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