By Henry Kuska last revised 5-21-2024
retired, Associate Professor, Department of Chemistry, University of Akron
"This page gives the information that I have collected from my own literature searches and from others posting on the internet. Please let me know if you feel anything is not clear or is not addressed at all as I am continually updating/modifying it as I get feedback." The bold face was added by me for emphasis (H.Kuska).
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Prunus necrotic ringspot virus (PNRSV) belongs to the genus Ilarvirus and the family Bromoviridae. Historically, this virus was considered by many to be the main virus that infected commercial U.S. roses. Of particular importance is that many/most early articles stated that this virus did not spread naturally in roses. Later, this "rule" was amended to allow for the possibility of spread by root to root grafting between neighboring roses. However, this possibility was/is often downplayed.
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What is the present scientific view concerning PNRSV spread in roses? Here are 4 examples:
1)
See: https://intapi.sciendo.com/pdf/10.2478/hppj-2024-0002
Of particular interest (to me) is the following: " This finding rises important issues concerning rose production. In fact, PNRSV is difficult to control, because it is transmitted in several modes, mainly by grafting (Seitadzhieva et al., 2022), by seeds and by some pollinator insects. "
2)
The quote below is from: Title: Viruses Rose Virome Analysis and Identification of a Novel Ilarvirus in Taiwan (mdpi.com)
https://www.mdpi.com/1999-4915/14/11/2537
"The main way the rose viruses spread is likely through vegetative propagation in commercial nurseries and subsequent nationwide distribution to gardens through root grafting. However, some viruses may have other transmission mechanisms once in the environment including seed, pollen and arthropod vectors [7,55]. ApMV, PNRSV, RoCV-1 and ASGV are reported to be transmitted by seed and pollen [28,47,56,57]. Some ilarviruses can be transmitted by thrips and other flower-visiting arthropods. For instance, PNRSV is spread throughout New Zealand by the western flower thrips (Frankliniella occidentalis) [7,47]; however, F. occidentalis does not harbor in Taiwan. It cannot be excluded that PNRSV has other insect vectors. The arthropod vector of ApMV, RoCV-1 and ASGV is still unknown. RSDaV is known to be transmitted by rose-grass aphid (Metopolophium dirhodum) and yellow rose aphid (Rhodobium porosum) [31]. R. porosum is one of the common pests of roses in Taiwan [58], which may cause the domestic spread of RSDaV. The transmission mode of RoPV and RIV-2 remains unknown and needs to be investigated. Damage to roses by pests including aphids, mites, thrips and whiteflies could be observed in the surveyed areas. Whether these arthropods are responsible for transmitting the rose viruses needs to be investigated. Although the above-mentioned viruses were not detected in the Changhua and Nantou nurseries, it is still necessary to continue to monitor rose seedlings in commercial nurseries to eliminate the virus source.
To our knowledge, among these rose viruses, ASGV is the only one recorded in Taiwan from pear (Pyrus pyrifolia var. Hengshen) [59]. This is the first finding of ASGV in Taiwan roses. In conclusion, this is the first report of viruses infecting roses in Taiwan, including ApMV, PNRSV, RIV-2, RoPV, RoCV-1, ASGV and RSDaV, of which RIV-2 is a newly identified species of the genus Ilarvirus. The synergy between these viruses was observed in co-infections of RIV-2 with ApMV, ASGV, RoPV and RSDaV, causing severe damage to roses in Chiayi. The rose varieties cultivated in Taiwan are mainly imported from abroad, such as the Netherlands, the USA and Japan, and there is a risk of invasion by foreign pathogenic microorganisms and pests. Although the HTS technology has been a powerful diagnostic tool, the development of detection techniques, such as RT-PCR and ELISA, is also critical for virus inspection. The RT-PCR methods developed in this study can be adapted to detect rose viruses in samples from nurseries, fields and imported materials. Nepoviruses such as ArMV and SLRSV, which are commonly associated with RMD, were not detected in our HTS analysis. These viruses also need to be tested in the future."
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3)
This a recent (copyright Dec 20, 2021) Utah state extension service paper that mentions aphids.
https://extension.usu.edu/planthealth/ipm/ornamental-pest-guide/diseases/rose-mosaic
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and 4)
An encyclopedia of plant virus has been published:
https://www.worldcat.org/title/encyclopedia-of-plant-viruses-and-viroids/oclc/1134076625
This is what it states about PNRSV and roses (pages 2094 and 2095):
"Prunus necrotic ringspot virus (PNRSV)
Taxonomic position
Genus: Ilarvirus Family: Bromoviridae
PNRSV occurs worldwide, in the majority of the Rosa spp. growing areas (Curtis and Moran 1986; Wong et al. 1988; Moury et al. 2001; Sala-Rejczak and Paduch-Cichal 2005; Rakhshandehroo et al. 2006; Yardimci and Culal 2009; Milleza et al. 2013; He et al. 2015; Mitrofanova et al. 2018). The virus infected rose plants show symptoms such as chlorotic and necrotic ringspots on leaves, leaf mottling, color breaking of petals, and bud failure (Fulton 1976; Moran et al. 1988; Abdel-Salam et al. 2008). Vein-banding may occur from PNRSV infections after prolonged periods of temperature above 21 C.
Roses infected with some strains of PNRSV also showed symptoms of necrotic streaks on the stem, and flowers remained undeveloped and malformed (Moury et al. 2001). When PNRSV was present with other viruses such as ArMV and RSDaV, an oak-leaf pattern was often observed on the leaves (Milleza et al. 2013). The virus is transmitted by thrips vectors, the virus present in/on pollen, entering the host through injuries caused by thrips while feeding. The virus is transmissible mechanically and has a very wide host range infecting species in 21 dicotyledonous families. The virus is also transmissible by root grafting and by seed (Abdel-Salam et al. 2008; Golino et al. 2011). This virus spreads primarily by using virus-infected buds, scions, or rootstocks (Casper 1973; Barbara 1981). For more details of PNRSV, refer to Prunus persica."
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My other rose virus sites can be reached from the following index page: