I HAVE ABOUT 8 CANNAS AND SOMETHING IS EATING ON THEM, I DO NOT SEE ANY KIND OF BUGS BUT WHAT COULD IT BE AND WHAT CAN I USE TO STOP IT?[/b]
No real help, but....I had the same problem with my Canna Tropicanna (spelling?). They were in a pot in a grouping of potted plants at the base of a tower covered in asian jasmine and purple sweet potato vine. After watching multiple leaves sprout but never fully open -- I unfurled one of the leaves and discovered the biggest natsiest looking larvea-ish type creature living happily inside - having 'glued' the leaf into a permanent tube.
I had a 'fit of the eebies' (this bug was really BIG and icky looking), fed the bug to our resident bluejay (he LOVED it), turned the hose on "soaker" and flooded all the other "leaf tubes" until I felt better. Then I moved the cannas to another location with no plants above them. No more bugs. No blooms this year, but no bugs. Hopefully next season will be better.