Help! Black spots not responding to fungicide (photo)

[Orchidreamer]

I bought this catt a month ago, and it had some small brown spots at first. I didn't think too much about them, but now, the spots have gotten out of hand, and they've "grouped" together into brown patches.

I treated with hydrogen peroxide. That didn't work, so I treated with an organic fungicide from HD. That didn't work, so now I'm using Daconil. It looks like the spots are appearing on a few other leaves too, even though I've been applying fungicide to almost all the leaves.

I've cut off a few other leaf tips and applied cinnamon, but the cut area is beginning to brown (maybe the fungus got there too?). Now I feel nervous about cutting leaves.

[Ray]

Treating the plant will not cause the already-damaged tissue to return to normal.

Plant tissues are not like ours - once damaged, the tendency to replace the damaged tissue with "good" isn't there - the damage remains until the leaf (or pseudobulbs, or whatever) dies and is dropped.

Alcohol is topical only, so you're better off with a systemic fungicide like Cleary's 3336WP.

When you cut off the damaged part of the leaf, did you also take a clean margin of 1/4"-1/2"? Were there any traces of dark, infected material in what remained?

A little bit of die-back from the edge of a cut is to be expected, and it could be that the plant is ditching the leaf altogether, in a self-protective move.

[Izzie]

I'd cut off the most infected parts, and as Ray said, cut into clean tissue, not just along the infection's border. Sealing it with cinnamon is a good idea, but I've had leaves continue to dry from the cut despite that, but no other ill effects.

If the Daconil doesn't work, you could try undiluted brown listerine. I know I can't afford Clearys, so that's what I make do with, in addition to just being ruthless in cutting out the infection.