Title: Citrus industry update
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Permanent Link: http://ufdc.ufl.edu/UF00086519/00004
 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: February 2008
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Bibliographic ID: UF00086519
Volume ID: VID00004
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.


Psyllid Management
Effectiveness of aerial applications for
controlling psyllids
We have recently concluded our second
of two psyllid control trials using aerial
applications of insecticides. The first trial was
conducted in Hardee county Florida in July
2007. In this trial, Dimethoate 4E was applied
at a rate of 2 pints per acre. Spray volumes
of 5 gallons and 10 gallons per acre were
compared to determine if increasing spray
volume resulted in better psyllid control by
increasing penetration of the spray inside the
tree canopy. In this trial we saw an immediate
reduction in psyllid numbers in blocks treated
aerially, but there was no difference in psyllid
control between the two spray volumes used.
After aerial applications were made, adult
psyllid numbers remained low the entire 25
days in which the trial was evaluated.

Twenty days after application, we began to
see some increase in the number of psyllid
eggs and nymphs on new flush that was
produced after applications were made
(and thus not protected). This increase in
the immature stages of the psyllid was likely
due to adult psyllids migrating into the grove
from the surrounding untreated areas and
reproducing on the new flush. Such an
increase in immature psyllid populations may
not have occurred as quickly if a larger area
had been concurrently treated.

A second aerial trial to determine the
effectiveness of aerial sprays for controlling
psyllid populations was begun in late October
2007. In this trial, a group of citrus growers in
DeSoto county, collaborated to treat 20,000+
acres of contiguous citrus acreage using
aerial applications. Applications were made
during the start of the winter dormant period
(when trees are producing little or no new
flush). Within this treated citrus acreage we
set up a trial to determine the effectiveness of
Dimethoate and Sevin XLR treatments applied

aerially compared to Dimethoate applied by
airblast sprayer on the ground. Blocks of
citrus were also left untreated for comparison.

Immediately following application, psyllid
populations were reduced to undetectable
levels in all insecticide treated areas,
regardless of whether treatments were made
using ground sprays or aerial applications.
Adult psyllids have remained undetectable
in the treated areas under our evaluation
through the beginning of this month while
psyllids were continuously found in the
untreated control plots throughout the
duration (Oct. 25 Feb. 5) of the trial.
(Michael E. Rogers, mrgrs@ufl.edu)

Timing ofAldicarb Applications
Reductions of 86 percent psyllid adults and
77 percent in shoot infestation were seen
in spring following application in January
2007 of 33 Ib/ac Temik to the bed side of
mature 'Valencia' trees in a 35-acre block near
Immokalee. These results were generally
better than the November and especially
February applications. Adults caged on
branches during spring flush in Mar and Apr.
also showed greater mortality on trees treated
in Nov or Jan indicating that the toxicant did
not have sufficient time to reach emerging
foliage when applied in mid-February. Spiders
and ladybeetles were equally abundant in
treated and untreated trees, indicating Temik
compatibility with these predators. These
findings indicate that application of Temik
2-3 months before spring shoot initiation can
significantly suppress ACP populations during
the critical spring growth period and afterward
with minimal impact to generalist predators.
A trial was initiated this year to look at rates
of Temik required to treat young trees of

continued on page 2
2008 Citrus Research & Education Center, University of
Florida, Institute of Food and Agricultural Sciences, 700
Experiment Station Road, Lake Alfred, FL, 33846, phone:

11 AS

continued from page 1
different sizes (small, medium, large). Temik
was applied in January and psyllid populations
will be monitored on the treated and untreated
trees during the season. (Phil Stansly and
Jawwad Qureshi; pstansly@ufl.edu).

Insecticide Trials for Psyllid Control
Mature 'Valencia' trees at SWFREC in
Immokalee were hedged to induce flush.
Insecticides were applied for the first two
trials with a tractor mounted hydraulic sprayer
operating at a pressure of 150 psi with an
array of 12 or 15 ATR-80 ceramic hollow cone
nozzles directed at the tree on 3, 5 foot booms
to deliver 54-66 gpa. One result from the first
trial was that a non-ionic surfactant (Induce)
or 435 Oil were more effective adjuvants
for Movento (spirotetramat) than MSO or
Kinetic. In the second trial, percentage
infested shoots at 24 days after treatment
(DAT) was lower on trees treated with the high
rate (5.5 oz) of Actara 25 WG (thiamethoxam)
and MANA AG 8412-094B (imidacloprid),
though not significantly less than Provado 1.6F
(imidacloprid) @ 12 oz, either rate (10 or 20 oz)
of Agri-Mek 0.15EC, the low rate of MSR 2E
or two experimental, GF-1640, or QRD 400.
An air-assisted speed sprayer delivering 200
gpa was used for the 3rd trial which showed
no effect from a guava leaf extract estimated
at 2 percent and only Danitol and oil showing
significant suppression at 14 DAT. In another
trial, two formulations of imidacloprid, Admire
Pro at 14 oz, Mana AG 8412-094b (4F) at 16 oz
and one ofthiamethoxam (Platinum 2F at 13.7
oz) applied as a drench to 6 ft 'Valencia' trees
on June 13, 2007 were still providing active
psyllid suppression 99 days later on Sept.
20, 2007. Full reports of these studies can
be found at http://swfrec.ifas.ufl.edu/entlab/
pubs/sta_rpts/index.htm (Phil Stansly, Jawwad
Qureshi and Barry Kostyk; pstansly@ufl.edu).

New Post-Doctoral Extension and Research
Entomologist On Board
In January, Alejandro Arevalo joined the citrus
entomology team at SWFREC Immokalee.
Dr. Arevalo is originally from Colombia and
received his M.Sc. and Ph.D. in entomology
at UF Gainesville. His charge is to work with
growers to design and test their psyllid control
programs. (Phil Stansly, pstansly@ufl.edu).

0 FEB UARY 008

Greening Diagnostics
Evaluation of Field Techniques to Aid in the
Rapid Detection of Citrus Greening
The objectives are to establish the proper
protocol in terms of sampling technique,
iodine solution, and parameters to be used for
visual detection; Analyze starch accumulation
patterns in symptomatic and asymptomatic
leaves from trees infected with Citrus
greening; Determine any limitations based
on varietal differences; Distinguish between
greening and other biological diseases and
horticultural deficiencies in terms of starch
staining. The progress on this project through
December 2007:

Results from our experiments have by now
completed objectives 1 and 2, with objective
4 nearly fulfilled. Based on our initial
observations that starch accumulation in HLB
infected trees far exceeds normal levels, we
devised an effective and rapid protocol for
its detection. The protocol was devised with
emphasis on ease of sampling, availability of
ingredients and versatility in terms of number
of samples and portability. The technique is
now in use by greening scouts and growers in

A survey of tissue samples from trees with a
variety of conditions revealed that abnormal
starch accumulation can be the result of few
other circumstances such as root-rot and in
leaves from severed branches. However,
when leaves of all ages were thoroughly
tested, we found that starch accumulation is
also evident in young and immature leaves
from HLB trees, making this a potential tool to
differentiate the few other conditions that lead
to starch accumulation (such as Phytophtora
and broken branches). This wil be tested in
Spring, 2008.

Samples from leaves, petioles, branches
and roots show that in HLB trees, starch
accumulates in high amounts in the aerial
parts whereas roots seem to be devoid. A
totally opposite distribution is observed in
healthy trees. (Ed Etxeberria, eje@ufl.edu)

continued on page 3

Citrus Industry Update
Community Service Bulletin

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continued from page 2

Citrus Production Systems
Methods to quick kill Huanglongbing
affected citrus trees allowing delay in
The objectives of this project are to
determine what combinations of citrus
grove legal herbicides, known phytotoxic
chemicals, spreader stickers and other uptake
enhancement chemicals will quickly kill citrus
trees; Determine if adverse effects occur
to adjacent, apparently healthy trees either
through transfer through natural root grafts
or from spray drift and evaluate spray drift
guards if needed; and determine if trunk or
foliar spray applications work best.

Test trees were secured from a grower
between Lake Alfred and Haines City. Four
tests were run during the Summer-Fall that
included various phytotoxic chemical mixtures
and two spray techniques. Mixtures that
included Remedy were more effective than
those with Glyphosate. Trees generally did
not die rapidly; however, the better mixtures
stopped new growth from forming, thus
stopping psyllid feeding and disease spread,
and the trees died over a two month period.
Over canopy sprays were difficult to confine
to the target tree. Inside canopy sprays
appeared to work well without cross-tree

Currently, tests are being run on HLB
affected trees on two properties in the
Lake Placid area. Chemical mixes and
varying concentrations are being tested and
application methods are being investigated.
A U-shaped spray boom will be tested that
will slide under the tree and around the
trunk with spray nozzles pointed upward
and slightly outward in order to get thorough
inside scaffolding/canopy coverage. (L. Gene

Citrus Industry Update
Community Service Bulletin

New HLB Testing Lab Open
The new HLB Lab at the University of Florida/
IFAS Southwest Research and Education
Center is now open and accepting samples.
2686 SR 29 North,
Immokalee, Florida
Telephone: 239-658-3400
Monday through Friday from 8 a.m. to 5 p.m.
For more information, growers may visit the
website, http://swfrec.ifas.ufl.edu/hlb/ for
sampling information and forms.

Citrus Canker
Exploiting moth communication as a new
tool for citrus leafminer management.
Citrus leafminer moth mating is dependent on
chemical communication between males and
females. In order for a female to mate, she
must attract her mate with a trail of chemical
called a pheromone. Male leafminers
follow these trails in the evening using their
antennae as sensors (insect noses). By
smelling their way up these chemical trails
males are able to locate females in citrus
groves and mate with them, which results in
fertilized eggs and subsequent damaging
larvae. Recently, the specific chemical
females use to attract males was identified by
chemists and entomologist at the University
of California in Riverside and Davis. Since
this identification took place, entomologists
Lukasz Stelinski and Michael Rogers at the
University of Florida CREC have been working
on practical implementation of this new
discovery for control of the citrus leafminer.
Given that pheromones mediate long-range
mate finding for numerous insect pests and
that this communication takes place at minute
amounts of chemical, pheromones can be
powerful tools for insect control. Furthermore,
pheromones are highly species specific. The
pheromone of citrus leafminer is produced
only by females of this species and only citrus
leafminer males use it as a signal to find
their mates, so deploying it in groves does
not affect non-target beneficial predators or

continued on page 4

0 FEB UARY 008

11 AS

continued from page 3

Recent findings:
Use of pheromones for monitoring:
Do you want to know if you have a major
leafminer infestation before you see flush
infestation? Monitoring with pheromones can
provide you with this information before the
flush is damaged. A commercial pheromone
lure has recently become available for
monitoring the occurrence of adult citrus
leafminers (Citralure, ISCA Technologies,
Riverside, California). Recent research by
CREC entomologists has proven that this
lure is highly effective in attracting male
leafminers to monitoring traps. Pherocon VI
Delta (Trece Inc., Adair, Oklahoma) traps are
highly effective when baited with this lure.
Within canopies of citrus trees 12-15 ft high,
traps at mid-canopy height (6-8 ft) are at
optimal height for monitoring this pest. On the
canopy perimeter and in between canopies,
traps near ground level (2 ft height) capture
the most moths. Traps deployed in trees on
the edge of groves capture more males than
traps within the grove interior. Males fly at
night on calm evenings, so several nights of
monitoring under calm weather conditions
is needed in order to get a good reading of
moth presence. It is possible that pheromone-
monitoring of leafminer may become a tool
for timing pesticide applications. Preliminary
data suggests that peak male moth catch
in traps precedes peak larval infestation of
new leaf flush by one month. So, if sprays are
targeted against this peak adult moth flight as
measured by pheromone traps, perhaps adults
could be effectively eliminated before larval
damage appears. This will be verified by IFAS
researchers shortly.

Use of pheromones for direct control:
Given that female citrus leafminers use minute
amounts of pheromone to attracts their mates,
this chemical communication system can be
disrupted by deploying synthetic pheromone
into groves. This control tactic is commonly
known as mating disruption. Recent studies
on mating disruption conducted in mature
citrus groves in Florida demonstrated that
very small doses of the pheromone per acre
of crop (0.3-1.5 g / acre) could reduce citrus
leafminer larval infestation by 69-98 percent.
Although very little pheromone is required to


achieve this effective control, current use of
this technology remains cost prohibitive for
use in mature citrus because of the current
complicated and expensive synthesis protocol
for the pheromone. However, research is
underway to develop a cheaper synthesis of
the pheromone and an efficient mechanized
delivery system for the pheromone to make
it economically feasible in the near future.
(Lukasz Stelinski, Stelinski@ufl.edu).

"Cybridization" to develop potential canker
resistance without transformation
A few years ago, Jude Grosser, a CREC plant
improvement program student and canker
pathologists in Jim Graham's lab collaborated
to evaluate transfer of citrus canker resistance
derived from kumquat into improved seedless
triploid acid lemon and lime hybrids. The
hybrids evaluated in this project came
from crosses of'Lakeland Limequat' with
allotetraploid acid-fruit somatic hybrids
created by protoplast fusion. The results
indicated that the limequat as a maternal
parent could provide a high level of canker
resistance in hybrids with very susceptible
'Key' lime (a host even more susceptible than
grapefruit). Another approach that utilizes
protoplast fusion, somatic cybridization,
combined cell culture protoplasts (naked
cells) of the maternal 'Meiwa' kumquat with
leaf protoplasts of rough lemon 8166 (also
highly susceptible to canker). The diploid
rough lemon "cybrid" shows inheritance
of a resistance response we identify as
"hyposensitivity". Movement of the resistance
from the maternal kumquat to the susceptible
parent (recipient) appears to occur via
mitochondrial transfer in the "cybridization"
process. Although other research indicates
that there are some nuclear kumquat genes
involved in canker resistance, transfer of
mitochondrial kumquat genes for resistance
to canker alone to this rough lemon "cybrid"
was adequate to impart resistance. To prove
the transfer of the resistance, we will follow
the expression of known mitochondrial genes
that we have identified in Jackie Burns' lab by
microarray analysis of kumquat as important
in the resistance response. Based on the
continued on page 5

Citrus Industry Update
Community Service Bulletin

1' 0 E RU R 2 0

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Citrus Industry Update
Commumnty Service Bulletin

continued from page 4
concept that resistance can be transferred
from 'Meiwa' kumquat via mitochondria, a
dedicated effort is underway in the plant
improvement program to develop "cybrids"
of highly susceptible grapefruit and early
season oranges to transfer canker resistance
into these important cultivars. Since "cybrids"
acquire resistance by cell hybridization, this
process doesn't require transformation of
citrus with foreign genes that create regulatory
and public perception concerns.
(Jim Graham, Jude Grosser, Marta Francis, Igor
Kostenyuk, and Jackie Burns, jhg@ufl.edu)
Management of Citrus Canker
The objective is to screen copper products
and leading chemical prospects in Florida
groves to gain efficacy data required for a
Section 18 registration on Florida grapefruit
and to determine the period of fruit
susceptibility of grapefruit to canker.

Trials are conducted in commercial groves
of companies that have allowed epidemics
of canker in grapefruit. The programs are
applications of foliar sprays at 21 day intervals
with formulations of copper and rotations of
Firewall (streptomycin,) on grapefruit. Also, to
determine the duration of fruit susceptibility,
copper sprays are terminated at different
times during the fruit growth period. Disease
progress is evaluated on foliage and fruits to
determine the incidence of infected fruit and
copper toxicity. (Dr. Jim Graham and Monty
Myers, jhg@ufl.edu)

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2008 Greening Summit
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