Title: Citrus industry update
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Permanent Link: http://ufdc.ufl.edu/UF00086519/00003
 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: December 2007
 Record Information
Bibliographic ID: UF00086519
Volume ID: VID00003
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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Citrus Industry Update Iormedou

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.

During November, the UF, IFAS Citrus Research and Education Center at Lake Alfred
celebrated its 90th anniversary of support to the Florida citrus industry with the grand
opening of the new Plant Pathology Building and re-dedication of Ben Hill Griffin Jr.
Citrus Hall. With important challenges to the well-being of Florida's premier agriculture
industry, the addition of capability at CREC to address greening, canker and other citrus
issues comes at a critical time. IFAS is proud to have new and improved facilities to go
along with new faculty who have been recruited to address citrus industry challenges.

Greening Transmission
and Spread
New Post Doc Entomologist at CREC
Dr. Timothy A. Ebert, a new post-doctoral
entomologist, began work at the Citrus
Research & Education Center in Lake
Alfred on Nov. 5. Dr. Ebert's research will
involve field studies examining the spread
of the citrus greening pathogen by the
Asian citrus psyllid in addition to other
work focused on biology and management
of the psyllid. Dr. Ebert will work under the
direction of Drs. Michael Rogers and Ron
Brlansky. (Michael Rogers, mrgrs@ufl.edu)

Biology of the
Greening Pathogen
Cell Line Presentation held in Gainesville
As part of an IFAS project to develop a citrus
psyllid cell line, a specialist in insect cell
line establishment, Dr. Dwight Lynn (USDA),
was invited to the UF Gainesville campus,
Department of Microbiology and Cell
Science, to collaborate in developing the
cell line. His visit included the presentation
of a week-long workshop on insect cell lines
(establishment, maintenance, storage, etc.)
in conjunction with Faculty at Entomology
& Nematology and participants from other
units. The workshop was held Nov. 7 14.
(Nemat Keyhani, keyhani@ufl.edu).

Psyllid Management
Aerial Pesticide Application Under
A large-scale trial is underway to
evaluate the effectiveness of aerial
pesticide applications for reducing psyllid
populations. Monitoring of the adult psyllid
population began in early October at
the study site with pesticide applications
made in the later part of the month. Three
treatments are being compared in this
trial including 1) aerial applications of
dimethoate, 2) carbaryl applied aerially and
3) dimethoate applied using a conventional
airblast sprayer. Several blocks of trees
were left untreated as a control. At
the time applications were made, the
majority of trees were (and continue) to
produce little if any new flush needed for
psyllid reproduction. Thus psyllids were
located deeper in the canopy at the time
of application. Thus, the results of this trial
will provide insight as to the effectiveness
of aerial applications for targeting adult
psyllids when the majority of trees are not
flushing. (Michael E. Rogers, mrgrs@ufl.edu)

2007 Citrus Research & Education Center, University of
Florida, Institute of Food and Agricultural Sciences, 700
Experiment Station Road, Lake Alfred, FL, 33846, phone:


11 AS

Psyllid Management
Asian Citrus Psyllid Biology
In collaboration with David Hall's group,
specifically his post-doc Erik Wenninger
(USDA, ARS, Ft. Pierce), Dr. Lukasz Stelinski
has been working toward identification of
psyllid attractants. The ultimate goal of
this work is isolation and identification of
the active compounds. Synthetic copies of
these compounds will then be developed
into effective lures for monitoring this pest.
The first step in this work is to determine the
role pheromones and kairomones may play
in the mate finding and host plant finding
behavior of the psyllid. Our initial work
suggests that male psyllids respond to a
volatile female-produced pheromone that
may be involved in long rage mate finding.
An abstract of a paperthat currently is in pre-
submission review on this topic is attached.
The role plant volatiles play in psyllid host
finding behavior also is being investigated.
We are finding that psyllids are attracted to
citrus flush plant volatiles. Females appear
more attracted than males, but the results
are preliminary to date. The next step will
be isolation and identification of the active
plant compounds followed by confirmation
of their behavioral activity. We hope this
will lead to the development of a more
effective monitoring lure in the near future.

Behavioral evidence for a female-produced
sex attractant in Diaphorina citri Kuwayama
(Hemiptera: Psyllidae). Erik J. Wenninger,
Lukasz L. Stelinski & David G. Hall.
Abstract Diaphorina citri Kuwayama
(Hemiptera: Psyllidae) is an importantworld-
wide pest of citrus. It vectors three phloem-
restricted bacteria in the genus Candidatus
Liberibacter that cause huanglongbing
(citrus greening disease). Studies were

Citrus Industry Update
Community Service Bulletin

conducted to examine the behavioral
responses of male and female D. citri to
conspecifics of the same and opposite sex,
with and without associated citrus host
plants, in both open-air arena choice assays
and Y-tube olfactometer assays. Virgin and
mated male D. citri preferentially colonized
citrus plants that were currently or had
been previously colonized by virgin or
mated female D. citri compared with control
plants without females. However, males or
females did not preferentially accumulate
on plants colonized by conspecifics of the
same sex compared with uninfested plants
and females showed no preference for
plants pre-infested with males compared
with uninfested controls. In complementary
Y-tube assays, virgin and mated males
showed preference for arms with odor
sources from mated females compared with
blank controls in the absence of associated
citrus host plant volatiles. In both behavioral
assays mated female D. citri appeared more
attractive compared with virgin females. The
vibrational calling behavior of male D. citri
was reduced when males were challenged
by the odors of conspecific mated females
relative to when males were challenged by
the odor of other males. Collectively, our
results provide behavioral evidence for a
female-produced volatile sex attractant
pheromone in D. citri. Future identification
and synthesis of a sex attractant pheromone
will be an important contribution to current
monitoring and management practices for
D. citri. (Lukasz Stelinski, stelinski@ufl.edu).

11 AS

Citrus Canker

Update of Trials on Control of Canker
with Copper and Novel Compounds
In Florida, fresh and processing citrus
are heavily based on canker susceptible
grapefruit and Hamlin orange, respectively.
This makes it necessary to rely on the use
of IPM measures including windbreaks and
bactericidal copper sprays to suppress the
pathogen, Xanthomonas axonopodis pv.
citri. Observations of late season infection
ofgrapefruiteven after season-long copper
sprays confirms that windbreaks will be
mandatory for production of blemish-
free fresh market grapefruit in Florida.

We determined from trials conducted in
southern Brazil on moderately susceptible
orange varieties, that copper sprayed at
21 day intervals at rates from 0.5 to 1 Ib.
metallic copper per acre substantially
reduces fruit disease and yield loss
due to premature fruit drop. We also
completed trials in Brazil to confirm that the
antibiotic streptomycin, a well-known crop
bactericide, controls canker alone and in
combinations and rotations with copper.

Young trees of all citrus varieties are
susceptibleto canker becauseofthegreater
frequency of leaf flushes compared to
mature, fruiting trees. Foryoung trees upto 3
years old, imidacloprid (Admire Pro) applied
as a soil drench has a well-known canker
disease management use by controlling
citrus leafminer to reduce wounding and
exacerbation of the disease. In trials in
Florida and Brazil, we have discovered
that soil applications of imidacloprid also
have a direct activity against canker in the
field. The mode of action against canker is
induction of innate citrus host resistance.
The leafminer and disease control activities
of imidacloprid are high enough that its
use on young trees might preclude the
need for copper sprays except for highly
susceptible grapefruit and certain varieties
of early oranges. (Jim Graham,jhg@ufl.edu)

Collaborations from Outside of Florida
During November, 2007, three groups of
visiting scientists were hosted by IFAS.
This is part of an ongoing effort to bring
experts from outside of Florida to share
information on citrus diseases and other
topics, to discuss collaborations, and to
forge partnerships. During this period the
following collaboration events occurred:

Dr. John da Graca, Plant Pathologist and
Director of the Texas A &M University
Citrus Center, Weslaco, and Dr.
Mamoudou Seatmou, Assistant Professor
of Entomology, visited CREC on Nov. 8. A
seminar was presented by Dr. da Graca.
John shared information on current efforts
in Texas to track the movement of Asian
citrus psyllid in the state's commercial
and residential trees, as well as efforts
to scout for and run diagnostics against
Huanglongbin. He also spoke briefly about
his previous work in South Africa on citrus
greening. Dr. DaGraca is one of the most
experienced greening researchers in the
world. Dr. Seatmou presented an overview
of his work on citrus psyllid in Texas.
Mr. Ray Prewett of Texas Citrus Mutual
accompanied the Texas A&M scientists
and participated in discussions related to
citrus greening during the two-day visit.

A scientific exchange between USDA-
ARS, Ft. Pierce scientists and Dr. Nguyen
Minh Chau, Director of the Sothern Fruit
Research Institute, Ministry of Agriculture
and Rural Development,Viet Nam and Dr.
Katsuya Ichinose, an entomologist in the
Laboratort of Plant Protection, Okinawa
Subtropical Station, Japan International
Research Center for Agricultural Sciences
provided an opportunity for discussion
at CREC on Friday, Nov. 9. Dr. Ichinose
is the entomologist who first recognized
See "Collaborations" on page 4

Citrus Industry Update
Community Service Bulletin


111 AS

"Collaborations" continued from page 4
an interaction between guava and citrus
psyllids when guava is planted close
to citrus. Informal discussions with the
visitors and Dr. David Hall, USDA-ARS, Ft.
Pierce, allowed IFAS scientists to learn
more about the observations of guava-
citrus interactions in Viet Nam and research
projects that have ensued to determine
the nature of the reported interaction.
Research is ongoing at USDA-ARS, Ft.Pierce
to further investigate this phenomenon.

Finally, during the period Nov. 27 to Dec. 7,
CREC is hosting a group of citrus scientists
from Brazil. The group of scientists from
San Paulo and Bahia, Brazil are part of
a USDA, Foreign Agriculture Service,
Cochran Fellows Training Program, and are
currently involved in citrus greening, citrus
canker and other disease research and
management in Brazil. In addition to several
days atCREC,where each Fellow presented
an overview of their work and engaged in
extensive discussions on research issues,
the Fellows are visiting other programs
and areas of the state. They are meeting
in Gainesville with the Plant Pathology
Department, Microbiology and Cell Science
Department, and with Florida Department of
Agriculture staff involved in citrus disease
issues. They also are visiting the USDA,
ARS Laboratory in Fort Pierce, and will be
visiting field citrus operations in East Coast,
Southwest and Central Ridge locations.

Through national and international visits,
seminars and other programs, we plan
to continue to build collaborations that
will strengthen research capability in
Florida and will increase communication
with other industries and regions
of the world where citrus greening
and canker are being addressed.

Citrus Industry Update
Community Service Bulletin

Upcoming Events

Dec. 6-7, 2007
Florida Ag Expo
University of Florida/IFAS Gulf Coast
Research and Education Center
Balm, Florida
For more information or to register,
please visit http://www.floridagrower.net/

Jan. 23-24, 2008
Indian River Citrus Seminar
St. Lucie County Fairgrounds
Fort Pierce, Florida
For more information or to register,
please visit http://www.floridagrower.net/

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