By Lisa Lochridge, FFVA director, Public Affairs
Division
There is no “raging infestation” of laurel wilt disease
among avocado trees in South Florida, say researchers who are working to
stop the march of the disease and the tiny beetle that carries it. Even
so, a task force of state, industry and scientific representatives
should not let down its guard, the scientists say.
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The redbay ambrosia beetle could prove deadly to Florida's avocado
trees. -Photo credit DPI
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The Redbay Ambrosia Beetle - Laurel Wilt Disease Working Group had
already been assembled before one infected tree was found in July in
Miami-Dade County. The group is engaged in research, outreach and
regulatory activities in a coordinated effort to prevent the spread of
the disease, which threatens the state’s $13 million-a-year
avocado crop.
The redbay ambrosia beetle itself has not been found in Miami-Dade
County, nor has any other instance of laurel wilt disease in avocados
except for the one presumptive positive discovery in July. So far, the
farthest south the beetle has been found is Martin County.
That doesn’t mean the state isn’t looking for it. About
180 groves – 4,500 or so acres – have been surveyed.
That’s roughly 65 percent of the state’s 7,000-plus acres of
commercially grown avocado trees. Pathologists and entomologists
with and UF/IFAS and FDACS’ Division of Plant Industry are
conducting extensive lab analyses of fungi and insect samples.
In addition, outreach efforts are underway to get word to the public
about the disease.
A TOUGH DIAGNOSIS
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Telltale - A string of redbay ambrosia beetle sawdust stands out on
a tree. -Photo credit DPI
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The only tree that has turned up positive for laurel wilt disease was on
272nd Street in Miami-Dade County – and that determination
wasn’t made until three separate labs were able to confirm
it. It took five weeks for scientists to get the pathogen to emerge in
the plates where they place the samples to grow.
Diagnosis is challenging and time-consuming because of the sheer
number of insects and pathogens turning up in samples. Although 13
types of ambrosia beetles have been found, the redbay ambrosia beetle
was not among them. And researchers at the working group’s
September meeting said it’s much more difficult to isolate the
pathogen in avocado trees than it is in redbay trees. So much secondary
fungi have been growing in the plates containing the samples that
scientists have started adding antibiotics, hoping to knock back other
fungi so the pathogen can emerge.
In the meantime, researchers are working to refine their diagnostic
tools. “The key is, what are we looking at in South Florida, and
what is considered a routine diagnostic in avocado?” said DPI
Director Richard Gaskalla.
The team is exploring many other questions, including:
• What kind of pesticides, including systemic ones, can be
used to combat the ambrosia beetle?
• What types of hosts are attractive to the beetle?
• What kind of “volatiles” -– chemicals or
any other type of sensory attractant -- may lure the beetle?
• Does topping a tree make it more susceptible to
infestation?
"SAVE THE GUAC"
Not all of the work is occurring on the scientific front.
To get the word out to the public about what consumers can do to help,
the state has launched an education campaign dubbed “Save the
Guac.”
“There is a significant effort underway to communicate with the
public and key stakeholders about the redbay ambrosia beetle and laurel
wilt disease,” said Denise Feiber, public information director for
DPI. “By coordinating our efforts with the scientific and
regulatory communities, we can be more effective in letting industry
know what’s being done to detect the disease and how consumers can
help prevent its spread.”
Visitors to the campaign's Web
site can find tips on how they can do their part. Those
include spotting signs of the disease on avocado trees in their yards,
properly disposing of ailing and dead trees, and using local firewood
only (the redbay ambrosia beetle and laurel wilt disease can be carried
on infested firewood brought into Florida from other places).
“Save the Guac” bumper stickers were distributed in October
at the Holy Moly Redland Guacamole Celebration, where local celebrity
chefs and students from several Miami-Dade high schools were hoping to
set the world record for the largest serving of guacamole.
In addition, the Dade County Farm Bureau is working to organize a
speaker’s bureau to identify speakers and set up presentations
about the disease and preventive steps to civic groups and other
organizations.
DPI also is producing a short video that will be distributed soon
through Web sites such as YouTube, public and cable television stations,
schools, extension offices and media outreach.
Note:
The Laurel Wilt Disease and Redbay
Ambrosia Beetle Research Symposium will be held on
Tuesday, Nov. 3, 8:30 a.m. - 3 p.m., at the Miami-Dade
County
Extension Service Auditorium. All stakeholders are encouraged
to attend. For information, email Dr. Greg
Hodges or call (352) 372-3505, ext.
118.
