GAINESVILLE, 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).
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
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,
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 Charles Bronson.
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 Rights Reserved.