Question about virus
 

This may seem like a very stupid question, but ask it I must. I was doing some virus testing and after finding a couple that tested positive, I have decided to test my whole collection. ( yea, right, at $6 a pop and 100 plants) My question is , I have one that the line just barely showed up meaning low titer, would you keep that plant if it was one you could not easily replace, keeping it separate from the others, or would you toss it anyway ?

Before pitching any orchids of which you are fond that may be difficult to replace, you may want to have them tested by a lab just to be certain. Critter Creek? I read somewhere that you should test everything at least twice as there are sometimes false positives or, if there is not enough of the virus present, false negatives.

I would keep the orchid in an isolated place and observe it. If it doesn't grow well, is slow to put out new growth, has weak new growth, has color break in the flowers or doesn't bloom when you expect it to bloom, this will prove that it is virused. A few years ago, I spoke with a professor who had spent his life collecting and growing all types of plants, including orchids and I asked him about viruses. He said that what he always noticed with virused plants was the lack of vigor. Even when the orchid/plant showed no other signs, it just didn't grow as well as it once did or as it should have been growing. When he would test it...virus.

Twice, I have found virused orchids. Both times, thankfully, I had reason to isolate them before they could infect anything else. One was an OS freebie, the other was healthy until I took it to an OS meeting and someone set a very nasty looking orchid against mine. The first, the freebie, didn't put out new growths when I expected and soon showed mosaic and ring patterns in the leaves...just like the pictures. The second had color break with the new flowers, delayed putting out the new growth until late in the summer...then the leaves began to get those tell-tale markings. Both were pitched, pot, medium and all.

I find that by only purchasing orchids from vendors with very high ratings, it very much improves the odds that the orchids will be healthy. Of course, someone who has used tobacco products could walk through a greenhouse, touch plants and infect them with virus but a vendor cannot prevent that.

Ideally, isolate it and re-test in a few months. False positives are always a possibility no matter how careful you are.

I think my first question to you would be why did you test them? Are there suspicious blemishes? Poor growth? Deformed/malformed/flowers? Color-break in the flowers?

I go w/the assumption that I likely have virus in the collection somewhere so I act accordingly and follow strict hygiene protocol. I've read enough articles that all say unless you are testing the minute a plant arrives and you have tested negative...it's best to assume you do have virus somewhere in the collection. So, with that in mind...I only test plants that do one of the above things and have created suspicion in my mind. Of all the plants that I've tested, only a few have ever tested positive.

The ones that tested positive were destroyed. And I would do the same thing w/any plant that tests positive if it's not growing well, bad flowers, or bad foliage. Even if it's rare.

I've never had a rare plant test positive so I don't know for sure how I respond but I suspect I would still destroy it...mainly because there must be something going on that prompted me to test it. If it's not growing well or the flowers are bad then, in my mind, there is no reason to keep it. What's the point in keeping a rare plant if it's ugly? Well, that's the way I look at it.

So...that was the long way of getting to...why did you test it? If it's got a flower problem or growing badly then I wouldn't want it any way. I figure there is no sense in taking up valuable space w/something doesn't look good and that could potentially infect other plants? If it's easily replaced then I would want to use the $6 toward a healthy new plant and save the tests for the next suspicious one.

That's just my opinion and if you talk to others you will likely get a variety of different opinions on the subject. In the end, you do what you're comfortable doing but if you opt to show the plant at a show or meeting then you really should let people know it's tested positive. Some folks are hyper-paranoid about virus and they won't want to even have their plants in the same room. Plus, even though transmission is highly unlikely in those settings...there is still a small chance and you wouldn't want to be responsible for that w/out having informed the others of the situation.

That is some of the wisest advice I've ever seen on an orchid forum.

I am of the opinion that any virus a plant has ever been exposed to resides within it forever - just as is the case with people. As long as your culture is good, and the plant is not unduly stressed, that virus may not gain a stronghold and be a problem. If you see the symptoms Kat mentioned, by all means take action.

If you do prove that an orchid has a virus, unless it is something very, very valuable and there is a desire that it be used in hybridizing, there is no reason to keep it. It will eventually die anyway unless you give it the absolute best care (Really great care can mask symptoms and help halt the decline. Stress can bring out the symptoms more quickly). Still, even with the best care, the orchid will never be what it could have been without the virus.

Strict hygiene is the way to go. If you ever watch any of those videos where people just wipe their cutting tools with alcohol or watering all their plants in the same bath, you know they are spreading viruses.

---------- Post added at 01:04 PM ---------- Previous post was at 11:28 AM ----------

Speaking of viruses, I wonder if this plant on Ebay for $75 plus shipping looks virused to everyone.

Laelia Anceps Lineata Orchid Plant Selected Lineata Type Cattleya | eBay

It looks VERY suspiciously like virus to me. No wonder he doesn't accept returns....
If I had an orchid like that and could possibly have a logical explanation for the color break that wasn't virus, I would still put that (and anything that might have been near it) in quarantine (color break in a Cattleya...not something one risks). If there was no other explanation, I would immediately toss it and then put anything that had been near it in quarantine...then watch the rest of my collection.

I had a lot of Datura wrightii growing all over my property. This is a magnificent Sonoran desert native angel's trumpet or jimson weed. It is in the nightshade family, along with tobacco, potato, tomato, petunia and eggplant/aubergine. All these are susceptible to tobacco mosaic virus. All tobacco products sold for smoking or chewing are infested with this virus, and the virus is viable in the open for years to decades.

A lot of my neighbors walk through the neighborhood daily. Somebody began throwing cigarette butts in my yard. I still haven't figured out who is doing this. Soon all my Datura showed the yellow mosaic pattern of virus infestation. I had to tear them all out. The virus can be passed through seed. I kept some seed and will try again later, but with the persistence of the virus in the environment, I probably won't be able to grow this plant again.

That's what I thought....

That is so sad :(

I am sorry to hear about what happened. :(
At least you know that they are an indicator plant and show signs of the virus readily.

I know viruses related to tobacco mosaic virus (TMV) can infect orchids, but I don't know whether the TMV itself does. I have heard that people shouldn't smoke around their orchids, but the TMV is so long-lasting and difficult to inactivate that it probably isn't possible to eradicate from the hands of smokers until the skin layers flake off. Since the smokers or chewers are constantly contaminating their hands with new product, they will always have TMV on their hands.

Re - the ebay plant -----

If that were on a leaf, I'd say it's leaf miner damage.

Admittedly, I am by no means an expert on color break but that doesn't really look like what I'm used to seeing in color break on flowers. There is a natural striation pattern in the flowers and that could be confusing the image to some extent. Strange, for sure, but I'm not sure I would rush to color break.

FWIW, I've had trouble due to low humidity w/some anceps buds when they are developing and it results in some very odd markings on flowers.

If I were interested in the plant, I would ask the seller if it's ever been tested. The leaves look clean (possible even if it is virused) but mostly the fact that the other flower shows none of the issues...leads me to believe that there is a strong possibility that it's not diseased.

Thank you all for your answers. As to the plant in question, it looks quite good. As I said in my original post, I had a couple of positive tests in my collection, which I did toss. The leaves all look fine except for one that has very faint yellowish spots just coming on it. It has some fairly new leaves that are wrinkled, probably from a water or humidity issue. I will take all of your suggestions in mind as I make my final decision.

The light patches on the sepals in the first picture could be from many kinds of physical damage, and the second flower doesn't have any of it. Doesn't necessarily look like virus to me.

As for the streaks in the petals, that is the distinctive feature of L. anceps var. lineata and looks appropriate for the type.

The light/white areas concerned me too but if you look closely at the other bloom it looks like it has some whitish areas there too. (although it isn't as clear as the other picture).

An orchid with virus generally does grow poorly - but not always. Classic example is C. Porcia 'Cannizaro' The original FCC/AOS plant had virus, and it was passed along to all of its mericloned progeny - for decades. It is very vigorous, produces copious heads of flowers every year (for me, and everybody else that I know that has one). I am certainly not going to pitch it! However, knowledge is power. It lives out in the "back 40" well separated from other plants. (It lives outside quite happily) I don't take it to meetings (it is too big anyway) I certainly "handle with care" when I pot it. But it is a great example of "you never know for sure" and so need to follow all the good practices so that material from one plant is never transmitted to another.