I just now read through this entire thread. (hadnt noticed it previously)
I had an absolutely IDENTICLE problem here on one of my potted plants.
My opinion is gonna go way off from that of the rest. Only my opinion from the problem here though.
Not slugs or snails
I have an amazing slug infestation this year. Beyond ANY i recall in the past..
I have since, rectified it. I bought some Ortho, Iron phosphate powder. Its killing slugs by the dozens around the plants.
The ones in ground that were originally affected are not at all anymore.
The two in 5 gallon buckets that were not infested initially, became so later on. Even though i didnt think the fuckers would climb up the buckets. (they never took the initiative in past years)
I PLASTERED the ground around the pots with that snail/slug killer since the roots are never going to come in contact with it.
Even though i had seen no more slugs on plants, and a crazy amount of dead ones around the containers, the problem of the minescule holes continued.
I dont know what part of the next step did it for me. The nutes or the residue from the nutes, but i gave a heavy foliar feed. (which i never do usually)
The tiny holes that were there still are. Havent "healed" or anything, but, the new growth beyond those affected leaves has been coming in flawless.
No more little holes. Just typical shiny green growth.
Dont know if itll help. Or if that was the solution to MY issue.
Maybe whatever was eating them just decided to back of and turn its attention to some other native foliage.
Either way.. once i had foliar fed the leaves started coming in like they should. So, im satisfied..