I have been monitoring the thread on Virus but have not had time to contribute. In 1986, I bought the remains of the Shaffer Phalaenopsis stud bench. At that time people were becoming increasingly aware of virus in older collections. I wanted to test all of the breeding stock so I would not be vectoring virus when I was making crosses.
At that time only anti-sera available were for CyMV and OSRV. Out of about 140 tests, I got a little over 50 positives for CyMV, and about 25 for OSRV. I cannot speak to the issue of false positives, as I had no way to verify the results of the serological tests. What I needed to do was figure out a way to use these plants for breeding, without further spreading the virus. Some people were advocating yearly testing, but for a large number of plants, this was prohibitively expensive, and would not guarantee that you do not transmit virus. The plan I came up with was essentially this: - Assume all plants have virus, - put pollen ONLY on backup copies of plants, (yes, I made LOTS of stem propagations), - dry sow all seed unless cross is such low fertility that green-capping was the only way to get seed, - control potential insect vectors, - of course, use sterile tools when repotting or removing old flower spikes, etc. This plan got me out from under continual testing. It ensured that I would not be transmitting any additional virus to my original stock plants. Twenty years later, I am still using the same plan. I have a large number of "heirloom" Phalaenopsis in my collection, many of which were virused when I checked them twenty years ago. I would like to comment on one thing about a false sense of security. There are a huge number of virii that could potentially infect orchids, most of which have no anti-sera available for testing. So, an anti-serum test showing no sign of CyMV or ORSV doesn't mean that your plants is not infected with BYMV or something else. It is much safer to assume that all plants are virused with something as yet unknown. This is not to say that there is no benefit to testing, but that a plant that tests clean for CyMV and ORSV may still be infected with something else. Just my two cents based on my experience. rob't Robert Bedard http://www.robert-bedard.com/orchids/ _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
