
Wisconsin ............. MajLS 10 3.8 1,188,000
Vermont ............... LD 5 3.4 171,200
Missouri. ............... LD 4 3.3 224,000
Tennessee ............... SE 9 2.9 106,889
Kansas................. MiLS 8 2.6 139,875
Illinois .......... .. LD 6 2.4 247,500
Connecticut ............. LD 7 2.2 83,714
North Carolina............ SE 8 2.2 175,500
Texas................... SE 7 2.1 56,429
Virginia. ................ SE 9 2.0 308,222
California .............. MiLS 1 2.0 263,000
Rhode Island ............ LD 2 2.0 12,000
Maryland ............... LD 8 2.0 96,750
Colorado................ MiLS 4 1.8 297,750
New Hampshire.......... LD 4 1.8 39,500
Oklahoma ............... SE 3 1.7 22,000
Georgia ................. SE 7 1.6 21,857
North Dakota........... MajLS 8 1.3 114,000
Utah..................... MajLS 4 1.3 44,750
Mississippi ............. SE 7 1.2 17,286
Massachusetts ........... LD 6 0.9 39,167
Louisiana............... SE 8 0.8 18,500
Maine .................. MajLS 4 0.8 343,250
Arizona.................. SE 5 0.7 2,800
South Carolina........... SE 6 0.5 13,167
Alabama ................ SE 3 0.3 13,667
Montana ............... MiLS 6 t +
Idaho ................... M iLS 8 t +
Oregon .................. MiLS 7 t +
Washington .............. MiLS 7 t +
Nevada ................. MiLS 1 0 0
Wyoming ................ MiLS 1 0 0
Florida.................. SE 1 0 0

United States............ 10 3.68 17,596,500

1MiLS = Minor Late Surplus MajLS = Major Late Surplus
LD = Late Deficient SE = Southern Early
"2t = trace + = loss too small for actual estimate.









10 Florida Agricultural Experiment Station

TABLE IV.-THE PREVALENCE OF EARLY BLIGHT (Alternaria solani (E. & M.)
J. & G.) OF POTATOES IN THE DIFFERENT STATES OF THE UNITED STATES AS
INDICATED BY THE PERCENT AND BUSHEL LOSSES REPORTED DURING THE 10-
YEAR PERIOD FROM 1918 TO 1927 IN THE PLANT DISEASE REPORTER, BUREAU
OF PLANT INDUSTRY, UNITED STATES DEPARTMENT OF AGRICULTURE.

Classification No. of Years Average Losses2
State according to for available
Production' data Percent Bushels

Kentucky ............... LD 9 6.0 449,556
Tennessee. .............. SE 8 4.4 158,625
South Carolina........... SE 9 3.6 151,111
Delaware ................ LD 10 2.9 31,100
New Jersey.............. MajLS 10 2.5 311,000
Florida .................. SE 5 2.2 56,800
Georgia. ................ SE 8 2.0 32,111
New Mexico ............. SE 3 2.0 3,667
Mississippi. ............. SE 7 2.0 30,857
California. .............. MiLS 3 2.0 269,333
Colorado................ MiLS 6 1.8 231,500
Ohio.................... LD 8 1.8 222,625
Pennsylvania ............ MajLS 10 1.7 654,300
Illinois ................. LD 5 1.7 166,600
Michigan ............... MajLS 9 1.7 894,111
Kansas ................. MiLS 10 1.6 105,300
North Carolina........... SE 8 1.6 111,125
Alabama ................ SE 4 1.3 31,400
Maryland .............. LD 9 1.3 71,778
Vermont. ............... LD 7 1.3 56,571
South Dakota............ MiLS 8 1.0 50,875
Arizona................. SE 9 1.0 3,889
New Hampshire.......... LD 7 0.9 27,000
Louisiana ................ SE 9 0.9 31,000
Texas ................... SE 8 0.9 23,123
Oklahoma............... SE 5 0.9 32,000
Virginia. ................ SE 8 0.8 126,625
Arkansas ............... SE 8 0.5 16,750
Wyoming................ MiLS 1 0.5 18,000
Utah ............. ..... MiLS 7 0.4 12,857
West Virginia............ LD 10 0.4 25,700
Maine. ................. MajLS 6 0.3 139,833
Connecticut ............ LD 9 0.3 12,889
Rhode Island............ LD 4 0.3 1,750
Indiana................. LD 6 0.3 9,833
Minnesota............... MajLS 10 0.3 81,900
Wisconsin ............... MajLS 10 0.2 71,600
North Dakota........... MajLS 10 0.2 21,600
New York............... MajLS 6 0.2 86,714
Massachusetts ........... LD 8 0.1 6,000
Iowa ................... LD 8 0.1 17,000
Missouri................ LD 5 t +
Nebraska ................ MiLS 4 t +
Idaho................... MiLS 9 t 3,444
Oregon................. MiLS 8 t +
Montana................ MiLS 7 0 0
Washington .............. MiLS 9 0 0
Nevada. ................ MiLS 0 -

United States............ ... 10 0.845 3,980,000

1MiLS = Minor Late Surplus MajLS = Major Late Surplus
LD = Late Deficient SE = Southern Early
2t = trace + = loss too small for actual estimate.








Bulletin 222, Potato Spraying and Dusting Experiments 11














Ta iUAdNr STrATES AND TE UUtTED STATES t
-A RA6Z LOssES FI 141- n1*7
STATES PER CEMT
milur ion p ol w n .2Sl le r ha ta wrCe
ntmg + TA CE


WISE TSRAPPI
WI11O SI*C

Fig. 3.-Diagram showing the percentage losses of potatoes due to early blight
and its distribution in the United States.

million people, it was not until a half century later that trials were
made with the methods which are now generally known. Accord-
ing to Jones et al.(26), bordeaux mixture was first successfully
used for the control of late blight of tomatoes in 1884 by Jouet, in
France. That same year Vasey(66) described this disease on
potatoes in the United States, as did others during the preceding
20 years or longer(1) (44) (45) (49) (50) (58) (59), and remarked
"there is no known remedy against the potato disease." In 1888
Prilleux reported(26) some control on potatoes in France. One
year prior to Prilleux's report Scribner of the United States De-
partment of Agriculture definitely recommended and introduced
(52) the use of this fungicide into the United States by printing a
circular entitled "Treatment of the potato and tomato for blight
and rot." This was followed during the next few years by trials
and recommendations in the United States by investigators in
Massachusetts (19) (20), Tennessee (53), Ohio (67) (68), Maine (17)
(18), New Jersey(16), Connecticut(60), Illinois(6), Rhode Island
(27), Virginia(2), North Carolina(36), Vermont(22) (37), Iowa
(43) and probably elsewhere.
Experiments conducted over 10- to 20-year periods by Jones and
Giddings(23) (4) (25), Lutman((30) (31), Morse(40) (41), Stew-
Giddings (2) (24) (25), Lutman(30)(31), Morse(40)(41), Stew-








12 Florida Agricultural Experiment Station

art et al.(54) (55) (56), Munn(42), and others demonstrated con-
clusively the efficiency of bordeaux mixture for controlling blight.
This material has never been replaced, and was used for over a
quarter century with but slight modifications.
Sulphur had appeared promising for a decade or two for dusting
orchard and other crops () (4) (70), but it was not until 1918 and
later that Sanders and Kelsall reported their results with copper-
lime dust for control of late blight of potato in Nova Scotia(46)
(47) (48). Whetzel and his associates conducted further experi-
ments that year in New York State with this so-called "Sanders'
dust" and obtained somewhat promising results(71). Within a
few years many experiments were reported from different sections
of the country in which bordeaux mixture and copper-lime dusts
were compared.

PRESENT STATUS OF BLIGHT CONTROL
Copper-lime dust has not replaced bordeaux mixture but experi-
mental results during the last five years indicate that, although
less efficient, if properly applied, it will give commercial control of
late blight, and probably tip-burn and hopper-burn. In Wisconsin
(9) both spray and dust were found to increase the yield and per-
centage of prime tubers. In New Jersey(32) (33)(34) (35) the
averages from 1913 to 1927 show that bordeaux mixture is more
efficient than dust in increasing the yield of all varieties tested, and
that spraying with double strength bordeaux controlled early
blight. Boyd, in New York(5) found that where equal amounts
of copper were applied to damp foliage in copper-lime dust or in
bordeaux mixture the control of early and late blight was about
the same. However, in 3 years' trials he found that.dust was less
adhesive than spray, did not produce as large increases in yield,
and was inferior to spray in controlling tip-burn. Stewart and
Parrott in New York (57)likewise found that spraying gave better
control of early blight and that dusting was of no value for con-
trolling tip- and hopper-burn. In Ohio, in 1924(12), dusting was
much inferior to spraying. Later trials in which bordeaux mix-
ture and home-made dust were compared indicated that the results
from the latter were about on a par with bordeaux mixture, at
times giving slightly lower, and again giving slightly higher in-
creases. Commercial dusts were inferior to either(13) (14) (61)
(62)(63) (64). The investigators in Michigan reported(28)(29)
(38) better control of foliage diseases from the use of bordeaux
mixture, and Butler in New Hampshire concluded(7) that the








Bulletin 222, Potato Spraying and Dusting Experiments 13

advantages of dusting are greatly overestimated and that weekly
applications of dust give results similar to fortnightly applications
of bordeaux mixture.
In Maine, where hopper-burn is nof a factor, dusting and spray-
ing were about equally efficient in the control of late blight, when
equal amounts of metallic copper were applied through each ma-
terial. It was found, however, that dust would not repel flea beetles
or control early blight as well as bordeaux mixture(11).
In Virginia(72) no increases in yields were obtained from either
dusting or spraying, as late blight is not a factor and early blight
appears too late in the growing season to cause severe losses. Thus,
dusting or spraying in that state is a matter of insect control only.
Similar conditions exist in South Carolina(39) and the growers
prefer not to use dust because of the tendency of the crop to mature
slightly later where this fungicide is applied. This is a very impor-
tant factor where the crop is harvested for the early market.
To judge from these and other investigations it is apparent that
most favorable results are obtained from spraying. This is prob-
ably because, in addition to its greater efficiency in control of fo-
liage diseases and greater increases in yield, spraying has proved
to be less expensive(5) (10) (11) (38) (64).
In many of the experiments reported the vines matured first in
the untreated, next in those plots which were dusted, and last in
the sprayed rows, and usually progressively larger yields resulted
in the same order. Occasional results have been reported where,
even with noticeable stimulation of growth and increased longevity
of the foliage, the yields were still not materially increased. The
failure to find significant increases in yield in some sections may
be explained by the work of Tilford and May(65). They suggest
that potato plants are cooled by spraying or dusting and that this
cooling effect is beneficial only in those sections where the air tem-
peratures are above the optimal for potato growing.
The factors which favor the use of dust in preference to spray
are the comparative ease, speed, and timeliness of application.
Much greater acreages can be covered with the same man- and
team-power in the same period of time and with much less close
supervision. However, in order to obtain best results, dust should
be applied where there is practically no wind and when there is
good moisture on the foliage. In most sections such conditions
obtain for only a small part of the day and it is necessary to make
the applications long before or long after regular working hours,
which is a decided disadvantage. On the other hand bordeaux








14 Florida Agricultural Experiment Station

mixture can be applied any time during the day after the vines
have partially dried.
SPRAYING AND DUSTING EXPERIMENTS IN FLORIDA
THE SCOPE OF THE WORK
Florida ranks eighth and sixth in the United States in percentage
losses due to late blight and early blight respectively, and tip-burn
and hopper-burn are unknown (Tables II, III, and IV, Figs. 1, 2 and
3). Considering the entire potato section of the state, blight control
as in many other sections, was never very successful before the
advent of dusting. This was probably due to various reasons,
among which are meager or improper knowledge of mixing bor-
deaux, poorly constructed sprayers which rendered very inefficient
service, inability to obtain good quality lime, and the variations in
the seriousness of the epidemics of late blight from year to year.
Dusting was much more favorably received, particularly because
of the greater ease of application in spite of the greater expense
involved.
Because of the loss caused by late blight, which occurs almost
every year, and the need for definite information on the compara-
tive efficiency of dusting and spraying in this important potato
section of the south, the experiments reported herein were under-
taken. These experiments were conducted in cooperation with a
commercial grower' who provided the field of potatoes, the duster
with a team and driver, and the dust. The actual operations were
conducted with the writer present at all times.
The duster, a commercial traction type which is in common use
in the Hastings section, covered three rows at a time. One of the
particular handicaps with this type of machine is the difficulty of
regulating it to deliver the dust at the desired rate per acre. How-
ever, by regulating the machine and then observing the amount
of dust used on a large tract of known acreage (10 to 20 acres) in
the commercial portion of this 100-acre farm, the actual amount
used in the experimental plot was easily determined when applied
under identical conditions.
The traction sprayer, laboratory owned, likewise covered three
rows at a time, and delivered from 75 to 100 gallons per acre at
each application.
The machine was equipped with a so-called Nixon boom with
three nozzles per row and was operated at from 200 to 300 pounds
pressure.

1G. W. Proctor and Son, Hastings, Florida.








Bulletin 222, Potato Spraying and Dusting Experiments 15

The dust used was the standard commercial copper-lime mix-
ture, either of the 20-80 or 25-75 formula as indicated below. No
arsenicals were used, as there were no chewing insects to combat.
Aphids were rather serious at times, but no insecticides were
applied for their control in the experimental plots.
The bordeaux mixture was always freshly made from stock
solutions. It was mixed by adding the concentrated lime solution
(1 pound per gallon of water) to the copper sulphate solution which
had been diluted in the sprayer tank with artesian well water to
about 75 gallons, promptly agitated, and the volume increased to
100 gallons. Lump lime was used in the experiments during the
first three years, but much difficulty was experienced because of
the coarse, gritty particles which it was impossible to eliminate,
and which constantly clogged the different strainers. Since it was
impossible to obtain a first class quality lump lime, hydrated lime
was substituted the last two years with much more satisfactory
results. The dust throughout these experiments was applied in
the early morning from 5:30 to 9:00 o'clock, when there was plenty
of dew on the vines, and the bordeaux mixture was applied during
the forenoon or early afternoon of the same day when the vines
were dry.
In Florida, frosts threaten until the middle of March and the
growers are prone to postpone dusting until all danger from this
source has passed. Since these were cooperative experiments it
was necessary at times to postpone the first applications for as
much as two weeks, when probably the proper time would have
been much earlier when the vines were six to eight inches high.
However, these first applications were always made long before
late blight appeared.
For the purpose of irrigation and drainage it is the almost uni-
versal practice in Florida to plant potatoes on ridged rows approx-
imately a foot high, with about every twelfth to eighteenth row
consisting of a comparatively deep water furrow. It is at once
evident that this method complicates experimental work, if the
plot arrangement shall eliminate all variables except the one under
investigation. In wet seasons the rapid drainage in those rows
along the water furrows is apt to cause leaching of the fertilizer,
and in dry weather, where irrigation is practiced through the water
furrows, the rows near them will have a more abundant supply of
moisture. Unless considerable caution is exercised when the beds
are built up, some of the rows will be slightly higher on one side of
the water furrow than on the other, offering further non-uniform-








16 Florida Agricultural Experiment Station

ity. Placing turn rows every 100 or 200 feet, to make the experi-
mental rows about the proper length is rather impractical in coop-
erative experimental projects where the grower is interested in
maximal yields and, therefore, wants as little waste land as pos-
sible. Also, the spraying or dusting of 10 to 20 acres to obtain a
sufficient number of replications to make the resulting data val-
uable is again impractical because of the amount of labor involved,
especially at digging time. The harvesting of potatoes in a coop-
erative project of this nature offers unique problems under Hast-
ings conditions. In this section the crop is dug rapidly and sold
immediately, and the difference of a day or two may make a differ-
ence of from a half to one or two dollars per barrel in selling price.
It is difficult to handle a mechanical digger with a large crew of
pickers, for harvesting plots, and one digger with a small crew
delays harvesting in the commercial part of the field. The most
satisfactory way under these conditions is to conduct small plots,
repeated several times, and to harvest a large number of sample
rows by hand ahead of the diggers in the commercial portion of
the field. Figure 4 shows the general arrangement of plots fol-
lowed during the last three seasons.
THE EXPERIMENTS IN 19242
In 1924 two plots consisting of 15 lands of one acre each were
devoted to comparative tests of 20-80, 25-75, and 30-70 commercial
copper-lime dust, which were manufactured by the same company.
No comparisons were made with bordeaux mixture. No copper
injury was observed, although this was predicted by some, espe-
cially where the 30-70 formula was used. No late blight was
observed, while early blight was severe in the dusted and in the
undusted rows, and there was no indication of control of the latter
by any of the dusts. The general plan of the experiments and
yields are given in Table V. The check rows matured about ten
days before the dusted rows, but no other differences were ob-
served. The general averages of the yields in the various treat-
ments indicate no important increases over the undusted rows, but
the general plan of the plots did not lend itself to the usual biomet-
rical measurements.
THE EXPERIMENTS IN 19252
Both copper-lime dust and bordeaux mixture were used in the
experiments this season. Approximately 70 gallons of a 4-4-50
bordeaux, and 21 pounds of copper-lime dust containing not less
"2See also bibliography reference No. 15.









Bulletin 222, Potato Spraying and Dusting Experiments 17


FIGURE 4.-THE GENERAL ARRANGEMENT OF THE SPRAY AND DUST PLOTS IN
HASTINGS, FLORIDA, IN 1927.

................ ... .. .. .......... ....... .. ... ............... ..
water furrow
.. dust............... ..... dust ................ ...... dust ................
.. dust............... .. .. dust................ .... dust.............
.... dust............... .... dust ................ ...... dust................
... dust................ ..... dust................. ......dust....... .......
S...... .dust..........dust. ....... ....... dust.............
dust....... ..... ...... check....... ...... ......dust ........ ......
...... dust.. .. ...... check....... ...... ...... dust ... .....
...... dust ....... ...... .... check ....... ...... .... dust........ ...
....dust ... ... ... dust.. ..... .......d.ust........ ........
.. spray ...... ...... ..... .spray................ ......spray...............
...... spray .............. ..... spray ............... ...... spray ...............
.... spray.............. ...... spray........ ....... .... spray...............
...... dust..... ......... ...... dust ................ ..... dust ................
S ... dust............... ..... dust ................ ..... dust...............
...... dust............... ..... dust............. .. ..... dust............. ..
. dust............... .... dust................ ...... dust. dus ...............
...... dust............... ... dust............. ...... dust................
water furrow
...... dust............... ...... dust ................ ..... dust...............
...... dust ............... ...... dust................ .... dust ...............
...... dust............... ...... dust ................ ...... dust ................
..... dust ....................dust............... .......dust...............
...... dust............... ...... dust ................ ...... dust ..............
...... dust...... .... ........ ... dust........ .... ..... dust........ ......
...... dust ..... .. ...dust.. .. .... .... ..dust....... ....
.... dust ...... ........... .d st. .. .dust... .. ....
...... spray........ ...... check.................... spray ...............
.... spray ............. ...... check..... ................spray......... ......
..... spray ................... check .............. ...... spray ...............
...... spray .. ... I .. ..... .. .. check .. . ....... ..... spray ..... .........
...... dust............... ...... dust ...... .......... ..... dust...............
..... dust ............... ...... dust................ ...... dust ................
...... dust................ .... dust ................ ...... dust...............

water furrow
...... spray .............. ...... spray ............... ...... spray ...............
...... spray .............. ..... spray ............... ...... spray ...............
.. .. spray .............. ..... spray ............... ..... spray ...............
...... dust............... ..... dust ................ ...... dust................
..... dust............... ...... dust ................ ...... dust ................
..... dust....... ..... ......dust .. .. . ... ... dust........ ..
.... dust .... .... ..... dust............. ..... dust..... ......
.... dust...... ....... ...... dust. .....-... .... ....dust... .
S.... spray...... ............spray....... ...... ......spray.... ......
.. spray............ ..spray.......I............dspray......... .
..... spray .............. ..... spray .............. ...... spray ...............
...... spray.............. ...... spray .... ....... ...... spray ...............
.... dust.................... dust............... ......dust..............
.... dust............... ...... dust ................ ...... dust...............
..... dust............... ..... dust .............. ...... dust ..............
.... dust............... .... dust................ .... dust............
..... dust............... ..... .dust................ ..... dust............
water furrow
. . . . . . . . . . . . . . . . . . . . . . . . . . 1 .. . . . . . . . . . .. .

*Rows continuous, but subdivided into sections 211 feet long.









18 Florida Agricultural Experiment Station

TABLE V.-YIELDS (IN UNGRADED FIELD BARRELS) OBTAINED FROM POTATOES
DUSTED WITH 20-80, 25-75, AND 30-70 PERCENT COPPER-LIME DUST IN 1924.

EAST PLOT WEST PLOT
Land* Strength
No. Barrels No. of dust No. of Barrels
per Acre rows rows per Acre


1 33.8 15 30-70 17 55.2**

water furrow water furrow


2 35.3 18 25-75 15 61.8**
I E -- -
water furrow water furrow

3 35.8 4 check 4 48.1
38.6 12 20-80 12 53.1


4 31.3 16 30-70 17 47.4

water furrow water furrow


5 40.8 16 25-75 13 43.7

water furrow water furrow


6 35.0 17 20-80 13 44.4

water furrow water furrow

7 42.0 7 check 7 47.2
33.4 9 30-70 9 47.2

water furrow water furrow


8 38.8 16 25-75 16 42.6

water furrow water furrow


9 45.3 17 20-80 18 41.4

water furrow water furrow


10 45.9 16 30-70 17 41.4

water furrow water furrow

11 37.9 4 check 6 32.1
40.1 12 25-75 12 46.7

water furrow water furrow








Bulletin 222, Potato Spraying and Dusting Experiments 19

TABLE V.-(Continued)-YIELDS (IN UNGRADED FIELD BARRELS) OBTAINED
FROM POTATOES DUSTED WITH 20-80, 25-75, AND 30-70 PERCENT COPPER-
LIME DUST IN 1924.

EAST PLOT WEST PLOT
Land* Strength
No. Barrels No. of dust No. of Barrels
per Acre rows rows per Acre

12 39.5 17 20-80 16 41.4
water furrow water furrow

13 46.7 16 30-70 17 30.9
water furrow water furrow

14 43.3 17 25-75 16 42.6
water furrow water furrow
15 38.5 5 check 6 35.4
42.5 12 20-80 12 39.8
water furrow water furrow


General average yields in barrels:

East Side West Side

38.2 30-70 41.7
39.7 25-75 43.9
40.2 20-80 44.0
38.6 check 40.7

"*172 rows constitute an acre.
"**Dug one week later than remainder of field.

than 6.8 percent metallic copper, were applied per acre at each
application. Six applications were made during the season. Since
3.93 pounds of copper sulphate is equivalent to 1 pound metallic
copper, it is evident that approximately the same total amount of
copper was applied in the dust as in the spray(69). Contrary to
last season, late blight but no early blight was present. The gen-
eral appearance of the plots at one time was that of a field which
was just beginning to be badly infected with the disease. A small
number of spots of the disease was observed in both the dusted and
the sprayed rows, but the spread was very light, while the check








20 Florida Agricultural Experiment Station

rows, and the undusted neighboring fields were dead 15 to 20 days
before the sprayed rows reached maturity. The latter were not
mature until at least a week after the death of the dusted rows.
Table VI indicates that approximately the same yields were ob-
tained with dust as with spray, both giving substantial increases
over the untreated rows.
In addition to the above, several comparisons were made in rows
206 feet long as between no treatment and small, medium and large
amounts of dust, and 5-5-50 bordeaux mixture. Four applications
were made at 10 days' intervals with a hand duster, and a knap-
sack sprayer. About 75 gallons of bordeaux mixture were applied
per acre at each treatment with a pressure as constant as that
particular type of sprayer would permit. A small amount of late
blight was observed in the check rows and the vines died about a
week before those in the dusted rows and at least 15 days before
those in the sprayed rows were mature. The amounts of dust
applied and the yields are given in Table VII. The increase in yield
of the plants in the treated rows over the untreated is consistent.
The sprayed rows produced the highest percentage of marketable
and prime potatoes, and the largest total and marketable yield.
A progressive increase of culls from sprayed to dusted, and from
dusted to check rows, was observed. Because of the relatively
small number of tests in which different amounts of materials
were used no conclusions can be drawn as to the proper amount of
dust required for maximal results.

THE EXPERIMENTS IN 1926
The experiments this season consisted of comparisons between
20-80 copper-lime dust (copper content not less than 6.8 percent)
and 4-4-50 bordeaux mixture on uwo different plots. Each plot
consisted of 7 lands of an acre each. One-half of each land was
either dusted, sprayed or left untreated in order that numerous
direct comparisons could be made at digging. The first plot,
planted January 5, received but 3 applications, the first of which
was made on March 22 after the danger from frost had passed.
The dusted section received 20, 28, and 40 pounds of dust per acre,
respectively, for each of the applications, or a total of 88 pounds of
dust. The sprayed portion of the plot received about 100 gallons
of the spray per application per acre at 250 pounds pressure.
Obviously, a total of approximately 6 pounds of metallic copper was
applied in both the spray and the dust throughout the season.
This plot was dug April 13, some time before the vines were ma-









Bulletin 222, Potato Spraying and Dusting Experiments 21

TABLE VI.-COMPARATIVE YIELDS OBTAINED FROM DUSTED AND SPRAYED
POTATOES IN HASTINGS, FLORIDA, IN 1925.
EAST PLOT

d Calculated No. of N o U. S. Grade M ket-
aNo. field barrels rows Fungicide rows Mable
per acre No. 1 No. 2

water furrow water furrow

70.0 4 20-80 dust 3 48.5 17.4 65.9
1 79.8 8 20-80 dust 9 41.4 19.1 60.5
76.2 4 20-80 dust 4 37.0 16.0 53.0

water furrow water furrow

60.3 4 check 4 41.8 16.0 57.8
2 76.5 8 bordeaux 8 49.6 17.3 66.9
73.3 4 bordeaux 4 45.4 17.3 62.7

water furrow water furrow

68.4 4 20-80 dust 4 53.4 18.4 71.8
3 70.0 9 20-80 dust 10 48.8 22.2 71.0
66.8 4 20-80 dust 4 49.5 17.3 66.8

water furrow water furrow

58.6 4 check 4 44.5 16.0 60.5
4 76.9 8 bordeaux 8 47.5 16.6 64.1
57.0 4 bordeaux 4 47.5 16.0 63.5

water furrow water furrow

66.0 4 check 4 43.8 18.4 62.2
5 79.0 8 20-80 dust 8 52.9 12.6 65.5
77.4 4 20-80 dust 4 44.7 16.0 60.7

water furrow water furrow

General average yields:

Calculated
eld barrels Fungicide Primes Seconds Marketable

73.5 20-80 dust 47.0 17.4 64.4

70.9 bordeaux 47.5 16.8 64.3

61.6 check 43.4 16.8 60.2

Increase over check
Primes Seconds Marketable

barrels percent barrels percent barrels" percent barrels percent

11.9 19.3 20-80 dust 3.6 8.3 0.6 3.6 4.2 7.0

9.3 15.1 bordeaux 4.1 9.4 0.0 0.0 4.1 6.8








22 Florida Agricultural Experiment Station

ture. The yields, given in Table VIII, were obtained by digging
numerous sample rows 50 feet long. Each sample row of the
different treatments was selected from similar positions of the
land so the results would be comparable. Although a small amount
of late blight was observed, no important increases in yield resulted
from either dusting or spraying. It is possible that this was due to
the fact that the potatoes were dug before they were mature, and
because only a small number of applications of the fungicide could
be made during the comparatively short growing season.
The second plot was planted January 21 and dug May 11. A
total of six applications of the fungicides were made on this plot
during the growing season. The dust was applied at an average
rate of 38 pounds per acre per application and the spray was ap-
plied as in the other plot, at the rate of 100 gallons, or approxi-
mately two pounds of metallic copper per application per acre. A
medium amount of late blight was observed in the check rows and
a small amount was observed in the dusted and sprayed rows.
There appeared to be slightly less infection in the sprayed rows
than in the dusted ones. Comparable sample rows were dug and
the yields, given in Table IX, were calculated as before. These
data show that the dusted plot outyielded in primes the check plot
with which it was compared by about one-fifth, while the sprayed
plot outyielded its particular check by about one-third. It may
also be observed that where the sprayed and dusted rows were

TABLE VII.-COMPARATIVE YIELDS OBTAINED FROM SINGLE DUSTED AND
SPRAYED ROWS OF POTATOES IN HASTINGS, FLORIDA, IN 1925.
Marketable tubers
o. f Lbs. dus' Per-
Treatment Nrel. per appi Yield Increase over check centage
per acre barrels Primes
per acre Barrels Percent
Copper-lime dust............ 2 19 53.5 5.4 11.2 64.2
Check .............. .. ... .. .. 48.1 .... .... 57.4
Copper-lime dust............ 2 35 56.9 4.4 8.4 66.4
Check...................... .. 52.5 .... ... 59.2
Copper-lime dust............ 2 47 53.5 9.0 20.2 62.2
Check ..................... ... 44.5 .... .... 55.2
Bordeaux mixture........... 6 .. 59.8 11.4 23.6 69.7
Check ............... .... .. .. 48.4 .... .... 57.2








Bulletin 222, Potato Spraying and Dusting Experiments 23

TABLE VIII.-COMPARATIVE YIELDS OBTAINED FROM DUSTED AND SPRAYED ROWS
OF POTATOES IN AN EARLY PLANTED AND HARVESTED PLOT AT HASTINGS,
FLORIDA, IN 1926.
Planted 1-5-26 Harvested 4-13-26
Yield in barrels per acre Percentages per grade
Treatment No. of
repl. Primes Seconds Unmar- Primes Seconds Unmar-
ketable ketable

4-4-50 bordeaux.... 7 34.8 16.3 8.4 58.5 27.4 14.1
20-80 dust.......... 7 35.9 14.9 6.3 62.9 26.1 11.0
Increase-spray over
dust
barrels........... .. -1.1 1.4 2.1 -4.4 1.3 3.1
percent.......... .. .-3.1 9.4 33.3 .
20-80 dust.......... 8 31.9 15.3 7.3 58.5 28.1 13.4
Check.............. 8 30.9 16.4 7.7 56.2 29.8 14.0
Increase-dust over
check
barrels............ .. 1.0 -1.1 -0.4 2.3 -1.7 -0.6
percent........... .. 3.2 -6.7 -5.2
4-4-50 bordeaux .... 5 38.5 16.0 5.4 64.2 26.7 9.1
Check.............. 5 36.2 17.2 5.8 61.2 29.1 9.7
Increase-spray over
check
barrels........... .. 2.3 -1.2 -0.4 3.0 -2.4 -0.6
percent........... .. 6.4 -7.0 -6.9


compared directly the sprayed rows yielded almost one-third more
prime tubers than the dusted rows. Even though high percentage
increases were obtained, a larger number of replications would
have given these increases even greater significance.

THE EXPERIMENTS IN 1927

Comparative experiments were again conducted this season
between home made bordeaux, as indicated below, and commercial
20-80 copper-lime dust. Only 5 lands of an acre each were devoted
to this experiment according to the plan given in Fig. 4. This plot
arrangement eliminated the necessity of spraying large acreages
in order to obtain a sufficient number of direct comparisons, per-
mitted the application of the different treatments on rows in
identical and comparable positions on the land and was readily








24 Florida Agricultural Experiment Station

TABLE IX.-COMPARATIVE YIELDS OBTAINED FROM DUSTED AND SPRAYED ROWS
OF POTATOES IN A LATER PLANTED AND HARVESTED PLOT AT HASTINGS,
FLORIDA, IN 1926.
Planted 1-21-26 Harvested 5-11-26

Yield in barrels per acre I Percentages per grade
Treatment No. of
Tramn P^ims ; Unmar- r, Unmar-
rep. Primes Second Primes Seconds Itar-
ns ketabld ketable

4-4-50 bordeaux .... 8 51.4 14.2 5.3 72.5 20.0 7.5
20-80 dust......... 8 38.8 13.8 5.0 67.4 23.9 8.7
Increase-spray over
dust
barrels........... .. 12.6 0.4 .3 5.1 -3.9 -1.2
percent.......... .. 32.5 2.9 6.0 ..
odds............. .. 40:1 1.50:1 59.2:1 .. ..
20-80 dust......... 6 37.3 12.4 5.0 68.2 22.7 9.1
Check............... 6 31.1 15.2 5.5 60.0 29.4 10.6
Increase-dust over
check
barrels........... .. 6.2 -2.8 -0.5 8.2 -6.7 -1.5
percent........... .. 19.9 -18.4 -9.1 .

odds............ .. 4.5:1 16.1:1 2.32:1
4-4-50 bordeaux.... 3 56.8 13.2 6.2 74.6 17.3 8.1

Check............... 3 43.0 12.2 4.6 71.9 20.4 7.7
Increase-spray over
check
barrels........... .. 13.8 1.1 1.6 2.7 -3.1 0.4
percent........... .. 32.1 9.0 34.8 ..
odds........... .. 9.16:1 2.85:1 5.83:1



adaptable to satisfactory biometrical measurements. Many 50-
foot sample plots were dug for direct comparisons because a
greater number of small replications would render more reliable
results than a lesser number of larger plots. Details of the appli-
cations as they were made throughout the season are as follows:









Bulletin 222, Potato Spraying and Dusting Experiments 25

Planted 1-25-27. Dug 4-22-27.

SPRAY DUST
Amount Metallic Metallic
Date Weather Formula er copper Amount copper
F per A. per A. per A.
1927
3-10 Calm-h'vy dew 4-5%-50 75 gal. 1.5 lbs. 20 lbs. 1.36 lbs.
3-19 ." 42-6-50 70 gal. 1.6 20 1.36
3-28 5-6-50 95 gal. 2.4 20 1.36 "
4-4 5-6-50 82 gal. 2.1 25 1.70 "
4-13 Sl. windy 5-6-50 70 gal. 1.8 35 2.38 "
Average 78.4 gal. 1.88 24 1.63 "




TABLE X.-COMPARATIVE YIELDS OBTAINED FROM THE DUSTED AND SPRAYED
ROWS OF POTATOES AT HASTINGS, FLORIDA, IN 1927.

Yields in barrels per acre Percentage per
No. of grade
Treatment
Primes Seconds Maket- Primes Seconds
able

Bordeaux mixture........... 8 66.4 16.5 82.8 80.1 19.9

Check ..................... 8 53.7 18.1 71.7 74.9 25.1

Increase-spray over check-

barrels ................... .. 12.7 -1.6 11.1 5.2 -5.2

percent........... ... .. 23.7 -8.8 15.5

odds.................... .. 525:1 4.14:1 103:1 ....

20-80 copper-lime dust ...... 12 62.6 19.0 81.6 76.7 23.3

Check...................... 12 49.8 18.8 68.6 72.6 27.4

Increase-dust over check-

barrels................... 12.8 0.2 13.0 4.1 -4.1

percent................. . 25.7 1.1 19.0

odds. .................. 1110:1 1.68:1 1110:1 ...

Bordeaux mixture ........... 27 64.4 17.7 82.1 78.4 21.6

20-80 copper-lime dust ...... 27 61.5 17.9 79.4 77.5 22.5

Increase-spray over dust-

barrels.................. .. 2.9 -0.2 2.7 .9 -.9

percent .......... ......... 4.7 -1.1 3.4 .... ..

odds...................... 7.79:1 2.26:1 7.79:1 ....








26 Florida Agricultural Experiment Station

The rate of application this year differed from that of last year
in that slightly more metallic copper was applied per application
in the spray than in the dust. A good grade hydrated lime was
used in making the bordeaux mixture. A small amount of blight
was observed in the sprayed rows, considerably more in the dusted
rows, and a heavy infection in the checks. The check rows ma-
tured about one week earlier than the dusted rows and about two
weeks earlier than the sprayed rows. The yields are given in
Table X. The yields of the sprayed and dusted rows were prac-
tically identical and they showed consistent significant increases
over the check rows.

THE EXPERIMENTS IN 1928
A 5-5-50 bordeaux mixture was again compared with 20-80
copper-lime dust in a plot arrangement similar to that used in
1927. Three lands of one acre each were devoted to this experi-
ment. At digging time only those rows were considered which
were entirely comparable in every respect. Only 4 applications
were made this season because, as before, the cold weather delayed
the first application by three weeks. The spray was applied with
250 pounds pressure, using three nozzles per row, as before, and
at the rate of 90 gallons per acre per application, making a total
of about 9.2 pounds metallic copper during the season. The dust
was applied early in the morning of the same day on which the
spray was applied. About 18 pounds per acre were applied at the
first treatment, and 20 pounds per acre in each of the three suc-
ceeding treatments, making a total of approximately 5.3 pounds
of metallic copper per acre from the dust.
No late blight was observed in the experimental plots but early
blight infection was particularly heavy in both the dusted and the
check rows. Although it did not give good control, bordeaux mix-
ture controlled early blight much better than dust, which appar-
ently gave no control at all. Considerable injury in the form of
small, circular, necrotic lesions was observed on the leaves of the
dusted plants after the first application but no injury was observed
after succeeding applications. This injury was perhaps due to
the plants being exceptionally tender when the first application
of dust was made. When dug, the check rows had been dead for
about a week, the dusted rows were practically dead, and the
sprayed rows lacked from 7 to 10 days of being in the same stage
of maturity as the dusted rows. The yields which are given in
Table XI show that very little increase in yield was obtained by









TABLE XI.-COMPARATIVE YIELDS OBTAINED FROM THE DUSTED AND SPRAYED ROWS OF POTATOES AT HASTINGS, FLORIDA, IN 1928.
Yield in barrels per acre* Percentages per grade
No. of
repl. Primes Seconds Marketable Primes Seconds Market-
able

5--650 bordeaux............................ 30 75.31.59 18.3.394 93.61.53 80.4 19.6 100.0 .
Copper-lime dust ........................... 30 63.41.23 19.9.376 83.31.20 76.2 23.8 100.0
Increase over dust-
barrels ................. .. ............... .. 11.92.00 -1.6 .547 10.3 1.94 ... .. .
percent................................ .. 18.73.15 -8.0.28 12.42.33 ....
odds..................... 19,230:1 22:1 1350:1 .. .. .

5-5-50 bordeaux ........................... 12 78.61.50 19.4.476 98.01.59 80.2 19.8 100.0
Check ................. .................. 12 75.10.97 20.7.323 95.71.13 78.4 21.6 100.0
Increase over check-
barrels................................. .. 3.51.79 -1.3.574 2.31.95 ... ..
percent ............................... .. 4.7 2.38 -6.3.277 2.42.07 ...
odds................ .................. .. 4.6:1 7:1 1:1. ..

Copper-lime dust........................... 8 54.50.99 21.91.09 76.31.63 71.3 28.7 100.0
Check................. ................. 8 64.81.37 21.80.36 86.51.71 74.9 25.1 100.0
Increase over check-
barrels ................................ .. -10.31.69 0.11.14 -10.22.36 ...
percent................................ .. -15.92.61 0.46.523 -11.82.73 .... ..
odds ................................... .. 19,230:1 1:1 267:1 .... .... ....

*PEm =.6745 X standard deviation

V Number of items

PEd = V a+b2 where a PEm of one item and b =PEm of other item concerned.








28 Florida Agricultural Experiment Station

the use of bordeaux mixture. The increase might have been some-
what larger if the plots had been left until the vines were com-
pletely mature. The copper-lime dust, even in the comparatively
small amounts applied, proved injurious, as the yields from the
dusted rows were consistently less than those from the checks
for each of the 8 replications. These results, although consistent,
are not in agreement with those obtained previously, as such defi-
nite decreases in yield in the dusted rows were not before observed.
Cook(8) has shown that when used alone, copper may definitely
increase, and lime used alone may definitely decrease yields. It
is doubtful if the injury obtained this year was due to the lime
applied, and it is suggested by Sanders and Kelsall(46) that dust
injury follows aphis injury. Aphids were particularly severe in
the plots during the latter part of the season. It is worthy of note
that a higher percentage of primes was obtained in the sprayed
rows than in the dusted or in the check rows, and where compared
directly the percentage of primes in the check rows was greater
than that in the dusted rows. If the vines in the sprayed rows
had been allowed to grow to complete maturity these percentages
might have been slightly different.

THE EXPERIMENTS IN 1929

Bordeaux mixture was not used in the experimental plots this
season. Spraying with this mixture is not practiced to any great
extent in the Hastings section and most growers are thoroughly
convinced that dust is the most practical fungicide for existing
local conditions. It is probable that more experimental consid-
eration should be given to the improvement of the methods of
dusting, unless spraying is demonstrated as more practical and
economical.
One-half of each of five lands, each land consisting of an acre,
was dusted every week and the other half every two weeks with a
commercial 20-80 copper-lime dust. In general, the entire plot
arrangement was similar to that given in Fig. 4. Since the num-
ber of rows in the lands was not a multiple of 3 (the number of
rows dusted at one trip by the duster used), it was necessary to
double dust several rows in each land in order to leave none un-
dusted. Consequently, several of the rows were given both the
weekly and the fortnightly applications. An attempt was made
to regulate the amount of dust per application on the rows dusted
at weekly intervals so that the total amount of dust applied during
the season would approximate the amount applied on rows at fort-








Bulletin 222, Potato Spraying and Dusting Experiments 29

nightly intervals. With the type of machine used it was not abso-
lutely possible to succeed with this plan. The number of pounds
of the fungicide per application per acre and the conditions at the
time the applications were made are as follows:

1929 Double Weekly Fortnightly Weather conditions.
3-9 40 15 25 Calm-heavy dew
3-16 15 15 0 "
3-23 46 23 23 "
3-30 16 16 0 Slight breeze-heavy dew
4-6 34 12 22 Calm-heavy dew
4-13 16 16 0 Very slight breeze-heavy dew
Av. per appl. 28 16.1 23.3
Total pounds
metallic cop-
per applied
during season 11.4 6.6 4.8

As the plants approached maturity it appeared that dusting at
weekly intervals might be more profitable than dusting at longer
intervals. The checks died first, the plants dusted every two weeks
died about a week later, while the plants dusted at weekly intervals
remained green fully seven days longer than those dusted fort-
nightly.
Late blight, early blight and aphids were present but the first
two did not prove extremely serious, and the latter were largely
controlled by entomogenous fungi.
Many sample plots were dug, as before, and the yields from
plots which were dusted at different intervals and which occupied
similar positions on the lands were compared. The calculated
yields are given in Table XII.
It may be observed in this table that no significant increases in
yield were obtained, although there was a marked difference in
the appearance of the foliage just before harvesting. It is believed
that if the experiments were conducted over a period of years and
with better and more accurately regulated dusters some valuable
information regarding the proper interval of time between appli-
cations of dust could be obtained. The results of this one year
must be considered as preliminary.

COMPARATIVE COST OF SPRAYING AND DUSTING
The relative cost of dusting and spraying has been much dis-
cussed. Some find dusting much cheaper (see above) and some
suggest that the entire operation is not much more expensive than
spraying(9). By calculating costs on a basis of a small experi-










Co





TABLE XII.-COMPARATIVE YIELDS OBTAINED FROM THE ROWS OF POTATOES DUSTED AT DIFFERENT INTERVALS OF TIME AT HAST- g
INGS, FLORIDA, IN 1929.
Primes Seconds
Time interval No. of Yield Increase over check Yield
sample per acre per acre over
plots --
Barrels Barrels* Percent Odds Barrels Barrels Percent Odds C

Fortnightly........... 34 46.6 .94 1.81.59 4.03.55 1.18:1 15.5.37 .5.73 3.34.87 1:1

Weekly .............. 35 46.4.84 1.61.53 3.63.42 1.18:1 15.2.35 .2.72 1.34.80 ....

Double ............... 18 48.7+.85 3.91.54 8.73.44 9.89:1 15.2.48 .2.79 1.315.27 ....

Check................ 13 44.8 1.28 .............. 15.0+ .63 ...... ......... ....


"*PEm = .6745 X standard deviation
-to
V Number of items

PEd = V a+b2 where a = PEm of one item and b =PEm of the other item concerned.








Bulletin 222, Potato Spraying and Dusting Experiments 31

mental plot, there is probably opportunity for frequent error. An
estimate of cost based on a large commercial scale of operation is
more accurate, and it is for this reason that such comparisons are
given below.
The basis of this comparison consists of the time, labor, mate-
rials and equipment which are required on two large farms in the
Hastings district where spraying and dusting are done with good
equipment and a high degree of thoroughness.
On one farm of 160 acres, where spraying was the customary
practice, it was found that two power sprayers, two mixing sta-
tions and two supply carts, operated by six men and three teams,
covered about 50 acres daily. On another farm consisting of 100
acres where dusting was the preventive measure, one man, one
team and duster with no auxiliary equipment covered about 20
acres daily. The life of the two sprayers with simultaneous
usage, with five applications per season on 160 acres, was esti-
mated at eight years or a total of 6,400 acres for the two sprayers.
The life of the duster with a similar number of applications per
season on the 100-acre farm was estimated at six years or about
3,000 acres.
The actual costs are estimated as follows:

DUSTING:
Equipment
Initial cost of 1 duster ............................$325.00
Cost per acre, not including repairs, 325/3000 ................. $0.1083
Materials per Acre
25 pounds dust @ .06................... ................... 1.5000
Labor
1 man @ 2.50 per day ............................... 2.50
Labor cost per acre 2.50/20 .............................. .1250
Team hire
1 team @ 3.00 per day............................... 3.00
Team cost per acre 3.00/20 ........................... .1500
Total cost per application, per acre ..................... $1.8833








32 Florida Agricultural Experiment Station

SPRAYING:
Equipment
Initial cost of 2 sprayers........ .......... $900.00
Initial cost of 2 mixing stations and 2 supply
carts .................................. 500.00 $1,400
Cost per acre, not including repairs, 1400/6400 .............. $0.21885
Materials per Acre
10 lbs. copper sulphate @ 6c per lb............. .60
13 lbs. hydrated lime @ Ic per lb............... .13
Total cost of materials per acre. ............................ .73000
Labor
3 men @ 3.00 per day........................ 9.00
2 men @ 2.50 per day ........................ 5.00
1 man @ 1.50 per day......................... 1.50 15.50
Total labor cost per acre 15.50/50 ................... ....... .31000
Team hire
3 teams @ 3.00 per day ....................... 9.00
Total team cost per acre 9.00/50 ............................ .18000
Total cost per application, per acre ......................... $1.4388

According to these estimates the cost per application of dusting
is $0.444 greater per acre than spraying. In an average season
with 5 applications, the absolute minimum number which should
be applied under ordinary conditions, the operation would cost
$2.22 more per acre than spraying, and a greater number of appli-
cations would increase this difference accordingly.
Obviously, in the above figures, a longer life of the sprayers
would increase the difference between spraying and dusting costs,
while in the event of longer life of the duster, which is doubtful,
the costs would be somewhat more nearly alike. Also, if the cost
of commercial dust would be reduced to 4 or 41/2c per pound, or
if home-mixing should take the place of the commercial dusts now
used, the difference in cost of the two operations would be prac-
tically eliminated. It is further worthy of note that if "Instant
Bordeaux,"3 as described by Schneiderhan(51) is satisfactory,
and can be substituted for the old method of making bordeaux,
the time, labor, and expense of spraying may be reduced.
Estimates of repair charges are not given in this discussion, but
these probably would not influence the final cost data to any great
extent as repairs are necessary from time to time on either ma-
chine.

"3This method consists of dissolving powdered copper sulphate first, di-
rectly in the sprayer tank and later likewise dissolving a fine chemical hy-
drated lime, agitating the mixture constantly.








Bulletin 222, Potato Spraying and Dusting Experiments 33

It has been shown by these experiments and by other investi-
gators that greater increases frequently result from the use of
bordeaux than from the use of copper-lime dusts, and therefore
the mere calculation of actual costs of application is insufficient.
A careful analysis of the net returns based on the differences in
operating costs and on the actual yields, or on theoretical yields
for that matter, obtained from the sprayed and dusted plots in
this series of experiments, and calculated on the. average sale
prices of a low and a high price season, is justifiable. Obviously,
when identical yields are obtained from both sprayed and dusted
fields the only differences in net returns will be the actual differ-
ences of the cost of application. The difference as estimated above
for five applications per season is $2.22 per acre less for spraying
than for dusting. It is at once apparent that when spraying in-
creases the yields more than dusting the net returns per acre will
be greater in proportion to the increase in yield. Calculations of
such net returns based on medium-low sale prices on the actual
yields obtained from the comparative experiment reported for
1926 in this bulletin (Table IX) where the dusted rows yielded
considerably less than the sprayed, indicate differences as follows:
Spraying-primes, 51.4 bbls. @ $5.00............ $257.00
seconds, 14.2 bbls. @ $3.00 ............ 42.60 299.60
Less spraying costs for 5 applications,
@ $1.44 per application .................. 7.20 292.40
Dusting- primes, 38.8 bbls. @ $5.00 ........... $194.00
seconds, 13.8 bbls. @ $3.00............ .41.40 235.40
Less dusting costs for 5 applications,
@ $1.88 per application .... ............ 9.42 225.98
Increased returns per acre in favor of spraying .................. $ 66.42

Much larger differences in net returns will be observed from
these same yields if the sale prices are medium-high rather than
medium-low as indicated in the following calculations:
Spraying-primes, 51.4 bbls. @ $7.50.......... ..$385.50
seconds, 14.2 bbls. @ $5.00............ 71.00 456.50
Less spraying costs for 5 applications,
@ $1.44 per application ...... ............ 7.20 449.30
Dusting- primes, 38.8 bbls. @ $7.50............ $291.00
seconds, 13.8 bbls. @ $5.00............ 69.00 360.00
Less dusting costs for 5 applications,
@ $1.88 per application .................. 9.42 350.58
Increased returns per acre in favor of spraying ................. $ 98.72







34 Florida Agricultural Experiment Station

To judge from these data it is evident that dusting is more ex-
pensive than spraying, and that the greater the number of appli-
cations the greater the difference in the cost of the two methods
of blight prevention. Furthermore, by assuming that sprayed
and dusted rows give identical yields, the net returns would still
be much in favor of spraying, even in a year of low sale prices.
When larger increases are obtained by spraying than by dusting,
much larger net returns result from spraying, even at low sale
prices. With high prices, as were actually obtained in 1926, the
net gains by spraying border on the fantastical. The actual sale
prices in 1926 were $9.00 and $6.00, respectively, for primes and
seconds, rather than $7.50 and $5.00, as were used in the calcula-
tions, and calculations on that basis would make the difference in
net returns even more enormous.
These data demonstrate the fact that it is necessary not only
to calculate actual costs of dusting and spraying but to deduct
such cost figures from actual sale prices to determine whether
dusting is more expensive than spraying.

DISCUSSION OF RESULTS OBTAINED
The results herein reported are consistent with those obtained
in other sections. Various investigators have occasionally and
recently reported good blight control by either dusting or spray-
ing, but when compared under identical conditions, spraying has
been observed to give somewhat greater increases in yield.
Much discussion has been devoted to the disadvantages and ag-
gravations of spraying, and there is no doubt that a much greater
acreage can be covered with less equipment in the same period of
time by dusting. However, Boyd(5) and others have demon-
strated that for greatest efficiency the dust should be applied
when there is plenty of moisture on the foliage, and no wind blow-
ing. In most sections this means that dusting should be done at
night or early morning. Some growers have been observed in
the Hastings area to apply the dust more or less regardless of
wind and moisture conditions. As a result, it frequently happens
that very little dust actually reaches the leaves at any time during
the season. If spraying and dusting were to be compared under
such conditions, the differences in net returns in favor of spraying
would be even much greater than indicated above.
Dusting is much more fool-proof than spraying, but either
method must be followed carefully and thoroughly if satisfactory
results are to be obtained, and the ordinary laborer in this par-








Bulletin 222, Potato Spraying and Dusting Experiments 35

ticular district must be given constant and careful supervision
even with dusting. Dusting has great disadvantages and often
too much emphasis is placed on its advantages. It is also to be
observed in these experiments that the sprayed yielded the
largest, and the untreated rows the smallest percentage primes.

CONCLUSIONS

Although late blight (Phytophtora infestans (Mont.) de Bary)
does not appear every year, either late blight or early blight is
present every season, and the growing of a crop without the ap-
plication of bordeaux mixture in either the wet or dry form is un-
safe and unthought of in the Hastings potato section by the best
growers.
Early blight (Alternaria solani (E. & M.) J. & G.) is not com-
pletely controlled by dusting or spraying, but in exceptionally se-
vere epiphytotics dusting may afford slight relief, and spraying
some control.
Thorough applications of dust or spray afford commercial con-
trol of late blight in the Hastings section, although the latter at
times affords slightly better control.
Dusted foliage remains green about 10 days longer than the
untreated (checks) and the sprayed remains green from 10 to 14
days longer than the dusted.
Actual differences in yield between dusted and sprayed, and
between treated and check rows are not always demonstrable,
but at times they may be very significant. Some increases from
spraying may be usually expected when the experimental plots
are carefully planned and many direct comparisons are used in
order to eliminate soil variations.
The actual cost of dusting with commercial copper-lime dust,
as commonly practiced, is much greater than spraying, and the
comparison of net returns from sprayed and dusted plots demon-
strates that spraying is much more economical at present prices,
even though much more equipment and labor are required for
the use of the liquid fungicide.

SUMMARY
The average losses from late blight (Phytophthora infestans de
Bary), occurring chiefly in the northeastern section of the United
States, Florida, Arkansas, and Wisconsin, were estimated as 3.58
percent or about 14 million bushels annually for the 10-year








36 Florida Agricultural Experiment Station

period, 1918 to 1927. The average annual losses in Florida alone
from this disease during this period were about 7 percent, or al-
most 165,000 bushels (60,000 barrels).
Tip-burn and hopper-burn, although they cause no damage to
the potato crops in Florida and very little in the northwestern
states, were otherwise well distributed over the country, and
caused losses about as extensive as those produced by late blight
during this same period of time.
Early blight (Alternaria solani (E. & M.) J. & G.), although
of general occurrence wherever potatoes are grown, caused rela-
tively small losses, approximately 0.85 percent, or over 3 1/3 mil-
lion bushels of the total crop produced annually in the United
States. In Florida this pathogene caused average losses during
this 10-year period of approximately 2.2 percent, or 56,800 bushels
(20,654 barrels).
A review of the most recent literature indicated that (a) both
bordeaux mixture and copper-lime dust gave commercial control
of late blight, but that the former at times is somewhat more
efficient; (b) bordeaux mixture, although it does not control tip-
and hopper-burn completely, offers greater protection than cop-
per-lime dust; (c) dusting is more expensive than spraying.
Six years' trials in Florida yielded results similar to those of
other investigators in different sections of the United States.
Both spraying and dusting gave commercial control of disease and
usually produced significant increases in yield over the untreated
rows. Bordeaux mixture was more efficient at times than copper-
lime dust in controlling late and early blight, and significant dif-
ferences in yield between the two fungicides were sometimes
shown. When equivalent amounts of metallic copper were applied
by the two methods of treatments such yield differences were not
always demonstrated.
Spraying and dusting costs were estimated to be $1.44 and $1.88
per application per acre, respectively. Therefore, the cost of five
applications of dust is $2.20 per acre greater than the cost of the
same number of applications of spray. Since spraying usually
increases the yield more than dusting, the differences in net returns
to the growers assume large proportions, depending upon the dif-
ferences in increased yields, and actual sales prices.








Bulletin 222, Potato Spraying and Dusting Experiments 37

LITERATURE CITED

1. ABBOTT, L. S. Potato culture in Lake County, Ohio. U. S. Dept. Agr.
Rept. 1865: 295-299.
2. ALWOOD, WM. B., and R. H. PRICE. Variety tests with potatoes. Virginia
Agr. Exp. Sta. Bul. 6: 1-20. 1890.
3. BLODGETT, F. M. Hop mildew. Cornell Univ. Agr. Exp. Sta. Bul. 328:
281-310. 1913.
4. .Experiments in the dusting and spraying of apples.
Cornell Univ. Agr. Exp. Sta. Bul. 340: 149-179. 1914.
5. BOYD, O. C. The relative efficiency of some copper dusts and sprays in
the control of potato diseases and insect pests. New York (Cornell)
Agr. Exp. Sta. Bul. 451: 1-68. 1926.
6. BURRILL, T. J., and G. W. McCluer. Use of fungicides upon the apple,
the potato, and the grape. Illinois Agr. Exp. Sta. Bul. 15: 489-496. 1891.
7. BUTLER, O. Hand spraying and hand dusting potatoes. New Hampshire
Agr. Exp. Sta. Cir. 26: 3-16. 1927.
8. COOK, F. C. The influence of copper sprays on the yield and composition
of Irish potato tubers. U. S. Dept. Agr. Bul. 1146: 1-26. 1923.
9. DUDLEY, JOHN E., JR., and C. L. FLUKE, JR. Spraying versus dusting to
control the potato leafhopper in commercial potato fields of Wisconsin.
Wisconsin Agr. Exp. Sta. Research Bul. 82: 1-16. 1928.
10. FERNOW, KARL. Spraying and dusting potatoes. American Potato
Journal, 5:157-159. 1928.
11. FOLSOM, DONALD, and REINER BONDE. Potato spraying and dusting ex-
periments, 1921 to 1925. Maine Agr. Exp. Sta. Bul. 334: 205-284. 1926.
12. Forty-third Annual Report (for 1923-24). Spraying and dusting pota-
toes. Ohio Agr. Exp. Sta. Bul. 382: 30-31. 1924.
13. Forty-fifth Annual Report (for 1925-26). Spraying and dusting pota-
toes. Ohio Agr. Exp. Sta. Bul. 402: 39. 1927.
14. Forty-sixth Annual Report (for 1926-27). Spraying and dusting pota-
toes. Ohio Agr. Exp. Sta. Bul. 417: 35-37. 1928.
15. GRATZ, L. O. Irish potato disease investigations, 1924-25. Fla. Agr.
Exp. Sta. Bul. 176: 1-23. 1925.
16. HALSTED, B. D. Fungous diseases of various crops. Potatoes. New
Jersey Agr. Exp. Sta. Rept. 3: 345-347. 1890.
17. HARVEY, F. L. The potato rot. Maine Agr. Exp. Sta. Bul. 2:5-7. 1889.
18. The potato rot. Maine Agr. Exp. Sta. Rept. 1889:
174-181.
19. HUMPHREY, J. E. The potato blight and rot. Massachusetts Hatch
Exp. Sta. Bul. 6: 17-19. 1889.
20. Department of vegetable physiology. Massachusetts
Agr. Exp. Sta. Rept. 7: 226-227. 1890.
21. JONES, L. R. Potato blight and rot. Vermont Agr. Exp. Sta. Rept. 4:
131-138. 1890.
22. --. Potato blight and rot. Vermont Agr. Exp. Sta. Bul.
24: 19-32. 1891.
23. Certain potato diseases and their remedies. Vermont
Agr. Exp. Sta. Bul. 72: 1-32. 1899.
24. JONES, L. R., and N. J. GIDDINGS. Potato spraying experiments. Ver-
mont Agr. Exp. Sta. Bul. 136: 190-201. 1908.
25. Potato spraying experiments. Vermont
Agr. Exp. Sta. Ann. Rept. 20: 334-342. 1908.
26. JONES, L. R., N. J. GIDDINGS, and B. F. LUTMAN. Investigations of the
potato fungus Phytophthora infestans. Vermont Agr. Exp. Sta. Bul.
168: 1-100. 1912.
27. KINNEY, L. F. The downy mildew of the potato or the potato blight.
Rhode Island Agr. Exp. Sta. Rept. 3: 137-152. 1891.
28. KOTILA, J. E., and G. H. CooNs. Spraying and dusting of potatoes in
1922 at Chatham, Michigan. Phytopathology 13: 54-55. 1923.
29. Potato spraying and dusting experiments
in Michigan. Michigan Agr. Exp. Sta. Technical Bul. 72: 3-15. 1925.








38 Florida Agricultural Experiment Station

30. LUTMAN, B. F. Plant diseases; potato spraying. Vermont Agr. Exp.
Sta. Bul. 153: 619-629. 1910.
31. Twenty years' spraying for potato diseases. Potato
diseases and the weather. Vermont Agr. Exp. Sta. Bul. 159: 215-296. 1911.
32. MARTIN, W. H. Potato spraying in 1924. New Jersey Agr. Exp. Sta.
Rept. 1925: 464-467.
33. MARTIN, W. H., and L. G. CAMPBELL. Potato spraying in 1925. New
Jersey Agr. Exp. Sta. Rept. 1926: 324-329. (1927).
34. MARTIN, W. H. Potato spraying. New Jersey Agr. Exp. Sta. Rept.
1927: 221-224.
35. A. G. WALLER, and H. B. WEISS. The potato industry in
New Jersey. New Jersey Agr. Exp. Sta. Bul. 454: 3-31. 1927.
36. MCCARTHY, GERALD. Potato blight. North Carolina Agr. Exp. Sta. Bul.
76: 16. 1891.
37. MINOTT, C. W. Experiments with a fungicide. Vermont Agr. Exp. Sta.
Rept. 3: 117-118. 1889.
38. MOORE, H. C. Results of potato spraying and dusting experiments, 1926.
Michigan Agr. Exp. Sta. Quarterly Bul. 9: 131-133. 1927.
39. MOORE, W. D. Some important diseases of the potato in South Carolina.
American Potato Journal 5: 162-164. 1928.
40. MORSE, W. J. Potato diseases in 1907. Maine Agr. Exp. Sta. Bul. 149:
287-330. 1907.
41. MORSE, W. J. Two recent epidemics of late blight and rot of potatoes in
Aroostook County. Maine Agr. Exp. Sta. Bul. 169: 165-184. 1909.
42. MUNN, M. T. Lime-sulphur vs. bordeaux mixture as a spray for pota-
toes, II. New York (Geneva) Agr. Exp. Sta. Bul. 352: 319-326. 1912.
43. PAMMELL, L. H. Potato rot. Iowa Agr. Exp. Sta. Bul. 13: 51. 1891.
44. Report of the Commissioner. The potato and the cause of the potato rot.
U. S. Dept. Agr. Rept. 1867: 352.
45. The potato. U. S. Dept. Agr. Rept. 1868: 225-244.
(1869).
46. SANDERS, G. E., and A. KELSALL. A copper dust. Nova Scotia Ent. Soc.
Proc. 4: 32-37. 1918.
47. A further report on the new copper-
arsenic dust. Nova Scotia Ent. Soc. Proc. 5: 77-94. 1919.
48. Dusts and dusting for insect and fungus
control. Sci. Agi. 1: 14-18. 1921.
49. SANDERS, WM. The potato rot. U. S. Dept. Agr. Rept. 1883: 187-188.
50. The rot of the potato. U. S. Dept. Agr, Rept. 1885:
45-46.
51. SCHNEIDERHAN, F. J. "Instant bordeaux"-its preparation and advan-
tages for potato growers. American Potato Journal, 6: 237-242. 1929.
52. SCRIBNER, F. L. Potato blight and rot. U. S. Dept. Agr. Rept. 1887:
331-333.
53. Diseases of the Irish potato. Tennessee Agr. Exp.
Sta. Bul. 2: 27-43. 1889.
54. STEWART, F. C., G. T. FRENCH, S. M. MCMURRAN and F. A. SIRRINE.
Potato spraying experiments in 1909. New York (Geneva) Agr. Exp.
Sta. Bul. 323:17-52. 1910.
55. STEWART, F. C., G. T. FRENCH, and F. A. SIRRINE. Potato spraying ex-
periments in 1910. New York (Geneva) Agr. Exp. Sta. Bul. 338: 115-
151. 1911.
56. Potato spraying experiments, 1902-1911.
New York (Geneva) Agr. Exp. Sta. Bul. 349: 99-139. 1912.
57. STEWART, F. C., and P. J. PARROTT. Experiments with potatoes. Dusting
vs. spraying. New York (Geneva) Agr. Exp. Sta. Bul. 518: 3-29. 1924.
58. TAYLOR, THOMAS. Potato blight and rot. U. S. Dept. Agr. Rept. 1872:
198.
59. Potato blight and rot. U. S. Dept. Agr. Rept. 1873:
186-187.
60. THAXTER, ROLAND. Experiments with bordeaux mixture. Connecticut
Agr. Exp. Sta. Rept. 1889: 174-177.








Bulletin 222, Potato Spraying and Dusting Experiments 39

61. TILFORD, PAUL E. Potato spraying and dusting in 1924. Ohio Agr. Exp.
Sta. Monthly Bul. 10: 20-22. 1925.
62. Potato dusting and spraying in 1925. Ohio Agr.
Exp. Sta. Bimonthly Bul. 11: 141-144. 1926.
63. Potato dusting and spraying in 1927. Ohio Agr. Exp.
Sta. Bimonthly Bul. 13: 21-23. 1928.
64. Potato spraying and dusting in Ohio. American
Potato Journal 5: 192-194. 1928.
65. and CURTIS MAY. The effect of bordeaux mixture on
the internal temperature of potato leaflets. Phytopathology 19: 943-949.
1929.
66. VASEY, GEO. Report of the Botanist. U. S. Dept. Agr. Rept. 1885: 83-84.
67. WEED, C. M. An experiment in preventing the injuries of the potato rot.
Ohio Agr. Exp. Sta. Bul. 2: 157-170. 1889.
68. A second experiment in preventing the injuries of
potato blight. Ohio Agr. Exp. Sta. Bul. 3: 239-240. 1890.
69. WALLACE, ERRETT, and L. H. EVANS. Commercial bordeaux mixtures:
how to calculate their values. U. S. Dept. of Agr. Farmers Bul. 995:
1-11. 1918.
70. WHETZEL, H. H., and P. M. BLODGETT. Dusting as a substitute for spray-
ing. Proc. New York State Fruit Growers Association, 16: 61-75. 1917.
71. WHETZEL, H. H. Potato dusting. New York State Potato Association
Proc. 7: 15-20. 1920.
72. ZIMMERLEY, H. H. Dusting and spraying early potatoes in eastern Vir-
ginia. American Potato Journal, 5: 160-161. 1928.





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