I know that at the US Dept. of Agric./Univ. of Calif. Riverside citrus research center they have perfected the technique they use to obtain virus-free versions of various citrus cultivars. They actually graft and grow the virused cultivar in pots in a large room that is an oven where they raise the temperature to a certain point and keep it there continuously (somewhere between 100 and 120 deg. F. but I can't remember exactly what). Then when new growth appears, they take just the growing tip and tissue culture from that. They discovered that above a certain temperature, viruses are unable to migrate into the newly grown cells. Thus they are able to clone completely virus-free plants. I've read that this method was used to clean up the 'Meyer' lemon variety some years ago. I don't know if this technique would work for lilies or other geophytes as well. --Lee Poulsen Pasadena area, California, USDA Zone 9-10 On Jul 7, 2004, at 9:37 AM, John Bryan wrote: > Thanks for your message. Rather than an inner scale, I think the very > tip of the growing point is better in order to obtain virus free cells. > Hopefully they are taken before the virus can get to them, this would > be > even more the case if the tissue was taken from a plant that was > growing > rapidly, i.e. with added warmth to stimulate fast growth. > > DaveKarn@aol.com wrote: >> Judith Freeman (of Columbia-Platte Lilies and The Lily Garden) has >> said the >> issue is that meristem culture did not remove all the virus particles >> in the >> bulbs multiplied by meristem culture. The remaining few particles >> were too few >> to be detected by ELISA tests. For that reason, it is necessary to >> periodically repeat these tests to have any assurance of virus >> freedom. What, in >> effect, is happening with these supposedly virus-free lilies is that >> the >> undetectable virus gradually works itself back up to levels that >> present the standard >> symptomology. I would imagine to get a truly virus free lily, one >> would have to >> continuously to incubate sections of the innermost scales.