Orchids and frosts. And what happens when the leaves are burnt via a frost. Have a look at the photos
YUK! What a mess,so what to do.
Simply leave them alone until mid spring.
In most cass they will abort and drop off on their own.
If not use a scalpel and trim off the dead tissue into a rough leaf tip shape.
You may not even notide the damage after its carefully trimmed.
The black mouldy bits are simply secondary fungi and bacteria eating the dead leaf matter.
It never seems to progress into healthy tissue so relex.
No sprays needed.