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U.S. DEPARTMENT OF AGRICULTURE AND FLORIDA DEPARTMENT OF AGRICULTURE CONFIRM DETECTION OF CITRUS GREENING

WASHINGTON, Sept. 02, 2005--The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service today 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 area and after initial testing in the Department’s Gainesville laboratory, were sent to APHIS for confirmatory testing.

Using several different polymerase chain reaction (PCR) tests, APHIS’ National Plant Germplasm and Biotechnology Laboratory in Beltsville, Md., confirmed the samples were infected with the bacterial disease, which already seriously affects citrus in India, Asia, Southeast Asia, the Arabian Peninsula and Africa. The disease does not pose a threat to human health.

“APHIS is committed to working closely with the state of Florida to assess the situation in the area where the samples were taken,” said Bill Hawks, USDA’s Under Secretary for Marketing and Regulatory Programs. “In coordination with Florida, we have prepared for the possibility that this disease could one day reach the United States, and we will move swiftly to protect the U.S. citrus industry.”

During a Cooperative Agricultural Pest Survey (CAPS), an entomologist with the Florida Division of Plant Industry was conducting a targeted citrus greening survey in Homestead when two citrus trees in separate locations showed symptoms of citrus greening. The survey is 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.

Citrus greening, or huanglongbing, is a bacterial disease that 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). 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.

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. Because of the threat this disease poses to Florida citrus, federal and state agricultural officials have had on-going discussions planning for the appropriate detection and response initiatives that would need to be employed if and when the disease was identified in the United States. The early detection of the disease by FDACS and the citrus greening survey is the result of these pre-planning activities.

“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 is 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, as shown in the attached photos. The inside of the fruit is lopsided and is inedible due to poor taste. The fruit drops off before ripening and has poor color. Molecular tests are needed to confirm the presence of this disease.

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