If the only cannas you are growing appear reasonably clean why would you consider discarding them?
Many gardeners are growing cannas, hostas, roses, tulips, etc that are diseased, but perform to their satisfaction. The individual unsatisfactory plant would be discarded when necessary. Most cannas in the last few years have been diagnosed with virus infections. The virus is not new, but we can now identify the problems we were seeing in the plants for the last 20 years along with the name of the causal agent. The result has been widespread panic by the somewhat knowledgeable gardeners and many horticulturalists.
For many of us our cannas, depending on the viral load, grow and bloom well. I personally continue to grow both clean and virused plants, taking precautions to delay or prevent the virus spread between plants. They are grown in separated areas. I do discard plants that are poor performers or display heavy viral load.
At the present time, it is impossible to purchase many of our older outstanding cultivars that are virus free.
Hopefully in the future we will have available virus indexed stock at a reasonable price and in the quantities required to meet the market demand. Until that time comes, we will deal with the current issues until something new comes another.

Kent

Kent, thanks so much for responding. It was my understanding that the virus weakened, disfigured, and eventually killed the plant. I freely admit I panicked, but it was a slow panic. These cannas had speckles and streaks from the first or second leaf, but I let them grow hoping it was caused by something else. The bigger the plants got, the more "marked" they were. I kept reading posts on this forum where people with virused cannas were told to discard them.

I don't have anywhere to isolate suspect plants; my entire flower garden is about the size of a parked car. It's the narrow strip between my house and the sidewalk, on one of the main streets in my city. If there's a dying plant in my garden, it's a public eyesore; everybody sees it, and my outspoken neighbors will ask what's going on. I don't know how to tell if the remaining plants are healthy. I live in a densely populated and densely gardened area. I would not want to be responsible for spreading a disease to my neighbor's plants.

Maybe I should have kept all of them, anyway. At least I know for next year.

-Edie

I admit that I panic big time about the virus also. I suspected a few of my cannas had the virus so I potted them all in there own virus canna pot and some of them are actually making very nice blooms, but they wont go inside this year. And some cannas have there new leaves all rolled up and they arent opening but they are continuing to make new leaves so I assume that they also have a virus and they arent going in this winter either. I have a few cannas that are excellent and are doing very very well and those are going in. If something has signs of a virus I move it, but I dont discard any of the cannas unless its in really bad shape.
Good luck!
-Alex