Hard to say.
Could be any number of things....but the issue seems limited to a few leaves, so I wouldn't do anything. I would guess a fertilizer burn...? You know better than we do about what's happened in this plant's life.

Josh

That was my first hunch Josh, fert burn.
I've given it one application of Vigoro 24-8-16 and bone meal, that's it.
That was about a month ago.

Stoney

Sorry guys...leave?

How about leaf!

I was very tired when I posted this.

Stoney

ran short of water quite some time ago.
Keep those leaves as they have lots of healthy green tissue.

From one pic it seems that the crusty bits are close to the soil. Could be splashing of water or ferts. Nothing to worry about. And yes, keep the leaves as long as they are capable of doing their job. They will be overshadowed by top growth soon enough and fall to earth (er... mix).

Dennis

I get rid of my bad leaves. Plants are going to waste energy trying to fix it or it could spread depending on what it is. Clipping them will only bring new better growth. Just my opinion

Just might do that. This plant is bushing out nicely :-)

Stoney