virus testing - false positive?

[Louis_W]

So after the 'false positive' comment did you get back to her again? She might need to get a bunch of money back too from whoever the supplier is

P.S. i like your clever testing strategy. Its a great idea. Since im fairly sure my collection is clean, i could potentially test them all at once. Or is there some reasonable limit?

[Jmoney]

I emailed her back expressing my experience with members of the cattleya community who regarded this test as reliable, and then as she suggested I keep the plant and not toss it for no good reason, I suggested that I send it back to her in exchange for a refund. So far radio silence. I want to do some investigation before calling her out, but I have yet to find any reliable information calling the validity of this test into question. I mean, nothing is impossible, and no test is 100% reliable, but in my mind it seems far more likely that this plant is virused rather than the entire hobbyist testing platform being bogus. (which is almost verbatim what this vendor said)

[Roberta]

Originally Posted by Louis_W

P.S. i like your clever testing strategy. Its a great idea. Since im fairly sure my collection is clean, i could potentially test them all at once. Or is there some reasonable limit?

There is a limit...first, you need to have enough of each plant so that the titre is above the detection limit. The Rega test is actually more sensitive than Agdia (it requires a much smaller sample) A member of one of my clubs, who has approached the issue pretty scientifically, has found that the ideal number of bits for one test is around 6, not just for the sensitivity, but efficiency. If you do more than that, and hit a positive, then you are back to individual tests, and if you go more than that you're likelier to end up having to burn more tests than if you just did them one at a time I don't recall the details of the graph that he produced, but that was, as I recall, the result. He ran pretty extensive statistics (hundreds, possibly a couple thousand plants got tested). This was with the Rega test, so there would be just a sliver of a sample needed for each plant.