Occurrence of Alfalfa Mosaic, Hydrangea Ringspot, and Tobacco Ringspot Viruses in Hydrangea spp. in British Columbia. Arthur W. Chiko, Agriculture Canada, Saanichton Research and Plant Quarantine Station, 8801 East Saanich Road, Sidney, BC, Canada V8L 1H3. Sharon E. Godkin, Agriculture Canada, Saanichton Research and Plant Quarantine Station, 8801 East Saanich Road, Sidney, BC, Canada V8L 1H3. Plant Dis. 70:541-544. Accepted for publication 12 November 1985. Copyright 1986 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-70-541.

A survey for manually transmissible viruses in commercial stocks of Hydrangea spp. was conducted in British Columbia in 1983. Of 73 stocks of various cultivars of H. macrophylla sampled, alfalfa mosaic virus (AMV), hydrangea ringspot virus (HRSV), or both viruses were detected in 5, 18, and 10 stocks, respectively. HRSV occurred in two of two sampled stocks of H. serrata ‘Bluebird,’ and tobacco ringspot virus (TobRSV) was found in two of 23 sampled stocks of H. paniculata ‘Grandiflora.’ Evidence suggested that each of these viruses occurred universally in some stocks. No viruses were detected in four other species of hydrangea sampled. This is the first report of virus infection in H. serrata and H. paniculata and the first definitive report of AMV and TobRSV infecting Hydrangea spp. Adopting simple control measures might markedly improve the quality of some stocks, especially those partially infected with both AMV and HRSV.