Epidemiology of three viruses infecting the rose in the United Kingdom

Abstract

SUMMARYStudies on the epidemiology of arabis mosaic (AMV), prunus necrotic ringspot (PNRSV) and strawberry latent ringspot (SLRV) viruses were made in relation to commercial production of standard and bush roses. AMV or SLRV apparently induced either symptomless infection in rose cultivars and Rosa spp., or leaf symptoms ranging from small chlorotic flecks to severe chlorotic mosaic and, occasionally, plant death. Infection of R. canina ‘inermis’ or R. corymbifera by an isolate of SLRV from R. corymbifera also severely depressed flowering and hip formation. In addition, whereas this isolate could be graft‐transmitted to all Rosa spp. tested, isolates from R. rugosa and R. multiflora failed to be graft‐transmitted to R. canina ‘inermis’ or R. corymbifera. No difference was detected in graft‐transmission tests of Rosa spp. with several isolates of AMV or PNRSV.In plantings of up to 7 yr none of the viruses was transmitted through pollen to healthy roses grown in nematode‐free soil, and only SLRV was readily seed‐transmitted, particularly in R. rugosa. Nevertheless, in soil containing viruliferous nematodes, AMV and/or SLRV were transmitted to c. 80% of healthy plants.AMV and particularly SLRV were each damaging to field‐grown maiden rose bushes cv. Fragrant Cloud. SLRV delayed the onset of flowering, and reduced the number and size of blooms. Diseased bushes were less vigorous, and half or none of the AMV‐ or SLRV‐ infected bushes respectively, conformed to the British Standards Institution specifications for maiden bush roses.These results are discussed in relation to the commercial production of field‐grown roses in the UK.