Opinions on viruses - Orchid Board

Nlamr · #1 09-01-2020, 03:39 PM

In this I am looking more for opinions from more experienced growers than advice as I have seen many varied discussions elsewhere.... Every once in a while I question myself, should I be worried about viruses? Should I test just a select few, or should I go through the great expense of testing them all? Can a virused orchid live a long happy life and just be a carrier? I'm just a hobbyist, my orchids aren't going anywhere, I don't share water (except the vandas) and I sterilize tools and surfaces as best I can, so is it really worth worrying about? What are your thoughts or experiences?

Clawhammer · #2 09-01-2020, 03:45 PM

Quote:

Originally Posted by Nlamr

In this I am looking more for opinions from more experienced growers than advice as I have seen many varied discussions elsewhere.... Every once in a while I question myself, should I be worried about viruses? Should I test just a select few, or should I go through the great expense of testing them all? Can a virused orchid live a long happy life and just be a carrier? I'm just a hobbyist, my orchids aren't going anywhere, I don't share water (except the vandas) and I sterilize tools and surfaces as best I can, so is it really worth worrying about? What are your thoughts or experiences?

I think if you have sterile procedures to minimize transfer, including a pest (vector) prevention regimen, it is not worth worrying about as spread is unlikely.

I had to trash about 20 phals due to Phal chlorotic spot virus. I spread them among each other when repotting and not sanitizing the equipment. Since I have implemented sanitary procedures there have been no new infections (6 months).

rbarata · #3 09-01-2020, 03:47 PM

Why would you worry about viruses? Any symptoms?

I think most plants, especially those growing outdoors, are prone to get viruses but I really don't care. All my Cymbs have it (it was strange if they don't have it) but I take care not to bring any other plants near them when there's water involved.

Nlamr · #4 09-01-2020, 04:01 PM

Just a thought that pops into my head every now and then.... As an example I just repotted a Dendrobium (Phalaenopsis type) that I got back in June, and when I first recieved it it looked a bit iffy, but now while it still has those iffy marks on the old leaves, the new growth looks beautiful and has grown over 7 inches in the last couple of months, so yeah, chances are no it's probably totally fine, or if it is virused should I really be concerned considering how well it is growing? Kind of what led me to posting. There is so many varried opinions on viruses, and so many things that could look like a virus but isn't, was just curious how others handle it, especially in a situation where there may be thousands of orchids involved (no I don't have thousands, yet hehe).

rbarata · #5 09-01-2020, 04:12 PM

I believe you are doing what is possible to avoid, at least, the spread to other plants. That's standard procedure. So, why worry?

Roberta · #6 09-01-2020, 04:59 PM

There are some orchids that are "carriers".... test positive, but show no other signs. With those, knowledge is power. I have a few of those, just keep them away from the general population. I'll test if a plant isn't thriving, to decide whether to try to revive it or toss. (A note, I have had some Cyms with really ugly leaves that were negative... I have found a few that turned out to be virused but most of the Cyms that I have tested were clean...) I agree, mostly follow good hygiene practices so that if it's present you don't spread it and you'll be OK.

katsucats · #7 09-15-2020, 07:36 PM

I'll present a dissenting opinion. About 8% of the orchids I've bought over the past year were virused. About half of these had some mildly suspicious symptoms that made me want to test them right away. The other half -- no symptoms. All were from "reputable" nurseries and all would have been infectious. Most of the vendors offered a refund minus the shipping if I ship the plants back. They say they wouldn't resell it, but we know they're not going to just collect dust on the bench, let's be honest.

I bought two Dendrobiums from one eBay seller with about 200 sales and one negative rating ever (besides mine now). Both of them were a good size, had blemish-free leaves, and looked healthy overall. Both of them were positive for CymMV. That means there are 198 people out there that gave this guy positive feedback (the latest saying "gorgeous healthy plant") have a high chance of virus in their collection.

I bought one variegated species from a vendor that's highly respected by the members of this board. It had CymMV, and the vendor offered that he usually gives replacements, but couldn't because the whole grex had sold out. Again, the plant was a bit spindly but had no clear symptom.

I bought one species after following a thread from this board. Someone else was looking for an Oncidium sotoanum, so someone found a source for it. I bought it from the same source, and it tested positive for ORSV. That means the guy who bought it before me in that thread has a high chance of having ORSV in his collection.

And I understand that just because I bought a virused plant doesn't mean that every other plant in the same grex must be virused. There's just an increased chance, but the vast majority of people don't test without obvious symptoms, so they will never know. I have a relatively small collection and I only buy species for the most part, so just imagine the huge collections of mericlones and divisions that some might have. Most people only suspect virus when there are obvious symptoms. Most orchids that are virused in my experience don't have obvious symptoms or symptoms at all. I'm willing to bet most people have no idea what their virus rate is, no matter how experienced they are.

How many people never have a spider mite breakout, never splash water, and keep every one of their plants several feet apart? That's about as reasonable as keeping 6 feet apart, social distancing at a supermarket. Even the most meticulous must slip up here and there.

You don't have to test every plant at once. You could do a statistical test by randomly picking 25 orchids to test. There's always the chance that you got lucky or unlucky, having picked more than or less than the true average of virused plants in your collection. But if you only find 1-2, maybe you're willing to take that risk. More than that, you might want further testing. I suggest an annual statistical test gives you a good idea. Too expensive? Quit that AOS membership. When I buy orchids, I mentally factor in $10 for 2 tests per each plant. At $20-40 per orchid, $10 more stings the wallet but isn't disproportionate. If you only buy $5 orchids from the discount rack however, you can forget about this whole notion. But in my opinion for most people on this site, it's not really that expensive, considering the peace of mind that it offers.

MJG · #8 09-15-2020, 08:54 PM

I'll present a second dissenting opinion. My feelings about virused orchid are much the same as katsucats.

You ask about experiences with viruses. I do not have a huge collection of orchids (60 or so). Years ago I started testing each orchid that I acquired as it came in the door. I had one orchid that tested positive early on. I decided to keep it because it was sentimental -- a gift from my daughter. But I knew it was virused and decided I'd be careful not to expose my other orchids. It never exhibited any symptoms of virus, just a positive test.

A few years later a previously healthy and tested orchid started to go downhill badly. It exhibited some virus symptoms. I tested it, and it tested positive with the same virus as my daughter's gift plant. I had obviously transmitted the virus.

Meanwhile over those years, the gift plant had stopped growing and flowering. I threw them both out. The virus didn't go raging through my whole collection, but it was a wakeup call.

The other thing I'll mention is that for years almost all of the orchids I bought were virus-free. Lately it's been just the opposite. This spring alone I've bought 8 orchids that have tested positive. These were from 4 different merchants. In every case I've gotten rid of the orchids and gotten refunds or a replacement (with me paying the shipping). Warning -- some merchants are cooperative and professional and some are pirates. Anyway, I am not sure why I'm seeing so much more virus lately, but recent events make me very glad that I am testing everything. I cringe when I think that I could have added 8 virused orchids to my collection this spring.

There are lots of nasty orchid pests and ailments that everyone encounters. For me, the difference with viruses is that they are not curable. And at some point if you allow enough virused orchids into your collection in my experience they will spread.

Ray · #9 09-15-2020, 07:54 PM

OK. Let me offer a different perspective.

I've been growing orchids for over 45 years. I have never tested for viruses.

I'm certain some of the plants I had were virused. In fact, I think every plant ever grown carries everything it has been exposed to, but if the culture is good, the plant does not succumb to the infections - JUST LIKE PEOPLE. I have never had a broad breakout among my plants because I 1) keep them healthy and 2) try to avoid any cross-contamination.

I have had customers who were fairly sloppy about their culture - misting and dripping, splashing water, trying to grow to many plants with dissimilar demands together, and so on. They lost their entire collections to viruses.

Grow your plants well and they will not likely succumb.

When I was reselling plants, I got a bunch of plants from a supplier in Hawaii. A customer bought one and had it tested - positive. I refunded her money and mine was refunded from the seller. They continued selling them; I no longer was a customer.

Roberta · #10 09-15-2020, 08:01 PM

katsukats -
You may want to communicate with Kay Klausing. He has given some very interesting talks at several societies.(You can find synopses in various newsletters from a Google search) He has done systematic and scientifically rigorous work on the topic. PM me if you want his email address. (The presentations aren't online, he may be willing to share some of his data and conclusions, I don't know if he has published.)