Virus Testing

[Roberta]

Pragmatic, sensible approach.

[isurus79]

There's a lot to address here and I have to admit, I disagree with most of it.

Originally Posted by estación seca

I have read the majority of commercial outdoor landscape plant cultivars, and most house plants, are virused. They don't show symptoms. Most landscape and house plants are propagated via meristem or cuttings, with some of annual and perennial herbaceous plants propagated by seed. Mericloning and cuttings/bud grafting are much faster for bringing herbaceous and woody plants, respectively, to market.

I can't verify this since there is no citation or link indicating that the majority of landscape and houseplants are virused, but different viruses will affect different plants groups differently so the comparison doesn't seem useful.

Originally Posted by estación seca

Autopsy studies have shown almost all humans have herpes virus permanently in nerve cell bodies in our trigeminal nerve ganglions inside our skulls. That virus is what causes cold sores on the face. If the virus is in nerve cell bodies that innervate the eye, severe corneal damage can occur from cold sores on the eye. On rare occasion herpesvirus can infect the brain, causing severe permanent brain damage or death. Further studies have shown people usually acquire the virus in childhood, probably from kissing adults who are shedding virus though not having cold sores. Many people never get cold sores even though they have the virus in their ganglia. Should we test everybody? Then what?

This is an odd comparison and even further removed from the topic than the previous paragraph. Also odd that you pointed out the relatively benign cold sore virus in humans but overlooked the more invasive genital herpes!

Originally Posted by estación seca

With proper plant husbandry virus won't be transmitted by the gardener. But bugs can transmit virus when biting a virused plant, then biting a non-virused plant. It is possible to build and maintain bug-proof greenhouses, but it is very expensive. The ongoing rituals needed to prevent introducing bugs are cumbersome.

Exactly. Seems like eliminating viruses from the collection is cheaper than eliminating bugs.

Originally Posted by estación seca

Commercial tobacco products all contain tobacco mosaic virus. Tobacco mosaic virus can infect orchids. The virus is not reliably neutralized by hand washing. It has been shown people who handle cigarettes can easily transmit this virus to plants they touch. It is likely orchid keepers who smoke have infected most or all of their collection with this virus. Now what?

Quit smoking (luckily I never started) and toss the plants. No need to keep any type of mosaic virus around the greenhouse to infect other orchids and other garden plants.

Originally Posted by estación seca

I'm troubled at the thought of completely losing beautiful old clones of plants that are virused but without symptoms. These plants may be used as pollen parents without transmitting the virus. I have read some commercial growers keep a separate greenhouse for valuable old breeding clones that are virused.

I mention this in the video. For folks with a bunch of money, they certainly can keep a separate greenhouse full of heirloom plants! However, most folks aren't keeping heirloom varieties and most folks don't have the funds for a separate greenhouse.

Originally Posted by estación seca

Does it really make sense for a hobbyist to spend a lot of money on virus tests, then discard valuable plants that show no signs of illness?

Yes it does. Especially if that hobbyist plans to sell/trade divisions with other people. Why not do what you can to prevent the spread of viruses that can and do have a visible impact on some orchids but not others?

Originally Posted by estación seca

In theory viruses in orchids might be eliminated if all orchid growers in the world were to test every plant, over a relatively short period of time, then burn infected plants. This would be immensely expensive and will never happen.

Experience with other infections diseases shows testing and elimination will never work. Not even trying to destroy every orchid in cultivation would work. The same viruses that infect our orchids infect many other plants, and they will return.

This is called the slippery slope logical fallacy. I suspect that if growers had access to test strips 100 years ago and were diligent about testing their plants, the old heirloom plants would have a lower rate of virus infection. Testing now could have a beneficial effects to the varieties being created today so they aren't infected during the next 100 years.

Originally Posted by estación seca

The isolate and burn approach was tried in the Miami area in the early 2000s to eliminate the newly introduced citrus greening disease. Officials broke into people's gardens and pulled out all citrus trees, symptomatic or not. They went as far as killing one homeowner who tried to prevent the trespass. There was no effect on the spread of the disease, which now is in every citrus producing State in the US.

Not particularly relevant here since the viruses in question are endemic to the orchid population and aren't something new and novel. Also, no one is calling for breaking into people's collections to cull plants!!

Originally Posted by estación seca

If commercial growers took effective steps to eliminate completely virus for which testing exists from their stock, and prevent virus from being reintroduced, the price of our hobby would skyrocket, and nobody would be able to afford orchids. The hobby would disappear.

Wait, what?? Another slippery slope logical fallacy. Reputable commercial growers do take effective steps to eliminate viruses from the plants they sell and the hobby is still very much alive!

Originally Posted by estación seca

We can only test for a few viruses. It is likely there are many other orchid viruses infecting plants with no signs of disease. This is the situation in other organisms. Every time a new test were introduced growers would have to go through the very expensive process of culling healthy but virused plants again.

We test for two viruses because they account for the overwhelming majority of infections (that we know of) in our plants. And yes, as we gain more knowledge, we'll likely have to take steps to reduce/eliminate various plant pathogens as they arise. This is a tale as old as cultivation that will continue as long as humans grow plants.

Originally Posted by estación seca

I think for the vast majority of hobbyists, testing and destroying virused but otherwise healthy plants isn't necessary. A systematic effort to remove viruses from orchid collections would be impossible. The attempt would inevitably lead to nobody growing orchids.

Another slippery slope. Average hobbyists removing and/or destroying virused plants won't kill the hobby. People do it every day!

[estación seca]

Both herpesviruses are highly transmissible and highly invasive. The kind that occurs in the trigeminal ganglion blinds, causes brain damage in and kills far more people than the kind that occurs in the sacroiliac ganglia. People aren't afraid of cold viruses because these problems occur rarely. It's actually a very good analogy for orchid viruses.

that we know of

There it is. If you can't tell something is diseased without a test, you don't worry about it until you do the test. Is it really diseased?

[isurus79]

Originally Posted by estación seca

If you can't tell something is diseased without a test, you don't worry about it until you do the test. Is it really diseased?

Yes it most certainly is diseased. Even if it doesn't show symptoms, the virus can be passed along to another plant that will show symptoms.

[AnonYMouse]

Originally Posted by isurus79

I mention this in the video. For folks with a bunch of money, they certainly can keep a separate greenhouse full of heirloom plants! However, most folks aren't keeping heirloom varieties and most folks don't have the funds for a separate greenhouse.

So those of us without funds should not keep heirloom plants. Got it.

Originally Posted by isurus79

Another slippery slope. Average hobbyists removing and/or destroying virused plants won't kill the hobby. People do it every day!

It would kill the hobby for this hobbyist.

Byeeee!

[katsucats]

The two viruses that we test for are economically important, almost certainly causes demise, is highly infectious and untreatable, has shown to be able to survive in air exposed biological matter for decades, survives boiling and hot composting, and causes billions in economic damage.

It's very disingenuous to choose herpes as a way to minimize its effect, but then say that it technically kills. If herpes does in fact kill a large portion of its victims like polio, untreated typhoid or ebola, then yes absolutely everyone would test for it. It would only be responsible policy to shut down social gatherings and recommend treatments and isolation. Human lives are of course more valuable than plant lives. Covid wasn't transmissible by bug bites, incurable and capable of existing in external reservoirs in the soil for decades. If it was, you can bet every country would have taken a hardline quarantine stance like China did. Then, only the most hardcore libertarian would even think to argue about its practicality.

[katsucats]

Originally Posted by isurus79

Yikes! I hope my favorite vendors aren't on that list!

I've seen some of your YouTube videos. It seems you're a huge Catasetum fan as I am. Here's a little interesting story for what it's worth.

I bought a Clowesia dodsoniana once on eBay, from... (I forgot his name) we'll call him Bill, from NY. I asked him where the plant was sourced, he said wild collected, then we started a little conversation about his collection that he was planning to sell divisions of, and where to source some Catasetum species. The dodsoniana wasn't virused, thankfully, but I told him I was skeptical of buying it due to another vendor where dodsoniana's are sold, so his response of it being "wild collected" assuaged my fears.

So I relayed to him an experience I had with a well known Catasetum vendor where every Catasetum that I got from them except one (out of like 5) were virused. Hint: It's not SVO. To be fair, the vendor promptly refunded me after testing his own parent stock and confirmed the viruses, but that doesn't inspire much confidence for the rest of his plants. So Bill tells me, surely enough, he had also bought numerous plants from said vendor, and that he'd test some of those plants later on.

Two days later, I get a message on eBay, and Bill tells me his plans have changed, since he couldn't in good conscience sell virused divisions. So yep, the plants he had tested from said vendor were also virused.

I'm not going to go as far to say that there are some systemic issues going on, but statistically speaking, there probably is. In any case, buyer beware.

[isurus79]

Originally Posted by katsucats

I've seen some of your YouTube videos. It seems you're a huge Catasetum fan as I am. Here's a little interesting story for what it's worth.

I bought a Clowesia dodsoniana once on eBay, from... (I forgot his name) we'll call him Bill, from NY. I asked him where the plant was sourced, he said wild collected, then we started a little conversation about his collection that he was planning to sell divisions of, and where to source some Catasetum species.

Then, I relayed to him an experience I had with a well known Catasetum vendor where every Catasetum that I got from them except one (out of like 5) were virused. Hint: It's not SVO. To be fair, the vendor promptly refunded me after testing his own parent stock and confirmed the viruses, but that doesn't inspire much confidence for the rest of his plants. So Bill tells me, surely enough, he had also bought numerous plants from said vendor, and that he'd test some of those plants later on.

Two days later, I get a message on eBay, and Bill tells me his plans have changed, since he couldn't in good conscience sell virused divisions. So yep, the plants he had tested from said vendor were also virused.

I'm not going to go as far to say that there are some systemic issues going on, but statistically speaking, there probably is. In any case, buyer beware.

I plan to test my plants from the vendor you bought from that had the virused Catasetums when they start growing again. I really fear for my Cyrtopodiums, which I’ve purchased from that same vendor more frequently than the Catasetums.