Title: Citrus industry update
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Title: Citrus industry update
Series Title: Citrus industry update
Physical Description: Serial
Creator: Institute of Food and Agricultural Sciences, University of Florida
Publisher: Institute of Food and Agricultural Sciences
Publication Date: September 2007
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Bibliographic ID: UF00086519
Volume ID: VID00002
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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UF UNIVERSITY of
FLORIDA
IFAS


Working

Citrus Industry Update Iformedu

Published by the Universtiy of Florida, Institute of Food and Agricultural Sciences, with the mission
of keeping the Florida Citrus Industry informed of current research concerning canker and greening.


FUNDING FOR RESEARCH


he partnerships between the Florida
citrus industry and research agencies have
been vital in developing a response to the
presence of canker and greening in Florida,
and have been expressed in the planning as
well as funding aspects of learning more about
these challenges to the industry. Extensive
discussion, prioritization, and collaboration
has led to significant planning progress in
addressing the short term response to these
diseases that will allow growers, nurserymen,
harvesters, packers and processors to remain
viable as additional solutions are developed.
In addition, pathways for better understanding
the disease organisms, disease cycles in citrus
plants and the ultimate strategies to limit the
impact of these diseases in Florida citrus have
been charted and proposals developed.
Crucial to the progress that is being reported
in these monthly reports is the commitment of
fundingtofuel research projects. While research
agencies have redirected internal resources
to address these important challenges, it is
the application of external resources that
will magnify efforts to learn about how to
manage these diseases under Florida growing
conditions, and some examples are provided
here. Federal funding through a special grant
has supported IFAS canker research since
1999.
Furthermore, research projects on citrus
greening were initiated in 2006 with assistance
from the citrus growers, resulting in the start-
up of some pilot research while priorities and
plans were being developed. In 2007, funding
from the Florida Specialty Crop Foundation
allied with the Florida Fruit and Vegetable


Association was committed to jump start
priority greening projects. These funds allowed
initiation of projects that will provide short-term
information. Research on field detection of
greening, psyllid transmission characteristics,
disease spread dynamics, and methods to
neutralize standing infected trees is being
conducted as a result of this early commitment
of funding.
In addition, substantial funding has been
made available in 2007 through efforts of the
industryto match their research boxtax funding
(managed by FCPRAC) with state and other
industry funding. The various industry groups
who have supported the commitment of funding
and those involved in applying the funding
to UF, IFAS and other research investigations
are to be commended for their foresight and
diligence in obtaining the necessary financial
support to expand current levels of research on
canker and greening. These funds are currently
being contracted, and as accounts are made
available to IFAS scientists, acceleration of
research is expected. We plan to periodically
report on all aspects of this research.
As part of this newsletter, we intend to
acknowledge the many and varied sources
that are providing the necessary funding to
move the research, extension and industry
collaborations along to solutions.
For more information, please contact Harold
Browning at hwbr@crec.ifas.ufl.edu.









2007 Citrus Research & Education Center, University of
Florida, Institute of Food and Agricultural Sciences, 700
Experiment Station Road, Lake Alfred, FL, 33850, phone: 863-
956-1151.






WUF UNIVERSITY of
UF FLORIDA
IFAS


1 0 SEPTEMBE 200 7


HLB DETECTION UPDATE -
IODINE-BASED STARCH TEST


ASIAN CITRUS PSYLLID
SUPPRESSION


Greening


IFAS researchers, (Ed Etxeberria, Tim Spann,
and Bill Dawson) with assistance from Mike Irey
at the US Sugar/Southern Gardens Diagnostics
Lab, have developed a protocol for performing
a field-based test to rapidly detect elevated
levels of starch in leaves suspected of being
infected with HLB.
Early HLB research found that HLB infected
trees accumulate large amounts of starch in
their leaves. Starch readily reacts with iodine,
staining dark-grey to black in a matter of
minutes. The IFAS developed protocol for this
test has been outlined in an EDIS publication
that will be available online soon (http://edis.
ifas.ufl.edu/). This should not be used as a
definitive HLB test, as other disorders may also
lead to starch accumulation. However, it is a
good test to distinguish leaves that are highly
suspect and should be submitted for PCR
testing from those with mineral deficiencies
or other problems that lead to a mottled
appearance.
For more information, please contact Tim
Spann at CREC (spann@ufl.edu).

THE ROLE OF PSYLLIDS
IN GREENING SPREAD

Ongoing work on transmission of the citrus
greening pathogen by the Asian citrus psyllid
has shown that psyllids can acquire (pick up)
the greening pathogen when they feed on
greening infected citrus that has not begun to
show obvious disease symptoms (referred to
as asymptomatic).
The good news, however, is that our work
to date suggests that the number of psyllids
that pick up the greening pathogen from these
asymptomatic trees will be lower than if the
tree were in more advanced stages of disease
symptom expression.
Thus, growers should continue to remove
visibly infected trees that serve as a source
of the pathogen for psyllid acquisition. Psyllid
populations should be maintained as low as
feasibly possible to minimize psyllid acquisition
of the greening pathogen from asymptomatic
greening infected trees. Michael Rogers
(mrgrs@ufl.edu) and Ron Brlansky (rhby@ufl.
edu).


Dr. Pasco B. Avery, a new post-doctoral
entomologist, began work at the Indian River
Research and Education Center in Ft. Pierce
on Sept. 17. The primary focus of Dr. Avery's
work will be to aid growers, particularly on the
east coast, with the evaluation of their psyllid
management programs. Dr. Avery will be
working under the direction of Drs. Michael
Rogers (CREC) and Charles Powell (IRREC).
Michael Rogers (mrgrs@ufl.edu)
SOUTHERN GARDENS
DIAGNOSTIC LAB (SGDL) -
UPDATE
What is SDGL?
The SDGL is a partnership between United
States Sugar Corp/Southern Gardens Citrus
(USSC/SG) and UF/IFAS/CREC. The lab,
administered by Mike Irey (msirey@ussugar.
com), provides PCR-based testing to confirm
that leaf and fruit samples with suspect visual
symptoms are greening. USSC/SG provides
facilities, equipment, supplies and technician
support. UF/IFAS/CREC provides a technician
and additional supplies. There is no charge
for testing provided the submitter completes
the submission form and the disclaimer, both
of which can be found on the Citrus Mutual
website (http://www.flcitrusmutual.com/
content/docs/issues/can ker/sg_sa m plingform.
pdf)
The SGDL runs samples in order of submission
for three types of samples on a priority basis:
1) nursery and foundation budwood sources; 2)
grove samples; and 3) research samples.

What does greening look like today?
Growers conducting self surveys for greening
need to train/evaluate their scouting teams'
performance. Initially the recommendation is
to confirm that samples with symptoms from
each block are positive. At first, the tendency
is to send in every sample from a block for
confirmation. After symptoms in a given
location are confirmed as positive, usually just
a couple of samples per block are necessary
for confirmation. In areas of the state where
greening is not yet well established more
samples may be needed to determine if

Continued on page 3


Citrus Industry Update
Community Service Bulletin






UF UNIVERSITY of
UF FLORIDA
IFAS


Greening


1 0 SEPTEMBE 200 7


Continued from page 2
symptoms are greening.
After almost one year of sample submission from outside growers (with a range of sampling
experience) there is evidence that symptom expression varies during the year and from grove
to grove (Figure 1). Therefore, for best results, samples should be collected from August through
March (before the spring flush). However, with well trained scouts, it is possible to achieve
much more consistent results throughout the year (for example, for samples collected by an
experienced SG crew from March 1, 2007 to Sept 6, 2007, the percent of positive samples
was 95.4% out of 5448 samples submitted by that group). To achieve these consistent results
during the non-optimum times of the year, it will be necessary to observe symptoms and select
the samples for submission much more carefully.

SGDL statistics after first year:
S First grower samples received 10/31/2006;
S Total of 17,944 outside samples run through 9/6/2007;
S 3,561 samples from Bureau of Citrus Budwood Registration;
S 14,383 grower or research samples;
S Average turn around time (from receipt of sample to reporting of results) 15 days (including
weekends and holidays) (Figure 2). The January lag was due to a combination of Christmas and
New Years holidays and equipment breakdown;
S Over entire period, averaging 399 grower samples per week;
S Since June 1, averaging 464 grower samples per week;
S 118 different submitters (people sending in samples);
S 342 different groves from 19 different counties;
S Results sent directly to growers as available. Summary results sent to State and Federal
agencies every two weeks. Mike Irey (msirey@ussugar.com); Jim Graham (jhgraham@ufl.edu)


100%
90%
80%
70%
60%
50%
40%
30%
20%

10%

Nov Dec Jan Feb Mar Apr May Jun Jul Aug


Figure 1. After almost one year of sample submission
to SGDL, there is evidence that symptom expression
varies during the year.


S4000
E
. 3000

2000

1000
lO
:


25

20

15



5


Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
IMNumber of samples -Turn around time

Figure 2. SGDL is averaging 399 grower samples per
week with an average turn around time from receipt of
sample to reporting of results of 15 days.


Citrus Industry Update
Commumty Service Bulletin


GREENING TRANSFERRED FROM MURRAYA TO CITRUS
Sweet orange plants, grown and maintained in psyllid-free greenhouses in Gainesville, were
infected by dodder (Cuscutc pentagon) grown from seed. After the dodder had become well
established on the sweet orange plants, the two dodder infected citrus plants were moved adjacent
to the two C. Liberibacter-infected Murraya plants in the quarantine facility and the dodder from
the citrus was draped over the Murraya. Co-infection of Murraya by dodder occurred within a
few days. Sixty days later, both Murraya plants, both sweet orange plants and the connecting
dodder all repeatedly tested positive for C. Liberibacter by nested PCR. We conclude that M.
paniculate can serve as an epidemiologically significant host of a Select Agent, since it can
harbor the HLB pathogen for at least two months and the HLB pathogen can be transmitted from
Murraya to sweet orange during this time. Dean Gabriel (gabriel@biotech.ufl.edu)
3





0 SEPTEMBE 200 7


HLB HOST RANGE STUDIES


One objective of our laboratory is to examine
citrus varieties and relatives for resistance or
tolerance to HLB. We obtained seed or cuttings
of as diverse a collection of citrus as possible.
The first series of experiments contains 32
different citrus varieties and relatives. So far,
nothing we have tested resists HLB infection


by graft transmission. However, some plants
exhibit much more severe symptoms than
others. Poncirus and relatives appear to
have milder symptoms than sweet oranges,
grapefruit, or mandarins, butthese experiments
are ongoing and results may change with time.
Bill Dawson (wodtmv@crec.ifas.ufl.edu)


Upcoming Events

Citrus Greening Identification and Worker Survey Training
Thursday, Oct. 11, 9:30 a.m. 12:05 p.m.
Polk County Extension Stuart Center
1710 Highway 17 South, Bartow, Florida
To register, contact Polk County Extension Service 863-519-8677 ext. 111

Citrus Greening Identification and Worker Survey Training
Wednesday, Oct. 17, 9:30 a.m. 12:05 p.m.
Turner Exhibition Hall
2250 NE Roan Street, Arcadia, Florida
To register, contact DeSoto County Extension Service 863-993-4846

Citrus Greening Identification and Worker Survey Training
Tuesday, Oct. 23, 9:30 a.m. 12:05 p.m.
Southwest Florida Research and Education Center
2686 SR 29 North, Immokalee, Florida
To register, contact Hendry County Extension Service 863-674-4092

Citrus Greening Identification and Worker Survey Training
Wednesday, Oct. 24, 1:30 p.m. 4:05 p.m.
Lake County Extension
1951 Woodlea Road, Tavares, Florida
To register, contact Lake County Extension Service 352-343-4101

Citrus Greening Identification and Worker Survey Training
Tuesday, Oct. 30, 9:30 a.m. 12:05 p.m.
Highlands County Extension
4509 W. George Blvd., Sebring, Florida
To register, contact Highlands County Extension Service 863-402-6540

Citrus Greening Identification and Worker Survey Training
Wednesday, Oct. 31, 9:30 a.m. 12:05 p.m.
Indian River Research and Education Center
2199 South Rock Road, Fort Pierce, Florida
To register, contact St. Lucie County Extension Service 772-462-1660


Citrus Industry Update
Commumty Service Bulletin


UFT UNIVERSITY of
U FLORIDA
IFAS


Greening


Canker




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