Apologies if this is an obvious one, I looked in the archives and wasn't sure. My spearmint is having some sort of problem, or problems:

1. reddish spots that start on the leaves' undersides but eventually show through (rust?)
2. holes in the leaves, less common than the spots

The problems are worse for the leaves that are the most 'inside' the plant - closest to the ground, farthest from the sun. I don't know if the holes are related to the spots, or a separate issue.

I don't see any bugs, except for exactly one adorable green bug, almost half an inch long, that seems to hang around.

If this is rust, how far do I need to move this plant away from my other mint ( a potted chocolate mint) to keep it quarantined?

Thank you!