Title: Citrus industry update
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Permanent Link: http://ufdc.ufl.edu/UF00086519/00005
 Material Information
Title: Citrus industry update
Series Title: Citrus industry update
Physical Description: Serial
Language: English
Creator: Institute of Food and Agricultural Sciences, University of Florida
Publisher: Institute of Food and Agricultural Sciences
Publication Date: March/April 2008
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Bibliographic ID: UF00086519
Volume ID: VID00005
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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Citrus Industry Update Informed

Published by the University 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.

Open for Business

The HLB Lab at the UF/IFAS Southwest Florida
Research and Education Center (SWFREC) in
Immokalee opened Feb. 4, and morethan 1,000
citrus samples have already been received
from growers in central and southwest Florida.

The HLB Lab is the state's newest facility
dedicatedtothe Rea I Time PCR-based molecular
diagnosis of Huanlongbing (HLB) on citrus leaf
samples. Individual suspect-HLB samples are
prepared by hand, which constitutes the most
time-consuming aspect of the process. Once
DNA extractions are conducted, samples then
are analyzed in the PCR machine at the rate of
nearly 100 per each run.

For detailed information about how to collect
and submit citrus samples, growers should
review the HLB Sample Submission Form and
sampling and submission procedures, all of
which are available online at http://swfrec.ifas.

The HLB Lab is located at the SWFREC, 2686
SR 29 North, Immokalee, FL 34142. Operating
hours are Monday through Friday, 8 a.m. to 5
p.m. Growers wishing to submit large quantities
of samples at one time are encouraged to call
first (239-658-3400) so that arrangements can
be made by lab personnel to ensure that the
samples are processed in the most efficient
manner. (Pamela Roberts, pdr@ufl.edu)
Intensive Management

Systems for Citrus
Intensive management techniques for citrus
production are being tested at the CREC,
SWFREC and with grower cooperators to find
ways of mitigating the impacts of the HLB
disease psyllid vector complex to ensure the
profitability of Florida citrus. Fortunately, when
compared to many other global fruit production
systems such as apples, there is ample scope
for intensifying the Florida citrus production

systems to boost tree growth rates, yields and
shorten the orchard production cycle. Such
techniques could help to avoid or reduce the
impacts of diseases like HLB or canker on
citrus profitability since the rate of infestation
and tree decline is relatively slow, over many
years. Therefore, an intensively managed crop
which produces fruit a few years earlier would
show an early return on the investment, and
hopefully also delay the onset of tree decline
with boosted resistance.

Intensive irrigation and fertilizer management,
also known as open hydroponics systems (OHS),
could enable manipulation of the phenological
growth stages oftrees, limit root growth and may
prove useful for disease / pest avoidance while
increasing yield and fruit quality. For example,
manipulation of nitrogen and irrigation rates
during specific times of the year may reduce
excessive sporadic leaf flushes and their
accompanying pests, curtail alternate bearing,
improve fruit size and maturity, and increase
the soluble solids content. For the purposes of
this study, intensive orchard management will
involve increasing the tree density per acre
together with a dwarfing rootstock, intensive
irrigation and liquid fertigation as advocated
by the OHS. Other production systems such as
pruning / hedging and harvesting will also need
to be modified as necessary to accommodate
the new orchard architecture.Although versions
of the OHS are being used in citrus elsewhere
in the world, its applicability has not been
tested under Florida conditions. This research
relies heavily on modern automated fertigation
technology and is currently not funded by

Numerous IFAS faculty from CREC and SWFREC
are involved in the Intensive Management/OHS
research program. (Tim Spann, spann@ufl.edu)

2008 Citrus Research & Education Center, University of Florida,
Institute of Food and Agricultural Sciences, 700 Experiment
Station Road, Lake Alfred, FL, 33846, phone: 863-956-1151.

0 MA R A P R I L

11 AS

Huanglongbing Found
in Cuba
Drs. Raixa Llauger (Institute Investigations
on Tropical Fruitculture, Havana) and Maria
Carmen Perez (Minister of Agriculture) have
confirmed that HLB has been found in Cuba.

Earliest reports appear to be from western
Cuba, near Havana, but HLB is now reported
in several commercial citrus enterprises.
Confirmation assistance was provided by
FundeCitrus of Brazil.

It seems most likely that HLB was carried to
the island by wind-blown psyllid vectors since
Cuba's quarantine procedures are very strict.
Since Cuba is often in the path of hurricanes,
further spread in the Caribbean Basin might be

(Gene Albrigo, albrigo@ufl.edu)

Quick Killing Chemical Sprays for

HLB Infected Trees

The objective ofthis research was to determine
if some combinations) of approved herbicides
and phytotoxic chemicals could effectively
kill HLB infected citrus trees so that growers
could remove trees when convenient to their
schedule without leaving an HLB inoculum
source tree in the field for an extended length
oftime. Preliminarytests indicated that Remedy
with diesel or Landmaster with diesel were
fairly effective when sprayed to the canopy,
but adjacent trees were also scorched. A
subsequent test to the inside of trees (scaffold

A demonstration of the under tree spray boom (left), a tree killed following herbicide application using the under tree boom with
no visible damage to adjacent trees (middle), and poor tree kill on outer, lower limbs following herbicide application using the
under tree boom.

Citrus Industry Update
Community Service Bulletin

limbs and inside foliage) indicated that this
application technique worked, but the results
were evaluated a couple of months after
application in the winter. An under the tree
spray boom was designed to minimize next tree
spray contact while delivering 1 gal of spray in 5
seconds (see photos). Remedy and Landmaster
with diesel were tested using this spray boom
on Valencia trees of varying size near Lake
Placid using a trailer sprayer designed for hand
spraying at 200 psi.

Test results have been variable, but the
following conclusions can be drawn: 1) Remedy
has been more effective than Landmaster,
2) the spray boom contained the spray to
the target tree and almost no adjacent-tree
damage occurred, and 3) the spray boom did
not provide adequate coverage to the outer
canopy in the wider direction ofthe tree, across
the row. Some trees were effectively killed, but
others had only marginal damage. Landmaster
tended to cause leaf drop, while Remedy
caused better wood kill. Because there is more
tree growth out into the row middle, the boom
needs to be redesigned to put more spray in
the cross row direction. In many cases, three
weeks after application, the lower outer canopy
apparently was still healthy. Wider nozzle spray
and nozzles pointed outward across the row
may solve this problem. In order to be useful
during the growth period, the chemicals and
sprayer must provide a quicker kill to prevent
continued psyllid feeding on HLB infected trees.
A "hotter" chemical mix and a better design of
the spray boom may solve these problems.
(Gene Albrigo, albrigo@ufl.edu)


11 AS

Grower Forum: Systemic
Acquired Resistance
A grower forum targeting Systemic Acquired
Resistance (SAR): potential for control of citrus
bacterial diseases was held March 26 at CREC
This was in response to intense discussion in
the citrus industry regarding the use of salicylic
acid and other compounds to induce the
process known as SAR for control of greening.

The keynote speaker was Dr. Gary Vallad,
Assistant Professor of vegetable pathology at
the GCREC in Balm. Dr. Vallad recently joined
IFAS after gaining several years experience
with induced resistance mechanisms for
disease management in vegetable crops.

Dr. Vallad covered the different types of
plant disease resistance: how they work in
concert to defend plants and specifically
how SAR contributes to the plant's defense
arsenal against a wide array of biotic agents.
Furthermore, he explained with molecular
models and vegetable crop examples the
basic mechanisms for how SAR responds to
pathogens and chemical inducers including
salicylic acid, isonicotinic acid and commercial
SAR products. He finished with discussion
of results from research on crop protection
products such as acibenzolar-s-methyl
(Actigard, Syngenta Crop Protection) against a
broad range of pathosystems including virus,
fungal, nematode, as well bacterial diseases.
He identified the conditions under which SAR
works optimally for disease control, i.e., in a
preemptive use before pathogen infection.
He also warned about the plant toxicity of SAR
chemicals when used in certain forms and

Dr. Jim Graham, CREC's soil microbiologist,
followed with a discussion of his investigations
of SAR for control of citrus canker. He traced
the history of FCPRAC supported research
on SAR activity of Actigard for control of
bacterial spot and canker in greenhouse and
field studies and the innovation brought about
through the identification of SAR activity from
soil applied imidacloprid (Admire, Bayer Crop
Science). Dr. Graham presented evidence that
soil application of Admire produces sustained

Citrus Industry Update
Community Service Bulletin

SAR for control of canker on foliage and fruit
of young trees. He concluded by describing
a greenhouse experiment underway in
collaboration with CREC virologist, Dr. Bill
Dawson, for evaluation of Admire-induced
SAR activity against greening. The prospects
for use of SAR in greening management
were put into perspective with current IFAS
recommendations. The potential advantages
and disadvantages of SAR for greening
management were particularly highlighted
during the grower question and answer session
at the end of the forum program.

In the final presentation Dr. Arnold Schumann,
CREC's soil chemist and plant nutritionist,
informed the grower community about IFAS
and USDA collaborations in field research
for disease management with SAR and other
products. Dr. Schumann pointed out that
these products encompass a wide array of
active ingredients, some of which may not be
compatible in tank mixes and, more importantly,
may not be registered as a pesticide for use
on citrus. Growers running their own trials with
novel products were reminded that the LABEL
IS THE LAW! They were urged that when in
doubt contact IFAS research and extension
for advice and the opportunity to monitor the
study so that results may benefit everyone.
(Jim Graham, jhgraham@ufl.edu; Tim Spann,
spann@crec.ifas.ufl.edu; Arnold Schumann

Testing of SAR-inducers and other
compounds against HLB

A number of research projects are being
developed and/or monitored by IFAS
researchers to further our understanding ofthe
response of citrus trees to Systemic Acquired
Resistance (SAR) inducing compounds and
a wide array of nutritional, bactericidal and
fungicidal compounds. These studies are
being designed to carefully monitor any tree
responses to the various products being
applied, including quantifying HLB bacterial
titers, complete nutritional analyses, and
yield and fruit quality data. Stay tuned to
this newsletter for research updates as they
become available. (Tim Spann, spann@ufl.edu)

MA R A P R I L *

111 AS

Starch Analysis for
Rapid HLB Detection
Development Continues
Based on the observed build-up of starch
in the aerial parts of HLB infected trees, we
are developing a quantitative method to
differentiate starch levels in HLB leaves from
healthy ones.

The method involves homogenizing a very
small portion of a leaf (punch-hole size) using
a bead-beater homogenizer and sampling the
solution with iodine after a short boiling period.
With the proper equipment at hand, the method
allows the testing of a large number of samples
in a very short amount of time. Mass sampling
is possible by using a multi-sampling bead-
beater homogenizer and a colorimetric plate

Currently, data from healthy and HLB trees
have allowed us to formulate a table with
characteristic levels for both HLB and healthy
leaves. Our continuous efforts are aimed at
increasing the reliability of the method which
may serve as a solid post screening test for
PCR analysis. (Ed Etxeberria, eje@crec.ifas.ufl.

Effects of Foliar Micronutrient
Applications on HLB Symptom

A study is currently underway to understand
how HLB symptom expression is affected by
foliar nutritional sprays.

On Feb. 29, nine different treatments were
applied to both healthy appearing and HLB
symptomatic trees in a grove with previously
PCR confirmed HLB (none of the trees used
in the study have yet been confirmed HLB +
by PCR, but do display prominent symptoms).
The treatments included four different
commercially available nutritional mixes, four
individual minor elements (Zn, Mn, Mg and Fe)
applied individually, and a water control. All
treatments were applied with a hand sprayer
and a standard citrus adjuvant was included
with each product. Prior to the applications,
leaf samples were collected from all trees for

Citrus Industry Update
Community Service Bulletin

PCR, starch and nutrient analysis. Additionally,
each leaf was photographed prior to being
subjected to analysis so that future results
can be correlated with symptoms. A post-
treatment sample was collected two weeks
after application for the same analyses. The
starch tests have been completed for the both
of these samples, PCR is in progress and the
samples have been sent to a commercial lab
for complete nutritional analysis. Third sample
will be collected at four weeks post-treatment.
As the results of this study become available
and have been analyzed they will be reported
to the industry. (Tim Spann, spann@crec.ifas.
ufl.edu; Arnold Schmann schumaw@ufl.edu)

Biology of the

Greening Pathogen
HLB Database
The Southwest Florida Research and
Education Center (SWREC) of the University of
Florida in cooperation with the Florida Center
for Library Automation (FCLA) is creating a
comprehensive database to include studies
related to Huanglongbing or citrus greening
disease published worldwide.

Already 780 references in molecular biology,
entomology, plant pathology, extension,
integrated management of citrus greening
and its vectors in the U.S and elsewhere dating
back to 1908 have been entered. We hope
to have this database up and running in the
next couple of months as part of the extension
effort at SWFREC for greening management.
The database will be open to the public, with
access to the bibliographic references and
in some cases links to published articles. A
friendly interface will facilitate searches. The
database will be linked to the new SWREC
entomology laboratory website http://swfrec.
ifas.ufl.edu/entlab and hosted by the FCLA.
Please contact Alejandro Arevalo at greening.
database@ifas.ufl.edu for more information,
suggestions to offer, or interest in beta testing
the database before it comes on line. (Phil
Stansly, pstansly@ufl.edu)

1 M A R CH- A P R I L

Greening Transmission and Spread

Movement of
Asian Citrus Psyllid -Development
of Marking Technique
A protocol has been developed for marking
wild Asian citrus psyllids with soy and egg
albumin proteins. These markers can be
detected by a highly sensitive Enzyme-Linked
ImmunoSorbant Assay (ELISA). The marking
proteins are benign and inexpensive. The
proteins are sprayed onto citrus foliage with
hand-gun applicators and are subsequently
picked up by resident psyllids. Thus, we have
a technique for marking wild psyllids. This
technique is being implemented to determine
how far psyllids disperse within groves and
to determine the extent of migration from
abandoned groves into adjacent managed
groves. Given the recent development of the
technique, the actual field investigations have
begun in March, which coincides with the rise in
psyllid populations. (Lukasz Stelinski, stelinski@

Seasonality of Psyllid Transmission
of the Citrus Greening Pathogen

The purpose of this project is to determine
if there are times of the year when a higher
percentage of the psyllid population is carrying
the pathogen and thus disease spread is more
likely to occur.

The results of this study could be used to time
insecticide applications to those periods of
highest risk. Since joining the CREC research
group, Dr. Tim Ebert (post-doctoral research
associate) has been collecting psyllids from
groves throughout the state where greening
disease has been identified. Each month,
thousands of psyllids are collected from groves
under varying levels of psyllid management
including one organic citrus grove. In addition
to collections of "wild" psyllids, laboratory
reared non-infected psyllids are being caged
on symptomatic and asymptomatic trees at the
study sites to determine pathogen acquisition
rates throughout the year. The psyllids
collected are being analyzed for the presence
of the greening bacteria using real-time PCR.
Stay tuned for results from this ongoing project.
(Michael Rogers, mrgrs@ufl.edu; Ron Brlansky,

Evaluation of Ultra-Low Volume
Applicators for Psyllid Control

Studies have been undertaken to evaluate the
efficacy of ultra-low volume (ULV) or fogging
applicators for psyllid suppression. Three
types of ULV applicators were evaluated
against a standard airblast positive control as
well as a no spray negative control. Depending
on the type of ULV applicator used, treatments
were applied at either 5 or 10 miles per hour.
All treatments were applied near the end of
the dormant period on February 15-16. Thus
far, psyllid populations have been effectively
suppressed in plots treated with the ULV
application as well as the airblast standard for
five weeks. ULV and airblast treatments have
provided an equivalent high efficacy, while
psyllid populations in the no-spray control plots
have risen dramatically. Although these data
show that fogging applications are effective,
some pesticides known to be effective for
psyllid control are currently not registered
for application with ULV equipment. More
research and appropriate regulatory changes
to labels will be needed before fogging should
be implemented commercially.
Also, a post-doctoral research entomologist
(Dr. D. Raj Boina) has been recruited to work
on investigating ULV technology for psyllid
control. He is working under the supervision
of Dr. Masoud Salyani and Dr. Lukasz Stelinski.
Dr. Boina is conducting detailed laboratory
investigations of the effect of pesticide droplet
size, spray volume, and wind speed on psyllid
mortality as well as coordinating experimental
field trials. (Lukasz Stelinski, stelinski@ufl.edu)

Trap Crops
Grower interest in the possible use of trap
crops for psyllid management has spurred
testing of the effects of orange jasmine (Mur-
raya peniculata) both treated and untreated,
on psyllid infestations and parasitization in
adjacent citrus trees. Treated and untreated
citrus will be used as controls and movement
of the greening bacteria will be monitored.
The trial is being conducted at the SWFREC
grove in Immokalee. (Jawwad Qureshi, jaw-


Citrus Industry Update
Community Service Bulletin

1 M A R CH- A P R I L


Modifying Irrigation and Temik
Placement for Enhancing
Psyllid Control
The effectiveness of late season (Marc
April) applications of Temik can be negative
affected by a lack of rainfall. Many growe
have therefore opted to apply Temik earli
in the season (Nov-Feb) to ensure adequa
rainfall to activate the Temik in the soil. In la
March 2008, a study was initiated to look
the effects of modifying irrigation and Tem
placement in terms of psyllid control provide
In this study Temik was applied at a rate
331bs per acre to mature 'Hamlin' orange
trees either as a split application (two sid
of the tree) or as a one-sided application.
six plots where Temik was applied to only or
side of the tree, the irrigation emitters we
re-positioned so that the entire Temik treated
area received irrigation. For the remainder
the plots, irrigation emitters were left in the
usual placement adjacent the trunk of tl
tree. While it is too early to determine if the
are any differences between the treatment
in terms of psyllid control, the pictures belo
show the differences achieved in wettir
the Temik treated area by simply moving tl
irrigation emitters about 1 foot away from th
tree in the direction of the Temik treated are
(Michael Rogers, mrgrs@ufl.edu)


Characterization of the
Asian Citrus Psyllid
Antenna-psyllids Possess the
Structures Involved in Detecting
Plant Chemicals

id A recent study was conducted by new
of post-doctoral entomologist at CREC, Dr.
iir Ebenezer Onagbola, who is supervised by
ie Dr. Stelinski. The purpose of the study was
re to characterize the morphology of the Asian
ts citrus psyllid antenna using scanning electron
w microscope techniques. Five olfactory (smell)
ig and at least three mechanosensory (vibration
ie detectors) types of sensors called sensilla
ie were characterized on the psyllid antenna
a. supporting plausible use of smell and vibration
cues for host and/or mate finding in this
species. The results obtained from this study
provide direct morphological evidence that
the psyllid antennae possess structures, which
can play a role in both chemo- and mechano-
sensory modalities for mate finding and host-
plant location. These results substantiate the
possibility that synthetic repellents and/or
attractants may be developed for practical
pest control applications. (Lukasz Stelinski,

Photos to left Top: Emitter moved to wet the entire soil
surface where 33 Ibs. of Temik applied to one side of tree.

Bottom: Majority of Temik treated area remaining dry
where irrigation emitters not moved.

Citrus Industry Update
Community Service Bulletin

The Asian Citrus Psyllid Antenna

1 M A R CH- A P R I L


Citrus Production Systems

Horticultural Treatments
Citrus growers have been interested in
practices that McKinnon Corporation has been
using in its Orange Hammock grove in Felda
that has HLB. Scientists at SWFREC are trying
to duplicate this program and also determine
which component parts or combinations are
having the apparent effect of ameliorating
symptoms of greening disease.

To these ends we have set up replicated trials
using his program in our grove at UF/IFAS
SWFREC and in a 100 acre commercial block
of mature orange trees.

Another trial in a young commercial block will
evaluate interactions between the amelioration
program and insecticidal control. In addition,
we are monitoring other growers in the area
that are testing the program.

We also have replicated trials of the component
parts (nutrients, SARs, phosphites, etc.) alone
and in combination, underway in our grove at
UF/IFAS SWFREC and two commercial groves.
(Bob Rouse, rrouse@ufl.edu; Phil Stansly,

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