If you google canna virus you should get quite a few hits on mosaic and the other name(s) escape me at the moment. It would appear that the virus is transmitted by aphids and gardening tools that are not cleaned properly. It is highly unlikely that the virus can live in the soil.

What is really intriquing is that it is now believed that the virus' have been present for decades but only recently recognized.

It is purported that healthy soil, the equivilent of at least one inch of rain per week, proper soil temperatures, and excellent exposure to sunlight will mitigate the effects of the virus'.

Mr. Bernard Yorke of Australia is also experimenting with a product called Seasol(?) that appears to lessen and overcome the effects of the virus'.

There is no known cure.

You might also look up canna rust.

Marian