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United States Department of Agriculture

Agricultural Research Service

Exotic Pathogens of Citris Collection
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Now a part of the Molecular Plant
Pathology Laboratory

Exotic Pathogens of Citrus Collection

Yes, there are orange trees in Maryland!

History of the Facility

The Exotic Pathogens of Citrus Collection (EPCC) was created in 1984 and is funded by the USDA ARS. This unique facility is composed of a 3200 sq ft greenhouse opened in November of 2006 and a laboratory dedicated to the study of exotic diseases of citrus. Exotic diseases are those which either do not occur, or occur with only limited distribution in the United States. For biosecurity reasons the EPCC is located in Beltsville, MD, approximately 1500Km (930mi) away from commercial citrus growing regions. Cooperating scientists from Florida and California, as well as other countries around the world can conduct evaluations with plants which are maintained under similar conditions.

Research at the Facility

The EPCC includes several hundred strains of Xanthomonas axonopodis pv. citri (citrus canker) in frozen storage. These include the known diversity in this complex of species. We maintain all three Candidatus species of Liberibacter (Huanglongbing or citrus greening disease) in the collection as well as Xylella fastidiosa (citrus variegated chlorosis).

The EPCC includes an extensive collection of citrus viruses. These are maintained in plants. These include accessions of Citrus tristeza virus from 40 countries. There is exceptional variation in both the genotypes of CTV and in the symptoms induced in infected plants. Our collection includes strains representing symptom patterns and genotypes. We also have Citrus yellow mosaic badnavirus obtained from India in the collection and citrus chlorotic dwarf, an apparent virus from Turkey that produces spectacular symptoms but has resisted our efforts at purification.

Rapid and sensitive DNA-based diagnostic methods to assist in plant quarantine and phytosanitary applications have been developed for many of these pathogens over the years. These include Citrus Tristeza Virus, Citrus Yellow Mosaic Badna Virus, strains of Xylella fastidiosa that cause Citrus Variegated Chlorosis, bacteria called Xanthomonas axonopodis pv citri that cause citrus canker, and the pathogen that causes Huanglongbing or citrus greening disease.

For more information about Citrus pathogens please contact Dr. John Hartung

For more information concerning growing citrus please contact Cristina Paul


Last Modified: 3/27/2013
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