On some of the leafs it looks just like the picture posted by Hart canna on the net. Only a few of the leaves look this way on each plant. The rest of each plant has healthy leaves and are growing and blooming. Can this virus only be on a few leafs and not the majority? I have moved them away from my other cannas. If anyone can help it would be greatly appreciated.
Mosaic canna disease on black knight cannas
If caught early, contracted virus may not invade all divisions of a plant.
Most 'Black Knight' I have seen in the last years carries virus.
I fortunately still have 'Black Knight' .. no virus :)
Good growing conditions, heat, strong light, and humidity can mask virus to a good degree. But visible symptoms will return with cooler temps.
On a stalk of a canna, when some leaves carries symptoms and others not, chances are that whole division carries virus even though at times it can look healthy.