Incidence of Cymbidium mosaic virus and Odontoglossum ringspot virus affecting Oncidium orchids in Hainan Island, China

Oncidium is the most popular cut flower for the orchid industry in Hainan Island and several viruses have been reported to negatively impact their growth and yield. A survey of Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) in Oncidium orchids cultivated in Hainan Island was conducted during 2009-2012 with indirect enzyme-linked immunosorbent assay (ELISA). A total of 171,585 samples from adult plant, tissue-culture flask, seedling, and medium seedling were tested for CymMV and ORSV. Of the 24,125 adult plant samples from eighteen commercial orchid farms, 77.58% were infected with CymMV, 16.04% with ORSV, and 10.19% with both CymMV and ORSV. Of the 67,080 samples cultivated in tissue-culture flasks from eight tissue culture laboratories, 41.18% were infected with CymMV, 6.11% with ORSV, and 4.46% with both CymMV and ORSV. Of the 54,450 seedling samples from eight seedling nurseries, 53.20% were infected with CymMV, 9.00% with ORSV, and 5.23% with both CymMV and ORSV. And of the other 25,930 medium seedling samples from twelve medium seedling nurseries, 44.96% were infected with CymMV, 7.90% with ORSV, and 5.15% with both CymMV and ORSV. Plant material must be tested for the presence of viruses before being used for mass production by tissue culture, and sanitation during propagation of orchid plants and harvesting of flowers is essential in order to prevent the virus from spreading. These findings emphasize the need to implement a virus-free certification programme that would greatly enhance the management of these two prevalent viruses in the Hainan orchid industry.