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 Title Page
 Credits
 Table of Contents
 Introduction
 Review of previous work and...
 Experimental methods
 Results
 Discussion
 Literature cited














Group Title: Bulletin - University of Florida. Agricultural Experiment Station ; no. 450
Title: A curing procedure for the reduction of mold decay in citrus fruits
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027289/00001
 Material Information
Title: A curing procedure for the reduction of mold decay in citrus fruits
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 26 p. : ill., charts ; 23 cm.
Language: English
Creator: Hopkins, E. F
Loucks, Kenneth W ( Kenneth Wilfred )
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1948
 Subjects
Subject: Citrus -- Diseases and pests -- Control -- Florida   ( lcsh )
Molds (Fungi) -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 26.
Statement of Responsibility: by E.F. Hopkins and K.W. Loucks.
General Note: Cover title.
General Note: "Cooperating with Florida Citrus Commission"--T.p.
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00027289
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000925531
oclc - 18271820
notis - AEN6184

Table of Contents
    Title Page
        Page 1
    Credits
        Page 2
        Page 3
    Table of Contents
        Page 4
    Introduction
        Page 5
    Review of previous work and observations
        Page 5
        Page 6
    Experimental methods
        Page 7
        Page 8
        Page 9
    Results
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Discussion
        Page 24
        Page 25
    Literature cited
        Page 26
Full Text


October, 194?


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
HAROLD MOWRY, Director
GAINESVILLE, FLORIDA
(Cooperating with Florida Citrus Commission)









A CURING PROCEDURE FOR THE

REDUCTION OF MOLD DECAY

IN CITRUS-FRUITS


By E. F. HOPKINS and K. W. LOUCKS
Plant Physiologist and Associate Plant Pathologist
Florida Citrus Commission



















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


Bulletin 450









BOARD OF CONTROL

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


EXECUTIVE STAFF

J. Hills Miller, Ph.D., President of the
University3
H. Harold Hume, D.Sc., Provost for Agr.'
Harold Mowry, M.S.A., Director
L. O. Gratz, Ph.D., Asst. Dir., Research
W. M. Fifield, M.S., Asst. Dir., Admin.
J. Francis Cooper, M.S.A., Editors
Clyde Beale, A.B.J., Associate Editor3
Ida Keeling Cresap, Librarian
Ruby Newhall, Administrative Managers
Geo. F. Baughman, M.A., Business Managers
Claranelle Alderman, Accountant3


MAIN STATION, GAINESVILLE

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


AGRONOMY
Fred H. Hull, Ph.D., Agronomist'
G. E. Ritchey, M.S., Agronomist2
G. B. Killinger, Ph.D., Agronomists
H. C. Harris, Ph.D., Agronomists
R. W. Bledsoe, Ph.D., Agronomist
M. E. Paddick, Ph.D., Agronomist
S. C. Litzenberger, Ph.D., Associate
W. A. Carvar,-Ph.D., Associate
Fred A. Clark, B.S., Assistant

ANIMAL INDUSTRY
A. L. Shealy. D.V.M., An. Industrialist' 3
R. B. Becker, Ph.D., Dairy Husbandmran3
E. L. Pouts, Ph.D., Dairy Technologists
D. A Sanders, D.V.M., Veterinarian
M. W. Emmel, D'.V.M. Veterinarians
L. E. Swanson, D.V.M., Parasitologist
N. R. Mehrhof, M.Agr., Poultry Hush.3
G. K. Davis, Ph.D., Animal Nutritionist3
R. S. Glasscock, Ph.D., An. Husbandman3
P. T. Dix Arnold, M.S.A., Asst. Dairy Hush.S
L. E. Mull, M.S., Asst. in Dairy Tech.
Katherine Boney, B.S., Asst. Chem.
J. C. Driggers, B.S.A., Asst. Poultry Husb.3
Glenn Van Ness, D.V.M., Asso. Poultry
Pathologist
S. John Folks, B.S.A., Asst. An. Husb.3
W. A. Krienke, M.S., Asso. in Dairy Mfs.3
S. P. Marshall, Ph.D., Asso. Dairy Husb.3
C. F. Simpson, D.V.M., Asso. Veterinarian
C. F. Winchester, Ph.D., Asso. Biochemists


ECONOMICS, AGRICULTURAL
C. V. Noble, Ph.D., Agri. Economist' 3
Zach Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Associate
D. E. Alleger, M.S., Associate
D. L. Brooke, M.S.A., Associate
R. E. L. Greene, Ph.D., Agri. Economist
H. W. Little, M.S., Assistant

Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. Agr. Economist
J. C. Townsend, Jr., B.S.A., Agr. Statistician2
J. B. Owens, B.S.A., Agr. Statistician2
J. F. Steffens, Jr., B.S.A., Agr. Statistician2

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

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

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

PLANT PATHOLOGY
W. B. Tiadale, Ph.D., Plant Pathologist'6
Phares Decker, Ph.D., Asso. Plant Path.
Erdman West, M.S., Mycologist and Botanist
Howard N. Miller, Ph.D., Asso. Plant Path.
Lillian E. Arnold, M.S., Asst. Botanist

SOILS
F. B. Smith, Ph.D., Microbiologist 3
Gaylord M. Volk, Ph.D., Chemist
J. R. Henderson, M.S.A., Soil Technologists
J. R. Neller, Ph.D., Soils Chemist
Nathan Gammon, Jr., Ph.D., Soils Chemist
C. E. Bell, Ph.D., Associate Chemist
R. A. Carrigan, Ph.D., Asso. Biochemist3
H. W. Winsor, B.S.A., Assistant Chemist
Geo. D. Thornton, Ph.D., Asso. Microbiologist3
R. E. Caldwell, M.S.A., Asst. Chemist3
J. B. Cromartie, B.S.A., Soil Surveyor
Ralph G. Leighty, B.S., Asso. Soil Surveyor
V. W. Cyzycki, B.S., Asst. Soil Surveyor
R. B. Forbes, M.S., Asst. Soils Chemist
W. L. Pritchett, M.S., Asst. Chemist
Jean Beem, B.S.A., Asst. Soil Surveyor

SHead of Department.
'In cooperation with U. S.
a Cooperative, other divisions, U. of F.
4 On leave.









BRANCH STATIONS

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

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

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

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

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

CITRUS STATION, LAKE ALFRED
A. F. Camp, Ph.D., Vice-Director in Charge
W. L. Thompson, B.S., Entomologist
J. T. Griffiths, Ph.D., Asso. Entomologist
R. F. Suit, Ph.D., Plant Pathologist
E. P. Ducharme, M.S., Plant Pathologist4
R. K. Voorhees, Ph.D., Asso. Horticulturist
C. R. Stearns, Jr., B.S.A., Asso. Chemist
James K. Colehour, M.S., Asst. Chemist
T. W. Young, Ph.D., Asso. Horticulturist
J. W. Sites, M.S.A., Horticulturist
H. O. Sterling, B.S., Asst. Horticulturist
J. A. Granger, B.S.A., Asst. Horticulturist
H. J. Reitz, M.S., Asso. Horticulturist
Francine Fisher, M.S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
A. E. Willson, B.S.A., Asso. Biochemist
J. W. Kesterson, M.S., Asso. Chemist
R. N. Hendrickson, B.S., Asst. Chemist
,E. H. Bitcover, M.A., Soils Chemist
L. C. Knorr, Ph.D., Asso. Histologist
Joe P. Barnett, B.S.A., Asst. Horticulturist
J. C. Bowers, B.S., Asst. Chemist
D. S. Prosser, Jr., B.S., Asst. Horticulturist
R. W. Olsen, B.S., Biochemist
F. W. Wenzel, Jr., Ph.D., Supervisory Chem.

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


C. B. Savage, M.S.A., Asst. Horticulturist
D. L. Stoddard, Ph.D., Asso. Plant Path.


SUB-TROPICAL STATION, HOMESTEAD
Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
17. O. Wolfenbarger, Ph.D., Entomologist
Francis B. Lincoln, Ph.D., Horticulturist
Robt. A. Conover, Ph.D., Asso. Plant Path.
R. W. Harkness, Ph.D., Asst. Chemist
Milton Cobin, B.S., Asso. Horticulturist


W. CENT. FLA. STATION, BROOKSVILLE

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


RANGE CATTLE STATION, ONA

W. G. Kirk, Ph.D., Vice-Director in Charge
E. M. Hodges, Ph.D., Associate Agronomist
D. W. Jones, B.S., Asst. Soil Technologist
H. J. Fulford, B.S.A. Asst. Animal Hush.


CENTRAL FLORIDA STATION, SANFORD

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

WEST FLORIDA STATION, MILTON
H. W. Lundy, B.S.A., Associate Agronomist


FIELD STATIONS

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

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

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

Monticello
A. M. Phillips, B.S., Asso. Entomologist2

Bradenton
J. R. Beckenbach, Ph.D., Hort. in Charge
E. G. Kelsheimer, Ph.D., Entomologist
David G. Kelbert, Asso. Horticulturist
E. L. Spencer, Ph.D., Soils Chemist
Robert 0. Magie, Ph.D., Gladioli Hort.
J. M. Walter, Ph.D., Plant Pathologist
Donald S. Burgis, M.S.A., Asst. Hort.

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

1 Head of Department.
2In cooperation with U. S.
3 Cooperative, other divisions, U. of F.
4On leave.


















CONTENTS

Page

REVIEW OF PREVIOUS WORK AND OBSERVATIONS.....-..--.......----..---........ 5

EXPERIMENTAL METHODS --........----........... --------------. 7

RESULTS ..-... --. --.---------- --------------------- 10

Effect of Treatments on Stem-end Rot ..................-----.--- 10

Penicillium M old ........-... ...... --.-.---- ......... .......... 12

Time Factor in Curing ..... ---...-.....- ---.--_ -.........13

Curing Under Commercial Conditions .........------ ----------....... 18

Effect of Curing Artificially Wounded Fruits .........--.....--..---... 18

Curing in Relation to Peel Injury by Chemical Treatments ........... 21

Effect of Curing on Injury by Peel Oil ...............----------- ...... 22

DISCUSSION ..........-------------------------...... ..... 24

LITERATURE CITED ..............---- --------...------------ --. ---. 26








A CURING PROCEDURE FOR THE REDUCTION
OF MOLD DECAY IN CITRUS FRUITS
By E. F. HOPKINS and K. W. LOUCKS'

In the past few years mold infections caused by Penicillium
digitatum Sacc. and P. italicum Wehmer have constituted a
large share of the total decay in the marketing of Florida citrus
fruits. Such infections show a marked increase coincident with
the discontinuance of the ethylene coloring treatment. This is
true of such commercial varieties as Hamlin, Parson Brown,
Pineapple and Valencia oranges, tangerines and possibly grape-
fruit. Mold has been particularly high in the variety Pinedpple,
which for the last two seasons has needed very little treatment in
the coloring room.
The magnitude of loss caused by mold in commercial fruit can
perhaps best be emphasized by citing a particular case. Pine-
apple oranges after processing were collected from a large com-
mercial house in January 1948. No ethylene treatment was
used. On being held in storage they showed 34% of mold one
week from picking, 43 % at two weeks and 45% at three weeks.
Many other such records are available.
Any practical means of reducing mold decay is therefore im-
portant commercially and in this bulletin the authors as a result
of their experimental work outline a method of accomplishing
this.

Review of Previous Work and Observations
Some years back citrus fruits did not progress so rapidly
from the picking to the packing operation as at present. It was
considered essential that the fruits undergo a curing period
lasting one to several days before being packed. References to
this procedure will be found in earlier numbers of the Proceed-
ings of the Florida State Horticultural Society. For instance,
Hart (5)' recommended that citrus should remain in the pack-
inghouse at least 36 hours to cure and that oranges while curing
should not be over two layers deep.
Apparently one purpose of the curing operation was to allow

SCooperative investigation by the Citrus Experiment Station, Lake
Alfred, and the Florida Citrus Commission, Lakeland, Florida.
SItalic figures in parentheses refer to Literature cited in the back of
this bulletin.








A CURING PROCEDURE FOR THE REDUCTION
OF MOLD DECAY IN CITRUS FRUITS
By E. F. HOPKINS and K. W. LOUCKS'

In the past few years mold infections caused by Penicillium
digitatum Sacc. and P. italicum Wehmer have constituted a
large share of the total decay in the marketing of Florida citrus
fruits. Such infections show a marked increase coincident with
the discontinuance of the ethylene coloring treatment. This is
true of such commercial varieties as Hamlin, Parson Brown,
Pineapple and Valencia oranges, tangerines and possibly grape-
fruit. Mold has been particularly high in the variety Pinedpple,
which for the last two seasons has needed very little treatment in
the coloring room.
The magnitude of loss caused by mold in commercial fruit can
perhaps best be emphasized by citing a particular case. Pine-
apple oranges after processing were collected from a large com-
mercial house in January 1948. No ethylene treatment was
used. On being held in storage they showed 34% of mold one
week from picking, 43 % at two weeks and 45% at three weeks.
Many other such records are available.
Any practical means of reducing mold decay is therefore im-
portant commercially and in this bulletin the authors as a result
of their experimental work outline a method of accomplishing
this.

Review of Previous Work and Observations
Some years back citrus fruits did not progress so rapidly
from the picking to the packing operation as at present. It was
considered essential that the fruits undergo a curing period
lasting one to several days before being packed. References to
this procedure will be found in earlier numbers of the Proceed-
ings of the Florida State Horticultural Society. For instance,
Hart (5)' recommended that citrus should remain in the pack-
inghouse at least 36 hours to cure and that oranges while curing
should not be over two layers deep.
Apparently one purpose of the curing operation was to allow

SCooperative investigation by the Citrus Experiment Station, Lake
Alfred, and the Florida Citrus Commission, Lakeland, Florida.
SItalic figures in parentheses refer to Literature cited in the back of
this bulletin.






Florida Agricultural Experiment Station


some shrinkage of the fruit before packing to avoid later losses
which would result in slack packs. However, it was also con-
sidered that the drying which occurred while curing rendered
the fruits less susceptible to mold infections. This is brought out
in the discussion of a paper by McKay in 1913 (6), where it is
stated "if we can dry the fruit thoroughly, we can prevent the
decay that otherwise would take place."
According to Ramsey (7), fruit should be held from 24 to 48
hours or even longer after picking and before washing to avoid
injury from hot water. Later Fawcett (2) stated that lemons
are held from one to three days before washing in hot water
to avoid peel oil burn. In discussing fruit rots in general he
says also that citrus oil liberated from the glands has a severe
effect on the surface cells, causing them to break down and
allow the entrance of mold fungi.
Tindale and Fish (9) showed that in the case of oranges
inoculated with blue and green mold, decay was largely pre-
vented if they were held at 94 F. for five days, while Green (4)
claims that a contributing condition to infections by Penicillium
is the freshness of the wounds. If allowed to dry and remain
dry the wounds become fairly resistant to infection.
Since peel oil appears to be a factor in decay from mold it
may be well to point out that Bates (1) found a greater develop-
ment of Penicillium digitatum rot in Valencia oranges when
essential oil from Valencia oranges was added to wounds in the
fruits.
Fawcett and Barger (3) studied the relation of temperature
to citrus fruit decay by Penicillium italicum and P. digitatum.
They showed that temperatures between 65' and 80'F. are
conducive to rapid decay and as the temperature becomes higher
or lower than this range the rate is rapidly retarded. These
data show maximum infection of oranges by P. italicum at 74.8"F.
and a decreasing amount as the temperature increases until at
90.5 F. there was no infection at six days.
Ethylene gas coloring treatment which was not used in former
years may also be considered as a curing period, since the fruits
are held in the coloring rooms for 24 to 72 hours at an elevated
temperature and high humidity with constant ventilation be-
fore processing and packing. It was suggested by Rose et al
(8) that best results from the ethylene treatment are obtained
when the temperature is maintained between 80" and 85" F.,






Reduction of Mold Decay in Citrus Fruits


which markedly checks blue mold decay. Winston, Meckstroth
and Roberts (10) state that fruit subjected to ethylene gas for
48 to 60 hours was rendered less liable to green mold rot. In
these last two papers experimental work is not cited in respect to
mold reduction and it is not made clear if the ethylene gas or
the temperature is considered the important factor.
The coloring room treatment, of course, is used for the sole
purpose of coloring the fruit. Any reduction in mold infections
is incidental and in general the fact that it does occur is probably
not known. In the rapid handling of citrus fruit today the matter
of curing has been forgotten. The result is that in the early
part of the season, when fruit is being colored for from 60 to
70 hours, stem-end rot infections caused by Diplodia natalensis
Pole-Evans are high because of the stimulating effect of ethylene,
while mold infections are low, due to the curing effect of the
coloring room treatment. Later when the coloring is discon-
tinued or greatly reduced there is a sharp drop in stem-end rot
and a marked increase in mold, which rises to a maximum from
the middle of February to the middle of March.
From previous experimental work, results have been sum-
marized on all check lots of oranges for the four seasons 1943-
44 to 1946-47. In these experiments, which were extended over
each season, the principal commercial varieties of oranges were
used. Fruits were harvested by both pulling and clipping; some
were given the ethylene coloring treatment and others were not,
as in commercial practices. The total number of fruits in these
check lots only was 68,000. For these four seasons the average
percentages of stem-end rot and mold after three weeks in
storage and for 15-day intervals throughout the season are
shown graphically in Figure 1 to bring out the seasonal varia-
tions above mentioned.

Experimental Methods
The present investigation is the outcome of a series of experi-
ments which were designed to answer the question frequently
asked: Is it the ethylene gas in the coloring room process which
causes the marked increase in stem-end rot due to Diplodia
natalensis, or is it merely the effect of high temperature and
high humidity maintained during the degreening of the fruit?
From previous work of the authors and others it appeared
certain that ethylene is the agent which brings about the high






Florida Agricultural Experiment Station


incidence of Diplodia infections. Nevertheless, there seemed to
be available no experimental work especially set up to answer
the question directly. It was decided, therefore, to treat lots of
oranges which were as nearly alike as possible (i.e., randomized
from the same picking into two lots, one fruit at a time) in two
ways: (1) the ordinary degreening procedure using ethylene gas
in the coloring room, and (2) the same coloring room conditions
in respect to temperature, relative humidity and air movement,
but without ethylene.


60-

50-

40-


S. E. R.

20-



MOLD

OGT' NOV 'DEC JAN FEB 'MAR APR MAY JUNE
Fig. 1.-Stem-end rot and mold decay in Florida oranges after three
weeks storage. Average values for four seasons at 15-day intervals.

In the new packinghouse of the Citrus Experiment Station,
coloring rooms were available in which no ethylene gas had yet
been used. One of these rooms was used for the "minus ethylene"
treatments. It is quite certain, therefore, that none of this gas,
except possibly minute amounts produced by the fruit itself,
was present during the treating period. That this was the
case is shown by the fact that when green fruits were used
no coloring (degreening) occurred in the room without ethylene,
while excellent coloring was obtained where ethylene was used.
The coloring rooms were maintained at close to 86F. and a
relative humidity of about 90%. The rooms, designed by Dr.
A. F. Camp of the Citrus Station, are of the slatted-floor type







Reduction of Mold Decay in Citrus Fruits


in which continuous ventilation is maintained during the color-
ing process. The rate of ventilation may be varied, depending
on the amount of fruit, by manipulation of a shutter which con-
trols the intake of outside air. Ethylene, where used, was in-
troduced by means of the trickle system.
After the various treatments to be described the fruits were
placed in storage rooms and decay records were taken at week-
ly intervals for three weeks from the time of picking. The
storage rooms used for this purpose are 14 x 16 x 91/2 feet and
are well insulated. During most of the season temperature con-
trols were not available but the temperatures remained fairly
constant over a considerable period, changing very slowly with
outside temperatures. The temperature and relative humidity
values as determined from hygrothermograph records are shown
in Table 1.

Table 1.-Temperature and humidity conditions in storage rooms.
Mean Temperature Mean Relative
Period F. Humidity %
Oct. 13, 1947)
to ) 82.5 80
Nov. 17, 1947)
Nov. 17, 1947)
to ) 77.8 90
Feb. 18, 1948)
Feb. 18, 1948)
to ) 82.2 90
April 5. 1948)
April 5, 1948)
to ) 71 85
June 7, 1948)

Beginning with April 5, temperature control equipment was
installed and the conditions remained constant at the values
given above.
The above conditions are given in some detail because of
their possible bearing on the curing process under considera-
tion. That the variations shown would not greatly affect the
conclusions drawn in this paper are indicated by the following
experiment. Twenty-eight standard Bruce boxes of Valencia
oranges from the same picking were divided into two lots of 14
boxes each; one lot was placed in a storage room at 71 F. and
relative humidity of 851c and the other lot in another room






Florida Agricultural Experiment Station


at 80' F. and 80%. After three weeks in storage the decay
records presented in Table 2 were obtained.

Table 2.-Effect of storage conditions on decay in oranges.
Total
Room No. of Temp. Relative Stem-end Mold Total
Fruits I F. Hmdty. % Rot % % Decay %

1 2,620 71 85 35.6 8.6 44.2
2 2,736 80 80 39.1 4.1 43.2

The increase in stem-end rot at the higher temperature is
not great and the difference is not significant; the decrease in
mold at the higher temperature does show statistical significance
but is not very great and the total decay is practically the same.
Other details of experimental procedure will be given in con-
nection with individual experiments.

Results
Effect of Treatments on Stem-End Rot. In a series of 12
tests made early in the 1947-48 season with Hamlin oranges
a marked increase in stem-rot was found after three weeks in
storage in the ethylene-treated fruits when compared with check
lots which received no treatment at all. This was to be ex-
pected. There was also a marked increase when compared
with lots from the coloring room without ethylene which did
not differ significantly from the checks. The average values
for these tests are given in Table 3.

Table 3.-Effect of coloring room treatments on stem-end rot
in Hamlin oranges after three weeks storage.
Total No. Stem-end
Treatment Fruits Rot %

Ethylene coloring room 1200 47
Coloring room without ethylene 1200 29
No treatment at all 1200 24

This indicates that temperature and humidity of the color-
ing room have little effect on the increase in stem-end rot-
ethylene is the principal cause. There is, of course, the possi-
bility that high temperature and high humidity during the
gassing period may have a marked effect on the action of
ethylene in this respect, as they do on its degreening action.







Reduction of Mold Decay in Citrus Fruits


A series of seven tests made in the same manner with Parson
Brown oranges gave a similar result, as shown in Table 4.
Table 4.-Effect of coloring room treatments on stem-end rot in
Parson Brown oranges.
Total No. Stem-end
Treatment Fruits Rot '"
Ethylene coloring room 700 54
Coloring room without ethylene 700 41
No treatment at all 300 38

In tests made with Pineapple oranges no difference was
found in the amount of stem-end rot after three weeks storage
between ethylene-treated fruits and those not so treated. At
the time the experiments were made the fruits appeared to
have developed a natural susceptibility to stem-end rot, so that
exposure to ethylene had no appreciable effect. This is shown
by the high incidence of stem-end rot in the checks. The check
lots, it is true, showed somewhat less stem-end rot but this, as
will be explained later, was due to the high percentage of mold
infections which occurred before the stem-end rot had time to de-
velop. Average results of seven such tests are given in Table 5.
Table 5.-Effect of coloring room treatments on stem-end rot in
Pineapple oranges.
Total No. I Stem-end
Treatment Fruits Rot %
Ethylene coloring room 700 50
Coloring room without ethylene 700 50
No treatment at all 400 42
Valencia oranges which were more immature at the time of
testing gave a result more like that obtained with the Hamlin
variety. The average of five such tests which are available are
set forth in Table 6.

Table 6.-Effect of coloring room treatments on stem-end rot in
Valencia oranges.
I Total No. I Stem-end
Treatment Fruits i Rot %
Ethylene coloring room 500 36
Coloring room without ethylene 500 18
No treatment at all 300 16







Florida Agricultural Experiment Station


Here fruits from the ethylene coloring room have twice as
much decay from stem-end rot as those from the other two treat-
ments, which are not significantly different.
The foregoing data clearly show that the increased amount
of stem-end rot is caused by the ethylene gas and not by the
conditions of temperature and humidity maintained in the color-
ing rooms during the degreening period.
Penicillium Mold. In the same series of experiments dis-
cussed above in respect to stem-end rot, the first tests showed
low percentages of mold in the coloring room treatments both
with and without ethylene. However, when an additional check
lot which received no treatment at all was introduced into the
series an interesting fact was noted. These samples developed
much higher percentages of mold. The average values for
eight experiments set up in this manner are shown in Table 7
for one and two weeks storage.

Table 7.-Effect of coloring, room treatments on mold decay.
STotal No. I Decay Caused by Mold %
Treatment Fruits IAfter 1 Wk. After Wks.
Ethylene coloring room 800 2.4 14
Coloring room without ethylene 800 2.7 10
Check, no treatment 800 13.9 31

It will be seen that the amount of Penicillium mold decay in
the untreated checks is more than twice that for fruit receiving
a coloring room treatment. Later it was found that washing
and waxing the checks had no effect on the result. This is
brought out by eight other experiments in this same series of
tests in which neither coloring room treatment was used. In
this case the untreated checks (not washed or waxed) are com-
pared with washed and waxed fruits as follows:

No. of Penicillium Mold %
Treatment Fruits After 1 Wk. I After 2 Wks.
Washed and waxed 800 19.4 33.1
Check, no treatment at all 800 16.9 29.2

In both instances the incidence of mold is high and there
is no appreciable difference in the amount. It is evident from






Reduction of Mold Decay in Citrus Fruits


this that the reduction of mold is not related to the washing
and waxing but to the coloring room treatment.
As a tentative explanation of this marked reduction of mold
due to holding the fruit under coloring room conditions with or
without ethylene, we consider that there is a "curing" effect
which tends to heal mechanical injuries of the peel and thus
to a large extent prevent invasion by Pencillium species.
Time Factor in Curing. On the basis of the above, more
extensive experiments were conducted in which lots of fruit
were removed from the coloring rooms at stated intervals.
Fruits were treated simultaneously in two rooms, one with and
the other without ethylene. Conditions as regard temperature
and humidity were maintained as nearly alike as possible in
the two rooms. The average percentages of decay for four such
experiments and for two weeks storage are given in Table 8.

Table 8.-Effect of coloring room treatments on stem-end rot and
mold, 2 weeks storage.
Hours No Ethylene I With Ethylene
in Total Total
C. R. S.E.R. % I Mold % Decay % S.E.R. % Mold %/ Decay %
0 26 46 72 23 44 67
12 34 31 65 39 29 68
24 36 35 71 31 30 61
36 35 21 56 34 25 59
48 33 23 56 34 27 61
60 29 19 48 37 22 59
72 28 18 46 I 40 14 54
Note: 100 oranges were used in each case, or each item in the table
represents the percentage loss from 400 oranges.

The two lots at "zero" hours are duplicate checks which were
not placed in the coloring rooms but set directly in the storage
room. All lots were washed and waxed after treatment. In the
room without ethylene there was no consistent effect on stem-
end rot with increased time. Mold, however, was markedly de-
creased from 46% to 18%. With ethylene both an increase in
stem-end rot and a decrease in mold is shown with increasing
time. In this case one compensates the other so that total decay
is not greatly reduced. In lots from the "no ethylene" room,







Florida Agricultural Experiment Station


however, a marked reduction in total decay is shown after an
exposure of 60 or 72 hours.
Further experiments on effect of coloring room treatments
in reducing mold infections gave the same result as shown in
Table 8. These include three experiments with Valencia oranges.
With no exceptions, fruits held in the coloring room either
with or without ethylene show marked reductions in the per-
centages of mold. The percentage of mold is inversely pro-
portional to the time the fruits are held under coloring room
conditions and the data plot out as fairly smooth curves. The
effect is particularly striking after one week in storage but as
will be shown it is still very marked after two and three weeks.
From this it is evident that the "curing" action in the coloring




40
s\
35 \


30



25- -





o
SC2H4 C
15


W--
010 0
1-V ^ k
S Y^'-


10 20 30 40 50 60 70
HOURS IN COLORING ROOM
Fig. 2.-Effect of coloring room treatments
with ethylene (CH,) and without ethylene (cur-
ing) on Penicillium mold infections in oranges.






Reduction of Mold Decay in Citrus Fruits


rooms is not a temporary thing. The data will be presented in
the form of graphs.
In Figure 2 is shown the percentage of mold at one and two
weeks plotted against the time the oranges were held in the
coloring rooms. The curves represent the average of seven
experiments and include Pineapple, Parson Brown and Valencia
oranges. The similarity of the results with ethylene and with-
out ethylene is obvious. The reduction in mold at one week for
the 72-hour treatment in both cases is 80%, which is an amount
worth considering from the practical standpoint. It should be
mentioned that the lower incidence of mold following the color-
ing room treatments was not influenced by the occurrence of
high stem-end rot infections, since after one week in storage
practically no stem-end rot had developed. That is, the reduction
is real and not apparent.
At the end of two weeks storage a uniform decrease of mold
with time of treatment is again obvious and the curves with and
without ethylene parallel each other very closely. The reduction
of mold for the 72-hour exposure is approximately from 40%
to 14 %, or a decrease of about 65 %.
In Figure 3 the average results for these same seven experi-
ments are presented, this time for the checks and the 72-hour
treatments only, plotted against the time in storage. The stem-
end rot is also shown. In respect to mold the diagram clearly
shows that the curing effect is lasting, so that even after three
weeks in storage the amount of control is about 57%. As would
be expected, the plus ethylene samples show a marked increase
in stem-end rot when compared with the checks. Those without
ethylene show a greater increase at three weeks than we had
expected from our results reported in the first part of this
paper. However, in five of the seven experiments on which the
averages were based, Pineapple and Parson Brown oranges were
used. In these varieties at the time the experiments were set
up stem-end rot fungi may have been somewhat active when the
fruits were picked. It is possible, therefore, that exposure for
three days at the high temperature and humidity of the color-
ing room, even without ethylene, hastened invasion of the rot
organisms into the fruits.
Valencia oranges which were more immature did not show
an increase of stem-end rot over the check lots when held for
72 hours in the coloring room without ethylene. This is brought






Florida Agricultural Experiment Station


-I
0
23<
U.
0


I-
z
WIt
o

0.


+ C2 H4/


/
/
/


0C2 H4



CHECK


CHECK


+ C2 H4
0
+
<:


I 2 3
WEEKS IN STORAGE
Fig. 3.-Effect of coloring room treatments with ethylene (C2H4) and
without ethylene for 72 hours on stem-end rot and mold infections in
oranges. Average of seven experiments.

out in Figure 4. Otherwise, the curves are practically identical
with those in Figure 3 and the same control of mold is shown.
In this instance, with marked decrease in mold and no increase
in stem-end rot, a good reduction in total decay results.






Reduction of Mold Decay in Citrus Fruits 17




o /o

o 50 +C2H4 /


240-
0




S300
0 /

/ CHECK
0- /
o/

a 10 /
0 o



40 / CHECK

O /
.30
o /
O0







1 20 oCp02H4
0 2 3
0
-o






o




0
I 2 3
WEEKS IN STORAGE

Fig. 4.-Coloring room treatments for 72 hours with and without ethy-
lene (C,H,) and stem-end rot and mold infections. Valencia oranges.






Florida Agricultural Experiment Station


Curing Under Commercial Conditions. A commercial lot
of Valencia oranges was held in the coloring rooms of a large
packinghouse" for 72 hours. The usual conditions for coloring
were maintained as regards temperature and humidity but no
ethylene gas was used. The coloring rooms were filled to capac-
ity during the treatment. Uncured oranges from the same lot
were obtained before the curing was started. After one week
from picking samples of the uncured fruits held in storage at
70F. developed 5.3% of Penicillium mold, while the cured lots
showed none. After two weeks the average decay records were:
No. Total
Treatment Fruits S.E.R. %/ Mold 4% Decay %'
Not cured 286 10 19 29
Cured 72 hours 300 6 12 18

Both mold and stem-end rot were less in the cured fruit.
In another commercial trial carried out as before, uncured
fruits showed 3.4% Penicillium mold at one week and the cured
lot none. After two weeks in storage the following data were
obtained:

No. Total
Treatment Fruits S.E.R. '% Mold % Decay %
Not cured 268 1 22.5 18.5 41.0
Cured 72 hours 277 8.5 10.0 18.5

Possibly the lower amounts of stem-end rot in these two
commercial trials are due to chance variation in sampling.
However, no increase in rot due to curing is indicated.
Effect of Curing Artificially Wounded Fruits. The experi-
mental work described above was carried out with oranges just
as they came from the grove, that is, with only the wounds or
mechanical injuries incidental to picking as invasion points for
Penicillium molds. Since all the fruits used were harvested by
pulling, the injuries sustained varied with the stage of maturity
of the fruits, the variety and possibly with weather conditions
and time of day when picked.
To test the curing effect more rigorously, it was decided to

SThe generous cooperation of Mr. John Leslie and Mr. D. A. Rooks of
the Haines City Cooperative Growers Association in carrying out this test
is here acknowledged.






Reduction of Mold Decay in Citrus Fruits


wound the peel of the oranges artificially and then subject them
to the curing process. Oranges were first wounded by pricking
the peel in a large number of places with wires of a steel wire
brush. The punctures were about 1 mm. deep. Inoculation with
Penicillium spores was not deemed necessary and was not done.
Oranges thus treated were (1) processed at once and placed in
the storage room and (2) cured as previously described for 72
hours and then processed. The results after six days in storage
are shown in Table 9.

Table 9.-Reduction of mold in wounded fruits by curing.
Wounded, Not Cured Wounded, Cured 72 Hours
No. No.
No. Stem-end No. i No. Stem-end No.
Fruits Rot Mold 2 Fruits Rot Mold
25 0 11 25 2 0
25 0 11 25 1 0
25 0 12 25 0 3
25 1 7 25 0 2

Total 1 1 Total % 3 5

Based on this six-day holding period the data show a reduction
in mold infections in the cured lot of about 9i '.. On all of the
41 fruits infected with mold in the uncured lot there was profuse
development of Penicillium spores, while in the cured lot the
five fruits listed as infected with mold showed no sporulation
but were decayed by Diplodia which invaded the fruits through
the wounds. A photograph of uncured o- anges infected with
Penicillium mold together with sound fruits from the cured
lot is shown in Figure 5. In the latter case wounds rsade by the
punctures turned brown in color ani seemed to be healed over.
In another experiment 100 wounded uncured oranges deve hoped
30 Penicillium mold infections in one week while 100 i\'ii.'Ad
and cured ones showed none, but had ,'b*,wound infections
caused by Diplodia. I "
A third experiment was set up in which wounded fruits were
divided into three lots. The first was washed and waxed at once
and placed in the storage room, the second was held in the
storage room 72 hours and then processed and the third was
cured 72 hours in the coloring room without ethylene and then






Florida Agricultural Experiment Station


processed and stored. Result after one week in storage is shown
in Table 10. In unwounded oranges there was so little mold
that no effect of the curing treatment is obvious. However,
in the case of the wounded fruits the curing treatment entirely
prevented Penicillium mold infections but allowed for consid-
erable invasion by Diplodia through wounds. When processed at
once after wounding all infections were by Penicillium.
If the processing is delayed for 72 hours while the fruits are
kept in the storage room there is considerable reduction of
decay by Penicillium but at the same time a number of Diplodia
side infections occur, so that the total decay is about the same
as in the lot which was processed directly after wounding. It
would seem that the curing process will protect the fruits


Fig. 5.-Effect of curing on artificially wounded fruits: above, not
cured infected with Penicillium mold; below, cured 72 hours not infected.


,.?






Reduction of Mold Decay in Citrus Fruits


Table 10.-Effect of curing for 72 hours on Penicillium mold infections.
No. of Decay After 1 Week
Fruits Treatment Pen. Mold Diplodia*
100 Not wounded, not cured 3 0
100 Not wounded, cured 2 0
100 Wounded, not cured, processed at
once 43 0
100 Wounded, not cured, held 72 hours
in storage room and then processed 28 18
100 Wounded, cured 72 hours and
processed 0 26
Side infections.
against Penicillium but not against some wound infections by
Diplodia. Further experiments are in progress in an attempt
to explain this curing effect.
Curing in Relation to Peel Injury by Chemical Treatments.-
During experiments in which an organic mercurial compound,
phenyl mercury acetate, was being tested to determine its effect
on decay in oranges it was noted that the chemical caused severe
peel injury if the fruits were not washed or rinsed after treat-
ment. Also, if the fruits were rinsed after treatment the severity
of the injury was proportional to the time elapsing between
treatment and rinsing.
It was further determined that this compound, while effective
in controlling stem-end rot, did not, under the condition of our
experiments, greatly reduce mold. With this in mind it was
decided to combine the chemical treatment with the curing
procedure to combat both types of decay. This investigation is
still under way and will not be reported on here.
However, an interesting observation was made in respect to
the effect of curing on the severity of this peel injury. Oranges
were dipped in a 1:5000 concentration of the phenyl mercury
acetate in water solution. One lot was placed directly in a
storage room at 70' to 72'F. and the other under the usual col-
oring room conditions but with no ethylene gas. After 72 hours
both lots were processed (washed, waxed and polished) and
returned to the storage room. When examined four days later
the uncured lots showed severe peel injury as evidenced by red-
dish brown patches on the surfaces of the fruits. On the other
hand, the cured oranges had no evidence of peel injury from






Florida Agricultural Experiment Station


Fig. 6.-Prevention of chemical peel burn by curing. All fruits treated
in a chemical solution. Above, not cured; below, cured for 72 hours.

the chemical treatment. A photograph of both cured and un-
cured oranges from this experiment is shown in Figure 6. The
experiment was repeated several times with the same result.
Further investigation of the alleviation of chemical peel burn
by the curing treatment should determine its cause and reveal
if it is effective in reducing peel injury due to other chemical
dips. These results, however, show that damage to citrus fruits
from either mechanical or chemical injury is lessened by the
curing process.
Effect of Curing on Injury by Peel Oil. It was thought,
especially in experiments with wounded fruits, that peel oil
which is liberated when the peel is wounded may have been a
factor in the development of mold infections. Several experi-
ments were set up to test this idea. The results are given in
Table 11. Commercial cold pressed orange peel oil was atomized
on the oranges under test and applied as shown in the table. In
treatment No. 3 it was applied after curing and processing;
in No. 4 directly after wounding, held in storage at 70F. for 72
hours and then processed; in No. 5 directly after wounding and
then cured 72 hours before processing; No. 6 was like No. 3
except that peel oil was applied before waxing; in No. 7 the






Reduction of Mold Decay in Citrus Fruits


Tabe 11.-Effect of curing on injury by peel oil.
Percentage of Penicillium mold at one week.
(3) (7) I (8)
(1) Wo'nd'd (4) (5) (6) Not Not
Exp. Wo'nd'd (2) Cured Wo'nd'd Wo'nd'd Wo'nd'd Wo'nd'd Wo'nd'd
No. Not Wo'nd'd Waxed +P.O.* +P.O.* Cured Not Not
Cured Cured +P.O.* Not Cured +P.O.* Cured Cured
Cured Waxed +P.O.* Check
H-83 34 5 4 84 48 ......
87 43 ] 8 27 90 23 18 44 23
88 53 34 20 87 69 11 48 1

Ave. 43 16 17 J 87 47 15 46 12
Peel Oil.
unwounded fruit was atomized with peel oil and held in storage
72 hours before processing.
Atomizing unwounded uncured oranges with orange peel
oil brings about a large increase in mold. Compare treatments
7 and 8. If oranges are wounded the increase in mold is about
the same. Compare treatments 1 and 8. Curing wounded
fruits prevents the increase in mold caused by wounding. Com-
pare 1, 2 and 8. The curing procedure also prevents the large
increase in mold in wounded fruits when peel oil is present.
This is shown by the difference between 4 and 5. It is also
possible that curing renders the fruits resistant to the injurious
action of peel oil when the latter is applied after curing (Nos. 3
and 6). In No. 3 the oranges were waxed before applying peel
oil while in No. 6 they were waxed after the peel oil application.
More tests will need to be made to determine if wax interferes
with the action of peel oil but it appears at present that curing
makes the fruit less susceptible to injury by peel oil just as
it offsets the injury previously described caused by phenyl
mercury acetate.
Since both wounding and chemical treatments which result
in a large increase in the number of fruits attacked by Peni-
cillium molds bring about the release of peel oil and since it has
been shown that peel oil itself increases mold infections, it is
logical to assume it to be a primary factor in this type of decay.
The curing procedure therefore may act in two ways: (1)
to change the nature of the fruit peel so as to make it more
resistant to injury by peel oil or (2) to change the ratio of the






Florida Agricultural Experiment Station


peel oil constituents to make the oil less injurious to the peel.
The fact that oranges treated with peel oil after curing (3 and
6 in Table 11) do not show an increased amount of mold when
compared with treatment 2 indicates the first explanation to
be the correct one.

Discussion
It has been shown in this investigation that holding oranges
in a coloring room at 860F., 90% relative humidity and con-
tinuous ventilation (either with or without ethylene) causes a
marked "curing" effect which greatly reduces the susceptibility
of the fruits to decay by Penicillium molds. While ethylene
has been eliminated as a factor in this curing action of the color-
ing room, at present the relative importance of the other factors
such as temperature, relative humidity and air flow have not
been fully determined. However, preliminary experiments indi-
cate that neither air flow alone nor coloring room temperature
alone is effective. Several experiments in which oranges were
held at a low relative humidity indicate that the curing effect
is not caused simply by a drying out of the fruit.
Another important phase of the problem is: What is accom-
plished by the curing action which decreases the percentage
of infection by Penicillium species? Three possibilities may be
considered: (1) a change in the tissue of the citrus peel,
especially at the wounded surfaces, may take place during the
curing which renders it more resistant to invasion of Penicill-
ium molds; (2) the high temperature maintained in the coloring
room (880 to 90 F.) may have a weakening effect on the fungi
which cause this type of decay so as to reduce their pathogenic-
ity; (3) at the high temperature and high rate of air flow, peel
oil which is released by both mechanical and chemical injury
and which itself causes breakdown of the rind tissue may be
volatilized and carried off during the curing process. It would
seem that experiments could readily be devised to determine
which is the most plausible explanation. The fact that both
mold infections and chemical peel burn are prevented by curing
indicates that there may be a fundamental relation between
the two. Possibly removal or change in the peel oil may be
involved.
Results obtained in this work tie in very well with what
happens almost every year in the citrus industry. At the







Reduction of Mold Decay in Citrus Fruits


beginning of the season in the fall when fruit is fully green
when picked and requires long periods (60-72 hours) in the
coloring rooms for degreening, stem-end rot is high, due to the
action of ethylene, but the percentages of Penicillium molds are
low, due to the curing action of the coloring room treatment.
As soon as natural coloring on the trees has occurred and de-
greening is not resorted to, mold infections show a sharp in-
crease and reach a maximum usually from February 15 to
March 1 because the curing effect of the degreening process is
no longer operating. Thereafter as the weather becomes warm
and humid, mold infections drop to a low value.'
The large increase in mold which occurs when the ethylene
treatment is discontinued is brought out very forcefully from
our own decay records of samples of fruit taken from commer-
cial packinghouses for the season 1947-48. A few of these
records are presented in Table 12 for samples collected in each
case from the dump belt end of the processing line. Those
obtained in December when coloring rooms were being used
are compared with other samples not treated with ethylene
collected in January.

Table 12.-Relation of Coloring Room Treatment to the Incidence of
Mold in Citrus Fruits Commercial Packinghouse Samples.


Coloring Room


Tang. 12-
Tang. 12-
PA 12-
PA 12-
PA 12-


Treatment No Coloring

:S
U) O )

a o 1] a

6-47 FV 10 50 Tang.
S6-471 HC 8 46 Tang.
S9-47 McC 11 47 PA
10-47 McD 10 48 PA
10-47 AD 8 49 PA

9.4 Average


Tang. Tangerines.


P.A


Room Treatment






1-22-48 FV 63
1-19-48 HC 26
1 22 48 PK 50
1-22-48 ST 27
1-22-48 HC 25

38.2

.=Pineapple Oranges.


From the experimental standpoint the above comparison
might be open to question, since different lots of fruit are in-

This information is based on our own experiments (check lots only)
covering four seasons and involves some 68,000 citrus fruits, as shown
in Figure 1.


38 60
39 60
41 43
42 35
43 36


Average

CR=Color Room.







26 Florida Agricultural Experiment Station

volved in the two cases. The difference is so large, however, that
it is quite convincing. On the average there is about four times
as much mold without the coloring room treatment. It so
happens that the tangerine samples listed above with and with-
out ethylene were in each instance from the same packinghouse.
On the basis of the preceding results, curing at the end of the
ethylene degreening season as above described should greatly
reduce the amount of decay caused by blue and green molds
which constitutes a large item in total decay at that time. The
cost of such treatment would be far overbalanced by the advan-
tage gained.
Work on the curing of citrus fruits is being continued to
determine more exactly the conditions necessary for maximum
reduction of decay.

Literature Cited
1. Bates, G. R. The development of artificial coloration of oranges
in Southern Rhodesia and its relation to wastage. The British
South Africa Company. Mazor Citrus Expt. Sta. Pub. No. 2C.,
1933.
2. Fawcett, Howard S. Citrus diseases and their control. McGraw-
Hill, 2nd Ed. 1936.
3. Fawcett, H. S., and W. R. Barger Relation of temperature to growth
of Penicillium italicum and P. digitatum, and to citrus fruit decay
produced by these fungi. Jour. Agr. Res. 35: 925-931. 1927.
4. Green, F. Mary. The infection of oranges by Penicillium. Jour
Pomol. and Hort. Sci. 10: 184-215. 1932.
5. Hart, W. S. Methods of shipping and packing. Fla. State Hort.
Soc. Proc. 1908: 38-44.
6. McKay, A. W. Citrus fruit handling and storage. Fla. State Hort.
Soc. Proc. 1913: 30-45.
7. Ramsey, H. J. Handling and shipping citrus fruits in the Gulf
States. U. S. D. A. Farmers' Bul. 696. 1915.
8. Rose, Dean H., Charles Brooks, C. O. Bratley and J. R. Winston.
Market diseases of fruits and vegetables. U. S. D. A. Misc. Pub.
498. 1942.
9. Tindale, G. B., and S. Fish. Blue and green mold of oranges. Jour.
Dept. Agr. Victoria 29: 101-104. 1931.
10. Winston, J. R., G. A. Meckstroth and G. Lee Roberts. 2-Aminopy-
ridine, a promising inhibitor of decay in oranges. The Citrus In-
dustry 29: 3: 5-7, 16-17. 1948.




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