First report of Spiranthes mosaic virus 3 in the United Kingdom
The NPPO of the United Kingdom recently informed the EPPO Secretariat of the first outbreak of Spiranthes mosaic virus 3 (Potyvirus, SpMV3) detected in Phlox paniculata on its territory. So far, this virus was only reported from the USA where it has been found infecting both Phlox spp. (Polemoniaceae) and Spiranthes cernua (Orchidaceae). As SpMV3 is a potyvirus, it is presumed to be transmitted by aphids (but this has not been demonstrated).
In April 2013, several Phlox paniculata plants (approximately 24) showing unusual symptoms were observed at a garden centre in Basingstoke (Hampshire). Affected plants showed leaf mottling and the lower epidermis was delaminated from the leaf. These plants had been vegetatively propagated from mother plants at a UK nursery. Mother plants are thought to have been obtained 4 years ago from the Netherlands. However, it seems unlikely that the virus would have remained latent within the mother plants at the propagator nursery without symptoms for such long period. Therefore other sources of virus infection are being considered. All symptomatic plants have been destroyed and other lots at the same premises have been treated with insecticides to kill any potential aphid vectors. These plants will be monitored for disease symptoms. Individual samples will be collected from both first and second generation mother plants being maintained by the propagating nursery and will be tested for the presence of the virus. Investigations will be carried out to trace any other Phlox plants that may have been sent by the propagating nursery to other garden centres to ensure they are disease free.
The pest status of Spiranthes mosaic virus 3 in the United Kingdom is officially declared as: Present, under eradication.
Sources
NPPO of the United Kingdom (2013-05).
Guaragna MA, Ndum O, Jordan R (2006) Detection and characterization of two previously undescribed potyviruses in the terrestrial orchid Spiranthes cernua. Acta Horticulturae no. 722, 209-217.
Hammond J, Reinsel M (2011) Mixed infections and novel viruses in various species of Phlox. Acta Horticulturae no. 901, 119-126 (abst.).