Front Cover
 Director's message
 Managing canker and greening is...
 Extension education program slows...
 Economic effects
 Roadmap to the future
 A history of accomplishments
 Mechanical harvesting update
 The network that works for you

Title: Impact
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00044207/00016
 Material Information
Title: Impact
Uniform Title: Impact (Gainesville, Fla.)
Abbreviated Title: Impact (Gainesville, Fla.)
Physical Description: Serial
Language: English
Creator: University of Florida -- Institute of Food and Agricultural Sciences
Publisher: The Institute
Place of Publication: Gainesville FL
Publication Date: [1984-
Frequency: three no. a year
Subject: Agriculture -- Research -- Periodicals   ( lcsh )
Agriculture -- Research -- Periodicals -- United States   ( lcsh )
Genre: periodical   ( marcgt )
Statement of Responsibility: IFAS, Institute of Food and Agricultural Sciences, University of Florida.
Dates or Sequential Designation: Spring 1984-
Numbering Peculiarities: Vol. 2, no. 2 misnumbered as v. 2, no. 22.
General Note: Title from caption.
 Record Information
Bibliographic ID: UF00044207
Volume ID: VID00016
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 001107412
oclc - 10908183
notis - AFK3775
lccn - sn 84006294
issn - 0748-2353


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Table of Contents
    Front Cover
        Page 1
        Page 2
    Director's message
        Page 3
    Managing canker and greening is top priority
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Extension education program slows canker spread
        Page 10
        Page 11
        Page 12
    Economic effects
        Page 13
        Page 14
        Page 15
    Roadmap to the future
        Page 16
        Page 17
    A history of accomplishments
        Page 18
        Page 19
    Mechanical harvesting update
        Page 20
        Page 21
        Page 22
    The network that works for you
        Page 23
        Page 24
Full Text

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Senior Vice President for
Agriculture and Natural
Dean for Extension
Dean for Research
Dean of the College of
Agricultural and Life

Director, Citrus Research
and Education Center
Lake Alfred, Florida







IS FACING DIFFICULT if not unprecedented challenges
from hurricanes, urban development, rising labor costs,
global competition and diseases, such as citrus canker
and citrus greening, the University of Florida's Insti-
tute of Food and Agricultural Sciences (IFAS) is fully
committed to working with the industry to help solve
problems and ensure the future viability of the state's
signature crop. We have overcome difficult obstacles in
the past 100 years, and we can do it again.
Citrus canker and citrus greening spell double
trouble for the industry, and we are confident these
devastating diseases can be managed by continuing our
current research programs and working in cooperation
with the Florida Department of Agriculture and Con-
sumer Services and the U.S. Department of Agriculture.
The recent loss of USDA funding for the citrus canker
eradication program, coupled with the discovery of
citrus greening, means that these research priorities are
now more urgent than ever.
The IFAS research programs are focused on develop-
ing a series of management systems for growers that
will improve the ability to detect and prevent these
diseases from spreading. We are also developing ways
to effectively control these diseases and reduce their
economic impact on the industry. Our scientists are
working with scientists in Brazil and other countries to
learn how their citrus industry has been dealing with
canker and greening for many years.
For canker, which is spread primarily by wind and
rain, these efforts include protecting groves with wind-
breaks, greater use of copper-based chemical sprays
and decontamination procedures for personnel and
equipment. In the longer term, we are also confident
that the canker problem can be solved with genetic
engineering transferring genes to new citrus varieties
to make them resistant to the disease. In fact, scientists
at our Citrus Research and Education Center in Lake
Alfred have transferred canker-resistant genes from
other sources into citrus trees, and we are working with
other state and federal scientists to determine how
well the trees resist the most common strain of canker.
Other efforts are underway at UF research and educa-
tion centers in Fort Pierce and Immokalee, as well as
the main campus in Gainesville.
To manage greening, a potentially greater threat
than canker, we are focusing on methods to diagnose



the disease before symptoms appear. Right now, once
the symptoms show up in trees, it's too late to save the
tree. We have an impressive history in Florida citrus
of managing major citrus pests with biological control
methods (predators and parasites) as a complement
to the use of pesticides, and we have already released
a beneficial wasp that helps control the Asian citrus
psyllid, a gnat-sized insect that spreads greening. This
wasp is now widely established throughout the state.
And while biocontrol methods are only one way to help
manage the psyllid and the greening disease it trans-
mits, our integrated pest management program also
includes careful use of insecticides.
Through the years, IFAS has worked with growers to
improve commercial citrus production and homeown-
ers to improve their homegrown citrus. Our dedicated
and talented faculty has developed integrated pest man-
agement programs that reduce the need for pesticides,
microirrigation systems that reduce water consumption
and protect trees during freezes, a statewide automated
weather network that provides growers with real-
time data, and improved harvesting and postharvest
handling systems that reduce labor costs to name just
a few of our many accomplishments. A major focus at
present is the development of new varieties that will
withstand the challenges of disease infection as well as
producing higher yields and improved fruit quality.
Our statewide Extension program has offices in every
county, providing direct access to the vast resources
of one of the nation's top land-grant institutions. IFAS
Extension works closely with researchers to provide the
most current information to citrus producers and work-
ers about variety selection, cultural practices, integrat-
ed pest management systems, fertilizer and irrigation
practices, food safety and food technologies. Extension
will continue to work with producers and homeowners
to assure the continued success of citrus production.
We are proud to serve Florida, which not only pro-
duces 76 percent of the oranges grown in the United
States and 20 percent of the world's citrus crop, but also
produces the world's highest quality citrus. The chal-
lenges are formidable, but let me assure you that IFAS
is focused on Florida citrus and its future.

Senior Vice President
Agriculture and Natural Resources

University of Florida I Institute of Food and Agricultural Sciences

director's message

significant events have shaped the industry.
While we tend to focus on catastrophic events, such
as freezes and hurricanes, we can also look at subtle
changes that impact the industry. Early milestones
include the ability to ship fruit out of state and the
development of frozen orange juice concentrate. More
recently, the growing popularity of not-from-concen-
trate juice can be viewed as another major change. The
industry is also affected by external forces, including
changes in the consumer market, international devel-
opment and competition, and rapid population growth
in Florida.
In recent years, a convergence of circumstances and
events is beginning to reshape the industry's future.
Increasing commerce and tourism in Florida have
brought extreme pressure from exotic pests, diseases
and invasive plants. Residential trees and citrus groves
in Florida are often the "jumping-off" points for these
hitchhikers. The phenomenon is not new, but the rate
of introduction appears to be increasing, and the sever-
ity of the new pests and diseases appears to be growing
as well.
Nursery producers, growers, harvesters, packers, pro-
cessors, suppliers and research support groups face an
uncertain future. Loss of grove acreage to development
and other factors have downstream effects on other
sectors, and the response to these circumstances must
involve all sectors to be successful.
Looking ahead, the challenges are many, but they can
be addressed by the following goals that outline a posi-
tive future for the industry:
Citrus cultivation that leads to high productivity per
acre of land, per dollar of capital investment, per
unit of fertilizer, water and other inputs, and per
investment of personnel
Sustained productivity that enables reinvestment,
replanting and long-term business strategies to be
developed and implemented
Close cooperation between sectors of the industry
and regions of the state so that large-scale efficien-
cies can be realized
Economic viability that comes from quality fruit
and products in the marketplace
Solutions will come from many sources. The resolve
and commitment from within the industry to adjust
management systems is critical for overcoming the
potential impacts of citrus canker and greening as well
as other challenges. Resilience has played an important
role throughout the history of the industry and will
continue to be important. Equally important will be the

development and delivery of specific solutions that can
be used to address pest, disease, economic and produc-
tivity issues. That where's the University of Florida's
Institute of Food and Agricultural Sciences (IFAS) and
our partner agencies can help.
We have a long history of developing solutions to
emerging problems. Through commitment to research
and close communication across all channels, solutions
will be developed and tested, and effective remedies
will be implemented. For this to occur, support is es-
sential to leverage existing resources and pursue new
sources. Research and development also needs the
support and cooperation of growers and other industry
sectors to provide the testing grounds and feedback.
If the problems were simple and straightforward, all
of these elements would flow together easily and solu-
tions would emerge effortlessly. However, we recog-
nize that the complexity of the production system and
postharvest elements are far from simple. Thus, the
continued commitment of IFAS and our partners will
be essential to meet these objectives.
In the short term, modifications to grove production
practices can lessen the effects of canker and greening
on tree health and longevity. Adjustments to nursery
production, seed and budwood sources also will be
necessary. The immediate need is to modify practices
that will have the greatest influence on disease manage-
ment, balanced with the additional costs involved.
Experience gained from other regions of the world
where similar production problems exist combined
with Florida research will provide direction.
Recent workshops to discuss tools for managing
canker/leafminer and greening/citrus psyllid are start-
ing points. Modifying regulatory protocols to address
phytosanitary and other certifications are also impor-
tant first steps.
The future will be shaped by the results of long-term
research. Scientific advances on several fronts allow for
the development of resistant plants that may be capable
of withstanding the challenges of exotic diseases. These
advances will also make it possible to address some of
the broader production and post-production challenges
in Florida.
IFAS is committed to addressing the immediate
needs for revised management systems, and we are also
focused on long-term goals. The future, like the past,
will be challenging and rewarding.

Director, Citrus Research and
Education Center, Lake Alfred

This special report -
IFAS Responds to Chal-
lenge and Cl ...... I,.,
Florida Citrus Industry -
was produced by IFAS
External and Media
Relations (Jack Batten-
field, director) and IFAS
Communication Services
(Ashley M. Wood,

To request extra copies
of this report, please
contact Jack Battenfield,
Director of IFAS External
and Media Relations,
Institute of Food and Ag-
ricultural Sciences, P.O.
Box 110275, University of
Florida, Gainesville, FL
32611-0275 (352) 392-
0400, battenf@ufl.edu

Institute of Food and Agricultural Sciences University of Florida

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Citrus research-

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Sciences say new


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Jim Graham examines citrus trees in a greenhouse forthe presence of canker.

Ron Br[ansky checks trees for early signs of citrus greening. PHOTO BYJOSH WICKHAM


F lorida sacrificed more than 11 mil-
lion citrus trees over the last 10 years
in a desperate struggle to keep citrus can-
ker from spreading, but all of that effort
was wiped out in just a few short hours last
October when Hurricane Wilma rampaged
through the heart of the state's groves,
spreading the bacteria far and wide.
To make matters even worse, canker is
no longer the most significant threat to
Florida citrus, having relinquished that title
to a more destructive disease called citrus
Wilma's impact on the canker eradi-
cation program was so complete that in
January the U.S. Department of Agriculture
(USDA) announced it would no longer fund
removal of trees as part of an eradication
"Hurricane Wilma may have spread the
disease to the point where an estimated
168,000 to 220,000 acres of commercial
citrus could be infected and exposed to can-
ker," Florida Commissioner of Agriculture
and Consumer Services Charles Bronson
said in a Jan. 11 news release. "This is in
addition to the more than 80,000 acres of
commercial citrus that were affected by the
2004 hurricanes."
News of an end to the eradication pro-
gram which impacted commercial grow-
ers and backyard gardeners alike with its

requirement that all trees within 1,900
feet of an infected tree be destroyed was
greeted with mixed feelings, but it also
called for the development of an entirely
new game plan for dealing with the disease.
"Up until now, we've had canker research
proceeding along several tracks: one ori-
ented toward eradication, others focused
on detection, prevention and management
practices," said Jimmy Cheek, University
of Florida senior vice president for agricul-
ture and natural resources. "Since eradica-
tion will no longer be the strategy, we need
to make sure we're putting our resources
where they'll do the most good."
Canker is spread primarily by wind and
rain, causing citrus to develop small brown
lesions and trees to produce less fruit. The
current canker outbreak was discovered in
UF experts are working with the USDA,
and representatives of other agencies and
the citrus industry to develop a new state-
wide canker management plan, said Harold
Browning, director of UF's Citrus Research
and Education Center in Lake Alfred.
"We have been collaborating with cit-
rus researchers in South America for the
past 30 years, and we will try some of their
canker-suppression strategies," Browning
said. "Brazil has a different climate, but
their growers have been somewhat success-
ful protecting groves with a combination of
windbreaks, copper-based chemical sprays

and decontamination procedures for per-
sonnel and equipment."
Ensuring the quality of Florida's cit-
rus exports will be easier with the help of
genetically modified canker bacteria that
glow bright green when examined under
special microscopes, said Jim Graham, a
soil microbiologist at the Lake Alfred center
who has tested a wide range of canker con-
trol strategies since 1999.
Along with postdoctoral associate Jaime
Cubero, Graham led a research team that
modified the bacteria with a gene derived
from a species of jellyfish. The glowing
microbes are far easier to detect than their
unmodified counterparts, enabling faster,
more accurate evaluation of sanitizing
"To test a sanitizing system, you can
apply the bacteria to a test batch of cit-
rus and simply run it through the sys-
tem," Graham said. "The bacteria only glow
if they're alive, so it's easy to spot survi-
vors and determine how well the system's
The modified bacteria will also help
researchers learn how long canker bacteria
survive outside citrus plant tissue, he said.
This information will lead to more effective
quarantine and grove-care practices to keep
canker bacteria under control.
Citrus trees do not contain canker-fight-
ing genes, but they do have genes provid-
ing broad-spectrum disease resistance, said
Gloria Moore, a UF professor of

University of Florida I Institute of Food and Agricultural Sciences

horticultural sciences. She is trying to
understand how citrus trees can be coaxed
into expressing those genes more strongly,
giving them a better chance of resisting
canker and other pathogens.
In another study, Moore and Fred
Gmitter, a horticultural sciences professor
at the Lake Alfred center, lead a research
team that has examined natural canker
resistance in the kumquat, a fruiting plant
closely related to citrus.
"One of our graduate students has iso-
lated some of the genes that are responsi-
ble," said Moore, who has researched can-
ker genetics for the past five years. "By
transferring those genes to citrus trees, we
may be able to provide canker resistance."
Rice is another plant whose disease resis-
tance UF researchers have borrowed for use
in citrus, said Jude Grosser, a horticultural
sciences professor at the Lake Alfred cen-
ter. The grain has a gene that provides pro-
tection from rice bacterial blight, a disease
closely related to citrus canker.
Doctoral student Ahmad Omar, UF plant
pathology assistant professor Wen-Yuan
Song, Grosser and Graham have been work-
ing for more than five years on a project
to transfer the resistance gene to Hamlin
orange trees. The first of these trees is being
tested in a quarantine facility to determine
if it can resist the most common strain of
citrus canker bacteria.

If the test proves successful, the trees
will be field tested to evaluate their abil-
ity to resist canker and produce fruit in
a real-world environment, Grosser said.
Eventually, they could become the first can-
ker-resistant citrus variety UF makes avail-
able to growers.
"Genetics research has great potential
to help the citrus industry overcome this
threat," Grosser said. "We're confident it
will happen, and we've got a running start,
thanks to all the work that's been done

But as bad as canker is, citrus green-
ing has people in the industry even more
"In the long term, the industry can live
with and manage the canker problem, but
citrus greening is a fatal disease that's an
even larger threat to the state's signature
crop," said Browning. "In other areas of the
world where greening is a problem, it has
never been successfully eradicated."
The disease, which slowly weakens and
kills all types of citrus trees, causes fruit to
become lopsided and taste bitter. Fruit does
not develop the desired color hence the
term "greening." Although greening poses
no health threat to humans, there is no
known cure for the disease.

The disease is transmitted by the Asian
citrus psyllid (Diaphorina citri), a tiny insect
that is now widely distributed through-
out Florida, and the disease has been found
in more than 440 different locations in 11
counties. Browning said it's not practical to
eradicate citrus greening, but the spread of
the disease can be slowed with an effective
integrated pest management program that
includes beneficial insects that attack the
psyllid and limited use of insecticides.
The introduction of a beneficial wasp
was the first step in an expanded IFAS
research program to develop a wide range
of best management practices to prevent
greening from destroying the industry,
Browning said.
Marjorie Hoy, a UF professor of ento-
mology and biological control expert, said
the psyllid was first detected in two South
Florida counties in June 1998. At the time,
the psyllid was considered to be a signifi-
cant pest, and although it did not appear
to carry the deadly bacterial disease that
causes citrus greening, it made establish-
ment of greening more likely if the disease
were introduced.
"When citrus greening started show-
ing up in citrus trees across the state in
September 2005, we knew we had a poten-
tial disaster on our hands and that the
psyllid was carrying and transmitting the
deadly disease," Hoy said.

Marjorie Hoy (left) examines a citrus tree attacked by the Asian citrus psyllid, a tiny insect that spreads the deadly greening disease. PHOTO BYTHOMAS WRIGHT
Michael Rogers (right) checks new growth on a citrus tree for the presence of Asian citrus psyllids. PHOTO BYJOSH WICKHAM

11 F_76,r -

Institute of Food and Agricultural Sciences IUniversity of Florida


In an attempt to reduce populations
of the Asian citrus psyllid, Hoy and Ru
Nguyen, an entomologist with the Florida
Department of Agriculture and Consumer
Services, imported two natural enemies of
the psyllid from Taiwan and Thailand. After

evaluating the parasitic wasps under quar-
antine conditions to make sure they would
be effective against the psyllid and not
harm the environment, they began releas-
ing the biological controls about six years

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Sgreenin. Any control will require a holistic

approach. Hoy said.... .
"Management tools that 1.1,1 r developed
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control cannot be the only tool in managing
greening. Any control will require a holistic
approach, Hoy said.
"Management tools that are developed
should be compatible with these and other
natural enemies that suppress citrus pests,
such as mites, whiteflies, scale insects,
leafminers and mealybugs," Hoy said.
"Indiscriminate killing of their natural ene-
mies could produce serious pest outbreaks."
What complicates control of citrus green-
ing is the fact that symptoms don't begin to
show up in trees until several years after the
trees are infected by the psyllid insects, said

(Top) In addition to reducingthe size of fruit, citrus greening causes fruit to have curved central core and aborted seeds. PHOTO BYRON BRLANSKY
(Bottom left) Adult Asian citrus psyllid (Diaphorina citri) and psyllid nymphs feed on theyounggrowth of a citrus tree. (Center) Citrus psyllid nymphs, producingwaxy excre
ments, feed on the new growth of a citrus tree. PHOTOS BY MICHAEL ROGERS

University of Florida I Institute of Food and Agricultural Sciences

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Ron Brlansky, a professor of plant pathology
at UF's Lake Alfred center.
"Lack of early detection of the systemic
bacterial disease is a major problem for the
citrus industry," he said. "Once the symp-
toms show up, it's too late to save the tree."
Brlansky said early symptoms such as leaf
mottling and yellow discoloration may be
mistaken for other problems, such as nutri-
tional deficiencies, and laboratory tests are
needed to determine if greening is the prob-
lem. The disease can also be identified by
cutting open small and poorly colored fruit
and looking for aborted seeds.
UF researchers plan to attack the citrus
greening problem in three ways: by devel-
oping best management practices for the
bacterial disease, by improving diagnostic
methods and by testing the effectiveness of
systemic insecticides to stop transmission
of the disease by the psyllids.
Brlansky is working with Michael Rogers,
an assistant professor of entomology at the
Lake Alfred center, and Vern Damsteegt,
a plant pathologist at the USDA's Foreign
Disease and Weed Science Research Unit

in Fort Detrick, Md., to evaluate the abil-
ity of systemic insecticides to reduce trans-
mission of the disease by psyllids. The
Maryland quarantine facility was selected
because it is far from commercial citrus in
Unlike broad-spectrum insecticides that
are applied to the foliage of citrus trees,
soil-applied systemic insecticides are less
likely to impact other beneficial insects that
control citrus pests in existing biological
control programs, Rogers said.
"Recent results in our field trials have
demonstrated that soil-applied systemic
insecticides can reduce psyllid populations
on mature citrus trees and provide a signif-
icantly longer period of control than foliar
applications," he said. "These research proj-
ects will allow us to manage psyllids with
fewer pesticide applications than grow-
ers use in other regions of the world where
greening is a problem."
The effectiveness of the beneficial wasp
in controlling the Asian citrus psyllid is
being evaluated by Rogers in cooperation
with Phil Stansly, a professor of entomol-

ogy at UF's Southwest Florida Research
and Education Center in Immokalee, and
David Hall, an entomologist at the USDA's
Horticultural Research Laboratory in Fort
With the help of participating grow-
ers, the study will identify citrus produc-
tion areas where the beneficial wasp is
established and determine when it is pro-
viding effective biological control of the
psyllid and when broad-spectrum insecti-
cides should not be used. The wasp will be
released in groves where the biological con-
trol is not yet established. *







(863) 956-1151
(863) 956-1151
(863) 956-1151
(352) 392-1901
(863) 956-1151

(Bottom right) Asian citrus psyllid nymphs are parasitized by a beneficialwasp (Tamarixa radiata) that is now widely established throughout Florida; note exit holes made by the
parasitoid. (Inset photo)An Asian citrus pysllid has been turned overto reveal the beneficialwasp parasitoid (Tamarixia radiata) that is developing and almost ready to emerge.

Institute of Food and Agricultural Sciences IUniversity of Florida

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In the battle against citrus canker, the University

of Florida's statewide Extension Service is educat-

ing diverse audiences ranging from residents and

landscapers to commercial citrus growers about the

disease and ways to prevent its spread.

E radicating canker may no longer be possible, but UF's Citrus
Canker Education Program is getting the message out to key
audiences statewide about controlling the bacterial disease before it
does irreparable harm to the state's $9.3 billion citrus industry.
Initiated in 2002, the education program has targeted residents
as well as citrus growers and related businesses. The program has
increased awareness about citrus canker to prevent the bacteria
from spreading throughout Florida.
"In an effort to meet the immediate needs of the citrus industry,
the Extension education program has been geared to helping the
industry through the transition from an eradication campaign to
implementing post-eradication management strategies," said Holly
Chamberlain, coordinator of the program.
"The effort has been effective in reducing the negligent spread of
citrus canker by educating citrus industry employees about decon-
tamination practices and avoiding the movement of infected plant
material, especially during rainy or wet conditions," she said.
Working with Chamberlain on the project are various multi-
county Extension agents and Pete Timmer, a professor of plant
pathology at UF's Citrus Research and Education Center in Lake
Alfred. The Extension education program, which is part of UF's
Institute of Food and Agricultural Sciences, is being coordi-
nated with regulatory agencies such as the Florida Department of
Agriculture and Consumer Services and the U.S. Department of
"Since its inception, the program has kept pace with the changes
in the industry, including hurricanes and adjustments in prices and
acreage, all of which are related," Chamberlain said. "We cover all

aspects of the disease, including citrus canker biology, epidemiol-
ogy, history and regulations. We also provide current information
on management, decontamination and survey efforts."
She said the goal is to educate all client groups to adopt behav-
iors that will help make citrus canker a manageable disease.
Education efforts have largely focused on the residential/dooryard
citrus grower and the commercial citrus industry because these
groups are most frequently associated with the spread of canker to
new areas. Statewide citrus canker education activities have also
focused on the national and international aspects of the disease.
"In cooperation with state and federal agencies during 2004 and
2005, we have provided citrus canker training to more than 4,200
residents, Extension agents and regulatory personnel," Chamberlain
said. "In addition, we have presented training to more than 3,500
English-speaking and 1,500 Spanish-speaking commercial citrus
She said educational materials ranging from fact sheets and
PowerPoint presentations to videos and training modules for
Extension Master Gardeners have been produced and presented
to these and other groups. A citrus canker education display is
in use at county fairs, meetings, seminars, workshops and other
events. All of the information is available on Extension's citrus can-
ker Web site: http://canker.ifas.ufl.edu.
When the Canker Education Program started, Extension's highly
successful Master Gardener groups became a key part of the effort.
"Their information about planning and maintaining urban, subur-
ban and rural landscapes emphasizes environmental stewardship,"
said Tom Wichman, a UF Extension agent in Gainesville who

Holly Chamberlain, lett, and Pete I immer use a sanitizing agent to decontaminate
personnelwho may have been exposed to citrus canker. Awalk-through decontamina-
tion station is in the background. PHOTO BY MARISOLAMADOR

Institute of Food and Agricultural Sciences IUniversity of Florida

The Extension canker education program recommends that allvehicles entering or leaving citrus groves should go through a decontamination spray loop such as this.
PHOTO BY MARISOL AMADOR (Below) A DVD that helps growers identify citrus canker is available from the IFAS Extension Service.

coordinates the Master Gardener program. "Master Gardeners are active in county
Extension offices and plant disease diagnostic clinics, and they handle phone calls regard-
ing pest and disease management. For these reasons, the program is an essential part of our
Canker Education Program."
Information about the Master Gardener program can be found at the following Web site:
http://hort.ifas.ufl.edu/mg/. A UF fact sheet for homeowners on citrus canker is available on
the Electronic Document Information Source (EDIS) Web site: http://edis.ifas.ufl.edu/PP116.
Twenty counties have been impacted by citrus canker during the past 10 years: Brevard,
Broward, Charlotte, Collier, DeSoto, Hendry, Highlands, Hillsborough, Indian River, Lee,
Manatee, Martin, Miami-Dade, Monroe, Okeechobee, Orange, Osceola, Palm Beach,
Sarasota and St. Lucie counties. Et CHUCK WOODS

HOLLY CHAMBERLAIN (863) 990-7268
PETE TIMMER (863) 956-1151

University of Florida I Institute of Food and Agricultural Sciences




A comprehensive economic analysis of the state's $9.3
billion citrus industry was completed in March by
UF's Institute of Food and Agricultural Sciences in
cooperation with the Florida Department of Citrus.
The 166-page document "An Economic Assessment
of the Future Prospects for the Florida Citrus Indus-
try" measures the impact of citrus canker and citrus
greening, as well as other factors such as hurricanes
and higher land prices associated with urbanization.


Ron Muraro, left, and Tom Spreen review data for the comprehensive economic analy-
sis of the Florida citrus industry. PHOTO BYTHOMAS WRIGHT

Over the next 15 years, citrus canker
and citrus greening will reduce the
volume of fruit produced in Florida, and ris-
ing land values will affect the willingness
of investors to commit capital to citrus pro-
duction in Florida.
Orange and grapefruit production is
expected to decline before it begins to
rebound, and the state may never return to
the level of fruit harvested in 2003 before
destructive hurricanes spread canker
throughout South Florida.
However, growing world demand for
Florida's high-quality citrus is expected to
help boost prices at all levels ranging from
growers to juice processors and consumers.
In other words, higher prices should offset
lower production volume.

These are some of the findings in the
new economic assessment report devel-
oped by UF's Department of Food and
Resource Economics. Tom Spreen, chair of
the department, distributed the report to
the Florida citrus industry in March. He
said canker and greening will affect citrus
producers in different ways so the economic
impacts of the two diseases must be mea-
sured separately.
"Industry response to suppress citrus
canker and greening will increase produc-
tion costs in the near term," he said. "These
diseases will also affect revenues through
decreased fruit yields and packout in fresh-
fruit operations eroding the overall profit-
ability of the industry."

Because of canker, 62 percent of the
nursery trees in the state have been
destroyed, severely limiting the amount of
grove replanting over the next three years,
Spreen said.
The presence of citrus canker and green-
ing will also require new greenhouse invest-
ments and practices to ensure disease-free
nursery trees.
Citrus canker attacks the fruit and leaves
of a citrus tree, resulting in increased pre-
mature fruit drop. The bacterial disease
affects the external appearance of fruit
grown for the fresh market, and the disease
may open pathways for other pest problems,
resulting in increased tree mortality. Spreen
said it is likely that citrus canker will have
more profound effects on fresh fruit

Institute of Food and Agricultural Sciences I University of Florida




1 ri

-LNI4AJ L9 Vl A'4 I L 1 i i a q a ILt









1rp_-----I ----Ili r-.---- --1 1 13 1. 10 -11 = --

I I I I I I I I I I I I I I0-

producers than on to the processing seg-
ment of the industry.
Citrus greening, a more worrisome threat
than canker, is already a formidable dis-
ease in Asia, where little citrus is now pro-
duced. Considering the fact that the Asian
citrus psyllid, which spreads the disease,
is already present throughout Florida, it is
likely that greening will eventually move
throughout commercial citrus production
areas of the state, Spreen said.
Greening results in increased tree mor-
tality. It is more likely to attack young trees
than older trees, and there are many ques-
tions regarding economically sound man-
agement practices with respect to greening,
he said.
"It is crucial that answers be found to
these questions because increased tree

mortality rates have a detrimental effect on
the ability of a business to survive and com-
pete in the global market," Spreen said. "We
need to identify practices that suppress cit-
rus greening for the most economical pro-
duction of citrus in Florida."
Because of Florida's importance as a cit-
rus producer, diseases that adversely affect
production of various citrus varieties in the
state will also affect prices. With the strong
competition between Brazil and Florida in
the world orange juice market, it is impor-
tant to assess the supply response in both
regions as they begin the process of man-
aging citrus canker and citrus greening,
Spreen said.
Analyses of the world market for orange
juice and fresh and processed grapefruit
were conducted to quantify the price effects

of these diseases. This work was combined
with grove-level analyses to assess the
future profitability of citrus production in
the state.
According to a separate agricultural land
values report released in January by John
Reynolds, professor emeritus in the UF food
and resource economics department, the
value of farmland in Florida increased by
more than 80 percent between 2004 and
Spreen said increasing land prices have
implications for all commodities grown in
Florida, particularly citrus. Higher land
prices mean higher investment costs for
new grove development, he said.
This factor combined with increased
costs of grove maintenance, lower yields
and higher tree mortality associated with

University of Florida I Institute of Food and Agricultural Sciences











citrus canker and greening will likely sig-
nificantly increase the fruit price required
to justify new grove development," Spreen
"With the large number of bearing acres
affected by the hurricanes in 2004 and
2005, along with groves that have been
eradicated because of citrus canker, bearing
citrus acreage in the state is down, point-
ing the way to smaller citrus crops in the
future," he said.
The new economic study also incor-
porated the effects of greening in Brazil,
Florida's main competitor in the world
orange juice market. Citrus greening has
been present in the state of Sao Paulo for
two years and has spread to most of its com-
mercial citrus production area.

Spreen said citrus production contin-
ues to be an important part of Florida agri-
culture and the state's overall economy.
A study based upon the 1999-2000 sea-
son provided an estimate that the total eco-
nomic impact of citrus in Florida was nearly
$9.3 billion, and this study was updated to
reflect the 2003-04 season. The study also
includes detailed projections on the future
economic outlook for the industry as it
begins an aggressive program to manage
citrus canker and citrus greening.
Other economists who worked with
Spreen on the project are Alan Hodges,
an Extension associate in the department;
David Mulkey, a professor in the depart-
ment; Ron Muraro, a professor at UF's
Citrus Research and Education Center in
Lake Alfred; Fritz Roka, an associate pro-

fessor at UF's Southwest Florida Research
and Education Center in Immokalee;
Mark Brown, senior research economist
at the Florida Department of Citrus in
Lakeland; Bob Norberg, economic and mar-
ket research director at DOC; and Robert
Barber, director of economics at Florida
Citrus Mutual in Lakeland. Robert Rouse,
an associate professor of horticultural sci-
ences at UF's Immokalee center, also con-
tributed to the report.
For the complete economic assessment
report on the future prospects of the state's
citrus industry, go to the UF Department
of Food and Resource Economics Web site:
http://www.fred.ifas.ufl.edu. *
TOM SPREEN (352) 392-1846

Institute of Food and Agricultural Sciences I University of Florida





1|006 0 |00i000.007 1 01 01 101 10 T0 016 01 101 9 01 200

With the spread of citrus canker and the appearance of cit-
rus greening disease in the state during 2005, Florida
citrus producers face many challenges in maintaining the economic
viability of a critical industry. Hurricane damage, loss of prime
farmland to development and increasing global competition further
complicate the picture.
"When federal and state changes in the citrus canker eradication
program were announced in January, we began a comprehensive
review of all production, harvesting and postproduction practices to
manage canker as well as greening," said Harold Browning, direc-
tor of UF's Citrus Research and Education Center in Lake Alfred.
An international workshop on citrus canker and greening held in
Orlando during November 2005 brought together more than 150 of
the world's leading researchers with expertise in these diseases, and

Bill Castle, left, a professor of horticultural sciences at UF's Citrus Research and
Education Center in Lake Alfred, and Pete Spyke, owner of Arapaho Citrus Manage-
ment in Fort Pierce, check grove data on a laptop computer. Spyke is workingwith UF
researchers to increase the use of precision farming methods in the citrus industry.

to the Future

they are helping UF faculty and staff establish vital management
and research priorities.
In its mission as the state's land-grant institution, UF's Institute
of Food and Agricultural Sciences (IFAS) performs a critical role
in bringing together current information, innovative thinking and
practical solutions for the citrus industry. IFAS, in cooperation with
the industry and other agencies and organizations, is developing a
roadmap to the future, Browning said.
"Citrus production in Florida has been successful thanks to the
industry's willingness to face challenges and to adopt new methods
and technologies when they are available," he said. "Now, perhaps
more than ever, is a critical moment."
Browning said all aspects of citrus production and related oper-
ations must be adjusted to reduce the impact of citrus canker and
greening. "We must develop and implement new management sys-
tems to assure tree health and productivity," he said.
insulate it from infection with canker, greening, citrus tristeza
virus and other invasive diseases. This will require recapitaliza-
tion of facilities and introduction of stringent requirements for
those who will be providing certified, disease-free
citrus trees to commercial growers as well as to res-
idents who want trees in their yards. This is vital to
the future health of the industry.
promote necessary tree growth for productive
groves without promoting excessive growth
favorable for the diseases.
PROGRAM to suppress canker and greening as
~ y well as reduce populations of citrus leaf min-
ers, citrus psyllids and other insects that spread
S ." disease.

INCREASE SANITATION MEASURES for all equipment and personnel
in citrus operations to reduce the risk of spreading disease.
movement of disease or diseased plant material. This is essen-
tial for promoting continued shipment of high-quality fresh cit-
rus fruit from Florida. Domestic as well as international phytos-
anitary requirements must be strengthened and maintained.
INCREASE EDUCATION in all industry and the public sectors on
the effect of these diseases on citrus in commercial groves and
residences, and successful management of these properties.
Education programs, conducted by the IFAS Extension Service
and other agencies, provide the best available information on
these and other diseases, as well as modifying current practices.
As new information becomes available, it is being presented to
nurserymen, growers, harvesters, processors, packers and
homeowners. A wide range of constituencies must participate
in this process to achieve the best solutions and outcomes.
Browning said research is the key to solving these and other prob-
lems facing the industry. The IFAS citrus research program will
help develop short- and long-range solutions to these diseases. "The
obstacles to better detection and suppression are known, and our
research faculty and staff are working with bacteriologists, molec-
ular biologists and other experts from across the nation to correct
these problems.
"In the short term, we will improve our ability to detect canker
and greening," he said. "Both diseases are very difficult to locate in
the field, interfering with early suppression or removal. Methods
and products to suppress canker and greening as well as leafmin-
ers and psyllids are being evaluated; we are developing new recom-
mendations for the most effective use of these tools. New candidate
materials are being identified regularly."
In the long term, both greening and canker will be managed
through the deployment of resistant plants for a healthy and sus-

Brian Boman, left, an associate professor of agricultural and biological engineering
at UF's Indian River Research and Education Center in Fort Pierce, and Chris Wison,
an assistant professor of soil and waterscience at the center, check map showing
citrus production in the Indian Riverarea. PHOTO BYTHOMAS WRIGHT

tainable Florida citrus industry. The development of resistant vari-
eties will require transfer of resistant components from other plants
or systems because there is limited availability of resistant genes in
"Rapid advances in technologies allow us to consider new options
for developing resistant plants, and IFAS researchers are working
with cooperators to achieve permanent and economical solutions to
these diseases," Browning said. "With this roadmap to the future,
we are confident that Florida growers will implement measures that
protect them from these diseases, maintain their profitability and
ensure a brighter future." CHUCK WOODS


(863) 956-1151

Institute of Food and Agricultural Sciences IUniversity of Florida

-- r ~ ;TS

I '
n_41.4 *r,

r" U; I ILJ L 2Jf&J AqLtLJ V I J q K-1 I i F 1V
In addition to combating problems such as citrus canker and citrus greening, UF researchers are developing controls for anothertroublesome pest called the Diaprepes citrus
rootweevil (Diaprepes abbreviatus). Catherine Mannion, left, an assistant professor of entomology at UF's Tropical Research and Education Center in Homestead, and Jorge
Pena, a professor of entomology atthe center, record data on parasites of the Diaprepes citrus rootweevil, which has invaded more than 1oo,ooo acres of Florida citrus and
causes more than $70 million in damage annually. PHOTO BY ERIC ZAMORA

T he University of Florida's Institute
of Food and Agricultural Sciences
(IFAS) combines scientific expertise from
many disciplines with state-of-the-art
research technologies to address the com-
plex scientific questions and issues fac-
ing the Florida citrus industry and other
"To assemble the widest possible level
of expertise and help obtain the fund-
ing needed to support these efforts, our
researchers often partner with other insti-
tutions and agencies nationally and inter-
nationally," said Harold Browning, direc-
tor of UF's Citrus Research and Education
Center in Lake Alfred. "Our scientists also
work with other national and international
In many cases, real-world problems can
only be solved by balancing the best avail-
able science with practical engineering and
economic considerations, Browning said.
"Our research must also go the distance -
spanning the discovery, evaluation and
implementation phases over many years,"
he said.

Publishing research data realizes one
aspect of the science and engineering mis-
sion, but the real mission is not accom-
plished until these research findings are
used to solve problems. By any standard,
Browning said, the recent accomplishments
of UF citrus research and education pro-
grams are impressive.

Good nutrition, delivered in a timely
manner, is essential for the growth and
productivity of citrus. Florida soils offer
numerous challenges for irrigation as well
as the application and retention of nutri-
ents; deficiencies or excesses of either can
lead to undesirable outcomes. IFAS faculty
have conducted research to define require-
ments for nutrition and moisture based on
tree age, variety, planting densities and soil
"Application of nutrients to soil as dry
materials or through irrigation systems
is complemented by foliar application of
micronutrients, and the basis for these

nutrient delivery plans lies in IFAS research
programs," Browning said. "Similarly, with
a wide range of soils and shallow water
tables in some regions, provision of optimal
moisture to promote tree growth and pro-
ductivity is challenging. Research has also
advanced our understanding of the dynam-
ics of providing irrigation to supplement
rainfall and groundwater."
Evolution of low-volume, controlled irri-
gation delivery has provided useful tools to
the industry, and the testing of sensors and
other monitoring equipment and controls
will improve irrigation efficiency.
IFAS research conducted in partner-
ship with county and local governments
has demonstrated the value of reclaimed
municipal water in meeting citrus mois-
ture needs, leading to general acceptance
of this practice in several areas of the state,
he said.
"Most notable is WaterConserv II, a
large-scale reclaimed water project in
Orange and Lake counties, that demon-
strates how municipalities can solve their
wastewater disposal objectives and satisfy

University of Florida I Institute of Food and Agricultural Sciences

agricultural irrigation demands at the same
time," Browing said.

In addition to providing proper irri-
gation and fertilization for citrus, grow-
ers must manage water and applied nutri-
ents to avoid water quality and other
environmental problems. The Florida cit-
rus industry has been proactive in recog-
nizing water quality issues, participating
in research leading to appropriate man-
agement tools. Nearly a decade ago, IFAS
developed a series of Best Management
Practices (BMPs) in partnership with
other state agencies, growers and private
groups. The use of BMPs began in the cen-
tral ridge of the state, and then the program
was expanded to other production areas.
Citrus BMPs have now been developed,
approved by state regulatory authorities
and implemented in the Indian River/St.
Lucie estuary region, the Peace River and
Manasota Basins, and in Southwest Florida.
Continuing research by IFAS will lead to
updates and improvements.

Advances in computer technology, sen-
sors and imaging are being applied to
Florida citrus production. Site-specific man-
agement of grove inputs, characteristics and
history have been facilitated by the avail-
ability of these new tools, and additional
applications are being tested in Florida cit-
rus operations. IFAS scientists are partner-
ing with growers and technology providers
to adapt off-the-shelf technology, leading
to more accurate data management and
increased ability to respond to different site
Specific applications have been tested for
variable-rate fertilizer application, appli-
cation of restricted pesticides, and remote
management of irrigation and other on-
farm systems. Evaluation of site-specific
technologies being used by individual com-
panies also is underway, and results are
being shared through workshops, short
courses and publications. Other sensing
technologies for measuring tree canopies
and tree growth, and detecting fruit loca-

tion in trees and fruit quality are showing

The availability of rootstocks on which
quality scion fruit varieties can be grown is
fundamental to the success of the Florida
citrus industry. In addition to meeting the
fixed requirements of the state's unique pro-
duction system (climate, soils, topogra-
phy and water), rootstocks and scions are
challenged by pests and diseases as well as
changing consumer interests. The IFAS cit-
rus improvement team is conducting basic
research on the genetics of citrus and its
relatives, as well as applied efforts to gener-
ate combinations of genetic traits that meet
Florida's needs. With numerous endemic
diseases such as citrus tristeza virus, blight,
greasy spot, scab and post-bloom fruit drop,
development of disease tolerance or resis-
tance is a major challenge that is further
complicated by invasive diseases such as
canker and greening.
In addition to these diseases, other organ-
isms such as insects, mites and nematodes
damage trees and fruit, stress trees and
limit productivity. Research on these prob-
lems is being conducted by teams in plant
pathology, entomology and nematology.

Florida citrus has a rich history of relying
on biological control for assistance in long-
term management of insect pests. IFAS
research on the introduction or conserva-
tion of natural enemies such as predators,
parasites and diseases has led to the impor-
tation and deliberate release of natural ene-
mies. Examples include a wasp that was
released decades ago to control Florida red
scale, leading to a permanent reduction of
scale populations and damage.
More recently, researchers have been
investigating biological control of brown
citrus aphid, citrus leafminer and the Asian
citrus psyllid. Parasites for leafminer and
psyllid have been introduced, and natural
enemies have become established, contrib-
uting to lower levels of these pests. In addi-
tion, the search for additional beneficial
insects continues. Integration of biological
control with the appropriate use of pesti-

cides leads to a desirable, long-term balance
of pests and natural enemies. As new pests
continue to be discovered in Florida citrus,
biological control will continue to be an
important tactic.

Florida fruit and citrus products are
viewed as wholesome components of a
healthy diet. Quality standards are high
for Florida products, necessitating ongoing
research and education to ensure that con-
taminants and pathogens are excluded from
these products.
Research by faculty in the IFAS depart-
ment of food science and human nutrition
has focused on sources of potential risk of
microbial contamination of citrus juices
and other processed products, containers
used in juice packaging and in bulk trans-
portation containers. Methods for detect-
ing and identifying microbes in the process-
ing stream have been developed, along with
procedures to assure sanitation in all phases
of processing and handling.
With increased food security issues in
recent years, IFAS has led the development
and delivery of training on Hazard Analysis
and Critical Control Points (HACCP) and
its incorporation as standard operating pro-
cedures for citrus processing facilities. IFAS
research continues to investigate possible
pathways by which fruit and juice quality
can be compromised, delivering this infor-
mation for use by the industry.

The statewide IFAS Extension Service is
the educational link between research and
the citrus industry, consumers and other
clientele groups. The citrus Extension team
includes multi-county agents and citrus spe-
cialists located at research and education
centers in Fort Pierce, Immokalee and Lake
Alfred, as well as the main UF campus in
Gainesville. Close communication between
research faculty and their Extension coun-
terparts allows for rapid transfer of new
practices, tools and information. o

HAROLD BROWNING (863) 956-1151

Institute of Food and Agricultural Sciences I University of Florida


--) V~:i; '~~
Fe I..~ Ic

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Citrus canker, greening and hurricanes have diverted attention
away from mechanical harvesting, but work on the labor-saving
technology continues at UF's Institute of Food and Agricultural
Sciences (IFAS). Researchers say new tree-shaking mechanical
harvesting systems are nine times more efficient than picking
oranges by hand and will help the state's $9.3 billion citrus in-
dustry compete with low-cost producers, such as Brazil.

University of Florida I Institute of Food and Agricultural Sciences

;Y414 i i:

. .... .. .. .... .. .....

IL~iJliiiii::: i'; ''.
':"''':' "'


Fritz Roka walks by a continuous-canopy shake-catch (CCSC) mechanical
harvesting system manufactured by Oxbo International Corp. in Clear Lake, Wis.

S [l.- .. l .-- 1l. I I l. 1 I 1.L11, 1, 1 1 _
l,,,, I I rrll,, ,i'' (.. F l. II'Fl,, ,l I I,.I

Cit researchh and Education ,,Center in Lake Alfred, has de vel-

'n ,li ,,t Ir 1- rl I l ", i .1 br h ,lr

oped cost comparisons between the Brtilian and F .lorid citrus
h I-ll. .1 I, 1. .11 1 1. 1 t (,l 'In tLi 'I. I '". t F I, i -, ... -- I I. II .1 I

industries.I tForI I ex le, during the 2000-1 hI ..arsting son, t.

cos I .i a i nI .. 1 Iin" fruit ino a trailer was $1.60 per

II ltgro ers t o P .l I l IiI .. L.. l BI Iz
l i l .' R .ai a ,I. i .ii .I a l... I t t t .... .I

..And, while the current U.S. I .. tariff on imported Brazilia...n frozen

Ron Muraro, a professor of food and resource economics at UF's
Citrus Research and Education Center in Lake Alfred, has devel-
oped cost comparisons between the Brazilian and Florida citrus
industries. For example, during the 2000-01 harvesting season, the
cost of picking and "roadsiding" fruit into a trailer was $1.60 per
90-pound box of fruit in Florida compared to 38 cents per box for
growers in Sao Paulo, Brazil.
And, while the current U.S. tariff on imported Brazilian frozen
orange juice concentrate eliminates their advantage in the domes-
tic market, all tariffs on imported agricultural commodities would
be eliminated under the proposed Free Trade Area of the Americas
agreement, Muraro said.
Roka said previous mechanical harvesting research programs
were motivated by fears of labor shortages. "The goal of shake-and-
catch systems during the 1970s was to help grove workers increase
the number of boxes they could harvest from eight or 10 boxes per
hour to 30.
"Today, we're looking at new tree-shaking and catch-frame har-
vesting systems that allow one person to collect more than 90 boxes
per hour. Higher labor productivity should translate to lower har-
vesting costs," he said.

Institute of Food and Agricultural Sciences I University of Florida

Roka said the Florida Department of Citrus (FDOC) in Lakeland
has invested more than $10 million since 1995 from grower assess-
ments to develop mechanical harvesting systems.
The FDOC Harvesting Research Advisory Council, which
includes growers, harvesters and processors, was established in
1995 to coordinate development of mechanical harvesting technol-
ogies. Currently, UF researchers are evaluating different machine
systems from six manufacturers, and two systems are achieving
commercial success in Southwest Florida.
"During this year's harvesting season, the trunk-shake-catch
(TSC) and the continuous-canopy-shake-catch (CCSC) systems
removed at least 95 percent and recovered 90 percent of the fruit
from trees in Southwest Florida," Roka said.
He said CCSC systems have greater harvesting capacity than TSC
systems. One set of CCSC machines can load up to 20, 500-box
trailers in one day. One set of TSC equipment can fill five trailers
in one day. However, the TSC system requires only two operators
while the CCSC system requires six people.
"As a result, harvest labor productivity is similar for the two sys-
tems," Roka said. "Hourly labor productivity was measured at more
than 90 field boxes per hour, which represents a nine-fold increase
in labor productivity over a hand-harvesting crew."
However, in order for these systems to perform effectively, trees
and groves must be well prepared. Tree canopies must be trimmed
or "skirted" at least 30 inches from the ground to create a "clear
trunk" of at least 12 inches, he said. TSC systems are being used
in groves with a tree density up to 175 trees per acre and on trees
between 10 and 18 years old.
He said the two shake-and-catch systems are most efficient in
the newer groves of Southwest Florida where tree age, height and
spacing are more uniform. Older groves in the ridge area of Central
Florida have lots of resets or tree replacements and lack the unifor-
mity needed for efficient machine harvest.
"One of the biggest challenges for growers is overcoming the idea
that groves can be planted like they were 50 years ago," Roka said.
"Older groves need to be replanted with smaller trees that are closer
together and more uniform, allowing shake-and-catch machines to
move down tree rows more efficiently."
Roka has developed a computer spreadsheet program so that
growers can organize information on mechanical harvesting and
determine when it is profitable. Key parameters include the sys-
tem's fruit recovery percentage, fruit price, crop yield and the cost
difference between mechanical and hand harvesting. The model
is available at the UF Southwest Florida Research and Education
Center Web site: http://www.imok.ufl.edu/economics.
"Growers need to recognize that 100 percent fruit recovery is not
necessary for increasing revenues," Roka said. "A sufficiently large
differential between hand and machine costs could more than off-
set the value of nonrecovered fruit."
However, during the last two years of production shortfalls, fruit
prices have risen significantly and the high value of the fruit would
warrant gleaning, he said.
Foremost in the minds of growers is how a mechanical harvest-
ing system will affect the long-term health of trees. Jodie Whitney,

a retired professor of agricultural and biological engineering at UF's
Citrus Research and Education Center in Lake Alfred, has been
involved in developing and testing mechanical harvesting equip-
ment since the 1970s. "Our research, coupled with the harvest-
ing experience of commercial growers, indicates that trunk or can-
opy shaking has no adverse effect on tree yield through seven years
of harvesting," he said. With each additional year of experience,
uncertainty among growers should diminish."
Another tool for more efficient mechanical harvesting is the use
of abscission agents, chemicals that help loosen mature fruit from
trees, said Jackie Burns, a professor of horticulture at UF's Lake
Alfred center.
"Spraying trees with an abscission agent a few days before har-
vest increases fruit loosening and makes harvesting faster and eas-
ier," she said. "Abscission agents must be nontoxic, selective, cost-
effective and environmentally safe."
Burns, who manages the abscission research team at Lake Alfred,
said the selectivity of the chemical agent is especially important on
Valencia trees that have young, developing fruit and mature fruit at
the same time. Removing too much of the developing fruit with a
mechanical harvester decreases the next season's yield.
Burns and her research team are working on three promising
abscission agents CMNP (5-chloro-3-methyl-4-nitro-1H-pyr-
azole), Ethephon and Coronatine, all of which are at least five to
seven years from being commercially available.
During the 2005 legislative session, UF received $1.25 million
of recurring new funds to support mechanical harvesting research
and Extension programs. A mechanical harvesting advisory com-
mittee of growers and harvesters put abscission research and reg-
istration at the top of the priority list. Improvements in machine
designs and an effective grower education program were other high
priority objectives.
Within a few months, a new UF Web site will present all current
and relevant information on citrus mechanical harvesting, Roka
A team of researchers is working on various aspects of the
mechanical harvesting problem. In addition to Burns and Muraro,
team members at UF's Citrus Research and Education Center in
Lake Alfred include: Reza Ehsani, an assistant professor of agricul-
tural and biological engineering; Jim Syvertsen, a professor of plant
physiology; and Rene Goodrich, an associate professor of food sci-
ence and human nutrition (food safety).
In addition to Roka, team members at UF's Southwest Florida
Research and Education Center in Immokalee include: Robert
Rouse, an associate professor of horticultural sciences, and Kelly
Morgan, an assistant professor of soil and water science.
In Gainesville, Tom Burks, an assistant professor of agricultural
and biological engineering, is analyzing mechanical enhancements
and applications of robotic technology. '



(863) 956-1151
(239) 658-3400

University of Florida I Institute of Food and Agricultural Sciences

The Network

that Works for You

\\!'J tr frItt-t:s tn I'ill. ii it' 11.1ii. other crops, growers rely on the Florida
.-XAtlr.lilitrLd \Wti uitHr Ntru'i ', i. F-A\VN) for accurate weather data to protect
ttlir crn ui. hIn uMiiti0i rn i.' lii./'c ing vital weather data 24 hours daily, the
\tltatrtid liaruri,, i: i .,r.irti UF's Institute of Food and Agricultural
Sci.cil'cs I IAS I li~l/p fmiin improve their irrigation efficiency and pro-
vidtIs I Cliailt Clitiirt, p i.dlihris, ,i, months in advance. The information saves
,r, n'csr, f~alt th a.mn $3,S miiiiil.ii .iliiually.

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asphalt can make cities 10 degrees warmer
than farms in rural areas. When cold
weather moves through the state, the differ-
ence can be devastating to citrus and other
cold-sensitive crops."
Started by IFAS in 1998 after the
National Weather Service discontinued
special forecasts for agriculture, the net-
work is now a widely used management too-
for thousands of growers around the state,
Treadaway said. Calls to the weather net-
work rise as much as 13 times during freez-
ing temperatures, he said, to as many as
4,000 from the daily average of 300.
Nick Faryna, owner of Faryna Grove Care
and Harvesting in Umatilla, said he uses
the network to keep track of cold weather.
"It is an extremely valuable asset to those
who protect our crops from freezing tem-
peratures," he said.
Phil Cross, senior project manager of the
WaterConserv II near Orlando that dis-

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riuii d ina Ldbt a
freeze at the ear-
liest possible

Larry Treadaway, left,
and Mark Mealo, a field
technician, check
a FAWN moni-
in Bronson,



b. -

time, thereby saving thousands or even mil-
lions of gallons of water," he said.
Anita Simpson, owner of Simpson Groves
in Mt. Dora, said, "FAWN is an important
part of our cold-protection plan we use
the network constantly during freeze situ-
ations, which saves thousands of dollars in
irrigation costs."
Each solar-powered station in the FAWN
network collects weather data and trans-
mits it to a computer in Gainesville every 15
minutes. The stations measure air temper-
atures at two, six and 30 feet above ground,
soil temperature, wind speed and direc-
tion, rainfall, relative humidity, barometric
pressure, leaf wetness and solar radiation.
Real-time weather data from the network is
available at 352-846-3100 or 866-754-5732
and at the FAWN Web site:
"We invite everyone to visit the FAWN
Web site to see current weather condi-
tions as well as the unique and educa-
tional weather-data-graphing java applet,"
Treadaway said. "Also available are daily,
weekly and monthly data summaries,
charts of chilling degree days and histori-
cal data."
He said growers are looking at FAWN as
a source of reliable information not only for
cold protection, but also for weather-driven
computer models in pest control, irrigation
scheduling, fertilizer rates and other man-
agement programs.
"It's all part of the growing trend toward
precision agriculture," Treadaway said.
John Jackson, a UF Lake County
Extension agent in Tavares, Fla., who works

Anita Simpson, ownerof
Simpson Groves in Mt.
Dora, said FAWN is an im-
portant partof their cold-
protection plan. PHOTO

with Treadaway
on the project,
explained how
FAWN provides
growers with critical
information on when
it's safe to turn off
their irrigation sys-
tems used for freeze

"Some crops such as ferns and strawber-
ries utilize relatively large amounts of water
to protect an entire crop, while citrus uses
much smaller application rates per acre to
protect the tree trunk and lower limbs," he
said. "When growers use water, they must
determine the critical temperatures for
crops and turn irrigation systems on and
off to prevent temperatures from reaching
damaging levels while minimizing water
use at the same time."
FAWN has two management tools to
help growers protect their crops, he said.
One tool is the Brunt minimum tempera-
ture guide to determine when critical tem-
peratures are reached. The other is the wet-
bulb irrigation cutoff tool that should be
used by every grower using water for cold
"The wet-bulb tool provides a safe cutoff
temperature based upon moisture content
of the air, saving growers millions of dollars
and reducing water demand by millions of
gallons per year," Jackson said.
"Over the last three years, we estimate
FAWN has helped citrus, strawberry, fern,
vegetable and ornamental growers save 20
billion gallons of water and $10 million in
cold protection costs," he said. "Many grow-
ers also use FAWN to determine when to
start their irrigation systems."
The planned integration of FAWN with
the AgClimate climate forecasting system
during the next two years will provide pro-
ducers with additional management tools,
said Jim Jones, distinguished professor in
UF's agricultural and biological engineering

University of Florida I Institute of Food and Agricultural Sciences

1-WI = liki jA

An expert in computer modeling cli-
mate effects on cropping systems, Jones
said AgClimate is operated by the Southeast
Climate Consortium, which includes UF,
Florida State University, University of
Miami, University of Georgia, Auburn
University and University of Alabama
in Huntsville. Information available on
AgClimate includes climate forecasts com-
bined with risk management tools and
information for selected crops, forestry, pas-
ture and livestock. For more information,
visit the AgClimate Web site:
"Climate extremes associated with
drought, floods, freezing temperatures and
hurricanes can be predicted with increasing
levels of skill, which has major implications
for agriculture," Jones said. "If producers
were aware of probable climate condi-
tions several months in advance, they could
adjust their resource management practices
to reduce crop losses, forest fires or water
shortages." -CHUCKWOODS

I U I I 1

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,r '., II ., n ni I nn ,I I 'I' I i .,,nI

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LARRY TREADAWAY (352)-392-0900
JOHN JACKSON 352-343-4101
JIM JONES (352)392-1864

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