A tobamovirus has been identified as being involved in a devastating disease of trailing petunia. Results from indicator plants and ELISA suggested that the tobamovirus was a strain of Tobacco mosaic virus (TMV). This was confirmed from the full sequence of the coat protein gene and a partial sequence of the replicase gene. Sequence analysis revealed that TMV isolated from diseased petunia had high identity (ca. 98–99) with TMV vulgare type sequences reported from Korea and Japan. Mechanical inoculation of 23 varieties, representing 21 species of pot and bedding plants with the petunia isolate of TMV confirmed that 11 were infected by the petunia isolate of TMV, although several species remained symptomless after three weeks. This highlights a clear risk to a number of commercially important pot and bedding plant species from TMV infected trailing petunias.