The citrus gummy bark viroid (abbreviated CGBVd) is a

strain Strain may refer to: Science and technology * Strain (biology), variants of plants, viruses or bacteria; or an inbred animal used for experimental purposes * Strain (chemistry), a chemical stress of a molecule * Strain (injury), an injury to a mu ...

of ''

Hop stunt viroid The hop stunt viroid (abbreviated HSVd) is a viroid species that infects the common hop plant, citrus plants and grapevines, among others. It is a member of the Pospiviroidae family and the Hostuviroid Hostuviroid is a genus of viroid Vir ...

'', and thus is a member of the genus ''

Hostuviroid Hostuviroid is a genus of viroid Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most caus ...

''. As the name suggests, the citrus gummy bark viroid causes problems in the bark of the

sweet orange An orange is a fruit of various citrus species in the family Rutaceae (see list of plants known as orange); it primarily refers to ''Citrus'' × ''sinensis'', which is also called sweet orange, to distinguish it from the related ''Citrus × ...

tree. Scraping the bark exposes localized spots or a line of reddish-brown, gum-impregnated tissue around the

scion Scion may refer to: Arts, entertainment, and media Fictional entities *Scion, a playable class in the game ''Path of Exile'' (2013) *Atlantean Scion, a device in the ''Tomb Raider'' video game series *Scions, an alien race in the video game ''Ba ...

circumference especially visible near the bud union. The discoloration and gumming may extend above the bud union to the main branches of the sweet orange while in severe infection dark streaks of gum-impregnated tissue may also be observed in longitudinal sections.

References

Viroids Viral citrus diseases Infraspecific virus taxa {{virus-stub