Black patch on cattleya leaf

[ArronOB]

Merry Christmas everyone, and I was wondering if after the festivities are over someone suitably knowledgeable could take a look at this black patch on this young Cattleya plant and tell me what it could be.

I’ve googled a bit and think it looks like black rot (Pythium/Phytophthora), though it isn’t in perfect alignment with any list of symptoms.

The black patch just appeared, almost overnight. I don’t remember any damage or insect attack preceeding it. The part of the leaf already blackened is very mushy, while the rest of the leaf is in good shape.

For now I’ve isolated it, and will trim off the affected part and treat the cut. Then keep it isolated till I have a bit more understanding of what to do.

Conditions:
Growing outdoors in a shadehouse. Screened so not much chance of sunburn. Potted in 100% bark. Watered daily or thereabouts. Our weather has been very warm and wet lately, so I guess it’s good fungus weather. This week is predicted to be hot and humid, which I know spells trouble as I have very limited space so I grow my plants very close together.

Thanks for the help
Arron