What are the methods for controlling viral diseases in orchids?

For the foreseeable future, viral diseases will remain a stubborn and difficult problem for orchid growers. The difficulty lies first in the value of orchids. Whether in batches or as individual plants, ornamental orchids are perhaps the most expensive artificially cultivated plants. Potted flowering orchids retail for about 5 to more than 100 US dollars per pot. Certain strains of Cymbidium, Paphiopedilum and Vanda are worth more than several thousand US dollars. In addition, some orchids are rare varieties and are therefore especially precious; such orchids are generally not traded commercially. Even if such orchids become infected with a virus, they will be kept in the orchid nursery, as no orchid grower would be willing to discard them. Second, many orchid growers do not quite agree with the strict quarantine measures imposed on imported and exported orchids, believing that these measures hinder international exchange of orchid resources. Third, monopodial orchids such as  Af8lldl and Vanda are the most important varieties in cut-flower production in Southeast Asia, and they are difficult to propagate in vitro, which limits the application of tissue culture for producing large numbers of virus-free plantlets.

    For less showy orchids such as Vanilla and endangered varieties kept in germplasm nurseries, eradicating their viral diseases may be even more difficult. In fact, although more attention has recently been given to the conservation of germplasm of wild orchids and other orchids, growers have still made little or no due effort to protect them from viral infection during cultivation.

    The control of viral diseases in orchids depends mainly on prevention. Orchid growers should purchase guaranteed, virus-tested orchid plantlets, and at the same time use various detection techniques to inspect orchids plant by plant, taking all necessary measures to prevent healthy plants from becoming infected with viruses. If the above measures can be carried out, even if viral diseases cannot be completely eliminated, the vast majority of orchid growers can successfully prevent viral diseases from infecting their orchid nurseries.