Destroy all infected plants. Even those only suspect of being infected. That is what I do. Purchase only from reliable virus free sources, and quarantine those plants/rhizomes well away from your uninfected plantings. My collection has been decimated. I'm down to a single variety now.

I think you are correct. I kept buying hosta after the virus scare. I used to have a huge sum and substance and others. I don't know if it was the virus, but something happened.

I have just begun to appreciate canna; it is disappointing that this virus has popped up. I would not like to risk my tropicanna; I love them. I probably won't buy any more. I wonder if the virus can come through the seed. I see instructions on growing from seed on this forum.

From what I've recently read, yes the virus are trasmitted via seed. There are some who dispute it, and I have no first hand knowledge in that regard.

To date, I haven't read anything about virus being transmitted through the soil.