Canna virus and leaf damage

The first three images are of leaf and stem issues that are not canna virus. The first issue gave me some concern for a few years until I could establish this was not a virus. New leaves twist and do not unfold. Affecting groups of the same variety growing in the same conditions this can affect the plant for a few weeks and actually soon grows out. Despite looking serious I do not believe this is a virus as it doesn't affect the same plants over and over. At the nursery I usually see it at least once a year and there is no pattern to what plants are affected and it never affects large numbers of plants but there is an association with high day time / cool night time temperature extremes. 

Sunburn damage often alarms new growers who are worried about canna virus. It occurs frequently. Shown on images two and three.



Growth distortion believed to be through temperature extremes. Can occur in Spring and early Summer . Uncommon.
Sunburn damage is the most common issue
Another image of commonly seen sunburn damage
Canna virus on a non variegated canna
Close up of the same leaf showing canna virus detail
Yellow streaks and blotches of a canna virus on a white striped canna leaf