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

[emmajs243]

I cannot tell you for sure if it is black rot or not. I can say that black rot is spread by water dripping so I would take extra precautions with watering for the next little while.

Maybe even separate any plants that may have come in contact with water droplets from this plant just in a different area from this plant? If you have the room that is.

From my understanding, most burns are fairly dry black areas and not really mushy as described so I too would be slightly more concerned with the black rot possibility. Especially with how fast moving it seems to be!

But, like I said, I would definitely wait for an expert to weigh in on this one! I am sure they will! I really hope it isn't black rot and that your catt does ok!

[estación seca]

If it's soft it's likely to be something bacterial. I would cut off the leaf far back from the black area, all the way back to the pseudobulb. It is likely a lot of tissue is infected, but hasn't turned black yet. Then wash your hands and sanitize the blade. Dust the cut end with powdered sulfur or cinnamon. Keep the plant in a lower-humidity area if you can until it's clear the rot isn't advancing.

[ArronOB]

Ok, thanks.
Few days gone by now and it doesn’t appear to be spreading.
Cheers
Arrom

[estación seca]

If that's the case I would wonder about a thermal burn.

[Ray]

I would still cut that tip off, but not the whole leaf; a 2 cm margin is likely sufficient, and then dust the wound with cinnamon.

[ArronOB]

Ok, thanks for the advice everyone. On the day I discovered it I cut it down 2cm, dusted it with cinnamon - and it hasn’t reoccurred or spread.

Cheers
Arron

[emmajs243]

Good news!!!