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HUANGLONGBING CITRUS - USA (FLORIDA)
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A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
In this 1st update for 2006:
[1] Citrus Greening, Lee County, FL, 22 Mar 2006: 1st report
[2] Citrus Greening, De Soto County, FL, 22 Mar 2006: 1st report
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[1] Citrus Greening, Lee County, FL, 22 Mar 2006: 1st report
Date: 22 Mar 2006
From: ProMED-mail <promed@promedmail.org>
Source: News-press.com [edited]
<http://www.news-press.com/apps/pbcs.dll/article?AID=/20060322/NEWS0101/603220419/1075>
Disease is deadlier to trees than canker
-----------------------------------------
Just when citrus growers thought it was safe to replant their trees, an
even deadlier disease has cropped up in Lee County.
State agriculture officials have confirmed a case of citrus greening at a
residence in northwest Cape Coral, according to a map posted by the state
agriculture department.
They would not release the address of the case due to security issues; the
disease has the potential to be used as a bioterrorism weapon, although it
is harmless to humans.
A "highly suspect" case was also found last month [February 2006] at a home
in Lehigh Acres, but the test results have not yet been confirmed,
according to Mark Fagan, spokesman for the agriculture department.
The discovery comes 2 weeks after the Florida Department of Agriculture
gave residents the OK to replant the more than 30 000 trees lost to citrus
canker. Local growers are being urged not to replace their citrus trees
because of the newest threat.
"With greening, just as with canker, we recommend wholeheartedly that they
remove the trees," Fagan said. "You're going to want to take the tree down
if it has greening, because it's good for absolutely nothing."
Unlike canker, which can be detected almost immediately after it has
infected a tree, greening symptoms are often mistaken as a simple nutrition
deficiency. 3 to 5 years may pass before an infected tree shows the deadly
signs. In most cases, trees are dead in fewer than 8 years.
Greening has been killing trees on the east coast of Florida since it was
1st discovered in Homestead in August 2005. Now, 240 trees are infected in
12 counties, and its westward movement has citrus industry leaders very
concerned.
"It may be the worst disease we've ever had in this industry," said Jay
Clark, CEO of Florida Citrus Mutual, which represents more than 10 000
growers across the state.
"At this time, there have not been huge financial losses, but we know that
it's spreading enough to be very concerned," he said. "It will be very
costly to growers."
All of Miami-Dade, Broward and Palm Beach counties are under quarantine due
to the high incidents of greening. There are 6 confirmed cases in Hendry
County and 3 in Collier.
While Clark is urging growers to destroy infected trees, Lee County
residents aren't so quick to chop up their backyard groves.
Jan Humphreys of Cape Coral just replaced 2 trees at her home, and she
doesn't plant on ripping them out.
"I've gone without my oranges for 2 years," she said. "Will it ever be safe
to grow citrus again?"
The only way to stave off the greening infection is by reducing the number
of psyllids, the small, grayish moth-like insects that can spread the
disease just by landing on a branch.
The state has released natural predators of the psyllid, "but that will
only knock the population back so far," said Tim Schubert, a plant
pathologist with the Florida Division of Plant Industry in Gainesville.
He also urges residents to use special pesticides to kill the psyllid,
which can also be found on noncitrus plants like jasmine and jackfruit.
Cinda Layton, who manages Danny Yates Landscape Nursery in Cape Coral,
stopped carrying those plants that host the bug.
"As long as we can keep an eye on (the citrus trees) coming in, I think
we'll be fine," she said. "People aren't concerned about it, they just want
to get back what they lost."
The canker quarantine reduced the nursery's business by 5 to 10 percent,
she said, but if greening breaks out, "it will be much worse, because it's
going to kill the tree eventually."
As growers spend more money on pesticides and harvest smaller crops,
Florida's citrus industry could take a serious hit, and the prices of
citrus products will probably remain high, said Mongi Zekri, a citrus
extension agent with the University of Florida in Hendry County.
He is trying to teach growers and gardeners to detect greening symptoms
early before it spreads to nearby trees. If a tree looks suspicious, he
urges them to send a sample to the state lab in Gainesville.
Zekri expects the state to impose stricter regulations to control the
disease, such as requiring nurseries to raise young citrus trees indoors.
"I wouldn't be surprised if it happens in the next couple of years," he
said. "But this is serious. It can be very devastating and even more
dangerous than canker."
[Byline: Kim Hart]
--
ProMED-mail
<promed@promedmail.org>
******
[2] Citrus Greening, De Soto County, FL, 22 Mar 2006: 1st report
Date: 22 Mar 2006
From: ProMED-mail <promed@promedmail.org>
Source: Charlotte Sun-Herald, sun-herald.com [edited]
<http://www.sun-herald.com/NewsArchive2/032206/tp1ch6.htm?date=032206&story=tp1ch6.htm>
Killer citrus disease spreads in area
---------------------------------------
The tree-killing citrus disease called greening [aka Huanglongbing -
Mod.JAD] has been confirmed by laboratory tests in 2 DeSoto County orange
trees off Airport Road. One has been destroyed and the other is being studied.
These are the 1st confirmations here of a disease growers fear far more
than canker [a bacterial disease of Citrus causing problems in Florida -
Mod.JAD]. A suspicious tree has also been located in Charlotte County, near
Sarasota County.
"We are not startled by this news," Barbara Carlton, executive director of
the Peace River Valley Citrus Growers Association, said Tuesday [21 Mar
2006]. "The scientists told us greening has spread throughout the state."
Like canker, greening is a bacterial disease that attacks citrus trees.
Unlike canker, it kills infected trees and renders their fruit unusable for
juice or fresh fruit sale.
The greening bacterium is carried from tree to tree by a small fly-like
insect called a psylla. The psylla is not native to Florida and was 1st
discovered near Daytona Beach about 15 years ago.
Greening was found last August [2005] in trees 14 miles apart, near
Homestead in South Florida.
Since then, greening has spread into 13 counties. Counties such as
Miami-Dade, Broward, Palm Beach and St. Lucie are at pandemic levels for
greening.
Late last year [2005], greening was found on a tree at a United States
Department of Agriculture research station on Fruitville Road in Sarasota.
That was the 1st jump across the state.
As a result of that discovery, a 4-square-mile quarantine area has been
created by the state Department of Agriculture and Consumer Affairs,
prohibiting plant movement in or out of the area within a mile of the
agricultural station.
The zone extends north to Tallevast Road in Manatee County.
In Charlotte County, the 1st suspected case of greening turned up on an
orange tree in a residential yard near the Sarasota County line at the
Myakka River.
And in Lee County, there has now been a confirmed greening case among 3
suspicious trees, according to Denise Fieber, spokeswoman for the state
agriculture department. 2 of the trees are in Cape Coral.
Fieber said quarantines might be needed in areas where new confirmed
discoveries have been made, including DeSoto and Lee. The quarantines will
affect nurseries and stock dealers, she said. No plants can be moved into
or out of the quarantine zone to another area of the state, and any plant
destined for export to another country must be treated with a pesticide.
Beyond that, a course of action to contain greening has not been
determined, Fieber said.
A committee mapping a new plan to control citrus diseases told the state
agriculture agency last week that the psylla that spreads greening is "hard
to find and hard to kill." The psylla doesn't depend on citrus trees and
can live on ornamental plants without harming them. Indeed, it "hitchhikes"
on ornamentals shipped out of South Florida.
Carlton said growers are so concerned about this threat that they are
talking of joint action to fight the pest.
"Machinery in a grove could spook the insect," Carlton said. "So it might
fly off to another nearby grove."
For that reason, adjacent grove owners might agree on a concentrated
attack, such as aerial spraying, which was done to rid the state of the
Mediterranean fruit fly in the 1960s.
The state wants infected trees destroyed, but has no power to order that.
"The scientists are looking for the best treatment," Carlton said.
"Ideally, we'd like to knock down the pest population."
[Byline: Robert Bowden]
--
ProMED-mail
<promed@promedmail.org>
[Huanglongbing (HLB) is the internationally accepted name for a disease
known as Citrus greening in English speaking countries. HLB is a disease of
the fruit crop citrus caused by a phloem-limited bacterium (_Liberibacter
asiaticus_). It is one of the most severe diseases affecting citrus
production in tropical and sub-tropical regions of the world. It can be
lethal to infected plants. It spread to citrus orchards in Florida for the
1st time in 2005. HLB is transmitted by the Asiatic citrus psyllid
(_Diaphorina citri_) as well as by grafting infected budwood.
The recent history in Florida since August 2006 can be followed in the 3
posts listed in the "see also" section below. This posting represents an
early [22 Mar 2006] report of the expected extension of the range of HLB to
additional counties in Florida, in this case Lee and DeSoto Counties. In
addition to providing details of the new finds, the articles provide a good
update on HLB disease and its impact in Florida, including the sense of alarm.
Detection is a problem, because initial symptoms resembles nutrient
problems and can take years to develop, and nursery practices may have to
change to accommodate the need to avoid the vector when growing seedlings.
The 2 diseases HLB and citrus canker represent a serious threat to US
citrus production. Any grower intending to replant after losses to canker
will have to consider the wisdom of placing attractive young trees in the
path of HLB and its psyllid vector. Texas, Arizona and California are all
on the alert for the arrival of HLB into the remainder of the USA citrus
industry.
Maps:
Lee County, FL
<http://www.floridacountiesmap.com/lee_county.shtml>
DeSoto County, FL
<http://www.floridacountiesmap.com/desoto_county.shtml>
Worldwide distribution of HLB
<http://www.eppo.org/QUARANTINE/bacteria/Liberobacter_asiaticum/LIBEAS_map.htm>
Pictures:
Tree death
<http://www.apsnet.org/education/IntroPlantPath/PathogenGroups/fastidious/images/fig14.jpg>
Infected shoot
<http://www.floridagrower.net/forging_ahead/images03/greening.jpg>
Psyllid vector
<http://ss.jircas.affrc.go.jp/kenkyu/katsudou/project/images/okinawa5b.jpg>
Links:
<http://spdn.ifas.ufl.edu/Citrus%20_Greening.htm>
<http://creatures.ifas.ufl.edu/citrus/acpsyllid.htm>
- Mod.JAD]
[see also:
2005
----
Huanglongbing, citrus - USA (FL)(03) 20051102.3203
Huanglongbing, citrus - USA (FL)(02) 20051017.3035
Huanglongbing, citrus - USA (FL) 20050910.2683]
.......................................jad/msp/dk
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