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Animal and Plant Health Inspection Service
U.S. Department of Agriculture

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Andrea McNally (301) 734-0602

USDA Confirms New Citrus Disease in Florida

WASHINGTON, April 8, 2010 - The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) today confirmed the presence of Guignardia citricarpa, or citrus black spot, in Florida.

During a routine grove survey, the Florida Department of Agriculture and Consumer Services' (FDACS') Division of Plant Industry (DPI) collected a suspect sample from a commercial orange grove in Collier County. After conducting polymerase chain reaction testing of the submitted tissue and DNA samples from Florida, APHIS' National Plant Germplasm and Biotechnology Laboratory and Molecular Diagnostics Laboratory in Beltsville, Md., confirmed the presence of G. citricarpa in the samples, thereby corroborating with FDACS-DPI's plant pathology laboratory's initial diagnostic results.

“This detection demonstrates the effective and collaborative nature of the citrus health response program,” said Rebecca Bech, deputy administrator for APHIS' plant protection and quarantine. “It has not only provided the infrastructure upon which we made this early detection but also the framework for APHIS' regulatory response.

“We are working in collaboration with the Florida Department of Agriculture and Consumer Services, the University of Florida's Citrus Research and Education Center and the citrus industry to limit the spread and impact of this disease through swift regulatory actions, education and informed compliance.”

A fungal disease marked by dark, speckled spots or blotches on the rinds of fruit, citrus black spot is an economically significant citrus disease. It causes early fruit drop, reduces crop yield and renders the highly blemished fruit unmarketable. While all commercial citrus cultivars are susceptible to citrus black spot, the most vulnerable are lemon and late-maturing citrus varieties like Valencia. Although disease symptoms are expressed clearest on the rinds of fruit, the risk of this disease spreading through fruit movement is minimal. The greatest risk of disease transmission is associated with the spores released from fallen, decomposing citrus leaves.

Citrus black spot occurs in subtropical regions of the world with summer rainfall. The disease has been found in Argentina, coastal areas of Australia, Brazil, China (mainland and Hong Kong), Indonesia, Japan, Kenya, Mozambique, Nigeria, Philippines, areas of South Africa with summer rainfall, Swaziland, Taiwan, Uruguay, Venezuela and Zimbabwe.

For information on the cooperative citrus health response program, log onto: plant_pest_info/citrus/index.shtml .


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