Natural Host: Rosa sp. (rose)

Causal agent: Prunus necrotic ringspot virus (PNRSV)

Etiology: The PNRSV, alone or associated with Apple mosaic virus, is the major virus causing the disease complex known as "mosaic of rose." It belongs to the Ilarvirus genus, family Bromoviridae consisting of RNA viruses, single stranded, positive sense, particles with isometric to bacilliform morphology, with about 30 nm in diameter.

Symptoms: The intensity of symptoms (from drastic to not visible) varies with the cultivar of rose, photoperiod and soil conditions. Mosaic, rings, chlorotic/necrotic drawings, leaf distortion and flowers break are the most recognizable symptoms. PNRSV, although often not induce visible symptoms can cause lack of vigor, scant bloom production or smaller blooms than are typical for their variety.

Economic importance: The virus causes severe damages to the production of stone fruit trees of the Rosaceae family, as plum (Prunus domestica), cherry (P. avium), peach (P. persicae) and apple (Malus domestica), besides rose.

Occurrence: PNRSV occurs worldwide and has already been reported in European coutries, Asia, Africa, Americas and Oceania, and probably wherever Prunus or Rose are grown.

Management: The spread of PNRSV occurs mainly through infected buds and rootstocks in vegetative propagation. Infected rose cuttings and buds produce infected plants, even though symptoms may not appear in the first year. The spread can also be made by pollen and contact means between roots. Transmission by nematodes has been reported but its biological significance is not clear. Therefore, it is advisable to use certified propagation material and eradicate sources of infection

Selected References

ALEXANDRE, M.A.V.; DUARTE, L.M.L.; CAMPOS-FARINHA. Plantas Ornamentais: Doenças e Pragas. Vol.I. São Paulo, 2008. 319p. IMENES, S.L.D.; ALEXANDRE, M.A.V. Aspectos fitossanitários da roseira. Instituto Biológico, São Paulo, 2003. 56p. FAUQUET, C.M.; MAYO, M.A.; MANILOFF, J.; DESSELBERGER, U.; BALL, L.A. Virus taxonomy. Eighth report of the International Committee on Taxonomy of Viruses. San Diego: Elsevier Academic Press, 2005. 1259p. HULL, R. Matthews’ Plant Virology. San Diego: Elsevier Academic Press, 2002. 1001p.
LOEBENSTEIN, G. Rose. In LOEBENSTEIN, G.; LAWSON, R.H.; BRUNT, A.A. (ed.). Virus and virus-like diseases of bulb and flower crops. Chichester: John Wiley & Sons, 1995. p. 426-437.