Garden Pests and Diseases: Gardenia leaf damage...bacterial? Burn? ..., 0 by Horseshoe

Horseshoe wrote:
Howdy Folks,

On some potted gardenia bushes I have outside I've noticed the past few days the damage shown in the following pic.

It seems to start on the sides of the leaf but I've also noticed a few of the brown areas between the main leaf vein and the outermost part of the leaf margin. The brown areas aren't dried and the leaf is still flexible (so far!).

Notice how this malady seems to work on one-half the leaf....and then seems to eventually spread to cover the whole leaf.

At first I kept thinking it was some kind of tip-burn (fertilizer burn) but I only see one leaf that shows that typical progress (i.e., tip of leaf turns brown then followed by the rest of the leaf browning). Also, doesn't fertilizer burn/tip burn start out with a brown and "dried" texture?

I don't see any sign of insects, bugs, scale, or spores indicating this is caused by those types of things. Have no idea if this is bacterially-oriented or what.

Any ideas?
Thanks!
Shoe