Citrus canker at the top of the...
 Faculty, staff, students, alumni,...
 Greetings to all PI's and...
 Where in the World Wide Web?

Group Title: PLP news
Title: PLP news. Volume 3, Issue 10. October, 1999.
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00067320/00010
 Material Information
Title: PLP news. Volume 3, Issue 10. October, 1999.
Series Title: PLP news
Physical Description: Serial
Creator: Plant Pathology Department, IFAS, University of Florida
Affiliation: University of Florida -- College of Agricultural and Life Sciences -- Plant Pathology Department -- Institute of Food and Agricultural Sciences
Publisher: Plant Pathology Department, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: October 1999
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067320
Volume ID: VID00010
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Citrus canker at the top of the polls
        Page 1
        Page 2
    Faculty, staff, students, alumni, and colleagues of our department
        Page 3
        Page 4
    Greetings to all PI's and REC's
        Page 5
    Where in the World Wide Web?
        Page 6
Full Text


* International Luncheon
* Interview with a Scientist

* Achievements of the Plant Pathology Family 1998-1999


The Newsletter of
the Plant '
Volume 3 Issue 10
October 1999

Citrus Canker at the Too of the Polls

By Bob Kemerait

Here in the
United States,
many people
are obsessed
with rankings,
polls, and
who's #1. For
Example, not
too many years ago, Gainesville was
rated as the best city in the country by
Money Magazine. Many of those who
have lived here for a period of time were
somewhat astounded by this honor and
curious about the criteria by which the
city was selected. Our curiosity was
piqued even further when in the follow-
ing year, our ranking dropped down to
sixth, though life here remained pretty
much unchanged. Today, I have no idea
if Money Magazine even remembers us.
Another area where rankings are taken
very seriously is in college athletics. In
the past couple of days, the Bowl Selec-
tion Committee has published their
rankings for the best college football
teams in the nation. Florida State tops
the list followed by Penn State. Florida
falls in at number six, behind Kansas
State. I really don't know how this was
decided, but I KNOW that we are better
than Kansas State, and how can we be
ranked behind Tennessee when we beat

them at the Swamp? A related area in-
volves the ranking of universities based
upon their perceived importance and
achievement. These rankings serve not
only as a source of pride for alumni, but
also a rallying point for administrators at
the institution. For example, if we are
not among the top five hallowed schools
or departments, we are asked what it will
take for us to join these elite. The point
of these examples is that rankings are
often quite subjective and this needs to
be considered before one becomes too
excited about failing to be at the very top.
Since coming to the Plant Pa-
thology Department here at the Univer-
I*. .."" sity of
ida, I
questions frequently by friends, family,
and acquaintances. The first is, of
course, "Plant :.;;11" After this ques-
tion is resolved, they want to know what
plant disease is most important in the
state. This is not a frivolous question
nor is there an easy answer. The thought
that is required to give an educated re-
sponse requires consideration of the
many ways in which plant disease affects
producers, commercial industries, and

ultimately, the consumers. Much of the
difficulty lies in defining the meaning of
"important". A peanut farmer who is
losing a field to southern stem blight
caused by Sclerotium rolfsii may feel that
this is the most important disease be-
cause of its impact on him. However,
neither peanut nor southern stem blight
is likely to be considered at the top of the
list by many plant pathologists around
the state. Some might argue that emerg-
ing diseases of tomato caused by gemini
viruses such as tomato mottle virus and
tomato yellow leaf curl virus are poten-
tially the most important plant diseases in
Florida. These pathogens affect a crop
worth millions of dollars and have the
potential to cause devastating losses. As
of now, there are not any truly effective
means of controlling these diseases.
I would agree that gemini vi-
ruses cause some of the most important
diseases, but on my own personal rank-
ing scale, I would put citrus canker at the
top of the list. As its name implies, this
disease affects the most important crop
in the state. Millions of dollars have
been spent
since the
1900's to
it, but like
the Ener-


gizer Bunny, the disease just keeps com-
ing back. If citrus canker did become
established in Florida, it would cause
tremendous damage to our citrus pro-
duction. Historic eradication programs
have been successful, but have not pre-
vented the reintroduction of the disease.
From a biological standpoint,
citrus canker appears to be a fairly simple
and unremarkable disease. It is caused
by the bacterial pathogen Xanthomonas
axonopodis pv. citi, formerly known as X.
campestis pv. citi. These bacteria cause
necrotic lesions on the fruit, leaves and
stems. The
So h lesions first
Appear as
round, light
green spots
that later
white. The
older lesions have a corky appearance
with brown sunken centers and are often
surrounded by a yellowish halo. The
lesions on the fruit do not affect the pulp
itself, but make it impossible to sell them
as fresh fruit. The pathogen survives in
the cankers on leaves, twigs, and the fruit
of citrus trees. During warm, rainy
weather, the bacteria ooze from the le-
sions and are spread by splash dispersal
from rain and irrigation onto young tis-
sue. The bacteria enter the young tissue
through wounds and stomates. Older
tissue is infected through wounds and
several cycles of infection may occur on a
single fruit. Spread of the disease is fa-
vored by free moisture and strong winds;
citrus canker is most important during
periods of high temperatures and rainfall.
Quarantine measures are often
used to try and exclude the pathogen
from citrus producing regions where it is
not yet found. Once the pathogen has
been identified in a region, efforts are
then made to eradicate it by destroying


infected trees and those that are planted
near them. In areas where the disease
has become endemic, growers can try to
use resistant varieties, windbreaks, and
copper sprays, though these measures are
generally not sufficient to permit com-
mercial fresh fruit production.
Citrus canker appears to have
been introduced to Florida around 1912,
perhaps on infected trifoliate orange

seedlings imported

from Japan. An
eradication pro-
gram was initiated
jointly by state and
federal agencies,
and Florida was
declared free of
citrus canker in
1933. The eradi-

cation effort had cost six million dollars
and resulted in the destruction of
250,000 fruit-bearing trees and 3 million
nursery trees. By 1949, the disease had
been eradicated from the entire United
States. In 1984, the discovery of a new
bacterial disease, citrus bacterial spot
(X. axonopodis pv. itrumeolo), and the sus-
picion that this disease might represent a
new strain of citrus canker, led to the
destruction of 20 million nursery trees
through 1990. However, in 1986, the real
citrus canker, also known as Asiatic can-
ker or canker A, was found and eradica-
tion procedures continued until 1992.

tu_ SU.02

In 1994, Florida was again declared free
of the disease. In October of 1995, the
disease was again found in Florida. This
time it was discovered infecting trees in

residential areas of Miami and the tree-
removal regulations were reinstated. As
of 1996, the infested area covered about
47 square miles. A quarantine area cov-
ering 170 square miles was established in
which citrus propagation, movement,
and sales were prohibited.
I recently had the opportunity to
talk with Dr. Tim Schubert, a plant pa-
thologist with the Florida Department of
Plant Industries. Dr. Schubert continues
to play an important role in the regula-
tory aspects of the citrus canker eradica-
tion program. Today, the majority of the
citrus canker appears to be confined to a
500 square mile quarantine area in south
Florida that includes parts of Dade and
Broward counties. Citrus trees cannot be
planted or moved in this quarantine area.
The Florida Supreme Court has ruled
that any citrus tree within 125 feet of an
infected tree can be legally removed and
destroyed by the state. However, Dr.
Schubert adds that for eradication pro-
grams to be effective, trees within 1900
feet of an infected tree must be removed
and destroyed. Although this distance is
supported by recent studies in urban epi-
demiology, it has been met with consid-
erable opposition and legal contention. It
should be added that there have also
been recent outbreaks of citrus canker in
commercial and residential trees in
Manatee, Collier, and Hendry Counties.
Dr. Schubert states that these areas are in
the "mop-up" phases of the eradication
Scouts are employed by the
Department of Plant Industry to search
for infected citrus trees. These scouts
form an important part of the citrus can-
ker eradication program and many have
college degrees and additional specialized
training. There are currently .4I, em-
ployees in the eradication program and
approximately 811" of them are involved
in scouting. Dr. Schubert hopes that the
total number of employees will be in-
creased to 1,500, so that each scout will
be responsible for a smaller area in the
two counties.

Essentially all of the infected
citrus trees in Dade and Broward Coun-
ties have been found in residential areas
and not in commercial groves. Once
trees are identified for removal, they are
cut down and taken to the street where
they are put through a chipping machine
and then hauled away for incineration.
Since October, 1995, approximately
156,000 trees have been destroyed by a
private company contracted by the state.
Some homeowners have been concerned
that the very act of chipping the trees
may aide in the spread of the pathogen
by introducing inoculum into the air. Dr.
Schubert acknowledges that there have
been rare instances where protocols were
not followed and chipping was con-
ducted in weather where spread of in-
oculum could have occurred. However,
he adds that such events have been iso-
lated and that chipping prior to incinera-
tion is an effective way of removing the
diseased trees.
The eradication program in the
Dade-Broward area has at times been
met with some heated opposition. On
occasion, homeowners have refused the
scouts access to their property and have
faced prosecution. On other times,
homeowners have threatened scouts with
dogs and even firearms. Dr. Schubert
emphasizes that most of the homeown-
ers living in the quarantine area are un-
derstanding and tolerant of the activities
of the eradication program. Many of the
homeowners are members of the Cuban
and Hispanic communities. Although a
number of the scouts belong to these
same communities, there remains suspi-
cion and distrust of some of the higher
officials in the program who live outside
of south Florida. Unfortunately, this
distrust does not help interactions neces-
sary for the successful eradication of the
citrus canker.
Dr. Schubert believes that it is
still possible to eradicate citrus canker
from Florida, at least from a biological
standpoint. However, the keys to the
eradication of this disease also lie in so-


cial and political issues. Success in the
eradication program requires voluntary
cooperation from those involved, which
is not always easy to achieve.
Is citrus canker truly the most
important disease in the state when it is
only found in a restricted area and does
not affect the commercial citrus produc-
tion? I believe it is, based upon the po-
tential threat it poses to the state's citrus
production and because we still have the
ability to either contain it or eradicate it
completely. Gemini viruses and Sclem-
tium rmpfsi are established in the state and
growers must accept at least some level
of co-existence. Citrus growers do not
have to co-exist with citrus canker yet
and this makes eradication of the disease
a number one priority for plant patholo-
gists. If the reader remains unconvinced,
I am sure that the editors of this news-
letter would welcome essays on other
important diseases.


Agrios, G. N. 1997. Plant Pathology.
Academic Press, New York, pp. 445-449.

Graham, J. H. and Gottwald, T. R. 1991.
Research perspectives on eradication of
citrus bacterial diseases in Florida. Plant
Dis. 75:1193-1211.

Schubert, T. S., Miller, J. W., and Gabriel,
D. W. 1996. Another outbreak of bacte-
rial canker on citrus in Florida. Plant
Dis. 8( 1 2.I:"

Stall, R. E. 1988. Canker. in Compen-
dium of Citrus Diseases. J. O. Whiteside,
S. M. Gamsey, and L. W. Timmer, eds.
APS Press, St. Paul, MN.

(Ed. Note- For more pictures and
information, go to Dr. Dean Gabriel's
web page on citrus canker disease at:

Faculty, staff, students,
alumni, and colleagues of our

Mariadaniela Lopez successfully
defended her Master's Thesis entitled
"Detection, Distribution, Incidence and
Impact of Dasheen mosaic virus po-
tyviridae in Caladium x hortulanum" on
October 22nd, 1999. Way to go!!!

The International Luncheon- A
Unique Gastronomic Experi-

The Plant
Pathology Graduate
Students' Association
sponsored the Intema-
tional Luncheon last
October 22 at the Fi-
field Hall conference rooms. Grad stu-
dents, postdocs and USPS prepared
dishes from their respective native coun-
tries or their country of choice.
Main dishes, side dishes, vege-
tarian dishes, and desserts were served to
an overwhelming number of guests who
decided to trade their lunch money for an
adventure into the world's cuisine. The
guests and the cooks
feasted on Em-
panada Chilena
(Chile), Jachshotel
(Holland), Em-
panada de Maduro
con Queso y Yuca- plantain empanadas
with cheese and cassava (Costa Rica),
Summer Wahe (Switzeralnd), Chicken
Pilau with Dates (Oman), Cuzcuz Bra-
sileiro- Brazilian couscous (Brazil), Paella
(Spain), Dal-lentil soup (India), Adobo
and Pancit- vermicelli (Philippines), Aji
de Gallina- chicken in pepper and cheese
sauce (Peru), Porkkana Laatikko- carrot
casserole (Finland), Eggplant Parmesan
(Italy), Sweet Corn and Rice (USA), Bo-
botie (South Africa), Lasagna (Italy),
Maionese -potato salad (Brazil), Beef

Stroganoff (Russia), Turkey Chili (USA),
Potatoes with White Sauce and Dutch
Cheese (Holland), mashed potatoes and
rice. The dessert table was loaded with
mouthwatering Baklava (Turkey),
Brownies and Strawberry Cheesecake
(USA), Molasses Cookies (Germany),
Caramel Cor and Pumpkin Pie (USA),
Doce de Abobura- pumpkin dessert
(Brazil), Banana Cake with Cream
Cheese Icing (USA), Doce de Leite- milk
dessert (Brazil), Bico- rice dessert (Phil-
ippines) and Quesillo Fan and Torta tres
leches (Venezuela).

Thank you all for making the
International Luncheon a success!


Peever, T.L., Canihos,
Y., Olsen, L., Ibanez, A.,
Liu, Y.-C., and Timmer,
L.W. 1999. Population
genetic structure and
host specificity of Alter-
naria spp. causing brown spot of min-
neola tangelo and rough lemon. Phyto-
pathology 89: 850-860.

Coffee Break Schedule and
Birthdays for October 1999

Friday Coffee Break
11-5 Kucharek, Kim-
brough and
11-12 Pring and
11-19 Niblett
11-26 Simone and Purcifull
12-3 Bartz and Berger


11/7 Dr. Kim-

11/7 Dr. Kucharek
11/18 Chuck Semer
11/29 Mark Elliott


Noteworthy Achievements

Gail Harris was one of the winners of
the IFAS Superior Accomplishment

Alison Walker was a University Scholar.

Dr. Richard Raid, professor at the Ev-
erglades REC, was presented with the
first Superintendent's "Partners in Edu-
cation .,-- iii." for Palm Beach County in
the non-profit category for installing 18
gardens in public schools with his SOAR
(Sharing Our Agricultural Roots) pro-

Jessica Roberts was recognized as a
Four Year Scholar for her academic ex-
cellence throughout her undergraduate
academic career.

Dr. Charudattan and Dr. Kucharek
received the 1998-99 UF PEP (Professo-
rial Excellence Program) Award.

Christina Fulford became a College of
Agriculture 1999-2000 IFAS Ambassa-

Dr. Robert Schmidt, professor at the
School of Forest Resources and Conser-
vation, received the Outstanding Forest
Pathology Extension Paper Award at the
Southwide Forest Disease Workshop.
Dr. Schmidt also received the Southern
Forest Pathologists Achievement Award
at the workshop.

Dr. Mike Olexa, professor of Food and
Resource Economics and graduate of
our department, was awarded the
Teaching Award of Merit by the National
Association of Colleges and Teachers of
Agriculture (NACTA) and also received
the USDA Secretary's Honor Award for
"Outstanding leadership in environ-
mental protection by developing effective
educational programs for culturally di-
verse audiences on laws and regulations

governing agricultural practices in the
United States.

Dr. George Blakeslee, professor at the
School of Forest Resources and Conser-
vation, received the School's Outstanding
Advisor of the Year Award.

Leisure and Culture in
Gainesville, Florida
November '99 and Beyond

S"Persistent Visions",
JWRU, 2nd floor gal-
lery. Through No-
vember 7, 1999. Call
* "DUAFE: A Sister in Primary Col-
ors" on display in the Center for
Women's Studies and Gender Re-
search. Through December 20. Call
* "Seeing Double" on display in the
Harn Museum through December 13.
Call 392-9826.
* "The Kamoff Collection: Etruscan
and South Italian Vases" on display in
the Ham Museum through January 2.
Call 392-9826.
* "Doing our Part: Saving Art" on dis-
play in the Harn Museum through
April 15. Call 392-9826.
* "Surplus of Memory" at the Univer-
sity Gallery through December 10.
Call 392-0201.
* Tibetan Sand Painting Demonstration
at the Florida Museum of Natural
History, on Sunday, November 14 -
19. Call 846-2000.
* "Asian Art from the Permanent Col-
lection" on display in the Harn Museum
through January 2000.
S"Equal Partners" on display in the
Harn Museum through November 28.
* "Two Centuries of American Draw-
ings" on display in the Ham Museum
through November 28.


* "American Impressionism from the
Sheldon Memorial Art Gallery" on dis-
play in the Har Museum through Janu-
ary 2. Call 392-9826.
* "EarthQuest; The Challenge Begins",
at the Florida Museum of Natural His-
tory. Thorugh January 30.
* "Children's Natural History Gallery",
at the Florida Museum of Natural
History. Through January 30. Call

Greetings to all PI's at REC's! We
would like to hear from you! Do you
have any visiting scientists/scholars or
post-docs that we haven't heard about?
If so, we would like to feature them in
future issues of PLP News. Please send
us a short summary of where they are
from, their educational background, the
project they are working on, and personal
interests and/or hobbies. You can email
us at plpnews@gnv.ifas.ufl.edu. We
look forward to hearing from you!

T-Shirts On Sale Now !!!!

The new departmental t-shirts are on sale now
through November 8". The shirts are silk
screened on 100% white cotton shirts and are
only $10.00! The back design is as seen below
and there is also a pocket design with an alli-
gator and the words University of Florida Plant
P.,.iil._.2- Comes in small, medium, large,
and x-large. XX-large available upon special
request. T-shirts will be ready for pick-up De-
cember 3rd or can be shipped for an extra $2.00
.Contact . i.. _..- fl.... ...1 for more in-
formation or to order!




Important Dates : November

November 5-6, Homecoming
All classes suspended
November 8, Deadline for Plant Pa-
thology T-Shirt orders.
November 11, Veterans Day
All classes suspended, all offices closed
November 15, Last Day of Submission
of Defended Master's Theses
November 25-26 Thanksgiving
All classes suspended, all offices closed

Plant Pathology Sunshine

The Plant P lr. .1.._-- Sunshine
Fund is a service managed by the Plant
Pathology Departmental University
Service Personnel where money is set
aside to help our colleagues in times of
need. The fund was started by Ruth
Kusky, who was a secretary in the front
office. To date, the sunshine fund has
been used to encourage those who's
loved ones have passed away or to cheer
up those who are sick. Since 1990 we
have distributed $1799.13 in cards,
flowers and donations to members of the
Plant Pathology Department. We also
provide gifts to the custodial staff every
year for Christmas.

We are always grateful to re-
ceive contributions from the entire de-
partment to help in this service. It is very
easy to donate if you are interested. On
payday Fridays, just drop your contribu-
tion in the wooden box next to the pay
check box in the front office. From our
experiences we have learned that as little
as a dollar per pay day from each person
is sufficient to finance the sunshine fund.
As a final point we recognize
that some people prefer such issues re-
main private. In this light we would like
to emphasize our intent to honor such a
person's wishes. If, however, you know
of someone in our department who is
enduring a difficult situation and think it
is appropriate to give fellow colleagues a
chance to respond to those needs, then
please communicate this information
through the front office.

Interview with a Scientist

Han Xiao was bom in the
Jiangxi Province of China and later at-
tended the Agricultural University there,
where he earned his B.Sc. in Plant
Breeding. Han then attended the Gradu-
ate School of the Chinese Academy of
Agricultural Sciences in Beijing to com-
plete his Master's work on the evolution
of rice and breeding for crop improve-
Han is currently working on his
Ph.D. at the Institute of Genetics (part of
the Chinese Academy of Sciences),
studying the genomics of rice. Han met
Dr. Song through colleagues in Califor-
nia, and Dr. Song invited him to join his
lab for one year to work on rice trans-
Han mostly works since his wife
is still in China (she will hopefully join
him later this year), but he enjoys listen-
ing to popular music when he wants to
We would like to extend a warm
welcome to Han. we hope that your stay
here is productive and enjoyable!


Where in the World Wide
Tired of being a witch? Looking for something
a tad more interesting than dressing up in a
sheet this year? Try this site for some creative
AND CHEAP ideas!
W1i p I ., i Ii.' .L' I .. i i. ii i /
Going somewhere but don't know what the
hottest sites are? Or the best restaurants?
Check out Excite's destinations website- you
choose your destination and it tells you where
the online travel guides are for that
city/country/or region. Great for finding dis-
counts before you leave!
http:/ /www.excite.com/travel/destinations /
Just Bee-cause-
I know everyone out there is wondering how to
start beekeeping but just doesn't know where
to look. Well, try the Apiservices Virtual Bee-
keeping Gallery for hints, news and updates on
the honey market!
li ip I cc c c 'I. 1'.i -..i i.-Ic ._us.htm

Search and Screen Commit-
tee for the Plant Pathology
Department Chair

Jerry Bennett, Chair
Raghavan Charudattan
Jeff Jones
Jim Kimbrough
Ken Pemezny
Jane Polston
Juliana Freitas-Astua

PLP News can now be ac-
cessed via the world wide web
at the following address:

For those of you who were
marveled by last month's
feature article on mangoes,
you might want to check out
some spectacular pictures
a t -, -, ir, i .t i i ., -. n i .,i .

If you would like to join our staff or con-
tribute an article, contact us!

PLP News
1453 Fifield Hall
P.O. Box 110680
Gainesville, FL 32611-0680

Or, you can e-mail us at:

News Team September 1999
Ronald French
Misty Nielsen
Angela Vincent
Camilla Yandoc
Eduardo Carlos
Juliana Freitas-Astua
Robert Kemerait
Mariadaniela Lopez

The opinions expressed in this newsletter are not
necessarily those of the PLP News '


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