Florida, September 12, 2005 (ENS): A bacterial
plant disease that could endanger Florida's $9 billion
citrus industry has been found for the first time in
the United States, agriculture officials said Friday.
The disease affects the vascular system of plants and
causes infected trees to die in a few years.
The U.S. Department of Agriculture’s Animal and
Plant Health Inspection Service (APHIS) confirmed the
first U.S. detection of Liberibacter asiaticus, or citrus
greening, on pummelo tree leaf and fruit samples collected,
tested and submitted by the Florida Department of Agriculture
and Consumer Services (FDACS).
||"Symptoms of citrus greening
disease are similar to plants with severe nutritional
deficiencies including yellow shoots, twig dieback,
tree decline and reduced fruit size and quality."
The samples were collected from two separate locations
in the Homestead, Florida area and after initial testing
in the USDA's Gainesville laboratory, were sent to APHIS
for confirmatory testing.
Using several different tests, APHIS’ National
Plant Germplasm and Biotechnology Laboratory in Beltsville,
Maryland, confirmed the samples were infected with the
bacterial disease, which already affects citrus in India,
Asia, Southeast Asia, the Arabian Peninsula and Africa.
The disease does not pose a threat to human health.
Citrus greening, or huanglongbing, attacks the vascular
system of plants. Once infected, there is no cure for
a tree with citrus greening disease. In areas of the
world where citrus greening is endemic, citrus trees
decline and die within a few years. There are three
forms: Asian, African and Brazilian. The strain found
in South Florida appears to be the Asian form.
The bacteria are transmitted primarily by insect vectors,
citrus psyllids, and through infected planting materials.
In June 1998, the insect that carries the Asian strain
of citrus greening, Diaphorina citri Kuwayama, was found
for the first time in the United States in Delray Beach,
but no citrus greening infection was found at that time.
Because of the extreme threat to Florida citrus, the
Department has been conducting a citrus greening survey
for many years. Once the Asian citrus psyllid was discovered
in 1998, citrus greening survey efforts were intensified.
The diseased trees were found in Homestead by an entomologist
with the Florida Division of Plant Industry during a
Cooperative Agricultural Pest Survey, part of a cooperative
effort between the state and APHIS.
Communities with concentrations of people from countries
where citrus greening is endemic may be at higher risk
of receiving infected plant material, and these areas
have been targeted in survey activities, APHIS said.
State and federal officials will begin a comprehensive
survey of the area to identify the extent of disease
spread. A team of experts, including scientists, state
and federal agricultural officials and academia, has
been established to quickly mobilize a response.
“We are assessing the situation to determine
exactly what course of action will be taken. We will
provide the citrus industry and public with information
as soon as it becomes available,” said FDACS Commissioner
A joint science panel is being convened by APHIS and
FDACS to obtain expert advice on the most effective
surveillance and control strategies based on the current
detection. If the disease was discovered early enough,
eradication may be possible.
Symptoms of citrus greening disease are similar to
plants with severe nutritional deficiencies including
yellow shoots, twig dieback, tree decline and reduced
fruit size and quality, often affecting only a single
branch at first. Older leaves develop a characteristic
mottling, or patches of discoloration. The inside of
the fruit is lopsided and is inedible due to poor taste.
The fruit drops off before ripening and has poor color.
Where the disease exists, management strategies rely
on preventing its spread into uninfected areas by regulating
the movement of propagating material, destruction of
infected trees, and control of insect vectors.
Copyright Environment News Service (ENS) 2005. All