Last year, I had three divisions of a canna variety in a large planting bed that I suspected had yellow mottle virus. I still had not learned how to reliably tell the difference between natural or benign leaf discolorations and virus-related discolorations, but I dug them out and threw them away late in the summer just to be on the safe side. It did not appear as though other cannas in the bed were affected.

This spring, I planted some new seedlings in the bed, all of which were from the same source. Now I see that those in or near the spots where the diseased ones had been have symptoms of the virus. Those in other areas, including the new ones and ones remaining from last year have no sign of it so far.

Maybe it's just by chance that only these certain new ones are showing the mottled-leaf symptom. If not, it looks like the virus survived over the winter in the soil or in detached pieces of root or rhizome that got left behind. This might be something to think about if you plan to replace sick plants with healthy ones. Meanwhile, does anybody know how long the virus can remain viable in the soil or how contaminated soil can be sterilized?