This Issue - Citrus Research Board

Transcription

Citrograph
July/August 2012
Citrograph
Conference chairman
Dan Dreyer
Program chairman
Justin Brown
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Citrograph
JULY/AUGUST 2012 • Volume 3 • Number 4
An Official Publication of the Citrus Research Board
Cover photo by Michael Alvarez, Visalia
IN THIS ISSUE
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Visalia, CA 93279
Phone: 559-738-0246
FAX: 559-738-0607
Web Site:
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Louise Fisher, Managing Editor
Dr. MaryLou Polek, Chief Science Editor
EDITORIAL BOARD
Ted Batkin
Richard Bennett
Franco Bernardi
Dr. Akif Eskalen
Dr. Ben Faber
Dan Dreyer
Jim Gorden
SCIENCE REVIEW PANEL
Dr. Mary Lu Arpaia
James A. Bethke
Dr. Abhaya Dandekar
Dr. Akif Eskalen
Dr. Stephen Garnsey
Dr. Joseph Smilanick
Editorial services provided by Anne Warring,
Warring Enterprises, Visalia, CA 93277
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project
30 Detector dogs protect California agriculture
33 Avoiding economic losses in California citrus from Citrus tristeza virus stem pitting
38 Unlocking the secrets of cross protection
to control severe strains of the same virus
ADVERTISING INFORMATION
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Phone: (559) 201-9225
screighton@farmprogress.com
4 Editorial
6 Chairman’s View
9 Industry Views
12 California Citrus Conference
20 CPDPP outreach engages all Californians
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44 Impact of high temperature on huanglongbing for development of a
field management strategy
52 Citrus Roots: Artists of the Era
58 Celebrating Citrus
Citrograph is published bimonthly by the Citrus Research Board, 217 N. Encina, Visalia, CA 93291. Citrograph is sent to all
California citrus producers courtesy of the Citrus Research Board. If you are currently receiving multiple copies, or would like
to make a change in your Citrograph subscription, please contact the publication office (above, left).
Every effort is made to ensure accuracy in articles published by Citrograph; however, the publishers assume no responsibility
for losses sustained, allegedly resulting from following recommendations in this magazine. Consult your local authorities.
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statements made in any of the advertisements. The Board does not warrant, expressly or implicitly, the fitness of any product
advertised or the suitability of any advice or statements contained herein.
July/August 2012 Citrograph 3
EDITORIAL
BY TED A. BATKIN, President, Citrus Research Board OMG, now what do we do???
Now it is time to review
strategies and plan for
keeping the California
citrus growers protected
from the invasion to
the best of our ability
as an industry.
4 Citrograph July/August 2012
A
s predicted, the Asian citrus psyllid (ACP) populations are
increasing faster than the treatment programs can keep up,
so once again the Citrus Pest and Disease Prevention Committee has been forced to revise their strategies for suppression and control. This is not new, nor is it a problem; it’s just a fact of life
when dealing with the invasion of such a prolific pest. So, now it is time
to review strategies and plan for keeping the California citrus growers
protected from the invasion to the best of our ability as an industry.
Many growers keep asking about the status of the Biological Control Program: Where are we? Why can’t we just start releasing mass
amounts of biocontrol agents and not have to spray? Why are we being
asked to spray when HLB is not in my area? The list goes on and on…
The answers are complex and based on certain realities not always
easy to see.
First, the development of the Biological Control Program is in very
early stages and involves finding which agents actually survive in California and will adapt to our complex climates. As previously reported
in Citrograph, University of California scientists have brought strains
of Tamarixia radiata from Pakistan to rear and test-release in Southern
California. These releases are now showing some level of success, but it
is still very early in the program to determine how successful this will
be. The team has recovered some survivors, and they have shown effective parasitism, so the news is very encouraging.
Second, the industry does not have any facility capable of mass
rearing the agents in quantities necessary to cover the populations
of ACP that now exist. This will require serious investments by
both public and private entities to build the necessary facilities to
provide adequate volumes of agents to be effective. To this end,
leaders from California Citrus Mutual, Sunkist, and the Citrus Research Board will be meeting with representatives from USDA,
CDFA, UC Riverside, and Cal Poly Pomona to discuss a plan to
provide resources to build adequate facilities to meet the goals of
mass releases of several species of biocontrol agents.
Finally, HLB may very well be in areas other than just Hacienda Heights. A massive search and testing program has begun
using every available tool for locating HLB-infected trees. This is a
combined effort of USDA, CDFA, CPDPC and the CRB. This search
and testing program is based on statistical risk models developed by
USDA. Everyone, hold on to your hats, because this is going to be an
“E Ticket”* ride!!
*If you are old enough to remember early Disneyland…
The Mission of the Citrus Research Board:
Develop knowledge and build systems for grower vitality.
Focus on quality assurance, clonal protection, production research,
variety development, and grower/public education.
CITRUS RESEARCH BOARD MEMBER LIST BY DISTRICT 2011-2012
District 1 – Northern California
District 3 – California Desert
Member
Allan Lombardi, Exeter Donald Roark, Lindsay Jim Gorden, Exeter Joe Stewart, Bakersfield
Etienne Rabe, Bakersfield
John Richardson, Porterville
Kevin Olsen, Pinedale Member
Mark McBroom, Calipatria
Public Member
Member
Seymour Van Gundy, Riverside
Alternate
Justin Brown, Orange Cove
Dan Dreyer, Exeter
Dan Galbraith, Porterville
Franco Bernardi, Visalia
Richard Bennett, Visalia
Jeff Steen, Strathmore
Tommy Elliott, Visalia
District 2 – Southern California – Coastal
Member
Earl Rutz, Pauma Valley
William Pidduck, Santa Paula
Joe Barcinas, Riverside Alternate
Alan Washburn, Riverside
James Finch, Santa Paula
Warren Lyall, Pauma Valley
Alternate
Craig Armstrong, Thermal
Alternate Steve Garnsey, Fallbrook
Citrus Research Board
217 N Encina, Visalia, CA 93291
PO Box 230, Visalia, CA 93279
(559) 738-0246
FAX (559) 738-0607
E-Mail Info@citrusresearch.org
CALENDAR
August 21-23
CRB Research - Review of Proposals
Double Tree Hotel - Bakersfield
August 27-29 USDA Citrus Health Response Program
Research Forum (ACP/HLB) - Ft. Collins, CO
September 18 CRB Annual Meeting
Lindcove REC - Exeter
October 10-11 California Citrus Conference
Porterville Fairgrounds - Porterville
October 12
California Citrus Conference
Optional tour of Lindcove - Exeter
November 1
CCM Annual Meeting
November 7-9 California Citrus Nursery Society
Annual Conference - Murphys
For more information on the above, contact the CRB office at
(559) 738-0246.
DO YOU KNOW...?
For the serious history buffs: 150 years ago, in
1862, President Abraham Lincoln signed into law
three very important pieces of legislation that
would have a profound and lasting impact on
American agriculture. Do you know what they
were? (Turn to page 24 for the answer.)
New!
Integrated Pest Management
for Citrus−3rd Edition
Now with even more photos,
more resources, and more pests.
What’s new in
the 3rd edition?
• 32 new pests
and diseases,
including Asian
Citrus Psyllid
• 500+ color
photos
• Detailed table of
contents
• Index for easy
searching
2012 • 270 pages
$40.00
ANR Pub #3303
Order yours today:
ucanr.org/citrusIPM
or: (800) 994-8849 • (510) 642-2431
University of California
Agriculture and Natural Resources
CHAIRMAN’S VIEW
BY EARL RUTZ, Chairman of the Board Changing of the Guard
I
As we anticipate
the transition to
new leadership,
we can be proud
of what the CRB
has achieved under
Ted’s leadership
and guidance.
n 1993, Ted Batkin was hired as the director of the California Citrus Research
Board. He broadened the scope of CRB research from a narrow focus of
research issues such as quality control, clonal protection, new variety development and general research to what it has become today. Ted became the
CRB President and research visionary for the industry.
Ted Batkin has done an exceptional job in leading the Board through years of
critical issues as well as expanding the scope of the Board. As his tenure comes to
a close, new leadership will be asked to fill his shoes in midyear of 2013. It is a time
to reflect on the challenges and visions of Ted’s career as our President.
Ted’s major challenge has been to chart new waters amongst ten different
chairmen, four Governors, five California Secretaries of Agriculture, numerous
CDFA officials, UC Presidents and Vice Presidents for Agriculture and Natural
Resources, many campus Deans, world-renowned researchers and Center Directors from the USDA /APHIS, Los Alamos National Labs, California and national
universities -- all of whom have assisted our program.
Ted has served on almost every state, national, and many international committees supporting the research efforts of the citrus community. He has tirelessly
worked on our behalf for two decades, and we are better off for his efforts. Some
of the highlights of the two decades of research, progress, and issues are as follows:
Ted Batkin currently serves as Chairman of the California Specialty Crops
Research Team, member of the USDA-APHIS Huanglongbing Technical Advisory Committee, and Co-Chair of the California Department of Food and Agriculture (CDFA) Huanglongbing Task Force. He is past Co-Chair of the CDFA
Diaprepes Task Force, Chairman of the National Citrus Research Council, and
Chairman and founding member of the National Plant Pathogen Research Consortium. He was a key participant in the development of the Citrus Health Response Plan (CHRP), the effort led by USDA-APHIS aimed at protecting citrus
production nationally.
He is a member of the UC President’s Advisory Commission for Agriculture
and the UC Riverside Chancellor’s Ag Advisory Council. He co-chaired the Governor’s Exotic Fruit Fly Task Force overseeing the Medfly sterile release program
and was involved with the development of the brown citrus aphid and ACP/HLB
national task forces.
He also served as a member of the CDFA Pierce’s Disease Task Force and
Chairman of its Citrus Subcommittee, Chairman of the California Citrus Tristeza
Research Coalition, and member of the Program Advisory Committee of the University of California’s Exotic Pests and Diseases Research Program. He served as
Co-Chair of the Safeguarding Review of USDA-APHIS’ entire Plant Protection
and Quarantine Program; the report became the guiding document for the reorganization of APHIS.
Ted guided the CRB’s creation of the Education and Outreach Committee
and the subsequent development of the mobile education lab and many grower
seminars. These efforts were important in the education of growers about glassywinged sharpshooter and its effects on citrus and grapes. The CRB now has an
annual presence at the World Ag Expo (Tulare Farm
Show) for the benefit of growers and the education
of the general public. The Citrograph magazine was
re-established and is now published by CRB and has
become an internationally respected journal.
During Ted’s tenure, funding for scientific research
transitioned from field level to molecular and genetic
issues, which is allowing for the development of disease detection and diagnostic platforms for the pathogens facing the industry.
Ted was instrumental in setting up a rapid response
to ACP in California. He aided in the formation of
the ACP-HLB operations program, commercial field
trapping, the establishment of our own nationally
certified laboratory for citrus disease detection, especially of ACP and HLB. At the CRB, he established
the research committee structure and the method in
which the Board evaluates research proposals. Ted
will be leaving us with a revised and current strategic
plan for the CRB.
As we anticipate the transition to new leadership,
we can be proud of what the CRB has achieved under Ted’s leadership and guidance. We have an internationally respected program. We give Ted our thanks
for his service and leadership. The industry will formally bid farewells during 2013. l
About the cover
D
an Dreyer and Justin Brown – the chair and vicechair of the CRB Communications Committee –
have had the lead roles in making plans for the California
Citrus Conference, which will take place in October (see
pages 12-19).
Dreyer joined CRB as an alternate in 2009-2010, and
Brown came on as an alternate in 2010-2011, both representing District 1. Each comes from a family with deep
roots in California citrus. Justin is a fifth-generation grower, and Dan is a fourth-generation producer whose family
began growing citrus in San Diego County in the 1920s.
Based in Exeter, Dan has wine grapes and some olives and pomegranates in addition to his citrus, and he also
owns and operates Ag Services, Inc., a farm management
company. Justin, whose family is a fixture in Tulare County citrus, grows several varieties along with table grapes
south of Orange Cove.
When it comes to industry issues and research interests, both are in leadership positions on the CRB Production Efficiency Committee. Dan lists other main interests
as new variety development, pest and disease management, and “irrigation innovations in combination with water supply issues and nutrient management.” Justin’s interests include marketing issues, and he notes with respect to
variety development that “we must never lose sight of, or
compromise, the high quality flavor and other characteristics that California citrus is known for.”
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INDUSTRY VIEWS
Citrograph asks: This season was marked by a stretch of cold nights,
but other periods were warmer than normal; there was very little precipitation
and even that came at odd times. How did all of that affect your trees’ irrigation
needs, and what tools did you use to aid your decisions?
W
e farm citrus on loams, clay loams, and adobe clay. We had so many cold nights that
we ran water for much of December and January to the point that the root systems in
several orchards were hurt by the exclusion of oxygen. So the dry February and first half of
March, during which ET was low even if above normal, provided a gentle and much-needed
drying out period. Then the late rains after mid-March made the usual assumptions about
April and May irrigation needs too inaccurate. So the unexpected really makes monitoring
soil moisture the chore that we should all do more of. Shovels, probe tubes, pokers, augers,
data loggers, and internet-iPhone devices. We are still looking for the perfect tool. We need
to be in the field, but we also need 24/7/52 information so that trends can be spotted and
alarms can alert us to the unexpected. Now, who can afford all of that, and will it really be
representative, and just how good are those sensors anyway? None of the products available
today are adequate, and we look forward to the fruits of research and innovation. — Allan
Lombardi, Griffith Farms
E
very year has its challenges, and there are no two years that are the same. I monitor my
soil moisture 12 months out of every year on every block. I amend my irrigation water
with gypsum to ensure both District and well water infiltrates the soil profile well. This past
winter, we ran irrigation water at different times when the soil moisture levels were low. We
also look at the rainfall and evaluate how far down in the profile it moved. Just because it
is wintertime does not mean the trees shut down. The fruit is still sizing, and the trees are
using moisture. Making sure the soil profile does not dry out is another important step in
maintaining solid tree health. The cold temperatures are tough on the trees, and if the soil
profile is depleted in moisture, that just adds extra stress on the trees. On the other side of
the coin, I limit my irrigations during a frost event so as to not saturate the soil profile. A
saturated soil profile can also induce stress on the trees by depriving the roots of oxygen.
Preserving root health is also something we address year-round as well. The soil moisture
monitoring equipment I utilize is the CropSense system from John Deere. It is a capacitance
probe measuring the moisture levels down to 40” in the soil profile. The data is transmitted
wirelessly to the Web where I can evaluate the data anytime, anywhere. — Craig Hornung,
Hornung Brothers Farming
T
his past winter season was indeed marked by odd weather. Some cold nights, extended
warmer periods, and what little precipitation we had came late. For us, the freeze had
little or no impact on water usage. The stretches of warmer weather meant that we started
irrigating earlier than usual. In fact, you might say we never really fully stopped irrigating from the summer before. We monitored our electronic sensors -- and also used some
good old-fashioned touch and feel -- throughout the fall and winter to know which groves
needed water and how much. As we did not run frost water, we were doing full irrigations by
February. We then needed to back off quickly due to the late rain, especially in the heavier
soils. — Randy Skidgel, Mittman-Denni Citrus Management
June 8, 2012
California Citrus Producers Approve the Continuation of
The California Citrus Research Program
To All Interested Parties:
In a referendum recently conducted by the California Department of Food and Agriculture (CDFA),
California citrus producers voted in favor of continuing the operations of the California Citrus Research
Program for another five years. The voting results of the recently completed continuation referendum are
presented below.
Percentage of eligible producers in the industry who submitted a valid ballot:
72.29%
Percentage of those voting who favored continuation of the California Citrus
Research Program:
96.46%
Percentage of the voted volume represented by those voting in favor of the
continuation of the California Citrus Research Program:
96.73%
Since the above voting results exceed the criteria required for continuation, as specified in the California
Marketing Act, CDFA has authorized the California Citrus Research Program to continue operating for
another five years (through September 30, 2017).
The California Citrus Research Program is a grower-funded state marketing order that has been in
existence since 1968. The Program is authorized to conduct general production research, a variety
improvement research program, a quality assurance program on agricultural chemical residues, and pest
and disease control activities.
Please contact Joe Monson of this office if you have any questions about this referendum. If you have
questions concerning the operations of the California Citrus Research Program, please call Ted Batkin,
President of the Citrus Research Board, at (559) 738-0246.
Sincerely,
Robert Maxie, Chief
Marketing Branch
2012 0605 2012 0606 0649
CDFA Marketing Branch ● 1220 N Street ● Sacramento, California 95814
Telephone: 916.900.5018 ● Fax: 916.900.5343 ● www.cdfa.ca.gov/mkt/mkt
State of California
Edmund G. Brown Jr., Governor
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October 10-11
Porterville Fairgrounds
Preparing for our future…
O
n October 10th and 11th, the
Citrus Research Board will
present the first-ever California Citrus Conference (CCC). The
event will be held, fittingly enough, in
the midst of citrus groves, at the new
Porterville Fairgrounds in Porterville.
In previous years. CRB and the citrus farm advisors of UC Cooperative
Extension teamed up to conduct an
annual series of seminars throughout
the state. Those small-scale, half-day
seminars were a means of disseminating current informational updates
and research developments directly to
growers.
But now, the idea is to bring members of the industry together at a single
location for a much larger meeting, in
order to (1) have a better exchange of
ideas and information, (2) to get more
thorough updates on problems and issues, and (3) to provide a much fuller
program of continuing education.
The CCC this October will be the
sum of several small seminars expanded into a two-day event. Our anticipation and excitement for this new approach cannot be overstated.
A great deal of careful thought and
consideration has gone into the development of this Conference to provide
the very best experience for all attendees.
Dan Dreyer and Justin Brown
We have designed the CCC to appeal to everyone involved in citrus production in California, not only grove
owners and grove care managers but
also pest control professionals, citrus
nurseries, packers and marketers, and
anyone else with a commercial interest
in the industry.
Incidentally, packers will want to
take note that the agenda has a special
session presented by CCQC.
Exhibits and live demonstrations
This change from what had been
a traditional seminar format is allowing for some important new additions
-- namely, a trade show with dozens of
exhibitors, and live demonstrations of
equipment including a “spray rodeo”.
While at the CCC, attendees will
have the opportunity to listen to, participate in, and learn from numerous presentations given by a diverse,
thoughtful, and highly qualified group
of lecturers.
California is home to the most diverse array of specialty crops, and citrus is no exception. In considering the
diverse interests within our industry,
we have gathered and organized a wide
array of topics to address the different
regions of the state.
Of course, ACP/HLB is the most
pressing threat to the entire industry.
Rather than giving an overview of a
topic that is already being covered
quite widely, at the CCC, attendees
will be presented with real-world situations arising from a post-positive HLB
California. Not only will the discussion
cover the actual current status of ACP/
HLB, it will also provide up-to-date research information and results so far in
dealing with this issue in other citrus
producing areas including Florida and
Texas.
Day Two of the conference does
not let up, covering hard-hitting issues
of the utmost importance. Obviously,
water is always on the mind of a California citrus grower. The availability
of water, what the future holds with
regard to nitrates, and where irrigation
technology is heading will dominate
the topics covered in the morning.
Special interest sessions
On both days, every person attending will find sessions that are tailored to
fit his or her special interests. For example, as a conventional grower, you may
want to sit in on the discussion about
controlling citricola scale in the San
Joaquin Valley, or dealing with leafminer in the coastal growing regions. If it’s
organics you’re interested in, there will
be a separate organics-only presentation as well, covering the important
topics of certification and economics.
Have you ever wondered what orange juice tastes like when the fruit is
from an HLB-infected tree? Well, there
will be a session covering just that subject, and there will also be a taste test.
Overall, the educational program
portion of the CCC will cover the big
issues in California citrus today and
into the future. Whether it’s ACP/HLB,
water, marketing citrus globally and
domestically, or economic realities of
growing citrus, you will leave this CCC
fully informed and, we believe, with a
glimmer of optimism looking forward.
Dan Dreyer is the Conference Chairman, and Justin Brown is the CCC Program Chairman. See About the Cover,
page 8.
Site of the 2012 California Citrus Conference, the new Porterville Fair facility is
surrounded by citrus orchards and within walking distance of the Porterville
Municipal Airport. This easy-to-get-to location is at 2700 W. Teapot Dome Ave. off
Highway 65 at the south end of Porterville.
PLANNED PROGRAM
Wednesday, October 10
Gate opens: 7:30 a.m.
Registration opens: 7:30
Exhibits open: 7:30
Continental breakfast: 7:30
Session One: 8:30 - 11:30
Expo Building
Asian citrus psyllid and huanglongbing
Welcome and Conference overview
Presentations and discussion
• Citrus Pest and Disease Prevention
Committee (CPDPC)
• Grower treatment programs
– California
– Texas
• Area-wide programs panel discussion
– Florida
– Texas
– California
• Biological control program
• Research progress report
Arena Activity
Spray rodeo
Spray demos, calibration
Detector dogs
Dog/handler team demo
Exhibit Visits and Luncheon:
11:30 - 1:30
Keynote address
Ricke Kress, Southern Gardens Citrus
CCQC presentation of the Albert G. Salter Memorial Award
Session Two: 1:30 - 3:30
Expo Building
Pests, diseases, and resistance
• Pest management panel
– Industry-wide
– San Joaquin Valley issues
– Desert issues
– Coastal issues
• Resistance management
• Pest and Disease management issues
– Export issues
Session Two Breakout:
1:30 - 3:30
Building B
Organics
• Introduction to certification
• Research overview
• Panel discussion on economics
• Panel discussion on marketing
Session Three: 3:50 - 4:40
Expo Building
California Citrus Quality Council
(CCQC)
• President’s report
• Status of specific issues
Session Three Breakout:
3:50 - 4:50
Building B
Citrus tristeza virus
• General situation update
• Shift in operations of Central California Tristeza Eradication Agency
• CTV impact on Lindcove Research
and Extension Center
• Information on virulent strains
• State quarantine changes
• What are growers with sour orange
rootstock doing?
Exhibit Visits: 4:40 - 6:00
Gate closes: 6:00
Thursday, October 11
Gate opens: 7:00 a.m.
Exhibits open: 7:00
Continental breakfast: 7:00
Session One: 8:00 - 9:30
Expo Building
Water issues
• State water picture
– Availability outlook
– Water quality issues (ILRP)
• Irrigation technologies
– Delivery systems
– Monitoring
Session Two: 10:30 - 12:00
Expo Building
Soil health and plant nutrition
• Soil health
– Amendments, biology, analysis
• NRCS funds
• Plant health
– Macro nutrients
– Micro nutrients
Session Two Breakout:
10:30 - 12:00
Building B
The future tree - living with HLB
• Is there resistance/tolerance to
HLB?
• How will new varieties come to
California?
• Transgenics research
• Fruit quality from HLB trees
Exhibit Visits and Lunch:
12:00 - 1:30
Session Three: 1:30 - 2:30
Expo Building
Citronomics
• Costs of production
– Increased costs due to regulation
– Costs due to water quality regulations
– Higher costs of inputs
• Future trees
– How new nursery regulations
affect handling and delivery of
trees
Session Four: 2:30 - 3:40
Expo Building
Marketing
• What do consumers want?
– Retail sales
– Specialty sales
• Global trends
• Domestic trends
Conference ends and gate closes: 5:00
(Plan to tour Lindcove on Friday.)
Florida leader to give keynote address
T
his inaugural California Citrus glongbing, Kress reports.
Conference will have as its keyHe says Southern Gardens is
note speaker an individual who is “one working “with multiple researchers
of the main leaders in Florida in pro- on projects aimed at developing envividing solutions to the devastating sit- ronmentally and scientifically proven
uation faced by their industry,” notes methods to manage and control canCRB President Ted Batkin. “We are ker and citrus greening disease.”
honored that he accepted the invitaKress is Vice President of the Cittion to share his experiences with us.”
rus Research and Development FounRicke Kress, who will address the dation, the coordinating organization
crowd at the opening day luncheon, is of the Florida citrus industry for dealPresident of Southern Gardens Citrus ing with the present disease challenges.
in Clewiston, Florida.
The Foundation’s mission
Southern Gardens is
is “to advance disease and
one of Florida’s premier
production research and
agribusiness companies,
product development acwidely acclaimed as an intivities to insure the surdustry leader in efficiency,
vival and competitiveness
vertical integration, modof Florida’s citrus growers
ern grove management,
through innovation”.
and citrus research. A
A graduate of Cornell
wholly owned subsidiary
University with a degree
of U.S. Sugar Corporain food science, Kress has
Ricke Kress
tion, Southern Gardens is
been employed in the fruit,
recognized as the largest
juice and vegetable indusbrand and private label premium not- try for nearly 40 years.
from-concentrate orange juice supHis career has largely involved
plier in North America.
working for food manufacturing comOne of the largest citrus growers panies including Libby, McNeill & Libin the state, the company owns and/ by, Nestle, Seneca Foods, and Northor manages 16,500 net acres of citrus land Cranberries, Inc. in a variety of
in southern Hendry County includ- senior management positions from
ing three company-owned properties, agricultural production to sales and
and all three of those properties are marketing. He joined the Southern
infected to some extent with huan- Gardens management team in 2005.
Seeking nominations for Salter Award
The California Citrus Quality Council is seeking nominations for the industry’s most prestigious honor, the Albert G. Salter Memorial Award.
The winner will be announced at the luncheon on the opening day of the Conference,
October 10.
The Salter Award is presented annually by
CCQC to applaud an individual who has made
significant contributions to the advancement of
California citrus.
This important award not only celebrates
specific achievements but also salutes dedication
and commitment, according to CCQC President Jim Cranney.
Nominations must be received by CCQC by Wednesday, August 22. For
details and nomination form, go to www.calcitrusquality.org.
Register online at www.citrusresearch.org
Sign up now for the lowest rate.
For more information, call CRB at (559) 738-0246.
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At the Conference,
you will hear from…
Michael E. Rogers, Associate
Professor of Entomology,
University of Florida, IFAS, Citrus
Research & Education Center,
Lake Alfred
Success of the Citrus Health
Management Area (CHMA)
program in Florida
ABSTRACT: Following the discovery of citrus greening
disease in Florida in 2005, psyllid control has become the
most important pest management consideration of Florida
growers.
Experience has shown that while it is relatively easy to
kill psyllids using commercially available insecticides, actually gaining control of psyllid populations is much more difficult. This is due to the high mobility of the psyllid, coupled
with the short residual activity provided by insecticides under field conditions. As a result, a recently sprayed grove
may become recolonized in a matter of days as psyllids migrate in from surrounding unsprayed citrus groves.
Also on the Conference
program…
Ed Stover, Research
Horticulturist/Geneticist, United
States Horticultural Research
Laboratory, USDA-ARS, Fort
Pierce, Florida
Conventional and transgenic
resistance/tolerance to
huanglongbing in citrus
ABSTRACT: Huanglongbing (HLB) is severely impacting Florida citrus and has been found in CA and TX. Citrus
researchers are immersed in extensive and broad-ranging
efforts to identify solutions to HLB. Previous research indicates susceptibility to HLB throughout cultivated citrus:
in Florida, none are immune and many are extremely adversely affected.
In order to enhance psyllid control programs and subsequently reduce the rate of spread of greening disease, Citrus Health Management Areas (CHMAs) were established
throughout the state.
The goal of the CHMA program is to coordinate the
timing of insecticide applications for psyllid control by all
growers within a CHMA. Such coordinated efforts will reduce “psyllid swapping” between groves and potentially
minimize the need for frequent reapplication of pesticides
to maintain psyllids below detectable levels.
A secondary goal of the CHMA program is to manage
pesticide resistance development in psyllid populations.
Thus, growers within a CHMA rotate (collectively) between
pesticide modes of action from one coordinated spray to the
next.
The CHMA program was officially kicked off in 2010
with seven CHMAs formalized in areas of the state where
grower interest was sufficient to attempt such a voluntary
program. Based on the success achieved in these original
CHMAs, grower interest and willingness to participate in
the CHMA program increased dramatically. To date, there
are 38 CHMAs encompassing 486,079 commercial grove
acres in Florida.
As grower participation in the CHMA program has
increased, there has been a corresponding drop in psyllid
populations statewide. Based on the results of the CHMA
ACP Monitoring program which scouts 6,000 blocks of citrus every three weeks, psyllid populations statewide have
declined nearly 70% over the last 12 months. Additional details on the function and success of the CHMA program in
Florida will be discussed in this presentation.
Numerous transgenic strategies are underway to develop HLB/psyllid resistance in established cultivars. Some
show promise, and new ideas are added regularly. With HLB
widespread in Florida, it is clear that not all cultivars are affected equally. HLB was assessed in commercial groves with
high HLB-incidence: ‘Temple’ had the lowest HLB symptoms and Liberibacter (Las) titer, while ‘Murcott’ and ‘Minneola’ had the highest.
The USDA Ft. Pierce farm is managed to reveal genotype HLB responses. Some current cultivars and conventional hybrid seedlings demonstrate resistance/tolerance, at
least to strain(s) of Las present. Some have abundant foliage
symptoms but full canopies and seemingly normal fruit set
and size.
For example, in a three-year replicated trial of
‘Triumph’(T), ‘Jackson’(J), ‘Flame’(F), and ‘Marsh’(M), all
trees had HLB symptoms and similar Liberibacter titers.
However, T&J maintained full canopies and had fruit with
normal size, yield and quality, while F&M fruit were fewer
and unacceptable. C. trifoliata is the best documented citrus
resistance source, and its hybrids are being evaluated with
some already showing near-commercial fruit quality.
Useful resistance/tolerance to HLB is present in cultivated citrus and more distant relatives, while transgenic
methods offer tremendous potential for greater resistance.
All are being investigated by the USDA citrus breeding program and collaborators, as well as other researchers.
Citrus trees sprayed with mineral oil show lower levels of transpiration - a sign
of greater stress levels - when compared with trees treated with OROCIT.
Mineral oil is known to induce stress in plants when applied as a
foliar spray. In an attempt to quantify the level of stress induced,
trials were conducted in which a single spray of mineral oil and
OROCIT were applied to citrus trees.
TRIAL 2
DR. D. UYS • A. MHLABA • M. MATTHEW • J. KOTZE | ORO AGRI SA (Pty) Ltd
120
39 %
Stomatal conductance (a measure of transpiration) readings were
taken using a Decagon SC-1 Leaf Porometer.
100
STOMATAL CONDUCTANCE ON CITRUS TREES
AVERAGE OF 7 MEASUREMENT TIMES
DR. D. UYS • A. MHLABA • M. MATTHEW • J. KOTZE | ORO AGRI SA (Pty) Ltd
160
32.3 %
IMPROVEMENT
OVER MINERAL OIL
26.3 %
IMPROVEMENT
OVER MINERAL OIL
29.6 %
IMPROVEMENT
OVER MINERAL OIL
120
80
80
60
40
20
OROCIT
MINERAL OIL
99.7
71.7
2 quarts / acre
139.5
105.8
117.8
92.6
128.3
4 gallons / acre
MINERAL OIL
3 quarts / acre
OROCIT
2 gallons / acre
MINERAL OIL
2 quarts / acre
OROCIT
OROCIT
0
1 gallon / acre
40
MINERAL OIL
0
1 quart / acre
STOMATAL CONDUCTANCE | mmol/ m2s
IMPROVEMENT
OVER MINERAL OIL
STOMATAL CONDUCTANCE | mmol/ m2s
TRIAL 1
STOMATAL CONDUCTANCE ON CITRUS TREES
AVERAGE OF 1 AND 4 DAA
98.8
2 gallons / acre
Both transpiration and the exchange of CO2 for photosynthesis
depend on the extent to which the leaf stomata open.
A lower stomatal conductance, as was found with the mineral oil
treatment, indicates that the stomata were less open and the
leaves had less potential for photosynthesis compared with the
OROCIT treatment.
Higher transpiration levels resulting from the stomata being more open indicate that there was greater
potential for photosynthesis in the trees treated with OROCIT than in those sprayed with mineral oil.
CHECK WITH YOUR STATE REGULATORY AGENCY TO DETERMINE REGISTRATION STATUS
ALWAYS READ AND FOLLOW LABEL DIRECTIONS
AVAILABLE FROM YOUR NEAREST QUALITY RETAILER
COPYRIGHT © MAY 2012 ORO AGRI INC. • ALL RIGHTS RESERVED • OROCIT IS A PROPRIETARY TRADEMARK OF ORO AGRI INC.
And in addition…
Elizabeth A. (Liz) Baldwin,
Supervisory Research
Horticulturist, United States
Horticultural Research
Laboratory, USDA-ARS, Fort
Pierce, Florida
Comparing fruit samples
from HLB diseased trees and
healthy trees for chemical and
sensory differences
ABSTRACT: Huanglongbing (HLB) disease has been
shown to result in citrus fruit and juice that is sour, bitter and
generally off-flavored. Recent research with fresh squeezed
and processed orange juice compared samples from HLB
ENTOMOLOGICAL SERVICES, INC.
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PO Box 3043
Visalia, CA 93278-3043
Phone: (559) 627-1153
Fax: (559) 635-4955
16120 Krameria Ave.
Riverside, CA 92054
(951) 285-5437
diseased trees and healthy trees for chemical and sensory
differences.
These differences include lower sugars and higher levels of acids; phenolic compounds; an alkaloid; and limonoids,
most notably the bitter compounds limonin and nomilin,
which impart bitter or metallic off-flavors in HLB juice.
Although levels of the bitter compounds, limonin and
nomilin, were found to be below reported thresholds in
water, our studies showed that their thresholds were lower
(meaning they were more detectable) in combination and
in orange juice. Furthermore, nomilin was associated with a
metallic descriptor.
As the disease has progressed throughout the state of
Florida, growers have become more reluctant to pull out diseased trees. Many prefer too to use foliar nutritional sprays
to compensate for the disease symptoms. These spray programs have worked to some extent in reversing tree symptoms and have now been adapted by much of the industry
who either are resistant or cannot afford tree removal.
Data so far does not support that nutritional sprays reverse fruit off-flavor symptoms. This being the situation, the
concern is that not removing diseased trees will ultimately
lead to nearly complete infection of Florida citrus. As more
trees become infected, the industry juice blends will consequently contain more infected juice and less healthy juice
and lead to flavor decline.
CONFERENCE PLANNING COMMITTEE
2012 California Citrus Conference planning committee. Back row (l to r): MaryLou Polek, Don Roark, Dan Galbraith,
Richard Bennett, Etienne Rabe, Chad Collin. Front row: Earl Rutz, Louise Fisher, Dan Dreyer, and Ted Batkin. At right:
Justin Brown and Mary Lu Arpaia. Not shown: Jim Gorden, Beth Grafton-Cardwell, and Kevin Severns. The group is made
up of CRB Board and committee members, CRB staff members, and representatives of UC Cooperative Extension. Others
contributing to program content include UCCE citrus farm advisors and representatives of California Citrus Mutual.
Post-conference event at Lindcove
T
he morning after the Conference, from 8:30 a.m. to 12:00
noon on October 12, the University of California’s Lindcove Research and Extension Center will host members of
the industry at a special open house complete with guided
tours of major operations.
Planned stops on the tour include citrus variety evaluation blocks, the Citrus Clonal Protection Program’s screen-
house/greenhouse complex, and the Citrus Research Board
Fruit Quality Evaluation Center research packline.
Sign-ups will be taken at the Conference to give the
Lindcove staff at least some idea of how many to expect.
LREC is located in the foothills just northeast of Exeter
about a 20-minute drive from Visalia. For background, go to
http://ucanr.org/sites/Lindcove/.
The UC Lindcove Research and Extension
Center is situated on 175 acres nestled against
the foothills of the Sierra Nevada Mountains.
This view toward the northwest shows a
portion of the field station in the foreground
with commercial citrus stretching out beyond.
Photo courtesy of Beth Grafton-Cardwell.
CPDPP outreach engages
all Californians
F
or years, California citrus growers have watched the devastation
to citrus industries around the
world at the hands of a tiny insect and
the deadly disease it spreads, huanglongbing (HLB).
While the discovery of the first
Asian citrus pysllids in California rattled the nerves of growers, the same
couldn’t be said about urban dwellers
with backyard citrus. California residents love their backyard citrus but
simply didn’t know about the threat
presented by the Asian citrus psyllid,
(ACP), and the deadly plant disease it
brings with it.
This realization taught us two
important things: (1) the first line of
defense against the psyllid and HLB
would be fought in urban settings, and
(2) we needed backyard citrus growers’ support in our fight to save California citrus. Thus, the campaign began
Louise Fisher
to create an environment of cooperation and support for combating ACP
among homeowners in the Southern
California region.
Since the inception of the Citrus
Pest & Disease Prevention Commit-
tee in October 2009, the program (CPDPP) has developed and implemented strategies aimed at educating Californians about the issue, encouraging
residents to inspect their trees and
report finds of the pest, and creating
an air of openness and cooperation
regarding California Department of
Food and Agriculture (CDFA) treatment programs for the psyllid. These
efforts are all designed to suppress the
Asian citrus psyllid as much as possible to protect the state’s citrus growing regions.
When HLB was discovered in
a Southern California residential
lemon-pummelo tree in March 2012,
the industry’s extensive outreach
switched into overdrive. An integrated plan was designed to hit audiences
from all angles – through traditional
media relations, broadcast placements
on television and radio stations, participation in community events, elected official outreach, and involvement
with nurseries.
Crafting research-based messaging
CPDPP communications specialist Lynn Sanderson giving out bookmarks at the
2011 L.A. County Fair.
While efforts have recently been
intensified, the industry has been planning for the Asian citrus psyllid and
HLB since 2008, when communications research was done to test knowledge levels and perceptions among
Californians related to the Asian citrus
psyllid.
The responses revealed that CA
residents are strongly attached to their
backyard citrus trees, and the concept
of losing those trees was unacceptable.
The research resulted in the development of messages to solicit the desired
behavior, i.e. encourage people to join
the fight against the pest and disease.
These messages are incorporated
into all outreach materials, including
fliers, presentations, news articles, public service announcements, and more.
As the presence of the psyllid and
disease fluctuates in California, so does
the messaging. Adjustments to outreach materials are made constantly,
so the messages reaching crucial audiences are up-to-date and will encourage the necessary steps to protect California citrus.
Participating in community events
California outreach timeline
2004 – (CRB initiated requests for scientific research.)
2005 – First ACP/HLB brochures developed by UCCE for growers.
2007 – Coordinated by a Statewide ACP/HLB Task Force, UCCE and others
began developing print materials for the public.
2008 – CRB enlisted a public relations firm, Nuffer Smith Tucker (NST), to conduct public knowledge surveys and message testing. In cooperation with UCCE,
new materials were developed to incorporate the findings.
2009 – CPDPC was created through legislation.
2010 – CPDPP Outreach Subcommittee was formed to oversee all manner of
outreach related to ACP and HLB.
To get the word out, CPDPP has
participated in trade shows, home
and garden shows, community events,
farmers’ markets and similar venues,
and provides presentations at service
and garden clubs. We go where the
people are and educate them on the
dangers of the Asian citrus psyllid and
HLB. We hand out fliers with photos to
help homeowners recognize the pest,
and we speak publicly about the issue.
Through all of the outreach, the
“call to action” is clear – go home, inspect your trees and call the CDFA
hotline if you think you’ve found the
psyllid. This “hyper local” outreach has
allowed the program to penetrate key
areas and engage in conversations with
residents.
Working with media in spreading
the word
Media has played a key role in CPDPP outreach, allowing a mass audience to be reached through targeted
outreach to these gatekeepers. Previous English- and Spanish-language
media tours – in which a combination
of interviews with print reporters and
television and radio interviews – resulted in extensive reporting on the
issue. CPDPP now has strong relationships with media who provide ongoing
coverage.
When HLB was discovered, CPDPP swiftly organized an emergency
media tour with the public relations
agency Nuffer, Smith, Tucker (NST).
Within a week, Ted Batkin, president
of the Citrus Research Board, was
whisked to newspapers and radio and
television stations throughout Southern California to communicate the vigilance needed to stop the disease from
spreading.
The result was dozens of stories in
Printed materials emphasize key messages. A QR code links to the
CaliforniaCitrusThreat website.
key news outlets covering the discovery of HLB and offering tips for how
homeowners can play their part in protecting California citrus. NST is currently planning two more media tours.
Broadcast support
To further reach California residents through the media, placements
on television and radio stations have
been secured through public service
announcements (PSAs), pre-packaged news stories sent to radio outlets,
and sponsored traffic spots. These information-rich pieces are aired often
by targeted media, resulting in millions of California residents hearing
our messages about inspecting their
citrus trees for signs of the pest and
disease and cooperating with agriculture officials on necessary treatments.
To date, our radio and TV PSAs alone
have generated more than 72 million
impressions.
Tom Shea conducts a seminar on ACP/HLB at the California Grown Show presented
by the California Association of Nurseries and Garden Centers (CANGC). A research
associate with UC Cooperative Extension in Riverside County, Shea assists in the
CPDPP outreach program, working with gardening-related groups.
Reaching an online audience
through social media
In 2008, websites in English and
Spanish were created to communicate
the complex issue to California residents and arm them with the necessary
tools to protect their citrus. This online
presence has continued to grow and
is a gateway to relevant news, recent
findings of the psyllid and HLB, and
step-by-step instructions for how to
save their citrus.
There are downloadable resources
in nearly a dozen languages as well as
links to the CPDPP Facebook page,
Twitter, YouTube videos, and the USDA
Save Our Citrus smartphone app which
Banners designed for display along highways have also been put to
good use in other locations, including this wall near the entrance at the
Imperial Valley Expo/California Mid-Winter Fair & Fiesta in March 2011.
All CPDPP outreach pushes
residents to visit www.
CaliforniaCitrusThreat.
com for more information
and photos to help
them identify the pest
and disease. There are
downloadable resources in
nearly a dozen languages
as well as links to the
CPDPP Facebook page,
Twitter, YouTube videos,
and the USDA-APHIS Save
Our Citrus smartphone app
which enables users to
report signs of the Asian
citrus psyllid and HLB
directly to the USDA.
Mark Olson, government relations specialist for
the CPDPP outreach program, announcing the first
HLB find in California at the Southern California
Association of Governments annual conference in
April 2012. More than 50 local elected officials from
throughout the region listened to his presentation
along with 300 conference attendees.
enables users to report signs of the
Asian citrus psyllid and HLB directly
to USDA-Animal & Plant Health Inspection Service (USDA-APHIS).
Tapping into elected officials
CPDPP also reaches out to city
governments and local elected officials throughout Southern California
through city council meetings, oneon-one briefings, and other communication efforts. Residents look to their
local officials as valuable sources of
information, and we make sure these
officials are informed about the Asian
citrus psyllid and how constituents can
protect their citrus.
Our efforts have helped us get
placement in local newspapers, have
our public service announcements run
on local television stations, and have
even resulted in Asian citrus psyllid
information being included in citywide
mailings like water bills.
The relationships we’ve built with
elected officials also help with cooperation of CDFA treatment efforts
and ensure residents are well educated
on the importance of suppressing the
Asian citrus psyllid through proper inspection and treatment.
Commissioners’ offices, UC Master
Gardeners, the Ventura County ACP/
HLB Task Force, and the California
Department of Pesticide Regulation
to create a cooperative environment
on all levels and ensure our messages
are reaching the right people.
Nursery outreach and treatment
promotion
CPDPP is beginning work with
nurseries, including the California
Association of Nurseries and Garden
Centers (CANGC) and the California Citrus Nursery Board (CCNB), on
programs aimed at educating nursery
staff about the Asian citrus psyllid and
arming them with information to educate consumers.
Providing support for training sessions and presentations, and making
collateral materials available, are some
of the ways CPDPP is working with
nurseries. In addition, CPDPP is in dis-
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Cohesive efforts
While the CPDPP campaign is
multifaceted, our efforts are strengthened by cooperation with other industry organizations as well as government entities.
California Citrus Mutual (CCM)
leads the charge for outreach to elected
officials in Sacramento and Washington, D.C. UC Cooperative Extension
(UCCE) has been instrumental in developing print materials. The CDFA
implements tactics aimed at homeowners, mainly in areas where treatments
are occurring. These efforts include notifications sent directly to homeowners
as well as public open houses. USDAAPHIS is also implementing outreach
efforts via its “Save Our Citrus” campaign that includes public service announcements, interactive efforts and
more.
All parties communicate regularly via a joint information committee (JIC) to ensure consistency in
messaging and to maximize all parties’ resources. Additionally, CPDPP
has worked closely with various Farm
Bureau offices, County Agricultural
800.909.5050
800.542.8072
800.800.4865
cussion with manufacturers of home
treatments for the Asian citrus psyllid
to leverage their marketing efforts to
support the suppression of the Asian
citrus psyllid and HLB.
End results
CPDPP outreach efforts are paying off. The CDFA hotline for reporting Asian citrus psyllid finds has seen
a steady increase in calls, and California homeowners have been eager to
do their part in protecting citrus by
inspecting their trees and cooperating
with CDFA treatments.
CPDPP will continue to work diligently to educate California residents
on the Asian citrus psyllid and huanglongbing and to equip them with the
information they need to take action
and help protect our state’s vibrant citrus culture.
Do you have feedback on CPDPP
outreach efforts related to the Asian
citrus psyllid? If so, we want to hear
from you. Take our survey at www.CitrusSurvey.com.
Louise Fisher is Director of Communications & Finance for the Citrus
Research Board (CRB), coordinator
of outreach for the CPDPP, and managing editor for Citrograph. She coordinates the ACP Joint Information
Center (JIC) and is a member of the
HLB JIC.l
“Like” California Citrus
Threat on Facebook.
Facebook.com/CaliforniaCitrusThreat
Follow @CitrusThreat
on Twitter.
Twitter.com/CitrusThreat
THE ANSWER
For the serious history buffs: 150 years
ago, in 1862, President Abraham Lincoln signed into law three very important
pieces of legislation that would have a profound and lasting impact on American agriculture. Do you know what they were?
(Do You Know, page 5.)
• An act to establish a Department of Agriculture set forth the USDA’s basic mission
“to acquire and diffuse among the people
of the United States useful information on
subjects connected with agriculture in the
most general and comprehensive sense of
the word.”
• The Homestead Act stimulated Western
agriculture by offering qualified individuals
160 acres of public land for settlement and
cultivation.
• The Morrill Land Grant College Act
provided public lands in U.S. states and
territories for the establishment of colleges
specializing in agricultural research and instruction. Among the schools created was the
University of California.
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Life after the CRB-funded research project
MaryLou Polek and Brian Taylor
E
ach issue of Citrograph features reports by the principal
investigators of CRB-funded research projects. You
certainly have wondered, what happens to the products
of this research? This article describes how some of these projects move forward and their products reach you, the grower.
In the March/April 2012 issue, Cristina Davis’ group at
the University of California, Davis reported on their progress in an article titled, “Reagentless detection of citrus
pathogens using differential mobility spectrometry (DMS)”
(pages 54-56).
This technology uses volatile organic compounds (VOCs)
as a means to detect the presence of pathogens within a plant.
The hope is that these pathogens can be detected before
symptoms appear that are visible to the human eye.
This research group has identified unique chemical
signatures for huanglongbing (HLB) and tristeza that are
detected by a relatively small piece of equipment called a
differential mobility spectrometer (DMS) (Figure 1). Ted
Batkin also addressed this technology in his editorial in the
May/June 2012 issue (page 4).
Readers must be cautioned that although this is promising
technology, it is still in the validation phase. Should a sample be found suspect using this testing method, repeated
testing must be performed in order to confirm the result.
Furthermore, before commercializing this methodology, it
must be thoroughly vetted by the scientific community.
This is fine in a controlled laboratory situation, but what
about in the real world, in your grove? Does this technology
really work? Well, with the assistance of CRB and CDFA
staff, Alexander Aksenov, a development engineer in the
Davis lab, took the equipment to the street.
Ideal location for field-testing
As you know, HLB-associated bacteria were detected in
a tree in Hacienda Heights in Los Angeles County. CDFA
has been visually inspecting citrus trees and collecting psyllids and plant tissue from trees adjacent to that detection
site -- (the positive tree has been removed) -- and luckily, no
psyllids or plants have tested positive since. What a perfect
location to test this device!
In addition, another researcher from the University of
California, Davis, Carolyn Slupsky, was funded last October
for a project titled, “Biomarkers for detection of Liberibacter infection in Valencia orange trees through H-NMRbased metabolomics of leaves and woody tissues”. Her report will be published in a future issue of Citrograph, but
she believes she has identified metabolites that are unique
to trees infected with HLB-associated bacteria.
So, the plan was for CRB’s Brian Taylor to coordinate
with Tina Galindo of CDFA to select appropriate residential
sites for Alex Aksenov, UCD, to test the DMS equipment. At
the same time, plant tissue would be collected and brought
back to the CRB Jerry Dimitman Laboratory for two purposes: one, the tissue would be tested by lab personnel by
the standard Polymerase Chain Reaction (PCR) method for
HLB-associated Liberibacter. The second purpose would be
to process the tissue by lyophilization (freeze-drying) and
send it to the Slupsky lab in Davis.
I am happy to report that the PCR results from the Jerry
Dimitman lab were negative. At the time this issue went to
press, we had not yet received the data analysis from the Davis and Slupsky laboratories.
CRB technology transfer
John Morgan, CRB laboratory technician, operating the
lyophilizer equipment that will freeze/dry plant tissue
samples This method preserves the tissue so that it can be
sent to other laboratories and analyzed at a later time.
Many growers see the faces of CRB staff at various
meetings but may not realize the roles and responsibilities of
staff behind the scenes. The Citrus Research Board doesn’t
just fund research projects; often, staff members actively
take part in the technology transfer of project products.
This means staff participates in making research results usable, including the field validation of technology and
methods and adjusting an assay method so it is usable by
laboratories.
As the Asian citrus psyllid continues to move throughout Southern California, we hope that technology such as
the advances mentioned in this article will detect infected
trees long before HLB symptoms appear. In this way, only
tens of trees will require removal instead of hundreds.
As it stands today, the Davis lab’s work with VOCs is still
experimental. Although the goal of the research is the early
detection of HLB, if a tree were to come back suspect using
this method, no regulatory action could result without the
substantiation by the currently approved method. Detection
of HLB-associated bacteria that would result in mandated
tree removal is PCR followed by sequencing the PCR products. Then, confirmation must be made by the USDA Diagnostic Laboratory in Beltsville, Maryland.
During this next year, two important activities will occur
concurrently: Drs. Davis and Aksenov will continue to refine
the VOC signatures and sensing probes, and a company –
Applied Nanotechnologies – will reduce the overall size of
the equipment and prepare the design for manufacturing. A
usable product will be in the hands of growers within the
next few years.
Dr. MaryLou Polek is Vice President of Science and
Technology for the Citrus Research Board which includes
providing oversight for all research projects funded. Among
other professional duties, she is the Chief Science Editor for
Citrograph. Brian Taylor, Field Operations Director for the
CRB, joined the program in 2009 with more than 30 years’
experience in the detection and eradication of exotic pests.
Kavitha Madishetty, CRB laboratory biologist, preparing
a plate of samples for Polymerase Chain Reaction (PCR)
analysis. The process of loading the PCR plate must be done
under a laminar flow hood. This hood is designed so that
air within the hood has been purified, thereby preventing
contamination of the samples.
While in the process of moving knowledge to the field…
‘‘I
was asked to help coordinate with the researchers
working on the EZKnows VOC system and CDFA
to test trees in the Hacienda Heights area of Los
Angeles for HLB. An EZKnows prototype had been tested
on Hamlin oranges in Florida with very encouraging results,
and now the researchers wanted to test the machine on
California-raised varieties and under California conditions.
After numerous calls to Cristina Davis’ lab and CDFA,
dates were set for the testing. I looked forward to the opportunity to observe and help in finding a quicker and earlier
detection technique for HLB.
“A good researcher not only needs to recognize the
problem and come up with a possible solution, but they must
also be able to execute that solution so that it is practical
and affordable. The use of VOCs is not
new. Dogs have been used for centuries to detect things for humans (and
yes, there are even dogs being trained
to detect HLB); however, dogs have
limitations that machines do not. Using
VOCs at airports to test for explosives
is now routine. So the Davis lab hopes
that they have come up with a way to
test trees for HLB by analyzing the
Brian Taylor
tree’s VOCs.
“There are sometimes many steps involved in solving some problems, as I appreciated once again in working
with Dr. Aksenov. Equipment must be designed to collect
(Left) Dr. Alexander Aksenov working with the entire setup of the DMS equipment. (Above) Differential mobility
spectrometer (DMS) prototype equipment used to detect
volatile organic compounds (VOCs) in the Los Angeles area.
the VOC sample and then
an analysis made to determine the VOC signature
of a healthy tree versus an
HLB-infected tree. Will the
signatures be the same if the
samples are brought into the
laboratory or sampled in the
field?
“Some of the variables
that must be analyzed include
not only the biological characteristics of the tree (will the
signature of an orange be the
same as a lemon?), age, production cycle; environmental characteristics (climate,
humidity, temperature, time
of day); and also the overall
health of the tree (stress, insect pests, etc).
“The Cristina Davis lab
recognized that there was a
difference in the signature of
a healthy Florida orange and
an orange from a known infected tree. The question was
how to move that knowledge
to the field and make it useful Sonya Segura, left, and Lydia Rodriquez, members of CDFA’s ACP/HLB survey crew, assisted
“Taking a laboratory full with contacting homeowners and arranging for sites to test the technology.
of instrumentation and ‘compacting’ it was the first challenge. Davis’ lab has succeeded and run extension cords.
in reducing the equipment package to a small suitcase and
“On the agreed-upon day, I met up with Dr. Aksenov
a laptop computer. They hope to reduce it even further and and CDFA Inspectors Lydia Rodriquez and Sonia Segura.
make it truly portable.
Lydia and Sonia had already made contact with homeown“In Florida, the testing was done in a commercial grove ers in the area and located Valencia orange trees for Dr.
and the equipment placed on the back of an ATV and run Aksenov to test. While Alex and I were busy setting up the
from batteries. Whereas this may be an efficient method in equipment, Lydia and Sonia conducted a visual survey for
a commercial grove, it is not very useful in someone’s back- ACP and HLB symptoms. No ACP were found, as the area
yard. Dr. Aksenov needed a platform for the equipment to had recently been treated as part of the HLB eradication
be placed on and a dolly for the batteries. The final set-up program. Plant samples were taken from each tree and sent
included a small folding table and a homeowner willing to to the CRB Jerry Dimitman Laboratory in Riverside for
allow us to plug the equipment into their electrical outlet PCR analysis.” — Brian Taylor. l
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Detector dogs protect
California agriculture
U.S. Customs and Border Protection canines
sniff out harmful plants, animals
Robin Wall
Editor’s Note: CBP’s detector dogs have
canine colleagues working in other
agencies. Watch for an article on CDFA/
County teams in an upcoming issue.
T
raditionally, dogs have been associated with the protection of
livestock or families. By protecting American agriculture, U.S. Customs
and Border Protection (CBP) and its
agriculture detector dogs build on this
partnership between humans and dogs.
We all know that dogs can pick up
on odors in amounts far lower than humans can. The ability to discriminate
and target a specific odor, such as that
of an orange or even a live snail, makes
dogs an invaluable tool in detecting
prohibited agricultural items hidden
from view.
When it comes to finding prohibited fruit, vegetables, plants and meat
products from high-risk countries, the
nose knows. A trained agriculture dog
can scan a piece of luggage for smuggled or forgotten fruits in mere seconds. Understandably, it takes a human
officer much longer to open and visually inspect the same bag.
Canine program launched in 1984
In 1984, a little more than 100 years
after beagles first landed in America
from England, the U.S. Department
of Agriculture established its detector
dog program at Los Angeles International Airport with one beagle trained
to sniff out plants and animal products
in luggage and carry-on items arriving
on international flights.
By 1995, the program had grown to
30 canine teams as part of the “Beagle
Brigade” at 19 international airports
throughout the nation.
Beagles and beagle mixes are the
preferred breed of dog at the airport
because of their keen sense of smell,
non-threating size, high food drive and
gentle disposition with the public.
In 2000, USDA starting using larger dogs outside the passenger environment by employing Labradors, with the
launch of the “border brigade” on the
Mexican and Canadian borders and
“cargo brigade” in cargo facilities and
at seaports.
In 2003, when USDA transferred all
the agricultural inspectors, including canines, to CBP, approximately 75 canine
teams came over to the new agency. Today, over 100 CBP agriculture canine
teams provide inspections at border
crossings, international cargo warehouses, international air passenger terminals,
cruise terminal and international mail
facilities and preclearance locations.
The effectiveness of the canine
program has certainly grown in California, too. We have over 20 agriculture
canine teams on duty, preventing the
movement of harmful pests including
“Salty” gets closer for a better sniff
while waiting air passengers look on
at San Francisco International Airport.
fruit fly-infested fruit and Asian citrus
psyllid host plant material.
The use of agriculture canines has
proven to be one of the best tools in
the fight against the detection and
spread of invasive species worldwide.
One such example involves brown tree
snakes that have infested the island of
Guam, causing the extinction of several
native species of birds.
To protect the rare flora and fauna
in Hawaii, it is important to avoid accidentally introducing this destructive
pest into the environment. The USDA
Animal Damage Control Program uses
terriers that are trained to sniff for
brown tree snakes in aircraft, vehicles,
household goods, and ships leaving
Guam for snake-free areas like Hawaii,
the Mariana Islands and Saipan.
Rescued dogs and donated dogs
“Floyd” educates the crowd at the
2012 Ag Day at the Capitol. Photo by Ei
Katsumata.
All the sniffer dogs in the CBP Agriculture Canine Program are adopted
from rescue shelters in the U.S. or come
to the program from private donations.
Before the selected beagles or Labs
can start their specialized work, they
have to go to school. At first, USDA
worked with the military at Lackland
Record-breaking career ends for San Francisco CBP canine
Souza. Jasmine is a pathway for psyllids, which can carry
Duffy has hung up his work vest and retired.
During his nearly six years at San Francisco Interna- citrus greening disease.
De Souza attributes Duffy’s success to his high food
tional Airport as a U.S. Customs and Border Protection
agriculture detector dog, the 8-year-old beagle set the port drive, a common trait for beagles. The handlers reward
record for the highest number of finds -- more than 14,000 their canine partners with a treat after every find. “Duffy
wanted that treat more than anything,” said De Souza.
-- that led to the seizure of prohibited agriculture items.
Duffy retired in early June and will spend his leisure
Together, CBP Agriculture Specialist Canine Handler
Peter De Souza and Duffy worked more than 4,500 arriving years as De Souza’s pet.
Agriculture detector
flights. Duffy sniffed more
dogs live in CBP kenthan 4 million pieces of lugnels during their working
gage, rooting out a record
years and receive ample
number of potentially harmplay and socialization
ful animal or plant agricultime. The food aromas
tural products.
of a home environment
One of Duffy’s most
could be confusing to the
surprising finds: two giant
dogs and could interfere
African snails. These snails
with their work skills. Incan destroy a variety of
deed, during his first days
plants, including food crops.
of retirement, De Souza
The snails also may carry a
said that Duffy would go
parasite that can infect huto the garbage can and sit,
mans with meningitis. “And
the CBP canine method
we don’t even train the
of alerting to a find.
dogs to find snails,” said De
But in just a week,
Souza. Although Duffy and
Duffy seemed to learn
his fellow working canines
that he’s no longer on
do not train on snails, they
the job. He has learned
develop a scent picture that
to relax and enjoy his reprompted Duffy to alert
tirement, even passing an
his handler that there was
apple lying on the ground
something in the bag that he
without giving it particushould definitely check out.
lar notice.
Duffy made many sigDe Souza is now trainnificant finds of Asian citrus
ing with his next CBP capsyllids, fruit flies and their
nine partner to continue
host materials. “One time
his agriculture inspections
he pulled me the length
at San Francisco’s airport,
of two baggage carousels
hoping that the new dog
-- about 500 feet -- because
will follow successfully in
he smelled a jasmine lei in a CBP Agriculture Specialist Canine Handler Peter De Souza
Duffy’s paw prints.
woman’s handbag,” said De and Duffy on the job at San Francisco International Airport.
Air Force Base in Texas to train the
beagle teams. In 1987, USDA opened
three canine training centers and began
training their own teams.
As the program grew and training
needs changed, one facility, the National Detector Dog Training Center
(NDDTC) was opened in Orlando,
Fla., in 1997. As the program expanded, a new facility was created in 2009
for NDDTC near Atlanta, Ga. That
facility incorporates environmentally
conscious features in accord with the
Leadership in Energy Environmental
Design certification by the U.S. Green
Building Council.
All CBP agriculture canine officers and canines complete the initial
10-13 week Agriculture Specialist Canine Training at the NDDTC. Training
and evaluation continues at the team’s
home port to maintain proficiency.
The beagles are trained to alert
passively -- to sit quietly to indicate
the presence of an agricultural product.
Labs work in a more intense environment alongside a cargo truck or in a
noisy mail facility. They are trained to
give an active response by pawing to
indicate found contraband. Regardless
of the behavioral response, food and
positive praise from their own handler
is the reward that increases the intensity and duration of their search time.
CBP agriculture canine team on the
southern border checks a vehicle for
contraband food items. Labradors are
used in more extreme conditions such
as cargo truck and passenger vehicle.
Beagles and beagle mixes are the
preferred breed of dog at the airport
because of their small size and gentle
nature with the public.
Interaction increases their
effectiveness
Because the canines employed by
CBP are actual working dogs, they are
highly visible at many locations. The
dog and handler team’s daily interaction with international travelers and
shippers as they search for prohibited
agricultural products only serves to increase their effectiveness.
Agriculture canine teams have
given thousands of demonstrations to
audiences of all ages. At schools, media
interviews, fairs or other events, the agriculture detector dog teams are always
ready to steal the show, greeting the
public with happy faces and wagging
tails.
The Beagle Brigade has been recognized twice by the Port Authority of
New York and New Jersey as airport
ambassadors for providing outstanding
customer service. The Pedigree All Star
Hall of Fame inducted the Beagle Brigade into the National Dog Museum
in St. Louis, Mo., as the outstanding
“Tino” can quickly scan luggage for smuggled or forgotten agricultural items,
which could harbor pests and diseases harmful to California agriculture.
service program in 1993. Several organizations have recognized the Beagle
Brigade for its work rescuing dogs and
giving them a second chance.
The New York Times, USA Today,
CNN, Animal Planet, Nickelodeon,
Dateline NBC, Telemundo network,
and the Christian Science Monitor,
among countless other local and national media outlets, have produced
stories featuring the Beagle Brigade.
In addition to their important detection work, agriculture canine teams
make the public aware of the important role that agriculture plays in CBP’s
overall mission and in the U.S. economy.
The agriculture detector dog program’s
special role in protecting American agriculture and its public appeal makes it
an ideal program for public outreach
activities, with dogs that perform a service rather than serve as mascots.
Robin Wall began her agriculture
career as a scientific aide in Sacramento with the California Department
of Food and Agriculture Biological
Control Program, then becoming a biologist with the CDFA Nursery, Seed
and Cotton Program, where she participated in various emergency projects,
including glassy-winged sharpshooter.
She began her federal career as a plant
protection and quarantine officer with
USDA at the port of Oakland in 2002,
since progressing to CBP supervisory
agriculture specialist. Wall originated
the position of California agriculture
liaison in 2010.
All photos courtesy of CBP Office of
Public Affairs. l
CRB Funded Research Reports
Research Project Progress Report
Avoiding economic losses in California citrus
from Citrus tristeza virus stem pitting
Svetlana Folimonova
C
itrus tristeza virus (CTV) causes two citrus diseases
which have had a major impact on global citrus production: quick decline on sour orange rootstock, and
stem pitting (SP) regardless of rootstock.
The first disease is effectively managed in California
with the use of resistant and/or tolerant rootstocks in combination with the removal of inoculum (Central California
Tristeza Eradication Agency-CCTEA). However, the introduction of SP CTV variants from outside sources or the
emergence of variants from unrecognized existing infections
is an ongoing threat to the California citrus industry.
There are multiple examples of inadvertent introduction
of SP CTV variants into many citrus-producing countries
due to the international movement of citrus varieties despite
established quarantine practices.
The California detection in 2000 of exotic severe SP
CTV in mandarin plantings which originated from illegal budwood imports (M. Polek and R. Yokomi, personal
communication), and the discovery of CTV SP VT isolates
in commercial citrus in Florida demonstrate this ongoing
threat.
CTV isolates with a strong SP phenotype may also
spread from potential internal “masked” foci of infection,
such as infected SP-tolerant varieties (i.e. mandarins and
Satsumas) and induce severe SP disease in more susceptible
cultivars.
Such isolates were identified during the multiyear Citrus
Research Board (CRB)-supported project that identified
and bio-characterized naturally occurring San Joaquin Valley (SJV) California CTV isolates conducted by Polek and
others. They found that some isolates collected from known
infected but asymptomatic trees induced severe SP symptoms in a standard bio-indexing procedure.
In addition, the probability that such foci will remain undetected and allowed to exist for prolonged periods has increased considerably for the SJV since the CCTEA recently
changed their suppression approach from the removal of all
CTV-infected trees to the selected tree removal based on
Fig. 1. With severe strains of CTV causing stem pitting, trunks may be so severely impacted that they have a ropey
appearance (left). At right, stem pitting (SP) symptoms in greenhouse Mexican lime seedlings that were (or had been?)
inoculated with CTV. Peeling away the bark reveals depressions or pits in the wood ranging in severity; SP-0 is a healthy
(not inoculated) stem whereas SP-5 is severely pitted. The pits can be so deep that it is almost impossible to peel the bark
off. Trunk photo by MaryLou Polek. Seedlings photo by Cindy Wallen, CCTEA.
serological and molecular methods.
The impact of SP on citrus production has been clearly documented in
many different countries. This disease
severely affects limes, grapefruit, and
sweet orange and results in reduced tree
growth and vigor as well as in reduced
fruit size and quality, which are highly
important economic concerns, especially
for fresh fruit market industries such as
in California. (See Figures 1 and 2 for illustrations of the impact of SP CTV.)
At present, the only means of protecting commercial citrus varieties from
losses due to SP is cross protection with
appropriate mild CTV isolates.
In some cases, earlier attempts to use
this approach had controversial results. Fig. 2. At left, a grapefruit tree affected by stem pitting. At right, fruit from a
For example, selection of mild protecting normally growing grapefruit tree (far left row) versus fruit from a tree infected
isolates has enabled the efficient control with stem pitting. Photos by Stephen M. Garnsey.
of SP disease of sweet oranges and limes in Brazil and Peru advanced our understanding of how CTV cross protection
and grapefruit in Australia and South Africa. However, simi- works.
We constructed a green fluorescent protein (GFP)lar mild-strain protection approaches had minimal or no success in other regions or with other varieties as reported by tagged CTV based on an isolate of the T36 strain. (T36 is
Ieki and Yamaguchi, Muller et al (1988), and Broadbent et al a severe strain of CTV identified in Florida.) The GFP(1991). Often, mild CTV isolates failed to protect or provid- tagged CTV construct allows visualization of the virus in
ed only limited short-term protection against severe disease. infected citrus trees (Figure 3). Using this system, we found
that only isolates within the same virus strain group crossprotect against each other, while isolates from different
Cross protection mechanism poorly understood
The mechanism as to why some mild isolates were ef- strains do not.
Figure 4 illustrates the results of the experiment in which
fective and others failed to protect is poorly understood
and thus poses challenges in using this approach to control citrus trees were initially pre-infected with isolates of differSP. The purpose of our research project is to elucidate the ent CTV strains and then challenged with the GFP-tagged
mechanism of cross protection so that it can be successfully T36 CTV. Only isolates of the T36 strain were able to provide protection against GFP-tagged T36 CTV. Lack of green
implemented as a management tool in commercial citrus.
For a number of years, elucidation of the mechanism of fluorescence on the right bottom panel indicates lack of the
CTV cross protection has been an important component challenge virus infection in those trees. All other isolates
of the research program in the laboratories of Drs. William that represented other CTV strains did not protect against
O. Dawson and Svetlana Folimonova at the University of T36-based challenge virus. The trees pre-infected with isoFlorida. Recently, considerable progress has significantly lates from those strains showed strong green fluorescence,
Fig. 3. Bark of a citrus tree infected with GFPtagged CTV shows green fluorescence in cells
that contain virus. The picture was taken using a
fluorescence microscope.
Fig. 4. Detection of GFP fluorescence on the internal surface of bark
of citrus trees challenge-inoculated with GFP-tagged T36 CTV. Only
isolates of T36 strain were able to provide protection against the
challenge virus.
which confirmed infection with the challenge GFP-T36 virus
(Figure 4).
The findings that only isolates within the same strain
protect against each other were also confirmed for different
combinations of protector and challenge CTV isolates using
various assay techniques.
Citrus Crop Insurance
‘We now know the basic rule’
As a result, now we know the basic rule of CTV cross
protection: mild isolates of a strain can only protect against
a severe isolate of the same strain. This understanding gives
us the ability to effectively select mild CTV that protects
against severe CTV in a given area.
Considering the high probability of the introduction of
aggressive exotic isolates and of the pre-existence of unrecognized sources of CTV SP variants within California, the
goal of our project that is being funded by the California
Citrus Research Board is to develop the reagents necessary
to avoid severe crop losses due to CTV SP in California and
to have these reagents in place at the first indication of an
emerging SP epidemic.
At the CTV Workshop (Emeryville CA, August 12-14,
2008), it was noted that the development of a mild strain
cross protection program or procedure requires years, and a
prudent approach is to develop the basic tools and strategies
in advance before the disease appears in the field.
The design of this project is based on collaboration between Dr. Georgios Vidalakis (Department of Plant Pathology and Microbiology at the University of California, Riverside, CA), Dr. Svetlana Folimonova (Department of Plant
Pathology at the University of Florida, Citrus Research and
Education Center, Lake Alfred, FL) and Dr. Raymond Yokomi (USDA-ARS, Parlier, CA).
This approach strives to combine and maximize the expertise and knowledge of these labs in order to provide comprehensive knowledge of the genetic and biological diversity
of CTV isolates in California, with the goal being to identify
and put in place mild isolates of the virus that can provide
sustained protection against severe SP isolates.
The project has three main objectives. The first objective is to assess the pathogenic potential of CTV isolates collected from the main citrus growing areas in California and
from existing collections of CTV isolates at the CCPP and
CCTEA, which is being done in the Vidalakis lab.
Since no eradication program was ever implemented
in Southern California, the genetic and symptom diversity
of CTV is expected to be higher than that in the SJV. Material is being collected from highly symptomatic and nonsymptomatic trees. Presence of CTV in those trees is verified
by ELISA with CTV-specific antibody. Non-symptomatic
trees in which CTV is detected represent a particular interest, since such trees may contain desirable mild CTV isolates
that could be used to cross-protect against severe SP isolates
belonging to the same strain group.
Budwood collected from CTV-infected trees is further
evaluated by grafting into citrus seedlings of different varieties for biological characterization, and symptom development is assessed over a period of 6-12 months. Isolates
that do not cause SP, especially in varieties that are of most
interest for California growers, are characterized to determine their genetic background, i.e. to identify which strain
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group of CTV they represent.
The second objective is to molecularly characterize selected severe SP and mild non-SP field isolates to identify
potential mild candidates to cross-protect against the SP
CTV. For this purpose, total nucleic acids are extracted from
infected tissue and sent to Folimonova’s lab for molecular
characterization using CTV genotype (strain)-specific molecular markers designed in Folimonova’s lab and in the lab
of Dr. Mark Hilf, USDA-ARS, Fort Pierce, FL.
Several mild candidates identified
As a result of our efforts, we have already characterized
the genotype composition of a large number of California
CTV isolates and identified several potential mild candidates that could be used for protection against aggressive
SP isolates.
Our next step (the third objective) is to test the potential of these mild field isolate candidates in greenhouse cross
protection trials, which is being done in collaboration with
Dr. Yokomi. The main question is how to choose protecting
and challenging isolates for the trials.
We are selecting sets of isolates that would be used as
protecting and challenging isolates based on our understanding of the CTV cross-protection mechanism, as determined
from the basic research conducted in Dr. Folimonova’s lab
and information from biological and molecular characterization of isolates.
Key Terms
Quick decline occurs in sweet orange varieties
grafted onto sour orange rootstock when infected
by certain strains of CTV. The virus induces a graft
incompatibility between the rootstock and scion,
causing the vascular tissues to die off. Water cannot
move up into the canopy, and carbohydrates cannot
move down into the roots. Trees rapidly die when put
under heat and water stress.
Sour orange rootstock has many advantages:
trees are highly productive even in poor soils; it is
tolerant to Phytophthora root rot and most grafttransmissible pathogens; and, it is compatible with
most scion varieties.
Stem pitting symptoms begin with an interruption of meristematic activity of the cambial layer between the bark and the wood. Where the cambium
is inactive, depressions or pits form. The greater the
inactivity, the larger or more frequent the pits.
Cross protection occurs when a mild strain
of a pathogen prevents the expression of disease
symptoms by a subsequent, more severe pathogen.
Also known as preimmunization.
Genotype: The genes or molecular sequence of
an organism.
Phenotype: The expression of genes giving an
organism its appearance; what it looks like.
The basic rule for the selection of protecting isolate/
challenging isolate sets is that both isolates in a trial set need
to have similar genotype composition. Initial in-greenhouse
cross protection trials have already been set up at the USDA-ARS San Joaquin Valley Agricultural Sciences Center
in Parlier. The results of those trials will be evaluated during
the current year. Protective mild isolates identified during
this project will be available for growers to use in California.
Dr. Svetlana Folimonova is an Assistant Plant Pathologist with the University of Florida’s Citrus Research and
Education Center (CREC) in Lake Alfred. Dr. Folimonova’s research centers on viral and bacterial diseases of citrus,
in particular diseases caused by Citrus tristeza virus and by
Candidatus Liberibacter asiaticus (huanglongbing). Her efforts are focused on understanding the mechanisms of the
infection process, host responses to the pathogens, improving
methods of detection, and developing management strategies
for these diseases.
CRB research project reference number 5300-147.
References
Bederski K, Roistacher CN, and Muller GW (2005).
Cross protection against the severe Citrus tristeza virus. Stem
pitting in Peru. In Proc. 16th Conf. Int. Org. Citrus Virol. Hilf
ME, Duran-Vila N, and Rocha-Pena MA eds, pp.117-126,
Riverside, CA.
Broadbent P, Bevington, KB, and Coote, BG (1991).
Control of stem pitting of grapefruit in Australia by mild
strain cross protection. In Proc. 11th Conf. Int. Org. Citrus
Virol. Brlansky RH, Lee RF, and Timmer LW eds, pp64-70.
Riverside, CA.
Costa AS and Muller GW (1980). Tristeza control by
cross protection: a US-Brazil cooperative success. Plant Dis.
64:538-541.
Cox JE, Fraser LR, and Broadbent P (1976). Grapefruit
stem pitting - field protection by mild strains. InProc. 7th
Conf. Int. Org. Citrus Virol.,Calavan EC, ed., pp.68-70, Riverside, CA.
Folimonov AS, Folimonova SY, Bar-Joseph M, and Dawson, WO (2007). A stable RNA virus-based vector for citrus
trees. Virology 368: 205-216.
Folimonova SY, Folimonov AS, Tatineni S, and Dawson
WO (2008). Citrus tristeza virus: survival at the edge of the
movement continuum. Journal of Virology 82: 6546-6556.
Folimonova SY, Robertson CJ, Shilts T, Folimonov AS,
Hilf ME, Garnsey SM, and Dawson WO (2010). Infection
with strains of Citrus tristeza virus does not exclude superinfection by other strains of the virus. Journal of Virology
84:1314-1325.
Hilf ME, Mavrodieva VA, and Garnsey SM (2005) Genetic marker analysis of a global collection of isolates of Citrus tristeza virus: characterization and distribution of CTV
genotypes and association with symptoms. Phytopathology
95:909-917.
Ieki H and Yamaguchi A (1988) Protective interference
of mild strains of Citrus tristeza virus against a severe strain
in Morita Navel orange. In Proc. 10th Conf. Int. Org. Citrus
Virol. Timmer LW, Garnsey SM, and Navarro L, eds, pp.8690, Riverside, CA.
Moreno P, Ambros S, Albiack-Marti MR, Guerri J, and
Pena L (2008). Citrus tristeza virus: a pathogen that changed
the course of the citrus industry. Mol. Plant Pathol. 9:251-268.
Muller GW, Costa AS, Castro JL, and Guirado N (1998).
Results from preimmunization tests to control the Capao
Bonito strain of tristeza. In Proc. 10th Conf. Int. Org. Citrus
Virol. Timmer LW, Garnsey SM, and Navarro L, eds, pp.8285, Riverside, CA.
Polek M, Gumpf DJ, Wallen CM, and Riley KM (2005).
Biological characterization of naturally occurring Citrus
tristeza virus strains in California citrus. In Proc. 16th Conf.
Int. Org. Citrus Virol. Hilf ME, Duran-Vila N, and RochaPena MA eds, pp. 68-74, Riverside, CA.
Roistacher CN and Dodds JA (1993) Failure of 100 mild
Citrus tristeza virus isolates from California to cross protect
against a challenge by severe sweet orange stem pitting isolates. In Proc. 12th Conf. Int. Org. Citrus Virol. Moreno P, da
Graca J, and Timmer LW, eds, pp.100-107. Riverside, CA.
Roistacher CN and Moreno P (1991). The worldwide
threat from destructive isolates of citrus tristeza virus. In
Proc. 8th Conf. Int. Org. Citrus Virol. Calavan EC, Garnsey
SM and Timmer LW, eds, pp.76-82, Riverside, CA.
Sieburth PJ and Nolan KG (2005). Survey of stem pitting Citrus tristeza virus in commercial citrus groves in Florida. Proc. Fla. State Hort. Soc. 118: 40-42.
Van Vuuren SP, Collins RP, and da Graca JV (1993).
Evaluation of Citrus tristeza virus isolates for cross protection of grapefruit in South Africa. Plant Dis. 77, 24-28. l
.
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Unlocking the secrets of cross protection
to control severe strains of the same virus
Raymond Yokomi, Maria Saponari and Harsha Doddapaneni
C
ross protection is defined as the inoculation of a host
plant with a mild strain of a virus to protect the plant
against a more severe strain or strains of the same
virus. Naturally occurring mild virus strains have been use to
control severe strains of tobacco mosaic virus, papaya ringspot
virus, zucchini yellow mosaic virus, and stem pitting strains of
Citrus tristeza virus (CTV).
For CTV, most mild strains selected empirically have
failed in cross protection tests against severe strains. Typically, cross-protective strains have been obtained from vigorous plants surviving an epidemic associated with a severe
strain of CTV.
Recent cross protection studies in Florida have shown
that CTV strain exclusion was genotype-dependent, namely,
that exclusion occurred among CTV strains of the same genotype but not between those of different genotypes. Therefore, a new paradigm of CTV cross protection is to find a
mild strain of a virulent genotype.
Cross protection has also been achieved by incorporation of a portion of the virus genome in transgenic plants,
such as papaya and plums. However, the actual mechanism
of cross protection remains largely unknown. Furthermore,
cross protection can break down, typically due to the introduction of a new strain or to the inability of the protective
strain to withstand strong challenge pressure.
To use cross protection as a control strategy for CTV, it is
important to understand how it works so safeguards can be
implemented, if possible, to guard against premature breakdown, or lack of stability.
Several severe CTV strains have been found in California. Early Meyer lemon trees were propagated from budwood infected with a severe “Meyer lemon strain” of CTV.
A statewide survey was conducted from 1955 to 1963, and
all CTV-positive Meyer lemon trees were eradicated. Subsequently, trees were produced from a clean source provided
by the University of California’s Citrus Clonal Protection
Program (CCPP) known as -Improved Meyer Lemon-.
A highly virulent form of CTV was found in citrus plantings in the Agricultural Operations (Ag Ops) fields at the
University of California at Riverside in the early 1970s.
Trees infected with this strain, known as SY568, are thought
to have remained symptomless in early citrus plantings
Fig. 1. Symptoms after 12 months in sour orange seedlings
graft-inoculated with the parental isolate mixture, or with
aphid transmitted (AT) strains obtained from the Dekopon
field isolate. Sour orange inoculated with the VT and T3
genotype AT strains showed strong seedling yellows (SY)
symptoms, while those inoculated with the NS genotype AT
strain showed only mild stunting and slight SY. Healthy control plants (not shown) grew vigorously like those inoculated
with the parental Dekopon isolate.
Parental
T3 sub-strain
VT sub-strain
NS sub-strain
Figure 1. Symptoms after 12 months in sour orange seedlings graft-inoculated with the parental isolate
(propagated with budwood?) imported
from abroad in a CTV-tolerant variety not readily fed upon by aphids. This
CTV strain remained unnoticed until it
was aphid-vectored to susceptible varieties, such as sweet orange and grapefruit,
which developed symptoms.
Another severe CTV strain was
found in an Orange Cove orchard by the
Central California Tristeza Eradication
Agency (CCTEA) in the mid 1990s. The
orchard had been illegally topworked
with Dekopon mandarin budwood from
Japan which was infected with a severe
strain of CTV. Mandarins are tolerant to
CTV and often remain symptomless even
when infected with a severe strain of CTV.
Fortunately, in this case, the severe strain
was detected and removed before being
spread to surrounding commercial citrus.
This brief history is presented as a reminder of how a severe strain can be introduced and spread by indigenous aphids
such as the cotton and melon aphid, which
are both widespread in California. Furthermore, establishment of the brown citrus aphid, the most efficient CTV vector,
would accelerate CTV spread as experienced wherever this aphid occurs.
Major advances in understanding
CTV genome
Table 1. Cross protection of sour orange and Duncan grapefruit seedlings
inoculated with parental Dekopon Citrus tristeza virus (CTV) isolate and
three aphid-transmitted (AT) strains from the Dekopon field isolate. Data
shows seedling yellows (SY), stem pitting (SP), and viral titer of the each
isolate or strain per host variety.
Sour orange1
Duncan Grapefruit1
Virus titer2
Virus titer2
RT-PCR Ct
RT-PCR Ct
Symptoms3
Symptoms4
0 to 5
VT & T3 AT NS AT 0 to 5
VT & T3 AT NS AT
strains strain
strains
strain
CTV strains and
sequence of
inoculation DK parental isolate
0SY
21.7
23.2
0SY;1 SP 22.5
22.9
T3, VT & NS AT
strains at same time
1SY
23.2
23.5
4SY
23.2
23.5
T3 AT strain followed
one month later by the
VT & T3 AT strains
3.5SY
23.7
23.6
4SY
28.9
28.5
VT & T3 AT strains
simultaneously followed
one month later by the
NS AT strain.
5SY
28.7
32.3
5SY
23.2
22.3
NS AT strain
0.5SY
N/A
22.9
1SY, 1SP
N/A
22.6
VT AT strain
4SY
23.4
N/A
4SY
23.2
N/A
T3 AT strain
5SY
29.3
N/A
5SY
27.5
N/A
0
N/A
N/A
0
N/A
N/A
Healthy control
Results are an average of three replications.
Virus titer measured by cycle threshold (Ct) value in real time reverse-transcription polymerase chain reaction
(RT-PCR) using strain-specific Taqman® probes. The lower the Ct value inversely correlates with high titer; as
Ct increases, titer decreases exponentially.
3
Sour orange disease rating 0 to 5: 0 = symptomless; 1 = mild stunting and no or very mild SY; 5 = strong
stunting, strong SY resulting in plant death.
4
Duncan grapefruit disease rating 0 to 5: 0 = symptomless; 1 = very mild SY, very mild SP; 5 = strong stunting,
strong SY.
5
N/A = no reaction.
1
2
In the last 10 years, profound advances have been made in understanding
the molecular biology, genomic organization and sequence of the CTV genome.
A book on CTV published in 2010 by
the American Phytopathological Society provides a good
current summary. Additionally, published scientific reports
showed that upon infection with some viruses, RNA-mediated cross protection occurs in plants, and in some cases
the plants recovered. Analyses of transient expression of virus genes proved that RNA-mediated cross protection was
equivalent to post-transcriptional gene silencing.
These studies provided new tools to study cross protection by examining the molecular events during viral infection, replication and host response. This should help us unlock some of the mysteries of cross protection and, possibly,
identify and develop biomarkers to rapidly screen CTV isolates for cross protection purposes.
With the continuous threat of introduction of severe
CTV strains in mind, we initiated a research project with
partial support from the CRB to investigate CTV cross
protection. Our focus was to examine gene expression and
regulation that may be involved in CTV-host interactions
that result in the attenuation of virulence and elimination
or amelioration of severe symptoms such as seedling yellows
(SY) and stem pitting (SP) in sweet orange and grapefruit.
The SY syndrome was chosen for our study because
symptom expression compared to that of SP occurs much
faster. Our hypothesis is that RNAi is involved in CTV cross
protection, and fundamental information gained on SY
should also be relevant for SP in sweet orange and grapefruit.
The Dekopon CTV field isolate was used because it includes a real-life severe CTV strain in California. The field
isolate of CTV was collected from the original orchard that
had been topworked with Dekopon budwood. It was found
to be composed of a mixture of CTV strains that were separated by aphid transmission (AT).
The parental isolate source strain induced sweet orange
and grapefruit SP but did not induce SY in sour orange or
grapefruit, whereas AT strains induced SY in these hosts
ranging from disease symptom ratings of 1 to 5 where 5 is
severe (Figure 1). Molecular analyses differentiated the
AT strains by genotype as VT-like; T3-like or non-standard
(NS)-like.
Test plants used were seedlings of sour orange (SO)
and grapefruit cv Duncan (DGF) inoculated with various
combinations of the Dekopon isolate and AT strains. Strain
interactions were examined by real-time reverse transcription polymerase chain reaction (RT-PCR) assay using strainspecific probes and Next Generation Sequencing technologies to characterize the small interfering RNA (siRNA) and
host-derived miRNAs.
Key Terms
A virus isolate, as defined here, is a culture of the
virus established from a field-collected source and maintained in a host plant.
Once the isolate is captured and characterized, it
is referred to as a strain. An isolate may contain one or
more strains of the virus.
• A severe CTV isolate or strain is defined to be
one that causes a severe phenotype such as stunting,
stem pitting (SP), or reduction of productivity or yield of
citrus grown on CTV-tolerant or resistant rootstock.
• Post-transcriptional gene silencing is the
blocking or destruction of the messenger RNA (mRNA)
of a particular gene. The blocking or destruction of the
mRNA prevents translation of a gene into a product such
as a protein.
• RNA interference (RNAi) refers to processes
that depend on small (s) RNAs to regulate expression.
In plants, these processes play critical roles in development and response to a wide array of stresses, including
defense against viral and bacterial pathogens.
• CTV AT strain is defined here as obtained by
aphid transmission and contains only a single strain
rather than a mixture of CTV strains, and its genotype
was determined.
• CTV genotypes VT- and T3 are often associated with phenotypes inducing SP in sweet orange and
grapefruit and SY in sour orange and grapefruit; the nonstandard (NS-) genotype was a mild phenotype in citrus
grown on tolerant rootstock. Caveat – there are strains
within each genotype which differ from the common phenotype.
• Next Generation Sequencing is a high-throughput sequencing method that produces thousands or millions of sequences at once, thus greatly increasing efficiency and decreasing costs.
• Small interfering RNAs (siRNAs) include RNA of
21 to 24 nucleotides (nt) in length which act as dicers in
the gene silencing pathway.
• Micro RNAs (miRNAs) are a class of host-derived
siRNAs complementary to messenger RNA which leads
to target degradation and, thus, gene silencing.
• SY (seedling yellows) cross protection occurred when the protecting strain was present before or
simultaneously at the time of challenge inoculation in SO
(sour orange).
• SY protection occurred between different genotypes of CTV strains. The symptom amelioration in this
study was considered to be associated with cross protection.
• Transcriptome analysis is examination of the
messenger RNA population in cells to determine which
gene(s) are actively transcribed and expressed during
the host-response to CTV infection.
• Degradome analysis is identification of the messenger RNAs that have been targeted and degraded by
the miRNA, and thus not expressed.
Monitoring CTV strains in cross protection trials
Clear treatment differences were observed in SY expression in SO and DGF two months post-inoculation, and
the titer of each CTV strain was determined after 12 months.
However, there was no correlation between viral strain titer and symptoms (Table 1). Mild strain titer was similar to
that of the severe strain in mixed infections, indicating viral movement was not involved in the protection observed.
Generally, however, as stunting and/or chlorosis increased,
overall virus titer was lower. No SY was observed in SO or
DGF inoculated with the parental Dekopon isolate. When
the three AT strains were inoculated simultaneously in SO,
no SY symptoms or only very mild SY was noted; however,
SY was observed in DGF.
RNA silencing and citrus-CTV interactions
Profile analysis of the viral siRNAs showed that the 3’
end of the CTV genome is actively involved in the generation of mature siRNA and likely involved in modulating
viral and host gene expression. These 21-24nt long siRNA
profiles were similar to that reported for Arabidopsis (a
highly studied model plant) and further supported the concept that the putative CTV silencing machinery in citrus involves a similar protein complex. Additionally, the majority
of the viral siRNAs from SY symptomatic SO plants were
derived from the mild (NS) Dekopon AT strain, whereas
those from SY-protected SO plants were associated with the
severe (VT-like genotype) Dekopon AT strain. These data
suggested that the severe
strain was more highly
CTV genotypes that
diced than the mild strain
by a putative RNAi pathinduce severe stem
way which resulted in SY
pitting are not a
symptom elimination or
reduction.
To identify the pu- problem in commercial
tative host antiviral defense pathway involved citrus in California, yet.
in our cross protection
However, this could
tests, the small RNA sequences derived from
change rapidly due
citrus were compared to
known citrus sequences
to an emergence of
to identify host small
a virulent strain like
RNAs that could influence CTV disease sympSY568 or Dekopon.
tom expression. Homology of 24nt small RNAs
was found in healthy and CTV-inoculated SO and Carrizo
in the 282 Kb Ctv resistance locus of Poncirus trifoliata. Carrizo showed a high frequency of homologous siRNAs in the
CTV.20 gene region, whereas SO had high frequency in the
region between the Ctv.11 and Ctv.12 genes as well as the
Ctv.20 gene.
Furthermore, SY-symptomatic SO had a higher level
of 24nt siRNA associated with Ctv.20 than that from crossprotected SO. In Arabidopsis, where genes with altered
24nt siRNA levels were correlated with DNA methylation,
changes occurred in disease severity.
Thus, our findings merit further examination into possible
RNA-directed DNA methylation in the Ctv resistance locus
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which could affect virulence and result in cross protection.
Among the siRNAs characterized, we found at least 26
families of known micro RNAs (miR166, miR167, miR168,
miR171, miR172) in CTV-infected plants, and eight of
these families showed different levels of expression in test
plants. SO expressing strong SY had higher levels of mi156
and miR166 than that in plants without SY. In Arabidopsis,
a higher level of mi166 was associated with leaf deformation and disorganized apical meristem, while a low level of
miR156 was associated with late flowering and delay in vegetative growth. Thus, there is precedence for higher miR166
and low miR156 being associated with growth reduction and
deformation. If these are involved in SY expression, regulation of these two microRNAs could change disease severity.
Analyses of citrus micro RNA targets revealed 433 were
common in SO plants regardless of symptomology, whereas
873 were found in plants without SY and 753 were found in
plants with severe SY. Thus, different Dekopon AT strains
induced different microRNA-messenger RNA (mRNA)
interactions. Research can now shift to determination of
changes in gene expression that lead to different disease
phenotypes. The level of each mRNA within a cell results
from the opposing contributions of RNA synthesis and degradation which can be explored by transcriptome and degradome analyses, respectively.
Unique siRNAs found associated with a cross-protective CTV strain could be tested as a biomarker to screen
candidate protective CTV strains. However, since this research is in the discovery mode and limited to SY, applied
outcomes will require a continued research effort. This will
also require selecting different strains, as the mild Dekopon AT strain did not fully protect against SP.
General conclusion
CTV genotypes that induce severe stem pitting are not
a problem in commercial citrus in California, yet. However,
this could change rapidly due to an emergence of a virulent
strain like SY568 or Dekopon. A severe strain in a tolerant
variety not preferred by aphids may stay dormant until it
infects sweet orange, mandarin or grapefruit where the virus
can be spread rapidly by aphid vectors.
Thus, it is important to be proactive and examine cross
protection strategies because it has been proven to be effective against SP-CTV strains. Only a few transgenic scion
varieties have been developed that incorporate CTV resistance; these plants are still in the experimental testing phase
and, if they are effective, registration, distribution of propagating budwood, production of plants and establishment of
commercial groves are in the distant future.
Research has shown that naturally occurring CTV populations consist of genetic complexes and mixtures; hence,
successful cross-protective strains must be able to withstand
multiple challenges by various genotypes of CTV under high
vector and inoculum pressure.
Project Leader Dr. Raymond Yokomi is a Research Plant
Pathologist in the Crop Disease, Pests, and Genetics Research Unit at the San Joaquin Valley Agricultural Sciences
Center, USDA-ARS, Parlier, CA. Dr. Maria Saponari was a
Visiting Scientist at the SJVASC and is a Plant Virologist at
the Istituto di Virologia Vegetale, CNR, Bari, Italy. Dr. Har-
800-992-2304
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IA. Dr. Doddapaneni is currently at the Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX.
CRB research project reference number 5300-138.
Selected references
Brodersen, P., Voinnet, O., 2006. The diversity of RNA silencing pathways in plants. Trends Genet. 22: 268–280.
Folimonov, S. Y., Robertson, C. J., Shilts, T., Folimonova, A. S.,
Hilf, M. E., Garnsey, S. M., and Dawson, W. O. 2010. Infection with
strains of Citrus tristeza virus does not exclude superinfection by
other strains of the virus. Journal of Virology, 84: 1314-1325.
Karasev, A. V. and Hilf, M. E. (eds.). Citrus tristeza virus
Complex and Tristeza Diseases. APS, St. Paul, MN. 260 pp.
Roistacher, C. N., da Graça, J. V., and Muller, G. W. 2010.
Cross protection against Citrus tristeza virus – A review. In. Hilf,
M. E., Timmer, L. W., Milne, R. G., and da Graça, J. V. (eds.).
Proc. 17th Conf. Intern. Org. Citrus Virol., p. 1-27. IOCV, Riverside, CA.
Yokomi, R. K., Saponari, M., and Sieburth, P. J. 2010. Rapid
differentiation and identification of potential severe strains of
Citrus tristeza virus by real-time reverse transcription-polymerase chain reaction assays. Phytopathology 100: 319-327. l
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Impact of high temperature
on huanglongbing for development
of a field management strategy
Yulu Xia, Xiaoling Deng, Guocheng Fan, Ronald Sequeira, Yu Takeuchi and Ignacio Baez
Background
The Asian type of huanglongbing
(HLB) is the most destructive and
widespread among the three known
types of the disease. This type is believed to be heat-tolerant, compared to
other types. However, our analysis of
scientific and anecdotal evidence suggests that summer temperature maxima may play a key role in the disease
distribution, spread, and occurrence.
In those regions of the world where
HLB is severe, there appears to be common climatic conditions -- year-round
warm temperature but with moderate
summer temperature maxima.
Recent studies in Florida and Brazil confirm that high temperatures in
the summer reduce the bacterial population in the infected plants and in the
insect vectors. High summer temperatures also significantly reduce the vector’s ability to acquire and transmit the
disease.
Lab and field studies are being conducted to quantify the impact of high
temperature on the bacteria and disease and to develop a heat-based technique for managing the infected groves.
The preliminary outcomes are encouraging; the bacterial titer in the plants
was dramatically reduced in all field
and lab trials, even eliminated from the
infected plants in the best cases.
Introduction
The Asian type of HLB occurs in
parts of United States, Mexico, Asia,
Brazil, and other citrus production
areas of the world. The bacterium
that causes the disease has long been
regarded as heat-tolerant, and so is
the insect vector, Asian citrus psyllid
(ACP), Diaphorina citri Kuwayama.
This type of HLB is associated with
the bacterium Candidatus Liberibacter
asiaticus (unless further explanation is
given, HLB in this article refers to the
Asian type).
Despite more than 50 years of research on HLB, techniques to manage
the disease are limited to the removal
of infected plants, control of vector insects, and planting pathogen-free seedlings.
Although removal of infected
citrus plants is an epidemiologically
sound measure, removal of maturefull-productive trees, and replacing
them with younger trees, is economically disruptive for producers. Additionally, there is strong evidence from
countries such as China and India that
newly planted young trees are more
susceptible to the disease than mature
trees. Furthermore, newly planted trees
are generally more attractive to psyllid
adults due to the continuous flushing of
young trees, and it takes less time for
the bacteria to spread to other parts of
a plant, especially into the root system.
Cultural practices, particularly a
nutritional-based approach, have been
used for disease management since
the disease was first reported in Asia
more than a century ago. The rationale
behind this is straightforward – HLB
causes a disruption in plant nutritional
transport; foliar application of micronutrients can compensate for HLBinduced nutritional deficiencies in the
infected plants.
Scientific and anecdotal evidences
suggest that the nutritional approach,
together with vigorous ACP control
Location
Avg. Temperature (ºC)
Raleigh, NC, US
47 (June, 2011)
Immokalee, FL, US
43 (June, 2011)
Fuzhou, Fujian, China
50 (July, 2011)
Yangcu, Guangdong, China
48 (July, 2011)
and cultural practices such as sufficient
irrigation and fertilization, can prolong
citrus production for another five to
ten years in the mature plants, depending on species/cultivars. Pomelo (pummelo) performs best under this type
of program, followed by sweet orange,
and then mandarin.
Our survey in China indicates that
even the most HLB-susceptible mandarin cultivars can maintain a certain
level of productivity for five to ten
years with sound nutritional and other
cultural practices.
However, there is no proof that
the nutritional approach can reduce or
eliminate the bacteria, reduce the disease severity, or the speed of disease
spread. Therefore, it would be highly
desirable to develop a complementary
technique that can reduce or eliminate
bacteria in the infected plants, especially in view of the widely adopted nutritional approach in Florida and other
HLB-infected regions.
Our data analysis and results suggest that a heat-based approach may
fill the urgent gap. This brief article
highlights some of the major findings.
For detail information, readers can refer to our peer-reviewed article (Xia et
al., 2012).
Evidences of impact of heat and/or
summer temperature maximum on
HLB
Heat treatment to eliminate the
pathogen from scions: Scientists in
China/Taiwan and India did extensive studies using hot water or other
heat-based approaches for producing
pathogen-free seedlings. Generally, scions treated with a temperature regime
of 45°C to 50°C (113°F to 122°F) for
10 minutes to 1 hour were essentially
pathogen-free, judging from symptom
expression.
Since molecular techniques for
HLB diagnosis were not available during this time, the scientific community
argued whether the heat treatment
eliminated the bacteria or simply suppressed the bacterial population temporarily. As we will discuss later in this
article, based on the latest molecular
technology, the bacterial pathogens
were likely eliminated or significantly
reduced in the cases.
Impact of high summer temperature
maximum on the bacterium in plants
and in vectors, and disease acquisition
and transmission by the insect vector:
Surveys and interviews in China revealed a wealth of scientific and anecdotal evidences that high summer temperature in certain regions or environments might reduce bacterial titer or
even eliminate the bacterium from the
infected plants.
Several reports suggest that summer disease transmission using grafting
was consistently low. As an example, a
four-year study resulted in 7.7 % disease transmission rate in summer vs.
70.8% in other, cooler seasons. It was
observed that the bacterium became
undetectable in the infected plants
after about three years in the greenhouses without the temperature cooling system.
Titer is a way of expressing bacterium concentration. A higher number
means less bacteria, and vice versa.
Recent studies provide us with
clear scientific evidence on the impact
of high temperature on the disease. A
study conducted by Brazilian scientists indicated that bacterial titers in
infected leaves were reduced dramatically once temperature reached 38°C
(100.4°F). An exploratory study in
South China Agricultural University
resulted in significantly reduced bacterial titer in the infected seedlings by
using rain showers to increase leaf surface temperatures.
Our study using environmental
chambers indicated that bacterial titer
in the infected seedlings can be dramatically reduced, even eliminated,
under 4-hour temperature treatments
of 45°C and 48°C (113°F and 118.4°F),
respectively.
Evidence from Brazil, U.S., Mexico, and China where HLB occurs, indicated that bacterial titers were the
lowest during the summer, strongly
suggesting the negative impact of high
temperature on the bacteria. The same
correlations between high temperature
and low bacterial titer in ACP were
also documented recently. Studies in
Florida and elsewhere also revealed
that bacterial acquisition and disease
transmission by ACP were reduced significantly when temperature reached
higher than 30°C (86°F), and there was
essentially no disease transmission by
ACP when temperature reached higher than 34°C (93.2°F).
Impact of high temperature on
global HLB distribution and occurrence: Dr. Bové first reported the heattolerant nature of Asian type of the
disease, in comparison to the African
type. Besides the laboratory evidence,
the distribution of HLB worldwide apparently supports the claim, too. The
disease occurs in Saudi Arabia, one of
the hottest citrus production areas on
the planet. HLB has long been present
in other hot areas, such as Punjab, Pakistan, and Guangdong, China.
However, our analysis of climate
data and global HLB occurrence suggests that summer temperature may be
a key factor limiting HLB distribution
and occurrence. We correlated HLB occurrence with areas having a maximum
daily temperature of 38°C (100.4°F) or
greater for at least five days in a year.
Our analysis showed that known
high incidence HLB regions in the
world are not within the areas with
high temperature maxima. Although
HLB occurs in Saudi Arabia, this area
has the “coolest” summer temperature
maxima in the region. The same observation applies to Pakistan, another hot
citrus production country.
The Punjab province of Pakistan
has a long HLB presence; the disease
was reported there more than a century ago, earlier than China. According to
scientists who visited Punjab province,
ACP populations have been very high.
There have been few research activities
and/or management practices to ad-
dress HLB; however, citrus remains a
major crop for Pakistan, and it is one of
the largest citrus production countries
in the world. Few would doubt that the
industry in Pakistan should have been
long gone. We believe that maximum
summer temperature limits disease severity and spread here.
One may argue that the less destructive nature of the disease is not
because of summer hot temperatures,
but because of the long exposure to
the disease and genetic difference and/
or diversity in citrus plants in countries
such as Pakistan. HLB originated in the
Southeast Asia region. Most scientists
agree that the family Rutaceae, which
citrus plants belong to, also originated
in this region. It is reasonable to argue
that a long history of disease with plant
co-evolution and the genetic diversity
in citrus plants in this region may result
in less disease severity.
However, so far there is no evidence of a true resistant or even tolerant citrus cultivar in Pakistan, India,
and China. In the Chinese province of
Guangdong, considered to be ground
zero for HLB, citrus plants still suffer
severe disease damage. Chinese scientists generally agree that mandarins are
more vulnerable to the disease than
sweet orange, and pomelo plants are
generally regarded as the most “tolerant” commercial citrus cultivars; however, this observation based on anecdotal evidence than scientific study.
Spread and distribution of HLB
in the U.S. may provide additional
evidence on the impact of high temperature on the disease. ACP was first
reported in Florida in 1998, then the
disease in 2005. The disease quickly
spread to all citrus production regions
of the state. Warm temperatures yearround and lack of extreme high summer temperatures in Florida appear to
provide an optimal environment for
bacterial multiplication and establishment.
In contrast, ACP was first reported in Texas in 2001, but the disease
was not found until recently (January
2012). It is also interesting to notice
that the newly found HLB-infected
trees in the Rio Grande Valley of Texas
appear in severe condition. This implies
that the disease might have been there
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for at least three to five years. However, only a few trees in a limited location are infected. This suggests a low
disease spread by ACP in Texas. ACP
populations were high in the area. This
suggests some other factor(s) may play
a role here; we believe it is because of
high summer temperatures in the Rio
Grande Valley.
Although annual average temperatures in the citrus production areas in
Florida and Texas are similar, summer
temperature maxima in Rio Grande
Valley of Texas is much higher than
Florida (McAllen,TX: 43°C (109.4°F)
vs. Miami, FL: 38°C (100.4°F). The high
summer temperature in Texas likely
slowed the disease from entering and
spread after disease establishment.
Southern California citrus production
areas share a similar summer temperature maxima pattern with southern
Texas. We believe that the same story
of disease entering and spread will happen there, too.
In summary, summer temperature
maxima plays a key role in reducing
HLB spread and severity. All severe
HLB occurrence areas share a com-
Field study using plastic sheeting to raise plant temperature. This photo was
taken in China.
mon climate character – warm temperature year-round, but lack of high
summer temperature maxima.
Development of heated-based
techniques for managing HLB
Small-scale exploratory field studies in using heat-based approaches for
controlling HLB were conducted in
China back in the 1960s. Due to poor
understanding of temperature dynamics in citrus, and lack of reliable techniques such as quantitative assessment
of bacterial change in the plants and
measuring canopy temperature, these
studies yielded few results.
Another similar exploratory field
study was conducted in South Africa
against the African type of HLB. Result indicated that the infected plants
covered with a polyethylene tent recovered from HLB infection, based on
symptom expression.
Because of the promising outcome
from our study, North Carolina State
University, USDA APHIS Center for
Plant Health and Science Technology
(CPHST), South China Agricultural
University, and Fujian Academy of
Agricultural Institute of China, are engaged in a cooperative project to con-
duct a series of experiments to test our
hypothesis. Since our results are being
reviewed by fellow scientists, we provide only the highlights in this article.
Understanding temperature dynamics in citrus plants in the summer: Using
data loggers and thermometers, canopy temperatures of citrus plants were
measured in Florida, North Carolina,
Fujian and Guangdong, China. Results
indicate that leaf surface (10:00 a.m. to
5:00 p.m.) in the outside of canopy can
easily reach temperatures higher than
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40°C (104°F) in the summer months
(Table 1), leaf temperatures inside of
canopy were close to the ambient temperature. The result has at least three
practical implications.
First, summer temperature in the
field should significantly reduce bacterial populations, this is why titers are
the lowest in the summer discussed
above. Second, heat-based treatment
in the summer should mainly target
the inside canopy, since temperature
outside canopy is already high enough
to kill the bacterium. Lastly, heat-treatment application in late spring and
early fall when ambient temperature
is optimal for bacterial multiplication
might be optimal timing, compared to
application in the hot summer.
Laboratory studies of impact of
high temperature on bacterium population: The objectives of these studies
were to obtain quantitative data on the
effect of high temperature on bacterial
titer in the infected plants. This information is critical to design field studies.
Three studies are being conducted. The infected citrus seedlings were
placed in environmental chambers
for 4 hours at 45°C to 49°C (113°F to
120.2°F and repeated three times during an interval of one week. Bacteria
titers were measured using qPCR before treatment, three weeks after the
last treatment, then every month. Results indicated a statistically significant
reduction in bacterial titer in all heat
treated plants. In the best case, bacteria
were undetectable after treatment.
Two field studies, led by two collaborators, are being conducted by using plastic sheeting to raise plant temperature to 40°C (104°F and higher.
Plastic sheeting treatment lasted for
4 hours (10:00 a.m. to 2:00 p.m.) each
time, repeated three times. Timing and
technique for measuring bacterial titer change before and after treatment
were the same as the lab study above.
All treated plants had significantly
reduced bacterial titers, three weeks
and two months (the latest data) after
treatment, respectively, compared to
the untreated check. The bacteria titers
in these plants will be tested on monthly base until no significant difference is
observed between the treated and untreated check.
The result might be the first field
success in demonstrating that bacterial concentration can be significantly
reduced by using a heat treatment.
Symptom differences between the
treated and untreated plants were
noted. The newly growing leaves in
the treated plants showed no apparent
disease symptoms. In contrast, disease
symptoms were observed on leaves in
the untreated plants.
We believe the results from these
ongoing studies provide a proof of
concept and critical information for
the continuation of future studies. For
example, we still have limited information on the impact of treatment length
and timing on the bacteria. We need to
collect data on bacterial concentration
in roots after heat treatment.
Acknowledgements
The authors are thankful to many
colleagues in China and the United
States for helping us with this study. The
authors acknowledge financial resources
provided by U.S. Farm Bill funds, China
Agriculture Ministry, NC State University, USDA-APHIS, Fujian Academy of
Agricultural Sciences, and South China
Agricultural University.
References
Barbosa, J.C., Eckstein, B., Belasque,
J.J., Bergamin Filho, A., 2011. Preliminary
study of comparative acquisition of Candidatus Liberibacter asiaticus and Ca. L.
americanus by Diaphorina citri under different temperatures. Proceedings of the
2nd International Research Conference
on Huanglongbing, January 10-14, 2011,
Orlando, Florida.
Bové, J.M., 2006. Huanglongbing: A
destructive, newly emerging, century-old
disease of citrus. J. Plant Pathol. 88, 7-37.
Bové, J.M., Calavan, E.C., Capoor,
S.P., Cortez, R.E., Schwarz, R.E., 1974.
Influence of temperature on symptoms
of California stubborn, South African
greening, Indian citrus decline and Philippines leaf mottling diseases, in: Weathers, L.G., Cohen, M. (Eds.), Proceedings
of the 6th Conference of the International Organization Citrus Virologists.
University of California, Swaziland, pp.
12-15.
Ebert, T.A., Brlansky, R.H., Rogers,
M.E., 2011. Seasonal changes in numbers
of Asian citrus psyllids carrying Candidatus Liberibacter asiaticus. Proceedings of
the 2nd International Research Conference on Huanglongbing, January 10-14,
2011, Orlando, Florida.
Gmitter, F., Hu, X., 1990. The possible
role of Yunnan, China, in the origin of
contemporary Citrus species (Rutaceae).
• Machine Shop
• Parts
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Econ. Bot. 44, 267-277.
Gottwald, T.R., Irey, M., Graham, J.,
Wood, B., 2011. Nutritional treatments:
Inconsequential effect on HLB control
and promote area-wide titer increase and
disease spread. Proceedings of the 2nd
International Research Conference on
Huanglongbing, January 10-14, 2011, Orlando, Florida.
Halbert, S.E., Manjunath, K.L., 2004.
Asian Citrus Psyllids (Sternorrhyncha:
Psyllidae) and greening disease of citrus:
a literature review and assessment of risk
in Florida. Fla. Entomol. 87, 330-353.
Irey, M., 2011. When should a grower
with HLB stop removing trees? , Proceedings of the 2nd International Research Conference on Huanglongbing
January 10-14, 2011, Orlando, Florida.
Lin, K.H., Lo, H., 1965. A preliminary
study on thermotherapy of yellow shoot
disease of citrus. Acta Phytophylacica
Sin. 4, 169-174.
Lin, K.H., Lo, X.H., Luo, Z.D., 1982b.
Heat treatment of citrus seeds for eliminating plant pathogens and pests. Acta
Phytophylacica Sin. 9, 237-242.
Lopes, S.A., Frare, G.F., Bertolini, E.,
Cambra, M., Fernandes, N.G., Ayres, A.J.,
Marin, D.R., Bové, J.M., 2009. Liberibacters Associated with Citrus Huanglongbing in Brazil: ‘Candidatus Liberibacter
1132 S. Main Street • Porterville, CA 93257
559.784.4967 or 800.533.4967
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Serving the Valley Since 1936
asiaticus’ Is Heat Tolerant, ‘Ca. L. americanus’ Is Heat Sensitive. Plant Disease 93,
257-262.
Morris, R.A., Muraro, R.P., 2011.
Economic considerations to treating
HLB with the standard protocol or an
enhanced foliar nutritional program.
Proceedings of the 2nd International Research Conference on Huanglongbing
January 10-14, 2011, Orlando, Florida.
Nyland, G., Gohhen, A.C., 1969. Heat
therapy of virus diseases of perennial
CITRUS – AVOCADOS – OLIVES
plants. Annu. Rev. Phytopathol. 7, 331354.
Spann, T.M., Rouse, R.E., Schumann,
A.W., 2011. The theory of managing
huanglongbing with plant nutrition and
real world success in Florida. Proceedings
of the 2nd International Research Conference on Huanglongbing January 10-14,
2011, Orlando, Florida.
Stansly, P.A., Arevalo, H.A., Rouse,
R.E., 2011. Role of nutritional and insecticidal treatments in mitigation of HLB:
main effects and interactions. Proceedings of the 2nd International Research
Conference on Huanglongbing, January
10-14, 2011, Orlando, Florida.
Xia, Y., Ouyang, G., Sequeira, R.,
Chen, J., 2011. A review of managing
Huanglongbing (Citrus Greening) using nutritional approach in China. Plant
Health Prog.
Xia, Y., Sequeira, R., Takeuchi, Y.,
Deng, X., Fang, G., Beattie, G., Baez, I.,
and Yang, R., 2012. Developing a Heatbased Approach for Managing Huanglongbing (Citrus Greening) Disease in
the Field: review and survey results. Crop
Protection (Under Review)
Zhao, X.Y., Jian, Y.H., Qiu, Z.S., Su,
W.F., Li, C.Y., 1982. A technique of graft
transmission of citrus yellow shoot disease. Acta Phytopathol. Sin. 12, 53-56.
Dr. Yulu Xia is Assistant Director,
National Science Foundation Center for
Integrated Pest Management (CIPM),
North Carolina State University, Raleigh,
NC. Dr. Yu Takeuchi is a research associate at CIPM. Dr. Ronald Sequeira and Dr.
Ignacio Baez are with the USDA-APHISPPQ Center for Plant Health Science and
Technology, Raleigh, NC. Dr. Xiaoling
Deng is with South China Agricultural
University, Guangzhou, China. Dr. Guocheng Fan is with Fujian Academy of Agricultural Sciences, Fuzhou, China. l
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Helping Growers for Over 20 Years
Citrus Roots
Preserving Citrus Heritage Foundation
P
L
E
H
R
U
O
Artists of the Era
WE NEED Y
in Finding Photos
of Citrus Packers in...
Delano
Dinuba
Dixon
Edison
Exeter
Fairoaks
Fillmore/Piru
Hamilton City
Ivanhoe
Lemon Cove
Lindsay
Orange Cove
Orosi
Oroville
Oxnard
Palermo
Porterville
Rocklin
Santa Paula
Seville
Strathmore
Terra Bella
Visalia
Woodlake
The photos we are asking for are from 1906 to present.
Your Foundation, through the work of Tom Pulley, is compiling a list of citrus brands of each
packer… A FIRST! We want to match a packinghouse photo to the majority of the packers
on this list, and that is where you enter!
Check out our website…
www.citrusroots.com
Our “Mission” is to elevate the awareness of
California citrus heritage through publications, education, and artistic work.
We are proud of our accomplishments as a volunteer organization, which means each donated
dollar works for you at 100% [for we have no
salaries, wages, rent, etc.]. All donations are tax
deductible for income tax purposes to the full
extent allowed by law.
Citrus Roots – Preserving Citrus
Heritage Foundation
P.O. Box 4038, Balboa, CA 92661 USA
501(c)(3) EIN 43-2102497
The views of the writer may not be the same as this foundation.
July/August2012
2012
52 Citrograph July/August
Tom Spellman
D
uring the last quarter of the 19th century, the California citrus industry exploded from a few fledgling
horticulturalists to a giant industry employing thousands of people. At one time the citrus industry was so massive
it spurred the development of many supporting industries
like irrigation, railroad, lumber, and nursery. In fact, many of
today’s leading agribusiness companies were, in part, founded
to support and supply the early citrus industry.
One of the industries that flourished along with citrus industry was lithographic printing. In California between the
years of 1887 and 1955, literally millions of crates of fresh
oranges, lemons and grapefruit were shipped east. Each box
was adorned with a colorful label designed to market the
sweet, healthy fruit. As many as three dozen individual litho
companies were in business simultaneously to produce and
supply these mini-poster style labels.
The labels were bold and beautiful, depicting all aspects
of western landscape, lifestyle, and promise. They were true
works of art that inspired California’s Second Great Gold
Rush.
During the era of the labeled wooden citrus crate, hundreds of staff and commissioned artists were employed by
the lithographers. Of the more than 10,000 different label
images produced for the California citrus industry, there
are only three artists who were ever able to put their signature to their label images: Herman W. Hanson, J. Duncan
Gleason and James G. Swinnerton. In fact, the lithographers
didn’t want artists to sign their work. Attribution of artists
to particular works would have promoted favoritism and, in
turn, allowed popular artists to command premium prices
for their work.
Many of the artists were specialized and worked only on
specific portions of a label. Some produced only pictorial illustration while others would produce the lettering and border images. The concept of two artists working on the same
label was a very popular way to produce high-quality work
by taking advantage of each artist’s individual talent. Some
of the more prominent artists were:
Herman W. Hanson – (1854-1924) Well known for his
realistic images of Western scenery, cowboys, Indians, horses and buffalo. Hanson was on the western frontier by the
1870’s and was fascinated by the landscape, inhabitants and
lifestyle. The subjects of his work were witnessed first-hand,
and he painted them as he saw them. Hanson was one of
a handful of successful Western artists including Frederic
Remington and Charles M. Russell who realistically captured the American West as it was unfolding.
Hanson’s oil and watercolor paintings of the late nineteenth and early twentieth century have recently sold in the
$20,000.00 to $70,000.00 range. He was a staff artist for the
H.S. Crocker Lithograph Co. in San Francisco from the mid1880’s until the late-1890’s. Advance and Polo are examples
of some of his work.
James G. Swinnerton – (1875-1974) Arguably history’s
first newspaper comic strip illustrator. His career began in
1892 and reached a pinnacle in 1904 with the comic strip
“Little Jimmy” which he illustrated for more than 50 years
until his retirement in 1958.
Shortly after he began work on the Little Jimmy strip,
Swinnerton was diagnosed with tuberculosis and was told
he had little time to live. He moved to the dry desert climate
of Arizona and proceeded to out-live his diagnosing physician by 30 years. The Sombrero brand dated and signed July
1905 may be his only contribution to citrus labels.
J. Duncan Gleason – (1881-1959) Gleason was a talented and well-trained artist who gained national notability by
producing illustrations for magazines such as Good Housekeeping, Ladies Home Journal, Cosmopolitan and Motor
Boating. Gleason also produced studio art for Warner Bros.
and MGM Studios.
Gleason created a very successful set of labels featuring
attractive young women: Doria, Favorita, Meritoria, Sonia,
and Gloriana. Although the women appear different, all
were painted from the same model – Gleason’s future wife.
In fact, they used the money from this commission to get
married and take a honeymoon trip.
Bill Law – As a young man, Law studied art in Canada.
About 1940, he emigrated to the United States and settled
in Los Angeles, where he went right to work for the Western Lithographic Co. Law’s specialty was producing vignettes of fruit and full figure illustrations. His images were
bold and prominent. The Native American image depicted
on the Pala Brave label is an example of Law’s work. Law
was employed as a staff artist for Western Litho until the
mid-1950s.
Dario De Julio –
(1916-present) Born and
raised in the vineyard
area near Ontario, California. De Julio attended
art school in the 1930s and
became a successful freelance artist. His career was
interrupted by World War
II, during which he served
in the U.S. Air Force as a
pilot. Before and after the
war, he was employed as a
staff artist by the Western
Lithograph Co. in Los Angeles, where he became art director in 1958.
De Julio was a master of the airbrush and specialized
in bold lettering and colorful graphics. Red, Blue and Green
circle are examples of his work as well as the lettering for
Pala Brave. His career spanned the last 25 years of the label era, and his contributions are easy to spot on many of
Western’s late-era labels. After his retirement from Western
Litho, De Julio operated a successful freelance art studio in
Los Angeles for many years. He is now retired and resides
in La Mirada, California
Frank Tenney Johnson – (1874-1939) Johnson’s career began in New
York, where he was a wellknown freelance illustrator producing images for
magazines such as Field
& Stream, Cosmopolitan,
and Harpers. In 1920, he
moved west and settled
in Alhambra, California,
where he became known
as a fine art painter of the
American West.
Johnson popularized a style of painting known as “The
Johnson Moonlight Technique“ using brushes, knives, and
his fingers to create detail and dimension. Western Lithographic had a contract with Johnson which gave them exclusive rights to reproduce his paintings as calendars, posters,
and at least one label. Johnson became very well-known for
his fine art, and today his paintings can sell for huge prices at
auction. Summit brand may be
his only contribution to label
art.
Armin Tesch – Tesch
worked for most of his career
as an artist and engraver of
currency, bank notes, and stock
certificates in the eastern and
western U.S. As he aged and
his eyesight began to fail him.
the fine engraving became
more and more difficult. About
1906, Tesch moved west permanently for his health and found
a second career illustrating for
Western Lithograph. He was
responsible for designing some
of the finest lettering on Western’s labels.
Tesch also worked with Pacific Title in Los Angeles
where he designed title and credit work for the early motion picture industry. The artwork for the lithographers and
studios was not so small and fine in detail. The lettering on
Bronco brand is an example of his work
At the end of the citrus label era, lithography was making some dramatic changes.
The last labels were printed
during the season of 1955.
Many of the citrus packinghouses were changing over to
pre-printed cardboard boxes
and no longer using the wooden shipping box or the labels.
These printed boxes were limited to two-color print and of
simple design. Fine art was no
longer an important consideration.
Fortunately for the lithographers and artists alike, printed advertising was expanding
into many new facets. Album
covers, board games, model boxes,
movie posters, and product packaging
were replacing the gap left by the demise of the citrus box label. Many of
the artists found work in the motion
picture and cartooning industries, producing movie title and animation art.
One thing is for sure, during the 75
years of the citrus packing crate label,
dozens if not hundreds of recognized
artists were able to hone their talents
in the fine art of illustration.
Acknowledgements
McClelland, Gordon T., and Last,
Jay T., California Orange Box Labels:
An Illustrated History, Hillcrest Press,
1985.
McClelland, Gordon T., and Last,
Jay T., California Watercolor Artists.
Hillcrest Press. 2002.
“Sombrero Brand”, The Citrus
Peal newsletter. Jim Compos, April
2009.
Interview of Gordon McClelland,
March 2012.
Tom Spellman is southwestern
sales manager for Dave Wilson Nursery, which specializes in the production of fruit and nut trees for the U.S.
wholesale and commercial markets.
Tom has been involved in the production and marketing of avocado,
citrus, and other fruit and nut trees
since 1981. He is a board member of
the Citrus Roots-Preserving Citrus
Heritage Foundation and also serves
on the board of the California Citrus
State Historic Park in Riverside. An
avid collector of original citrus packing crate labels, Tom is the president
of the Citrus Label Society. To learn
more about the Society, visit www.citruslabelsociety.com.l
UC and Citrus Roots Foundation
collaborate on videos
O
The three films will “premier”
through the Foundation’s section in
Citrograph. They will be free and initially available through the Citrus
Roots website at www.citrusroots.
com and from UC Davis. Later they
will also be available at the Riverside
Metropolitan Museum, from the Citrus
Label Society, and from various other
sources to be announced.
Barker, Ferguson and Johnson,
who led the production team, say
the “shoot” at the printing museum
wouldn’t have been possible without
the work of Johnson’s wife, Dr. Lynn
LeBeck , and also the museum’s executive director and curator, Mark Barbour. Barker adds that they’re especially
grateful to Kevin Hallaran of the Riverside Metropolitan Museum for the
loan of the “Monte Vista stone”.
n a recent Monday morning,
Richard Barker of the Citrus
Roots-Preserving Citrus Heritage
Foundation and two University of California Extension Specialists – Dr. Marshall Johnson, entomologist from UC
Riverside, and Dr. Louise Ferguson,
horticulturist from UC Davis – met at
the International Printing Museum in
Carson to shoot the first of three short
videos about California citrus history.
This leadoff production in the series will show how citrus crate labels
were printed, from etched stone to the
more modern technique of offset lithography.
Barker reports that the other two
videos “will tell the compelling stories
of two men, William G. Kerckhoff and
Russell K. Pitzer, whose vision and philanthropy helped form the California
of today”.
At the International Printing Museum are Marshall Johnson behind the camera,
Citrus Roots Foundation board member Tom Spellman conducting the interview, and
Gordon T. McClelland, author of numerous books and collector of citrus lithography.
Citrus Roots Series...
Selling the
GOLD
History of
Sunkist® and Pure Gold®
GIFT IDEAS!!
Citrus Roots...Our Legacy - Volume IV
Citrus Powered the Economy of Orange County
for over a half century Induced by a “Romance”
All donations are tax deductible for income tax
purposes to the full extent allowed by law.
Citrus Roots
For ordering information
visit our website
www.citrusroots.com
Preserving Citrus Heritage Foundation
CITRUS ROOTS . . . OUR LEGACY
Volume I of III
By: Rahno Mabel MacCurdy, V.A. Lockabey and others...
compiled and edited by R.H. Barker
Citrus Roots...Our Legacy - Volume I
Selling the Gold - History of Sunkist®
and Pure Gold®
Our Legacy:
$
ENTREPRENEU RS
Citrus Roots...Our Legacy - Volume II
Citriculture to Citrus Culture
Citrus Roots...Our Legacy - Volume III
Our Legacy...Baldy View Entrepreneurs
- 25 men & women who left a legacy
Including a fold out
time line chart of
American Business Cycles from 1810 to 1978
vs. the Life Span of Twenty-Five Entrepreneurs
by Marie A. Boyd and Richard H. Barker
CITRUS ROOTS ... OUR LEGACY
Volume III of III
(Fed. Tax ID # 43-2102497)
Keeping citrus heritage alive in the minds of those living in California through publications, educational exhibits and artistic works
1500
Baldy View
Citrus heritage to be showcased at L.A. County Fair A
t the L.A. County Fair in September, the Millard
Sheets Center for the Arts will present a special exhibit to mark the fair’s 90th anniversary, and a highlight of
the exhibit will be the story of citrus and its impact on the
development of Southern California.
The exhibit’s designer, Tony Sheets, is assembling “a
marvelous chronicle of artistic and historic displays that will
tell the story of what became the largest fair of its kind in
the world,” says Jim Cogan, the resident storyteller at the
Center who serves as interpretive director for their visitor
programs.
Cogan reports that the exhibit, themed “Art & Fair, a
90 Year Celebration”, will offer visitors an opportunity to
“learn, share, and enjoy the rich history and stories of this
unique corner of Southern California. Art has remained a
major ingredient of this fair throughout its history and will
be showcased in this exhibit as an integral part of telling this
story.”
The citrus heritage portion of the showing will be the
first thing people see when they arrive at the Center, which
is located in a heavily trafficked area of the Fairplex.
The display of historical photos and artifacts, titled
“California’s 2nd Gold Rush: Trees to Treasure, A Citrus
Bonanza,” is being created and crafted by Sheets in collaboration with gallery supervisor Mary
Santoro-Flynn and Richard Barker
of the Citrus Roots-Preserving Citrus
Heritage Foundation.
There is a direct tie-in between
the early development of the citrus industry in Southern California and the
origins of the L.A. County Fair. As Cogan and Sheets point out in the publicity for the exhibit, “by the 1920s, the
citrus, railroad and electrical power industries were flourishing. Colorful and
creative citrus advertising continued
to attract settlers from the East. Rallroads pioneered agricultural and scientific exhibits and highlighted them
with entertainment.
“In 1921, the Southern Pacific
Railroad staged a popular carnival by
Foley & Burk Shows. Seeing its success, a small group of local businessmen realized that it could become an
opportunity to bring recognition to
their home town of Pomona. “ The inaugural L.A. County Fair opened on
Oct. 17, 1922.
Artist Tony Sheets, the creator of
the “Art & Fair” exhibition, is the son
of the late Millard Sheets, the Art Center’s namesake. Born in Pomona, Millard Sheets was a highly accomplished,
award-winning artist, designer, and
educator who served for 25 years as
Director of Fine Arts for the Fair.
The L.A. County Fair is recognized as the largest county
fair in North America, with last year’s event drawing nearly
1.5 million visitors. This 90th anniversary edition will open
Aug. 31 with a special four-day Labor Day Weekend schedule and then after that continue every Wednesday through
Sunday for the entire month of September. l
Celebrating Citrus
Ventura chef Tim Kilcoyne
respects the produce
and the producer
Anne Warring
R
aised on a ranch in the Antelope
Valley, Tim Kilcoyne grew up
around agriculture. His family
didn’t farm commercially (his dad being
a full-time homicide detective), but they
had fruit trees and some chickens and
a few head of cattle. “But just having
that little bit of exposure was enough,”
he says, “to give me a true appreciation
and a deep respect for what farmers and
ranchers do on a big scale every day.”
It almost seems he was destined
for a career in the culinary arts because
his family has a photo of him at a very
young age wearing a toque.
And so, if you know about his
growing-up years, when you find out
what he’s doing with his life these days,
it makes perfect sense.
Kilcoyne is the owner and executive chef of The SideCar restaurant in
Ventura, where on a daily basis he honors and supports local farmers – first by
buying their produce and then by showing it off to its best advantage.
As he notes on his website, his concept is to keep it “simple, seasonal, and
fresh”, and he’s all about making
the ingredients “shine”. His approach is to “respect and enhance
the product, not to alter it.”
The SideCar is billed as “Ventura’s original farm-to-table restaurant”, and Chef Tim is recognized
as having been ahead of his time in
his commitment to sourcing locally. He
buys direct from area growers, and with
very few exceptions brings in everything he needs from within a 100-mile
radius. And, if it’s a farmers’ market day,
it’s a safe bet you’ll find him there.
Tim’s age – he’s only in his early
30s – belies the fact that he’s had considerable experience in the restaurant
business. At 14, he got a work permit
to help out at an upscale French restaurant, where he began as a busboy but
very quickly became a waiter and soon
was in the kitchen prepping food.
At 18, he was a kitchen manager,
and just two years later he was the assistant manager at a Louise’s Trattoria.
By age 22, he was already the general
manager of a seafood restaurant. But,
realizing that his
true calling was to
be a chef, he left
the management
job to enroll at
Le Cordon Bleu
Western Culinary
Institute in Portland, Oregon.
Finishing first
in his class, he apprenticed at the
Playboy Mansion
and then was the
sous chef at Café Melisse, the bistro spinoff of Santa Monica’s award-winning
French restaurant Melisse. He was two
years into running his own catering company when his mom and stepdad happened upon a vacant building in Ventura
that they knew would be perfect for the
restaurant he wanted to open.
The building was actually a 1910
Pullman dining car that he renovated
to create an environment of “casual
elegance.” Offering American and European cuisine, it’s a fine-dining restaurant but comfortable and relaxing, as
evidenced by the fact that Tuesdays are
Grilled Cheese and Jazz nights.
Kilcoyne, who was only 26 when he
opened The SideCar, very quickly established himself as one of the top chef/
restaurateurs in the region, including
taking center stage at prestigious food
and wine events not only in Ventura
County but all up and down the Central
Coast. A quick browse on the Internet
shows that, true to his roots, he’s especially enthusiastic about cooking and
competing at festivals and fairs that salute local ag.
For this summertime issue, we
asked if he’d be willing to share a few
recipes with lemons.
Anne Warring is a freelance writer
and editor based in Visalia.
The SideCar restaurant is a repurposed and
beautifully renovated 1910 Pullman car.
Jumbo Scallops with Corn
Pudding, Zucchini Salad,
Lemon Vinaigrette
Recipe serves 4
INGREDIENTS: 12 each.... Jumbo dry scallops
2 cups...... Yellow corn
4 each...... Summer squash, julienned
2 each...... Meyer lemons, zested and
juiced
1 tsp......... Honey
1 tbsp....... Rice wine vinegar
4 tbsp....... Canola oil
1 tsp......... Mint leaves, minced
1. In a mixing bowl, combine zest of
lemon, juice, honey and rice wine
vinegar. Whisk and slowly drizzle in
canola oil. Toss in squash, mint and
season. Set aside.
2. Gently heat corn with 1 cup of water
to cover in a saucepan. Let simmer for
2 minutes. Puree in blender till smooth
and season.
3. Pat scallops dry with a paper towel
and season.
Limoncello Cream Poached Oysters
Recipe serves 4
INGREDIENTS: 12 each.... Oysters, shucked, shells
discarded, oyster liquid reserved
1 each...... Fennel, bulb shaved thin, stalks
for pickling, fronds for garnish
1 each...... Meyer lemon, zested and juiced
2 oz.......... Ventura limoncello
1.5 tbsp.... Extra virgin olive oil
2 each...... Garlic cloves, minced
1 each...... Shallot, minced
1 tsp......... Fresh thyme leaves
FENNEL SALAD:
1 cup........ Heavy whipping cream
1/4 cup..... Pickled fennel
1. In a bowl, combine pickled fennel,
fennel, lemon zest, 2 tsp lemon juice,
1/4 cup..... Crème fraiche
2. Plate on top of oysters and serve.
2. Sweat garlic and shallots until fragrant.
Pickled fennel:
3. Add limoncello, zest of half the lemon,
and reduce by half.
4. Add heavy cream, thyme, oyster liquid
and simmer for 2 minutes.
4. Heat a sauté pan with a little canola oil.
5. Add oysters and remove from heat.
Don’t cook oysters – just warm gently
in cream.
5. When the oil is hot, add scallops, but
do not overcrowd the pan; turn down
heat to medium flame.
6. Arrange oysters on a plate and add
crème fraiche to oyster cream. Season
and blend.
6. Cook scallops 90% on one side until
golden brown. Turn and leave in pan
for 30 seconds.
7. Nap oysters with sauce.
7. Spread corn pudding on serving plate
and arrange scallops on top.
8. Mix the squash salad with the dressing
and top the scallops with the salad.
fennel frond, salt, pepper, and olive oil.
1. Heat 1/2 tbsp olive oil in a small saucepan over medium heat.
1/4 lbs...... Fennel stalks, sliced into
1/2 inch rounds
1/4 cup..... Distilled vinegar
1/4 cup . .. Water
3 tbsp....... Sugar
1 each...... Garlic clove, crushed
2 tsp......... Kosher salt
For the picked fennel: combine all ingredients except for fennel. Bring to a
boil. Let cool and add fennel. Refrigerate
overnight.
Heirloom Tomato BLT with Lemon Basil Aioli
Recipe serves 4
INGREDIENTS: 12 each....... Cooked bacon slices
8 each......... Heirloom tomato slices
4 each......... Crisp romaine leaves
8 each......... Slices of bread
2 each......... Eggs
1 tbsp.......... Dijon mustard
1/2 cup........ Lemon juice + zest
3 cups......... Canola oil
1/4 cup........ Basil leaves
1. In a food processor, add eggs, mustard, lemon juice, zest, and basil.
2. Slowly drizzle in oil and season. Keep refrigerated for up to one week.
3. Lightly toast bread and generously spread aioli on both sides of bread.
4. Place lettuce on bottom pieces of bread.
5. Arrange 2 slices of tomato on the lettuce and season.
6. Place 3 slices of bacon on each sandwich.
7. Top with other slice of toasted bread, cut and serve.
Photos on this page by DK Crawford© 2012.
C L E A N CITRUS
Clonal
Containerized
Certified
You have new options:
• Containerized citrus is cleaner, more flexible and secure
• Clonally propagated rootstocks increase uniformity
and expand your options.
• Professional field service from experienced horticulturists:
(559)977-7282
Ed Needham
Steve Scheuber (209)531-5065
(559)804-6949
John Arellano
Clean Plants
For Your Future
1 - 800 - GR AFTED
www.duartenursery.com • Hughson, Ca.

This Issue - Citrus Research Board

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