Virus positive plants, Agdia Immunostrip.

[Wfuavenger]

Originally Posted by lepetitmartien

The more you nurse a plant, the more it's prone to be infected. We, humans, are the main agent to infect orchids with viruses.

I may add on the Catts that a lot of old known hybrids are virused, so it'll happen one day of the other…

That's just it. If growers and people in the culture actually try to quarantine, sterilize and have safe practices, the viruses will be minimal. If people grow from seed, it will be minimal. If large scale cloners and growers continue to mass produce infected plants and people continue to buy them, the viruses will thrive.

The US has tons of importation disease and biological measures... Why are orchid viruses not tested for at random from the importers by US Customs or the Dept. of Agriculture?

[DavidCampen]

I wasn't terribly surprised when this C. loddigesii tested positive for virus. I have had the plant for about 6 months and I kept looking at it wondering why it did not seem to be thriving.

On the other hand, one of the other plants that I tested yesterday was a NOID Phalaenopsis hybrid given to my wife and it tested negative for ORSV and CymMV.

[samarak]

Amen to lepetitmartien's post. Without the numbers for false positive and false negative, it's not possible to actually calculate the probability that a plant is virused. I'm not (necessarily) doubting the efficacy or usefulness of the tests - I just want to know.

Thanks to goodgollymissmolly for the pointer to the IPA article which sounds like good reading.

Steve

[DavidCampen]

The Agdia Immunostrips use gold nanoparticles to produce the colored lines. See page 6 here:
http://scholar.lib.vt.edu/theses/ava...tion_Final.pdf

[DavidCampen]

Continuing with my testing, I have tested about 40 plants and about 6 have been positive for ORSV or/and CymMV. The virused plants have come from several different vendors.

One that tested positive today for ORSV I just got last week so I will be contacting the vendor. He is actually more than just a vendor, he is a breeder and this plant is a clone of one of his awarded hybrids.

[orchidsarefun]

2 questions
1) as these appear to come in large batch lots, what is the average shelf life of each lot ?
2) if a plant tests positive, what is the general reaction of vendors to you pointing this out ? Do they even care ? Are plants replaced ?

[DavidCampen]

You can also buy the Immunostrip tests in lots of 5 as well as 25. The lot that I got last week has a "Use by" date of Nov. 2013.

The first several plants that I found that tested positive for virus had been in my collection for many months to over a year, long enough to have acquired the infection while in my care (though I strongly believe that that is not the case) so I just trashed the plants without informing the vendor. Yesterday I tested an expensive clone of an awarded plant that I had just received from the breeder and it tested positive for ORSV; I sent him an email about this last night and I am waiting for a response.

Irregardless of how the vendors respond, I will test all of my plants and eliminate any virused plants from my collection.

[orchidsarefun]

I just trashed one last week, it always grew one leaf and then lost an old one. Looked terrible, leaves becoming all mottled when about 3 inches long. Maybe it was atypical for a virus.
I must admit to being apprehensive about testing, and will have to decide either way. Buying from vendors consequently becomes a huge issue.
However
- is reusing a scissors for example on one plant to another, the only way to transmit the virus ?
- I have read that harvesting green pods will prevent transmission to seedlings. Is this true ? What about naturally dehisced pods where seed is sterilised ?
- is there a fail-safe way or "tips" to know if a plant is likely to be infected - just be examining it visually ?

[DavidCampen]

My understanding is that infection occurs when sap from an infected plant enters an open wound on another plant. This could be from a cutting instrument or from sap on your hands or work surface or possibly from commingling of roots or possibly via sucking insects.

Of the 6 infected plants that I have found so far, 2 of them I selected for testing specifically because they looked unhealthy and lacking in vigor. None of the 6 plants had the classic chlorotic rings or mossaic patterns.

I don't understand your comment that
"I must admit to being apprehensive about testing, ... . Buying from vendors consequently becomes a huge issue."
If you don't want to confront the vendors then just trash the plants and if too many plants from a vendor arrive virused then stop buying from that vendor.

[orchidsarefun]

well - how would you suggest you increase your collection/breeding stock ? Its a bit of hit/miss if you have to purchase first and then toss, not to mention the potential considerable $ waste.
I am apprehensive because it could be that I have a lot of virused plants !