V I R U S !!!!!! Run for your lives..........

[goodgollymissmolly]

Lots of things have been said here. Unfortunately, Camille's is the most head in the sand. I wouldn't have expected that actually.

To hang your hat on the fact that plant viruses don't spread through the air is pollyana at best. There are several completely ridiculous "ifs" in her statement. For example if your collection is insect free...exactly how does one guarantee that? There are many other ifs she ignored...like if you sanitize your hands between touching each plant, if you never have water splash or drip on an adjacent plant when watering, or never have foliage rub on adjacent plants in the breeze. Unfortunately her position is similar to someone saying you can prevent fires by eliminating ignition sources. You can minimize them but they are infinite and uncontrollable..like lightning, or unanticipated arcs in switches, or static discharges from clothes of different materials rubbing together. You can only totally prevent fire by having no flammable materials or mixtures. You can only prevent virus by not having any in your collection..anything less is minimization, not prevention.

Rowangreen suggests some orchid viruses might come from wild collections. There is an excellent article in the current edition of Phalaenopsis magazine, the Journal of IPA. It is by Erin Wood, graduate Research Assisstant and JE Polston Professor, Dept of Plant Pathology, University of Florida,Gainesville, FL. Every one of you should find a way to get a copy. It's simple, down to earth, and in complete disagreement with most of the statements made here on this thread.

In speaking of ONLY CymMV and ORSV (the two most prevalent in orchids) they say, "CymMV and ORSV are unique in that they enjoy worldwide distribution and have only been found in propagated orchids---never found in wild orchids."

If you only have 6 orchids who the he** cares. You can throw them out and buy 6 more. If you have 2500 orchids like I do with a few really valuable ones, you must test and dispose/isolate infected plants. Anything less is fooling yourself.

As to which orchids get viruses...all of them though in my experience some genera seem more susceptible.

The article above also addresses the issue brought up by someone about asymptomatic plants. The explanation has nothing to do with the plant genetics and everything to do with strain of the virus and the stress endured by the plant.

This a complex subject. I sure am not an expert. Science in general is still learning about these things. That said, some of the stuff I see here is nothing more gut feel science with no effort to get informed.

Thank you.

[camille1585]

Originally Posted by goodgollymissmolly

Lots of things have been said here. Unfortunately, Camille's is the most head in the sand. I wouldn't have expected that actually.

To hang your hat on the fact that plant viruses don't spread through the air is pollyana at best. There are several completely ridiculous "ifs" in her statement. For example if your collection is insect free...exactly how does one guarantee that? There are many other ifs she ignored...like if you sanitize your hands between touching each plant, if you never have water splash or drip on an adjacent plant when watering, or never have foliage rub on adjacent plants in the breeze. Unfortunately her position is similar to someone saying you can prevent fires by eliminating ignition sources. You can minimize them but they are infinite and uncontrollable..like lightning, or unanticipated arcs in switches, or static discharges from clothes of different materials rubbing together. You can only totally prevent fire by having no flammable materials or mixtures. You can only prevent virus by not having any in your collection..anything less is minimization, not prevention.

I don't have my 'head in the sand' thank you very much, and no need to treat me like an ignorant little child. I didn't say that plant viruses don't spread the air, I said that they don't spread through the air like animal viruses. By that I mean that the particles themselves aren't airborne. The insect vectors, on the other hand, are airborne. The vast majority of viruses depend on insects (or bumbling humans with their tools) for transmission. Obviously that wasn't very clear to you in my first post, I hope that this time you understand.

I was also speaking about indoor orchid growing, where you can much better control what's going on. How do I know that my collection is insect free? Because I check each plant over carefully at watering time. No I can't guarantee there are no bugs, but regular checks keep the likelyhood of it very very low.

Also the risk of spreading virus just by handling plants is low, unless you get infected sap on your hands, and then handle damaged leaves/roots of another plant. Same goes for simply having leaves touching. Research shows that plant viruses can't infect via natural openings (stomata) or intact cuticles. For that reason splashing water also won't infect intact plants. If you want to be picky about it, yes, you could damage the plant with your infected fingernail and infect it that way... Everything I said in my first post is accepted, tried and tested prophylactic measures, for want of a better way to limit virus spread. (other than spending a fortune testing the plants, those test strips are freakin expensive over here)


I am no expert on plant viruses, but I should know what I am talking about after having followed several graduate courses on the subject, though I focused more on the molecular aspects of transmission. If you still think my head is in the sand (which you probably do) I'll gladly indicate scientific literature for you

Personally I think that unless people are growing rare and/or very valuable orchids, we need to chill out a bit about viruses and accept that it's a part of owning plants, or any other living thing. Or you can continue to stress out about it and forget to enjoy the orchids, which is why we have them. Don't get me wrong, I wouldn't like seeing virus in my plants and I'm all for their eradication, but limitation is a far more realistic goal. Eradication in greenhouses is already proving impossible, so those that want eradication also on outdoor plants/crops as well are beyond unrealistic. There have always been plant viruses, and always will be. Breeding longterm virus resistant plants is impossible, the virus will mutate very quickly. Unlike the human flu vaccine which can be changed yearly, the length of the breeding process makes it impossible to be as reactive to changes in plant viruses.

[Jayfar]

Originally Posted by goodgollymissmolly

There is an excellent article in the current edition of Phalaenopsis magazine, the Journal of IPA. It is by Erin Wood, graduate Research Assisstant and JE Polston Professor, Dept of Plant Pathology, University of Florida,Gainesville, FL. Every one of you should find a way to get a copy. It's simple, down to earth, and in complete disagreement with most of the statements made here on this thread.

Another surprising bit of information in that article is their contention that some viruses don't systematically spread throughout the plant, but can be eliminated by cutting off the afflicted leaves. Unfortunately CymMV and ORSVC do spread through the plant. TSWV and INSV, they say, don't spread through the plant, but may appear as ring shaped spots like the more common CymMV or ORSVC infections.

[lepetitmartien]

Originally Posted by Jayfar

TSWV and INSV, they say, don't spread through the plant, but may appear as ring shaped spots like the more common CymMV or ORSVC infections.

If so, a test conducted on multiple "rings" would be positive, and it'd be negative at some distance of them.

It may be an explanation (to be proven) on why some "showing signs" are "virus free".

If so, it's cool.

Now given my prevention/epidemiology background (over some science studies) I'm suspicious of any studies I haven't read thoroughly, including the articles cited in the study/statement/state of things.

So even if I find this interesting, I still need to be convinced (and I won't be until I read all I can put my paws on on the subject) but please continue ladies and gentlemen, it's an important subject for us all.