How many orchids have viruses?

[Davey]

Is there a ratio to tell how many orchid plants are infected with viruses? Has anybody ever reported a windowsill full of orchids that all had a virus?

I am just fascinated with viruses.

[Ray]

I have heard that all phalaenopsis have viruses, but have no idea how one would know that.

I do suppose that it is possible that all orchids are virused to some degree. Just because they do not show symptoms, does not mean that they are not infected.

As an analogy, you and I are probably carrying every disease to which we have ever been exposed, but we do not succumb to them until something weakens our immune systems. A plant given excellent culture probably won't show symptoms. Let it get stressed somehow, and it will.

There is scientific evidence that the virus load in an infected plant can go up and down over a wide and variable range, so it seems plausible that at the low end a test might show "no" virus, when it is actually present.

[Andrew]

There is also a tendancy to focus on the major orchid viruses and ignore the impact of those viruses we don't routinely test for; Rumsfeld's known unknowns and unknown unknowns, so to speak.

[Shirley]

Is it only my opinion or does it seem that Paphs are resistant to virus? My only negative experiences have been with Phals and Cattleyas.

[Ray]

From PAPHIOPEDILUM: Frequently Asked Questions (FAQ) at ladyslipper.com

Is it true that orchid viruses do not infect Paphs?


This is a common misconception. Paphs are capable of hosting virus infections. In the past we have isolated ORSV (Odontoglossum Ringspot Virus), CyMV (Cymbidium Mosaic Virus) and BYMV (Bean Yellow Mosaic Virus) from different clones, and there are other reports in the literature. What is true is that infection rates tend to be low, probably because Paphs are rarely divided by cutting with a sharp instrument, but are simply broken apart, or allowed to fall apart on their own. The only symptoms we have seen occasionally in those Paphs that were positive was a general unthriftiness in the plants that were infected with BYMV. Rates of virus infection in Phrags tend to be a bit higher than in Paphs, but still lower than with other commonly cultivated orchids. The most likely to be infected are the clones that have been around for a very long time and in mixed orchid collections, resulting in an increased chance of being exposed, again usually via cutting tools.

[Davey]

Awesome replies! It is just amazing how we have viruses and plants have viruses, and we have no cure for any of them. It seems to that, if viruses are living things, they are highly evolutionized.

[Shirley]

Thanks, Ray, for that clarifying information. Very helpful.