Viral Necrotic Spots in Vanda Flowers

Viral diseases in orchids are usually asymptomatic, meaning the plant may carry the virus but does not show any outward symptoms that it has the virus. It was stated by Dr. H. Kamemoto of University of Hawaii at Manoa, that orchid varieties fielded out fo

All that is needed to get the collection infected is to have one infected plant in the collection and the tools (e.g. knives, shears and cutters) used for grooming and propagation to transmit the virus/ es ad infinitum. The older the plant is in cultivation, the bigger the chances that it is infected.

A normal looking orchid may carry as much as 14 viruses and not show any symptom as the case of German study on Phalaenopsis. The danger is when the same virus is introduced to another plant that is susceptible to the virus and creates the damages like necrotic spots, discoloration, color breaks, foliar necrotic spots and render the flowers or plants unusable or unsaleable.

In 2016, one of the most devastating viruses showed up in Thailand. The flowers of vandaceous orchids started showing necrotic spots. This symptom used to be confined to Dendrobium potplants and is usually ignored because of the shear number of Dendrobium hybrids being milled out of Thailand.

On the slower growing vandaceous plants however, necrotic spots gives a very unsightly brown or black spots and the flowers do not last as long as it should. The flowers are not marketable.

There is no easy way of cleaning up the virus when the plants are infected. The most viable commercial way is to do meristem tissue culture. The main problem with the technique is that it is not easy to do. Heat treatment is still untested in orchids.

The best option when the symptoms show up in a collection is to burn or destroy the infected plants that show the symptoms.

The Vanda Necrotic Spots showed up recently in an orchid show in the Philippines. The danger is that it can infect other orchids that may be susceptible and will serve as the inoculum for devastation of the orchid industry in the future if growers are not careful.

Flowers of virus infected plants do not last as long as healthy plants.

Newly opened blooms may not show any symptoms but in just a matter of 3 days, the necrotic spots develop, making the flower very unsightly. The flowers wilt faster than normal.

Vanda Necrotic Spot – infected plants wilt earlier and are unsightly. The best thing to do is to destroy the plants.