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United States Department of Agriculture

Agricultural Research Service

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Exotic Citrus Pathogen 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 bio-security reasons the EPCC is located in Beltsville, MD, approximately 1500Km (930mi) away from commercial citrus growing regions. Cooperating scientists from Florida, Texas and California, as well as other countries around the world can conduct evaluations with plants which are maintained under similar conditions. In some cases environmental conditions in an area can affect symptom expression; this facility allows us to create a " base-line " for symptom expression. We also provide prepared tissue samples to other cooperating labs around the United States and world to use as positive control standards for comparison in research.

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 which 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 multiple symptom patterns and genotypes. We also have Citrus yellow mosaic badnavirus obtained from India in the collection and citrus chlorotic dwarf, a virus from Turkey that produces spectacular symptoms.

Rapid and sensitive DNA- or RNA-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 virus, strains of Xylella fastidiosa that cause citrus variegated chlorosis, bacteria called Xanthomonas citri that cause citrus canker, and the pathogen that causes huanglongbing or citrus greening disease.

Citrus Facts

orange line 

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

For more information concerning growing citrus please contact Cristina Paul

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Florida Juice Commision*
University of Florida*
Sunkist kid's stuff*
The Ultimate Citrus Page*
California Citrus Research Board*
Citrus from Down Under- Citrus Australia *
Texas Citrus*
* Goes to non-federal site

Last Modified: 5/16/2013
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