Quote:
Originally Posted by littlefrog
I'm surprised you don't see more virused cattleyas... They are really quite common. Not at all surprised about the phals. I don't think many of the big producers care about virus one little bit. They are growing for the mass market. If it is pretty and it grows and blooms well, it gets cloned to death.
I would hope if you purchase a plant (from me or anybody else) that tests positive for virus, that you tell the vendor. If they are reputable they should refund or replace the plant.
I would never knowingly send a plant with virus, but I also don't routinely test my collection. It just isn't something I can afford to do for every plant. And, as a professional biologist who knows quite a bit about this kind of thing, I can assure you there are viruses running around out there that you will never know about because there are no tests for them.... Many of them will never show symptoms in the host, and if there are no symptoms it just isn't there (even if it is there!).
If I see color break or other 'weirdness', I just compost them, and I'm ruthless about it. I think most people (yes, even judges and vendors) take this approach. Not saying it is right, just that is what most people do. If we can't see it, it isn't there (it is easy to fool yourself into believing that - and helps you sleep at night).
There are a few good steps to take to help keep known viruses out of the collection. 1) Buy seed grown plants, and buy them fairly young. If the seed is harvested properly, it should be free of virus even if the parent plant is virused, and young plants have had less opportunity to be infected. 2) If you absolutely must have a 'classic' plant, test it when you buy it. 3) Maintain good hygiene - sterilize your tools and pots. Dip your cutting tools in fresh 5% milk (powdered milk) - yes, that works and it is better than bleach or fire.
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I absolutely concur with all you have said and very much appreciate your helpful and concise outlook.
Every test we run has a sensitivity and specificity for detecting the intended "event".
First and foremost, for a test to be positive for a virus, there has to be a certain threshold of viral load in the test subject. Thus, a negative test is not 100% accurate ever...
As a screening test, ELISA type test are usually very sensitive with less attention to specificity. For a diagnostic test, it is the reverse.
Think of sensitivity as picking up "any little sign" of a problem and specificity as picking up "only the problem" (thus easily missing the problem existing in a small variation).
An example we are all familiar with would be HIV testing. This is an ELISA test and many people get the crap falsely scared out of them if they are positive. HOWEVER, a positive ELISA is then followed up with a Western Blot test for specificity...the WB test would ONLY be positive for someone with definitive HIV.
I absolutely notify the vendor with a positive test.
As a courtesy, I provide a high quality digital photo of the test and certainly offer to return the plant.
If a test is positive, I retest with half the tissue recommended. If this second test is positive, it implies to me the viral load is likely high. Also, using too much tissue gives a false positive in some cases and it's my crude way of eliminating that possible variable with the test.
The vendor responses are what concerns me.
Vendor #1: absolutely outstanding; got a credit and he handle his plants appropriately (item removed from sale)
Vendor #2: slow to respond, offering a credit but has yet after 2-3 weeks given me a means to use the credit; item removed from sale for 3 days and now back on the site.
Vendor #3 and #4: No response as of yet
Because in my opinion as well, virus is very common, I do not feel inclined to trash a vendor by name.
If you are buying a mericlone (which these were) then you have to acknowledge this is a risk. I am just surprised as HOW MUCH it is around.
And honestly, some of these places that get 25-30 plus items of one type of plant shipped in which are mericlones could simply run ONE test on a sample from that clone's "lot".
Then the distributor and/or vendor could call where-ever across the Pacific where the plants came from and give them hell!
Maybe a more aggressive attitude would cut down this problem.
The reason I test despite the price is that my interest is in acquiring large specimens of large flowering cattleya especially historic species. Thus, I would like to protect them/their "health". (I know you are smiling though because many of these are also virused...)
I do also enjoy Phals and other types of orchids as well.
With all our efforts at CONSERVATION, failing to acknowledge the danger and damage rampant virus infected plants can have on some important collections is foolish.
Finally, I have three large specimen plants WITH virus that I keep and LOVE! They are CymMV positive and I am careful in handling them. They show no outward signs of virus, growing and blooming vigorously...but they have a special spot away from the other plants and different tools are used when I handle them etc.
What started out as a practice of "overkill" for me with the virus testing....has not panned out to be "overkill"
Starting to think I'm too particular with orchid vendors
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