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Disease Note.

First Report of Citrus Tristeza Virus in Louisiana. R. A. Valverde, Dept, of Plant Pathology Louisiana Agricultural Experiment Station, Louisiana_ State University Agricultural Center, Baton Rouge 70803 . W. J. Bourgeois. Dept, of Plant Pathology and Crop Physiology and Citrus Research Station, Louisiana Agricultural Experiment Station, Louisiana_ State University Agricultural Center, Baton Rouge 70803, and R. F. Lee, University of Florida, Citrus Research and Education Center, Lake Alfred 33850. Plant Dis. 80:103. Accepted for publication 30 October 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0103D.

Citrus tristeza virus (CTV) is an economically important virus of citrus throughout the world (1). Visual inspections of citrus trees at the Citrus Research Station in Port Sulphur, Louisiana, during the past 3 years did not reveal evidence of viral diseases. However, since CTV is known to occur in the United States, we decided to conduct a survey of trees at the facility using molecular and serodiagnostic tests specific for CTV. Double-stranded RNA (dsRNA) was extracted from bark, samples collected from 34 trees. A sample from a tree infected with CTV was included as control. Citrus scions tested included: Washington Navel orange, Owari Satsuma, and Poncirus trifoliata (L.) Raf. Purified dsRNAs were analyzed by gel electrophoresis. Three Washington Navel orange and one Owari Satsuma were found infected with CTV. DsRNA banding patterns obtained with samples from these trees were similar to that of the CTV-infected tree. DsRNAs were not delected in all other trees tested. Further tests using the enzyme-linked immunosorbent assay (ELISA) with several polyclonal and monoclonal antibodies for CTV confirmed the dsRNA results. ELISAs using monoclonal MCA-13 specific for severe strains were negative.