* The Latest Publications from APS Press
* Things you didn't know
* Faculty, staff, and students
* From the Field : Blue Mold of Tobacco
The Newsetter of
the Plant ? '
Volume 3 Issue 6
Some Reasons for International Travel and a Report on
the 7th Plant Virus Epidemiology Symposium, Almirea,
Spain, April 11-16, 1999
By Dr. Charles Niblett
sure travel a lot;
Do you still
work here?; Are
they still paying
you? and other
semi-joking questions are often directed
at me by various members of the de-
partment when they see me after a trip. It
is always an enigma to me, and I try to
smile and explain why I have been trav-
eling. So let me explain a bit here and
report on a recent international meeting.
Each year the State of Florida provides
my salary, that of a Senior Biological Sci-
entist, about $1000 of operating funds
and space, equipment and utilities with
which to do our research. All of the rest
of the research in our program is funded
by grants from state, federal and private
agencies, and all of my travel is funded
by those grants. When I resigned as
Chairman in 1986, it was agreed that I
would do research on the molecular as-
pects of citrus viruses in Florida. To pre-
pare for this I went on year-long sabbati-
cals to Roger Beachy's lab, then at
Washington University, St. Louis, MO
and later to Pedro Moreno's at Instituto
Valenciano de Investigaciones Agrarias
(IVIA) in Valencia, Spain.
Citrus is a semi-tropical crop
grown throughout the world, and it is
propagated by grafting. Therefore, many
of its diseases are passed from one gen-
eration to the next, and also from one
country to the next in the absence of
strict and enforced phytosanitary and
quarantine measures. Because of its
threat to Florida and the region, we have
concentrated most of our research on
citrus tristeza virus (CTV). This has in-
tensified recently because of the estab-
lishment of its most efficient vector
Toxoptera citricida, the brown citrus
aphid, and the finding of stem pitting
influences the graduate education and
training components of our program.
You may have noticed that often I am
the only American citizen in our pro-
gram. The graduate students, post-docs
and visiting scientists generally come
from citrus producing countries includ-
ing Belize, Brazil, Chile, Colombia, Cuba,
India, Mexico, Morocco, New Zealand,
Portugal, the Philippines, South Africa,
Turkey and Venezuela, and many of
them provide their own assistantships or
other funding, indicative of the impor-
tance of citrus and CTV in many of their
I also travel internationally to do
research with colleagues in other coun-
tries, to serve as a consultant to FAO, the
World Bank, USDA and the individual
countries, as well as to organize and at-
tend international meetings and sympo-
sia. There is an unwritten law about
travel, that it comes in bunches, like ba-
nanas, and that is surely true in virology.
For me there are three very important
international meetings, all of which have
greatly impacted the direction of our re-
search and the personnel in our program.
These are the International Virology
Congress (IVC), the Plant Virus Epide-
miology Symposium (PVES), and the
Congress of the International Organiza-
tion of Citrus Virologists (IOCV). Each
occurs every three years. Unfortunately,
all three always occur within a 12 month
period!! This past September I was in-
vited to give the plenary address at
IOCV, but I knew that I would be at-
tending one or both of the IVC or
PVES. So Dr. Manjunath Keremane
delivered the address and represented us
very well. So I try to be selective and go
only where it will be useful to Florida, to
our program, or where hopefully we can
contribute something unique or help to
2 PLP NEWS
prevent some disaster. This last trip had
all of those elements.
I went first to the University of
Algarve in Faro, Portugal to do research
with Dr. Gustavo Nolasco, who has
given seminars here and at Lake Alfred
during his previous visits. He will visit us
again in June. With him we are develop-
ing more efficient and more sensitive
methods for CTV detection and strain
differentiation. A publication and new
techniques will result from that visit.
Then Gustavo and I drove to Morocco
to discuss CTV with Mustapha Zemzami
(who also has presented a seminar in this
department) of the Royal Domaines (the
agricultural holdings of King Hassan),
and also with Moroccan scientists, regu-
latory authorities and growers.
I had really questioned the value
of this part of the trip. I had been to Mo-
in the past
-- sented five
dea I d, out the threat
AFRICA CTV to
standing and valuable citrus crop (sold as
early fresh fruit in northern Europe) be-
cause of the presence of some CTV al-
ready in Morocco and T. citricida and
severe strains of CTV present on Ma-
deira Island, only about 250 miles off
their coast, and they also had heard it
from their own scientists. Yet they had
done nothing to address the problem. So
we gave several more seminars and
spoke at a large gathering of scientists,
regulatory authorities and growers. In the
moving, the Director of Plant Quaran-
tine was as before, in denial and down-
right hostile to me, asking how I knew of
and where the CTV was in Morocco. He
must have had a nice lunch, because
when he chaired the afternoon session,
he admitted the presence of CTV in Mo-
rocco and said they needed an immediate
program to combat it and protect their
industry. We are now working with them
jointly on the program, and I hope that
we have helped them to prevent a disas-
There were two other research
activities during the trip. Following
PVES, I went to IVIA to meet with col-
leagues, and we all shared our recent
progress on CTV. I hope that from this,
one of them will come to UF soon for
sabbatical. Then I went to Montpellier,
France to visit with John and Laurence
Quiot, who were here on sabbatical in
1984 with Dan Purcifull. Their research
is on the detection and differentiation of
the several strains of the plum pox po-
tyvirus, which is ravaging stone fruits
throughout Europe. I had met with them
on an earlier trip. They believed that our
CTV methods would be useful in their
program, and they applied to their agency
for sabbaticals to come and learn them.
Unfortunately, the sabbaticals were not
approved, but they do plan to come for
several weeks this fall. So that explains
my traveling and some of the benefits
The Plant Virus Epidemiology
Symposium is organized under the aus-
pices of the Plant Virus Epidemiology
Committee of the International Society
of Plant Pathol-
: ogy. The previous
six symposia have
been held in Ox-
I ford, UK, Corowa,
France, Bari, Italy
and Jerusalem, Israel. I have attended
three of the symposia, and have found
them to be one of the most useful meet-
ings I ever attend. This is because of the
relaxed structure of the meeting, the di-
versity of attendees (virologists, ento-
mologists, agronomists, horticulturists,
statisticians, etc.) and the many opportu-
nities for both structured and individual
discussions. Each speaker is expected to
view the posters and read the related
abstracts, and then to weave that infor-
mation into his/her presentation. That is
challenging, but it makes the talks
broader, more interesting and less per-
sonal. This year I spoke on CTV epide-
miology and co-chaired a session on
"Current Approaches to Plant Virus
Epidemiology", which described a lot of
"new" diversity in viruses and in their
vectors, and utilized a lot of molecular
biology. For this PVES there were a
total of 32 oral presentations and 93
posters, and there were 154 pre-
registrants. The major emphasis this year
was on geminiviruses and whiteflies, the
current scourges of the vegetable indus-
try in Spain and elsewhere. I have the
book of abstracts, and it is available to
anyone who is interested
Faculty, staff, and students
Interview with a visiting scientist:
Guozhen Liu. Guozhen is originally
from B i. li;_. China, but travelled to
Beijing to do his B.Sc., where he majored
in Biophysics at Beijing Agricultural Uni-
versity. Since graduating in 1984 he has
been working for Hebei Agricultural
University. He was employed while pur-
suing both his M.Sc. and Ph.D. Guoz-
hen received his M.Sc. in 1990 from
Zhejiang Agricultural University where
he worked on the somoclonal variation
of winter wheat. From 1996-1999,
Guozhen worked on his Ph.D. in Beijing
at the Institute of Genetics at the Chinese
Academy of Sciences. The focus of his
dissertation was the molecular cloning of
the home box gene from rice. Guoz-
hen and Dr. Song shared the same advi-
sor in China and met last year at UC
Davis. When Dr. Song was hired at UF,
he invited Guozhen to join him here.
Guozhen arrived here on March 18, and
since then, they have both been continu-
ing to work on the Xa21 gene in rice.
When he was younger, Guoz-
hen enjoyed playing badminton and soc-
cer, but doesn't do so very often any-
3 PLP NEWS
more. He now enjoys spending time
with friends chatting etc. Guozhen
mentioned that he is enjoying his time
here and that many people have been
very helpful to him. He also said that he
enjoyed our spring social last month at
Ginnie Springs, but is looking forward to
the next one so that he can have the
chance to go swimming and canoeing.
He found the springs to be beautiful and
hopes to visit all of the other famous and
interesting attractions that Florida has to
A new addition to the family: Bob and
girl on May 28th 1999. Her name is Mia
Perrine Lopez Kemerait and she is per-
fectly healthy and doing well with her
parents at home. Congratulations to both
of you and good luck with the Mia in the
future. We wish you the best as your
Another Award!: Alfred Addison has
again been recognized for his superior
work- this time with a Superior Accom-
plishment Award, the Gabor Employee
Recognition Award. Congratulations!
A fond farewell: Rodney and Liane
would like to say a final goodbye and if
you would like to keep in touch, here are
their e-mail addresses:
E ..._ i. w,, I n l ., ,i
Someone is leaving our department:
Wiejun Chen is leaving our department
to become a lab manager at the medical
school. At Shands, she will be working at
the department of biochemistry and mo-
lecular biology. Good luck to you in your
new career choice.
New faculty Member Dr. Carol Stiles
has been chosen for the new position as
faculty member of our department. As
you may remember she is currently
working at Valdosta State University. She
will be working on fungal pathogens of
turfgrass. She will also be responsible for
teaching many of the undergraduate
courses and some of the graduate level
courses in the department. We would all
like to welcome her aboard and would
like to wish her the best of luck as she
ventures in to her new career.
New Graduate Student Representa-
tives: The graduate students elected new
representatives recently at their monthly
meeting. Congratulations to the follow-
ing officers and good luck with your new
President Ricardo Harakava
Vice President Ronald French
Secretary Marlene Rosales
Treasurer Angela Vincent
A new graduate student
It is always a pleasure to introduce
new students to our team, especially be-
cause it may represent a new beginning
not only for him or her, but also for all of
us who will get to know that person. At
this time, it is our pleasure to welcome
Yolanda was bom and raised in Cape
Town, South Africa, and thus, her first
language is English. This is her first stay
in the U.S., and she will be working to-
wards a Ph.D. degree in Plant Pathol-
ogy. Her background is in microbiology
and her master's research involved bacte-
riophage characterization in Xanthomonas
spp. But for her, life isn't all studying.
Whenever she felt stressed, Yolanda used
to spend her available time playing tennis
or hiking in the mountains behind the
University of Cape Town. What a nice
From the Field
Blue Mold of Tobacco
By Bob I
This past spring, I had the op-
portunity to visit a field of young to-
bacco growing just across the Santa Fe
River in Union County. Given the cool
stillness of the morning, the historical
significance of the area (an old Spanish
mission was established nearby for
Timucuan Indians) and a vivid imagina-
tion, my thoughts wandered far from the
current litigation between the tobacco
industry and the State. Rather, as I
looked out over the rows of knee-high
plants growing in the sandy north-Florida
soil, I thought about the introduction of
the crop to the English colonies by John
Rolfe in 1612 and the important role that
tobacco played as an export during colo-
nial times. I also pondered the role that
tobacco played in the agriculture of the
Old South and the human struggles that
went with it.
Many people are not aware that to-
bacco remains a significant field crop in
northern Florida. It is an important
component of the economies of counties
such as Columbia, Suwannee, Hamilton,
Lafayette, Alachua, and Madison, and is
grown to some degree in neighboring
In 1998, tobacco was grown on al-
most 7000 acres in the state and the har-
vest was valued at nearly 30 million dol-
lars. Most of the tobacco produced here
is known as "flue-cured" and is used
primarily in the manufacture of ciga-
rettes. The tobacco derives its name
from the process by which it is cured in
metal flues for five to seven days at
which time it is ready for auction.
My daydream was abruptly in-
terrupted when a modem day tobacco
grower and owner of this field drove up
quickly in his pick-up truck and pulled
beside us leaving a long plume of dust
behind him. Despite his polite "good
morning" and firm handshake, his face
and gestures suggested concern and agi-
tation and a desire to speak directly with
Dr. Kucharek. This particular grower
4 PLP NEWS
also farmed tobacco fields in nearby Co-
lumbia County and was anxious because
of the incidence of "blue mold" in one of
them. Although the disease was also
present in the field in which we were
standing, the incidence was still relatively
low compared to what he was seeing in
the other field. Dr. Kucharek listened
patiently and promised to help him as he
could. In the end, the grower would be
forced to harvest his crop early resulting
in loss of profit and yield.
Blue mold, also known as
downy mildew of tobacco, is caused by
the oomycete Peronopora tabacina Adam
that is found in the order Peronosporales,
a sister to the Pythiales containing Py-
thium and Phytophthora. Peronospora tabacina
and is not con-
sidered to be
L 4 b -. other crops. The
sporangiospores, or conidiaa" are the
most important propagules in the spread
of the disease; the role of the oospores
remains unclear. The conidia are pro-
duced on sporangiophores that grow
through the sto-
mates on the un-
dersides of in-
fected leaves. The
may produce as
VF Wmany as a million
conidia per square
Centimeter of leaf
surface. The blue-gray color of these
spore masses gives the disease its name.
Spores are produced when the air tem-
perature is between 460 and 860 F; tem-
peratures that are higher or lower inhibit
Though the sporangiospores are
sensitive to both
ultra violet light,
F they can be spread
by wind and air
currents over considerable distances.
Optimal conditions for disease develop-
ment occur when night temperatures are
between 50 and 650 F and daytime
temperatures are between 700 and 800 F.
Ample leaf moisture, from rainfall, irri-
gation, or dew, is also required. The
pathogen is very sensitive to hot, dry
conditions and these help to slow the
spread of the disease. In Florida, condi-
tions that are most suitable for the start
of an epidemic occur in the spring during
the early part of the season when the
young plants are still in the seedling beds.
Symptoms of the disease in young plants
include yellowing and cupping of the
leaves. These plants are likely to turn
brown and die and are often arranged in
disease foci throughout the bed. The
infection in young plants may also be-
come systemic. Systemic infection is
characterized by the distortion and yel-
lowing of leaves coupled with brown
streaks occurring in the vascular tissue.
Infections that occur after the tobacco
plants have been transplanted into the
field usually produce yellow leaf spots of
different sizes. Blue-gray sporulation is
often visible on the undersides of these
leaves. The leaf spots will eventually
turn brown and necrotic and may coa-
lesce with other spots.
According to Dr. Tom Kucharek,
blue mold is capable of causing total loss
in a tobacco crop, especially when condi-
tions are conducive in the transplant
beds. When blue mold is uncontrolled in
the transplant beds, losses can approach
1(0"11,. However, during normal years in
Florida, losses due to blue mold on
plants that are already in the field rarely
amount to more than 2%, though he
adds that losses for individual growers
may approach 10 to 15%. In the latter
part of the season, higher air tempera-
tures normally help to slow the disease,
though severe losses have been reported.
The use of irrigation in current tobacco
production has increased the importance
of the disease. Unusually cool, wet
weather during 1979 and 1980 led to
epidemics of blue mold that cost growers
in the United States and Canada ap-
proximately ^')0 million and nearly
crippled the economy of Cuba where
tobacco remains a major export.
Control of blue mold is accom-
plished using both cultural and chemical
measures. Some of the cultural measures
that have been used successfully include
delayed planting of seeds in the trans-
plant bed until after January 10th, avoid-
ance of excessive nitrogen and irrigation,
careful scouting of fields for early symp-
toms, and the destruction of any plants
remaining in the transplant bed after the
fields are planted. Stalks and residue left
in the field after harvest should be
plowed under to reduce the amount of
inoculum present in the field in the fol-
lowing season. Recommendations for
chemical applications can be found in
Extension Plant P rl. 1. ._- Report Num-
ber 23, "Disease Control Program for
Flue-Cured Tobacco" by Dr. Tom
Kucharek. This publication can be ac-
cessed on the web at
Information for this report was taken
Plant Pathology Fact Sheet No. 15,
Common Leaf Disease of Flue Cured
tobacco, by Dr Tom Kucharek.
Florida Agricultural Statistics Service,
Field Crops, February 17, 1999.
Nesmith, W. C. 1984. The North
American Blue Mold Warning System.
Plant Dis. 11: 933-936.
Compendium of Tobacco Diseases.
1991. Eds. H. D. Shew and G. B. Lucas.
St. Paul, MN.
5 PLP NEWS
Pring, D. R., H. V. Tang, W. Chen, W.
Howad, and F. Kempken. 1999.
Aunique two-gene gametophytic male
sterility system in sorghum involving a
possible role of RNA editing in fertility
restoration. J. Hered.90:386-393.
Momol MT, Simone GW, Dankers W,
Sprenkel RS, Olson SM, Momol EA,
Polston JE, and Hiebert E. 1999. First
Report of Tomato Yellow Leaf Curl Vi-
rus in Tomato in South Georgia. Plant
July 5, Monday: Independence day ob-
all classes suspended. All offices closed
July 9, Friday, 3:30 PM: Deadline for
payment of fees
July 16, Friday, 41 11"' 1: Submission of
defended Master's theses.
Leisure and Culture
'99 and Beyond
1.. .1 i r Rauschenberg The Chines
Summerhall Series." Exhibition on dis-
S"Asian Art from the Permanent Col-
lection" on display in the Har Museum
through January 2000. Call 392-9826.
*The works of Isamu Noguchi on dis-
play at Har Museum through Septem-
ber 26, 1999. Call 392-9826.
*European Prints from the Har Mu-
seum Collection. Through August 22,
1999. Call 392-9826.
* "The British Landscape: Watercolors
from 1760 to 1860." Through August
15, 1999. Call 392-9826.
* "Masters of the Night: The True Story
of Bats", at the Florida Museum of
Natural History. Through September 6.
* "Nature of Fiber: Texture, Form and
Color" at the gallery, 2nd floor, JWRU.
Through July 7, 1999. Call 392-2378.
* "Gregory Barsamian" at the University
Gallery through July 30, 1999. Call 392-
0201, ext. 228.
* "Giving Honor: Native American
Women's Art from the Florida Museum
of Natural History." Through August
29, 1999 at Har Museum. Call 392-
* "Building the American Collections:
Selected Acquisitions Since 1995."
Through August 15, 1999 in the Har
Museum. Call 392-9826.
* "Children's Summer Classes-Session C:
Florida's Earliest People." For Children
K-5. July 12-16, 8:30 am to 12:00 pm.
* "Children's Summer Classes-Session C:
Bats, Birds & Butterflies." For Children
K-5. July 12-16, 1:00 pm to 4:30 pm. Call
* Plants and Pollination Public Program.
Discover Plants and pollinators from the
* "Children's Summer Classes-Session D:
Rock Riddles and Mineral Mysteries."
For Children K-5. July 19-23, 8:30 am to
12:00 pm. Call 846-2000.
* "Children's Summer Classes-Session D:
Ocean Odyssey."." For Children K-5.
July 19-23, 1:00 pm to 4:30 pm. Call 846-
*"Something's Fishy Public Program.
Examine freshwater and marine animals.
July 21, 1999 from 1:00 pm to 3:00 pm.
Things you didn't know, you
A crocodile cannot stick its tongue out.
A snail can
sleep for three
All polar bears
are left handed.
:4'.11.111) in 1987 by eliminating one olive
from each salad served in first-class.
Americans on average eat 18 acres of
pizza every day.
An ostrich's eye is bigger than its brain.
Babies are born without knee caps; they
don't appear until the child reaches 2 to 6
years of age.
Butterflies taste with their feet
Cats have over one hundred vocal
sounds, dogs only have about 10.
Cats' urine glows under a black light.
China has more English speakers than
the United States.
Donald Duck comics were banned in
Finland because he doesn't wear any
Dueling is legal in Paraguay as long as
both parties are registered blood donors.
Elephants are the only animals that can't
February 1865 is the only month in re-
corded history not to have a full moon.
Humans and dolphins are the only spe-
cies that have sex for pleasure.
"I am." is the shortest complete sen-
tence in the English language.
If Barbie were life-size, her measure-
ments would be 39-23-33. She would
stand seven feet, two inches tall and have
a neck twice the length
of a normal human's neck.
If the population of China walked past
you in single file, the line
would never end because of the rate of
If you yelled for 8 years, 7 months and 6
days, you will have produced
6 PLP NEWS
enough sound .. i i -- to heat one cup of
In ancient Egypt, priests plucked
EVERY hair from their bodies,
including their eyebrows and eyelashes.
In the last 41i ,,i years, no new animals
have been domesticated.
Leonardo Da Vinci invented the scissors.
Marilyn Monroe had six toes.
Michael Jordan has more money from
Nike annually than all of the Nike
factory workers in Malaysia combined.
No word in the English language rhymes
Nutmeg is extremely poisonous if in-
On average, people fear spiders more
than they do death.
One of the reasons marijuana is illegal
today is because cotton growers
in the 1930's lobbied against hemp
farmers-they saw it as competition.
Our eyes are always the same size from
birth, but our nose and ears
never stop growing.
Right-handed people live, on average,
nine years longer than
left-handed people do.
Shakespeare invented the words 'assas-
sination' and 'bump'.
Some lions mate over 50 times a day.
Starfish don't have brains.
Stewardesses is the longest word typed
with only the left hand.
The ant always falls over on its right side
The average human eats eight spiders in
their lifetime at night.
The catfish has over 27,000 taste buds.
The cruise liner, Queen Elizabeth 2,
moves only six inches for each
gallon of diesel that it burns.
The electric chair
The human heart cre-
ates enough pressure
when it pumps out to
to squirt blood 30 feet.
The male praying mantis cannot copulate
while its head is attached to
its body. The female initiates sex by rip-
ping the male's head off.
The most common name in the world is
The name of all the continents end with
the same letter that they start
The name Wendy was made up for the
book 'Peter Pan'.
The Pentagon in Arlington, Virginia, has
twice as many bathrooms as
necessary. When it was built in the
1941 ,'., the state of Virginia
still had segregation laws requiring sepa-
rate toilet facilities for
blacks and whites.
The strongest muscle in the body is the
The word racecar and kayak are the same
whether they are read left to right or
right to left.
There are two credit cards for every per-
son in the United States.
TYPEWRITER is the longest word that
can be made using the letters
only on one row of the key-
blink nearly twice as much
The Latest from...
"Tobacco Mosaic Virus: One Hundred
Years of Contributions to Virology."
Edited by Scholthof, Shaw and Zaitlin.
"The Formative Years of Plant Pathol-
ogy in the United States." By Campbell,
Peterson, and Griffith.
"Emerging and Reemerging Plant Dis-
eases Slide Set". Compiled by Schumann
"Biological and Cultural Tests, Volume
14." Edited by M.T. McGrath.
"Compendium of Cor Diseases, Third
Edition." Edited by D.G. White.
"Corn Diseases 3rd Edition Slide Set"
"Plant Microbe Interactions, Volume 4."
Edited by G. Stacey and N. Keen.
cilities and Safe-
guards for Exotic
( ~Plant Pathogens and
Pests." Edited by
R.P. Kahn and S.B.
"Citrus Health Man-
agement". Edited by L.W. Timmer and
"Illustrated Genera of Ascomycetes,
Volume II." By R.T. Hanlin.
"Combined Keys to Illustrated Genera
of Ascomycetes I & II." By R.T. Hanlin.
l., l! ,i... i-,i, and Other Fleshy Basidi-
omycetes Slide Set".
"Illustrated Genera of Imperfect Fungi,
4th Edition." By H.L. Bamett and B.B.
"Digital Image Collections; Diseases of
Field Crops CD-ROM
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7 PLP NEWS
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