Psychopsis leaf rot?
 

Hi guys,
I've noticed that one leaf has this black spotting - what could it be and how can I treat it?
Pics from top, all the leaves (the brown spot on the middle leaf is from mechanical damage) and the affected leaf against light.

Possibly secondary bacterial or fungal infection, maybe after sun damage? Hard to say, as I don't know your growing conditions.

Regardless, I would cut off the leaf, into healthy tissue below the damage. Let the tissue dry before watering again.

If you are not already doing it now, provide calcium to help increase resistance to infections. Calcium nitrate (1), or gypsum + Epsom salts (2), or a commercial CalMag preparation (3) will provide the calcium needed. 2 and 3 will also provide magnesium.

Thank you Orchid Whisperer!
I moved the plant from a darker cold room (South) into our North facing window (sheer curtain) now for winter, as that room is acceptably warm. Maybe it could have gotten a little too much sun.
All my plants get calcium and magnesium regularly, in small doses.
Well, let's get leaf cutting!
Thank you again :)

Have this gotten better yet. Mine is sprouting his first bubs

Well, the infection (or whatever it was) has not spread any further, but the roots are gone (when we got her, she was is pure sphag, so dense I couldn't get it all out and stupidly I though that would be fine) and it was waaay too late when I looked into the pot. Now it's full on ICU, sitting on moss doing nothing very actively. As I say, sitting is better than dying, I'm ready to give her all the time she might need :)

Sound just like mine, i spent 3 hour getting all that Spagnum of!

Same here, but I just gave up eventually. I've learned my lesson not to do that ever again :)

Luckily mine js making lots a new growths!

Lucky you! I guess I just have to give mine more time - it's only been a couple of months :)

Did mine October.