Citrus B Viroid Identified as a Strain of Hop Stunt Viroid. T. O. Diener, Research Plant Pathologist, Microbiology and Plant Pathology Laboratory, USDA-ARS, Beltsville, MD 20705. D. R. Smith, Rosemarie H. Hammond, Giuliana Albanese, Rosa La Rosa, and M. Davino. Microbiologist, Research Associate, Microbiology and Plant Pathology Laboratory, USDA-ARS, Beltsville, MD 20705; Research Associate, Research Associate, and Professor, Istituto di Patologia Vegetale, Universita, Catania, Italy. Plant Dis. 72:691-693. Accepted for publication 17 February 1988. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1988. DOI: 10.1094/PD-72-0691.

Citrus B viroid (CBV), differing from the citrus exocortis viroid in host range, symptom expression, and reaction with viroid-specific molecular probes, has been identified in many commercial citrus trees in Sicily. Citrus B viroid replicates in cucumber (Cucumis sativus L. ‘Suyo’) plants and produces symptoms similar to those induced in cucumber by the hop stunt viroid (HSV). Molecular hybridization with HSV-specific RNA probes has demonstrated that the nucleotide sequence of CBV is closely homologous to that of HSV, indicating that the viroid is a strain of HSV. Citrus B viroid, alone or in conjunction with other viroids, may be responsible for inducing the citrus cachexia (xyloporosis) disease.