Could it be leaf rollers?

The Northern Skipper butterfly lays its eggs on a new canna leaf & "stitches" the edges together with something that looks like spider silk.

Then the babies hatch & eat round holes in the leaves.

You can control them with bacillus therengensis (sp?) or trichogramma wasps, which are *not* stinging insects but microscopic wasps that eat the eggs or the larvae.

If it is a fungus, you might spritz the leaves, heavily, front & back, with a thin mixture of milk in water.

Best luck!