Because many, if not most, plants are infected with innocuous viruses, a positive test for their presence is of little value and does not establish cause and effect. Since Barbara McClintock's oringinal Nobel-winning research into transposable elements in Maize, a large body of research has been amassed on the genetic origins of variegated flower color patterns. While there may be a very remote possibility that this Sparaxis flower color pattern might be caused by a virus (I doubt it), the pattern itself is highly indicative of a transposon jumping into and out of a gene involved in the expression of the pigment in the petals at some point during the early development of the flowers. By the way, if you look at (Google) some examples of McClintock's colorful and speckled Maize kernels (think Indian corn), you probably might incorrectly think there is a virus involved. I found a good description here of how a transposon causes this type of variegated flower pattern: http://stanford.edu/group/dahlia_genetics/… Nathan At 09:33 AM 6/13/2013, you wrote: >On Thu, Jun 13, 2013 at 7:07 AM, Mary Sue Ittner <msittner@mcn.org> wrote: >I sent those in for testing I sent in something that looked > > suspicious to me and it was fine. It left me feeling that it may be > > challenging to tell by looking what is virused. > >I suspect that the lab only looked at the type of virus (if the tests >are available) but they didn't look at the amount of viruses. The >concentration (titer) of viruses in an infected tissue probably >determines the prevalence of mosaic. Some plants can keep that titer >down but others cannot. Unfortunately, virus research in bulbs is few >and far in between and we still don't know much about them in >non-commercial bulbs. > >Since we cannot be sure which ones are virused and which ones are not, >I suggest that growing your own plants from seeds is the best way to >go. Getting bulbs from a reliable grower/friend is also another good >way to go about it. > >Nhu >_______________________________________________ >pbs mailing list >pbs@lists.ibiblio.org >http://pacificbulbsociety.org/list.php >http://pacificbulbsociety.org/pbswiki/