FIFTEENTH ANNUAL CITRUS
SEPTEMBERi 8, 1976 SE
SEP 24 1976
AGRICULTURAL RESEARCH & EDUCATION CENTER
P. 0. Box 1088 LakeiAlfri d a3d~U Flrd1
STATE OF FLORIDA DEPARTMENT OF CITRUS
in cooperation with
FLORIDA CITRUS PACKERS
COOPERATIVE EXTENSION SERVICE
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
UNIVERSITY OF FLORIDA; GAINESVILLE
Once again we extend a sincere welcome to our visitors
n behalf of the Institute of Food and Agricultural Sciences.
'our presence at this meeting encourages us to believe that
re have a program of interest and also encourages us to
believe that we are in tune with the needs, problems, and
opportunities that are of concern to the fresh fruit industry.
I take this opportunity to express our appreciation to
ill the cooperators who participate in making this meeting
possible The cooperation of all the agencies and organi-
sations participating in the program is a necessary
ingredient in making these programs worth while.
Our combined group here at Lake Alfred, as well as those
Ln other agencies, stand ready to discuss with you and
possiblyy initiate studies on new problems facing the citrus
Eresh fruit industry. We do not have a static program, and
it is contact with the industry, itself, that guides us in
:he choice of projects on which we work. We hope that you
iave a pleasant as well as informative day.
Herman J. Reitz, Director
Agricultural Research and
Research on the new fungicides has continued during
the past year, and was broadened to include the new
experimental postharvest fungicide "Imazalil." The latter
material has considerable promise where spores resistant
to "TBZ" and "Benlate" have developed.
The study of pollution problems was greatly expanded
as a result of the need for ethylene dibromide fumigation
of grapefruit for export to Japan. Much of the overall
research is now concerned with the export area as it
continues to involve a larger and larger portion of the
There are now 3 abscission chemicals available, which
are contributing to greater progress in the mechanization
of harvesting. These are Upjohn's "Acti-Aid," Abbott
Laboratories "Release" and Ciba-Geigy's "Pik-Off."
Please feel free to stay after the conclusion of the
program to discuss your problems personally with the staff.
Come again anytime'
/ John A. Attaway \_
scientific Research Director
lorida Department of Citrus
Fifteenth Annual Citrus Packinghouse Day
University of Florida
Agricultural Research and Education Center
Lake Alfred, Florida 33850
Wednesday, September 8, 1976
9:00 A.M. Registration
9:40 A.M. WELCOME
Herman J. Reitz
Horticulturist and Director
Agricultural Research and Education Center
John A. Attaway
Director of Scientific Research
State of Florida, Department of Citrus
MORNING Arlen N. Jumper, Chairman, Scientific Research
SESSION Committee, Florida Citrus Commission
10:00 A.M. CONTROLLABLE RIND-BLEMISHING FUNGUS DISEASES
IN CITRUS GROVES THAT AFFECT PACKOUT Jack
Whiteside, Agricultural Research and Education
Center, Lake Alfred.
The old problems of melanose, scab and greasy spot rind
blotch (pink pitting of grapefruit) continue to reduce packouts
from many groves and mostly needlessly. Fungicides now
available do provide effective control of these diseases if
correctly used. However, it is not always possible to assure
good disease control if only one spray treatment is applied.
For example, one postbloom copper fungicide spray may fail to
provide long enough protection of grapefruit rind from melanose
attack, particularly if it is applied shortly after petal fall.
Similarly, a single spray of Difolatan or Benlate may not be
sufficient to provide effective control of scab on such highly
susceptible varieties as Temples and lemons. Under heavy
disease pressure, one extra spray for melanose or scab control
can make all the difference between a poor and a good packout.
In contrast, greasy spot rind blotch can nearly always be well
controlled by just one application of Benlate in June or July.
Growers of Dancy tangerines and Minneola tangelos are
now facing a new disease problem, namely Alternaria brown spot.
This disease can cause excessive fruit drop and its major
impact is therefore on yield. Nevertheless, it also reduces
packouts, because surviving fruit often carry pockmarks and
scabby pustules on the rind. Research is in progress to develop
economic methods of control for this disease.
10:10 A.M. CITRUS CANKER Ernie DuCharme, Agricultural
Research and Education Center, Lake Alfred.
Citrus canker (Cancrosis A) caused by the bacterium,
Xanthomonas citri, is a very severe and economically important
disease of citrus. The bacterium attacks fruit, leaves, and
stems and is easily spread from infected tissues including the
fruit. Insects, birds, tools, machinery, picking bags, ladders
clothing, and people all can carry the infectious bacteria from
tree to tree. The disease causes severe leaf drop, twig die-
back, and lesioned fruit unfit for marketing. Grapefruit is
very susceptible to canker and sweet oranges are next in
susceptibility. At present, there is no reliable chemical
control for canker and, where the disease occurs, production
of grapefruit and oranges is abandoned in favor of mandarin
oranges, tangerines, lemons, and limes that are tolerant to the
disease. The only effective control is best summarized as
total destruction of fruit, trees, and even groves as soon as
the disease is found.
Conditions in Florida are very favorable for canker to
develop. Canker gained entrance into Florida in 1910 on
infected nursery stock, and it was only eradicated from Florida
citrus groves at great expense to growers and the State after
16 years of persistent effort. Should canker be brought again
to Florida, the effects would be disastrous. Our extensive
areas of dense plantings of citrus would be conducive to a
very destructive epidemic; therefore, it is expedient to
maintain an effective quarantine against a reentry of canker
into Florida. At present, Japanese Unshiu oranges are allowed
to be imported only into the five Pacific Northwest states---
And that is already too close for comfort.
10:20 A.M. THE ROLE OF THE FRUIT CROPS DEPARTMENT Hilton
Biggs, Chairman, Fruit Crops Department, IFAS,
An overview of research, teaching and extension as related
to the fresh fruit industry of Florida.
10:30 A.M. USDA ROLE IN POSTHARVEST FRUIT RESEARCH Roger
Young, Laboratory Director, U.S. Horticultural
Research Laboratory, ARS, USDA, Orlando.
The USDA has an active postharvest fruit research program
coordinated with our production research. Upon harvest, fruit
of commercial and experimental varieties are evaluated for
storage and shelf-life qualities. Decay control and fruit
quality are being evaluated in storage, controlled atmospheres,
and transit, with special emphasis on overseas shipment of
grapefruit. New chemicals are being evaluated for decay control.
Airflow patterns in vans are evaluated in relation to stacking
patterns and new carton designs. Several new types of
containers are being tested for fruit shipment.
10:40 A.M. CURRENT STATUS OF ABSCISSION CHEMICALS Bill
Wilson and Earl H. Rowland, Florida Department
of Citrus, Lake Alfred.
ETHREL (ethephon) gives adequate loosening of tangerines
and tangerine hybrids with some colorbreak advantage.
Cycloheximide (ACTI-AID) now has a clearance for this purpose,
but will usually cause a light rind pitting which may cause the
fruit to be out of grade.
Abscission research with regard to fruit for processing
has continued with the most significant advances being in use
of chemical combinations. We have found that combinations of
RELEASE, ACTI-AID and chlorothalonil give superior loosening,
less fruit damage and phytotoxicity than the chemicals used
individually, and overall reduction in the total amounts of
chemicals required by 25-50%.
10:50 A.M. SOLAR ENERGY REPORT--PACKINGHOUSE APPLICATIONS -
Bill Miller, Agricultural Research and Education
Center, Lake Alfred.
Alternatives to the United States' heavy dependence upon
fossil fuels have been sought in the last few years. One of
the sources under much consideration is solar energy. Solar
energy has many advantages. Probably the major benefits are
its nonpolluting characteristics and constant long lasting
Utilization of solar energy has been under investigation
for its potential use in packinghouse operations. In 1975,
conventional flat plate collectors and an insulated water tank
were installed. This system has been used to analyze the
feasibility of two possible applications: surface moisture
drying of citrus and degreening room heating. Temperature
data has been collected on both applications. Results from
this data will be discussed and related to their potential
usage in packinghouse operations.
11:00 A.M. DEGREENING RECOMMENDATIONS Will Wardowski,
Extension Service and Andy McCornack, Florida
Department of Citrus, Lake Alfred.
The conditions recommended for degreening Florida citrus
fruit are in wide use in the industry:
Ethylene: 1 to 5 parts per million
Temperature: 82 to 85F
Relative Humidity: 90 to 96% R.H.
Fresh air ventilation: About one room change per hour.
Air circulation: 100 cu. ft. per minute per pallet
box based on the capacity of the room
See Extension Circular 389 (1973) for more detail.
Horizontal air movement gives more uniform condition in
degreening rooms. Most older style rooms do not have the air
movement necessary to give uniform degreening when fruit is
in pallet boxes.
Many commercial packers maintain these conditions but few
use their degreening facilities to best and fullest advantage.
Fruit is not always moved into and through the degreening
process as quickly as possible. A 24-hour delay often means
the difference between good and poor quality fruit in the
market. Delay between picking and the fungicide and wax
treatments may result in increased decay and peel injury caused
More attention needs to be given to the degreening needs
of individual varieties, and research in future years may help
to solve the problems of handling newer varieties. Test.
degreening should be as routine as maturity tests. Many losses
can be avoided by test degreening and not picking a particular
crop until it is ready to degree in reasonable time.
Finally, when degreening rooms are not in use for
degreening, they can be used as ambient temperature, high
humidity holding rooms during unavoidable delays in moving
fruit through your packinghouse. Use high humidity and air
movement but no heat or ethylene.
11:10 A.M. ETHYLENE DEGREENING OF 'BEARSS' LEMONS -
Charles Barmore, Adair Wheaton, Agricultural
Research and Education Center and Andy
McCornack, Florida Department of Citrus, Lake
The time required to degree Florida 'Bearss' lemons can
be greatly reduced by the use of 5 ppm ethylene at 780-850F
(250 to 300C). Degreening was accomplished in 2 to 3 days
instead of the 2 to 3 weeks required with the current commercial
practice of cool coloring at 600F (15C) without added ethylene.
Application of a benzimidazole fungicide (thiabendazole,
benomyl) prior to degreening adequately controlled decay. Rapid
degreening with ethylene eliminates the need for cool coloring
and brings lemon availability more nearly in phase with
11:20 A.M. A REVIEW OF RESEARCH AND OTHER DEVELOPMENTS
RELATING TO OPTICAL GRADING OF FLORIDA CITRUS -
Jerry Gaffney, Agricultural Engineer, SR, ARS,
Grading is perhaps one of the most important of operations
in the packinghouse, as the effectiveness of grading relates
directly to the appearance and keeping quality of shipped fruit.
The amount of fruit removed during grading may approach 50% of
the incoming fruit at some times, and the costs of handling
these eliminations through the packinghouse are substantial.
Use of automatic optical grading equipment to replace a
large portion of manual grading labor has the potential for
reducing labor costs and increasing overall packinghouse
efficiency. Improvements in the effectiveness of grading can
result in fruit of improved appearance and keeping quality being
made available to the consumer.
The basic technology required for optical sorting of
citrus for color and surface blemishes has been available for
some time. More recent research has resulted in development
of methods for detecting surface injuries and alternaria
decay. Studies are underway on the development of optical
techniques for measurement of other quality factors.
Automatic optical grading equipment has not been used to
date in the Florida citrus industry because of the lack of
suitable commercial sorting machines. Several companies now
have machines, with highly sophisticated optical scanning and
electronic decision making systems, in the prototype stages of
11:30 A.M. ANTHRACNOSE, A POSTHARVEST DECAY OF TANGERINES -
G. Eldon Brown, Florida Department of Citrus,
Anthracnose is a postharvest decay that can be quite
serious in certain seasons, such as the one last year, when a
good color break is retarded due to a warm fall and extensive
degreening is needed to enhance fruit color. The decay can
occur on 'Dancys', but 'Robinson' tangerines are, by far, much
more susceptible. Ethylene is needed to induce the disease
and development of the decay is much more extensive in poorly
colored green fruit than in fruit possessing a good orange
color break. Severity of the decay is also related to the
concentration of ethylene used during degreening. Aspects of
the penetration process by the fungus in peel of green versus
orange-colored fruit will be discussed.
11:40 A.M. EVALUATION OF SELECTED PACKAGES FOR EXPORTING
FLORIDA GRAPEFRUIT Philip Hale, U.S.
Horticultural Research Laboratory, ARS, USDA,
Eleven test shipments of Florida grapefruit packed in two
experimental packages were originated to overseas markets. We
examined the fruit upon arrival to determine differences in th,
amount of deformation between experimental and conventional
packs. The amount of serious deformation was significantly
reduced when specially designed polystyrene plastic trays were
used, compared with conventional cartons, packed with the same
size and quality of fruit. In the experimental Bliss-style
cartons, the amount of serious deformation of fruit was great:
than that found in the conventional cartons. One commercial
observation made of "one-inch-deeper" cartons showed that the
fruit arrived in excellent condition.
11:50 A.M. EQUIPMENT DEMONSTRATIONS Bill Miller, Agriculti
Research and Education Center and Will Wardowski
Extension Service, Lake Alfred.
NOON L U N C H Equipment Demonstrations:
(1) Labeling Machine H. C. Burns, FMC Corp.,
(2) Plastic Tray Harry Wallace, Kiefer McNeil
Corp., Largo, FL.
(3) Solar Energy for Degreening Rooms Bill
Miller, IFAS, Agricultural Research and
Education Center, Lake Alfred, FL.
Due to the early printing of this program, certain exhibitors
may not appear in the above list. Any additional displays will
be announced before the lunch break.
AFTERNOON Marvin Kahn, Chairman, Export Committee, Florida
SESSION Citrus Commission
1:40 P.M. CHILLING INJURY OF GRAPEFRUIT Bill Grierson,
Agricultural Research and Education Center, Lake
For some years now we have picked groups of grapefruit trees
over long periods, checking the fruit's resistance to chilling
injury. From this work, we have had to completely revise our
theories on seasonal changes in susceptibility to chilling
injury. It had been believed that resistance to chilling injury
increased with increasing fruit maturity. This is true, but
only as long as the tree is entering dormancy. As soon as the
tree breaks dormancy, the fruit becomes increasingly more
susceptible to chilling injury until, in the period of heavy
leaf flush after bloom, they are more chilling susceptible than
they were in the fall. It seems strange that we have not seen
this clearly before, but susceptibility to chilling injury is
affected by degreening, delays between picking and storage,
waxing, benzimidazole fungicides (TBZ and Benlate), and humidity
of the storage. In experiments in which these variables were
controlled, the return to extreme susceptibility in the spring
becomes very plain. This leaves us without a firm recommendation
for shipping conditions for grapefruit exported in the spring.
In terms only of controlling chilling injury, we should obviously
revert to the temperatures used for first shipments in the fall.
However, because very mature fruit is very susceptible to decay,
unless Japan allows use of fungicides such as TBZ (which
incidentally gives some control of chilling injury), higher
temperatures could cause prohibitive losses from decay. We ho
to publish a more definite recommendation prior to export
shipments in the spring.
1:50 P.M. EXTERNAL APPEARANCE OF GRAPEFRUIT FOR EXPORT -
Andy McCornack, Florida Department of Citrus,
The most frequent peel injury of grapefruit held in storaj
or in transit results from chilling injury. Pitting caused by
chilling develops during storage at 40F, and has been observed
on fruit held at 50 to 550F, but not on fruit held at 60F or
higher. Diphenyl pads used for decay control cause an increase
in the amount of chilling injury and the rate at which it
Reddish peel color (due to natural phenols in the peel)
may develop with rough handling, fumigation with more than the
recommended concentration of ethylene dibromide (EDB), or as a
result of the wax used. It is often difficult to determine
which factor causes the discoloration.
Grapefruit receiving too much or improper EDB fumigation
has a brown, cooked appearance which usually develops several
days after fumigation. Little if any increase in peel injury
results from EDB fumigation when done according to approved
Peel injuries caused by bruising may not be visible until
several days after packing so they often cannot be graded out.
Grapefruit picked when fully mature are easily bruised and
cannot be stored or shipped successfully for long distances as
they lack storage life. Dehydration due to low humidity
during degreening, or resulting from a delay in handling betwe
picking and waxing, may cause peel injury near the stem-end of
2:00 P. M. PACKERS CORNER Jim Ellis, Lake Garfield Citrus
Research and development programs for Florida packinghous
do not have to come from machinery companies.
Many practical ideas that can save time, human limbs and
help make plain money come from within the wooden, metal and
block buildings sitting on Florida sands. Let's share some of
these ideas that we can produce from the scrap bins behind our
2:10 P.M. PRESENT STATUS OF FUMIGATION FOR THE CARIBBEAN
FRUIT FLY Ralph Brown, Division of Plant
Industry, FDACS, Gainesville and Bill Grierson,
Agricultural Research and Education Center, Lake
Regulations by the states of Arizona, California and Texas,
and by Japan concerning the shipment of Caribbean fruit fly host
fruit to those areas require that these fruit be fumigated.
Presently, the only chemical approved for this purpose is
ethylene dibromide. Airtight chambers are necessary when using
this gas. At the present time, two chambers are located in
Gainesville, 12 in Wahneta (near Winter Haven) and 16 in Fort
Pierce. The Gainesville chambers handle fruit destined for
domestic delivery and some Japanese shipments. The other
locations handle shipments destined for Japan.
Where fruit has been damaged due to fumigation, this almost
invariably occurs, not during the actual fumigation, but due to
inadequate aeration after fumigation. This is particularly so
when the fruit remains in the truck for days or weeks, as in
truck shipments to California or van container shipments to
Japan. Front vents should be open during the postfumigation
aeration period at the fumigation station. In addition, truckers
should keep front and rear vents open for the first 24 hours
after fumigation. Fumigation in van containers with no vent
doors and whose air circulation fans do not work during the
over-the-road part of the trip is asking for trouble.
2:20 P.M. POLLUTION PROBLEMS IN FLORIDA FRESH CITRUS FRUIT
INDUSTRY: WASTEWATER TREATMENT AND FRUIT
FUMIGATION Mohamed Ismail, Florida Department
of Citrus and Bill Miller, Agricultural Research
and Education Center, Lake Alfred.
Traditionally, Florida packinghouses have not applied any
type of wastewater treatment to packinghouse effluents. As
regulations covering environmental quality become stricter, and
cost of water gets higher, the need for wastewater treatment will
increase. Due to space limitations around most packing
facilities, physico-chemical rather than biological treatment
methods are more suitable for the average citrus packinghouse.
One possible system provides for reuse of 75% of the volume of
effluent following coagulation and filtration. The remaining
25% of the effluent would be purified by adsorption and
chlorination for use as a final rinse.
EPA authorities have been investigating ethylene dibromid
(EDB) as an air pollutant. Citrus fumigation with EDB is
mandatory prior to export to Japan and the U.S. West Coast. A
activated carbon system has been designed and tested at the
Florida Department of Agriculture fumigation station at Wahnet
EDB in the chamber can be reduced by at least 60% within one
hour after fumigation. This greatly reduced exposure of
personnel to the toxic gas and could possibly result in
reducing peel damage associated with EDB.
2:30 P.M. ARRIVAL CONDITION OF U.S. CITRUS FRUIT IN JAPAN
John Smoot and Tim Hatton, U.S. Horticultural
Research Laboratory, ARS, USDA, Orlando.
From late February through early June, the arrival condit
of Florida grapefruit in Japan was generally good to excellent
with 1 to 3% decay in most lots. In some lots from certain
packinghouses, decay was from 5 to 50%, requiring grading and
repacking. In most instances, the excessive decay was due to
green mold and sour rot which are directly related to peel
injury following rough picking and handling. EDB fumigation
injury was slight, intermittent and inconsistent, causing no
real problems. A number of lots of California lemons and
grapefruit were observed to arrive in excellent condition with
to 3% decay. The current fungicide and food additive situation
with Japan will be discussed.
2:40 P.M. ADJOURN
This program is published at a cost
of $280.00 or 47 cents per copy to
inform growers, packers and others
of applied research in harvesting,
fresh fruit handling and marketing.