Black spot on Phal amabilis leaf

[Orquiadicto]

Yesterday evening I suddenly noticed this on one of the leaves of my Phalaenopsis amabilis variegata. I'm quite sure it wasn't there in the morning (or at least I didn't notice it). What could this be? Should I cut this part of the leaf? Could it spread to other plants? I've put her alone in another location just in case. Thanks for your help and advice.

[Cattleya17]

Looks like a sunburn to me. But it's so round and very focused. But it does look like sunburn. Is the wound wet or in anyway softer than the other leaves feel? Make a mark around the margins and see if it is spreading if so cut it off as soon as you can. When you water, do not let water splash on the leaves it can help spread it if it is a rot of some kind. Water only the media or dip the whole pot in water. Sunburn can happen very fast to though.

[Orquiadicto]

I discard sunburn. Not at the place I have her. The other ones that are standing before her would have sunburn too. Besides, this leaf is looking towards the inside, to towards the garden. The spot is dry and somewhat sunken. I never water from above. I always inmerse the pot into a pot with water.

[WhiteRabbit]

[james mickelso]

Could be one of three or four afflictions. Doesn't matter. Cut this out with a new razor or sterilized knife/scissors. Make sure you cut back to healthy tissue. Then dab on some cinnamon with a finger or Q-tip. I just lost nearly all of my phals to capsicum chlorosis. This is not capsicum but could be another virus. Debating what it is doesn't stop it's spread so do surgery right now. Keep it isolated for now or until you know you have contained it. This isn't sunburn as that isn't so well defined. And I doubt it is a cigarette burn. Calling Dr Adicto. Calling Dr. Adicto to surgery.

[King_of_orchid_growing:)]

It's a fungal infection. You can tell by what's in the center of the circle - the fungal mycelia is concentrated/isolated right there.

[james mickelso]

Good eye young man. I didn't see it at first. The mycylia are growing out into the surrounding tissue and therefore needs to be cut back further than just around the black scarring. I'd go for twice the distance from the center. And use an antifungal spray on your plant. What do you think the vector is Philip?

[Orquiadicto]

Thank you all for your advice. I'll do what you suggest as soon as I get home for lunch.

[King_of_orchid_growing:)]

Don't know what the vector is. Could be from water. Maybe it was watered during a cooler part of the day and the water got on the leaf containing the spores, and stayed on the leaf without being dried out before the spores germinated, I really don't know - it's a wild guess.

Could also be an insect that had spores on its body and it landed in that spot, I really can't say this definitively either.

Suffice it to say, something carried the spores there, and I just don't know what it is.

Could just as easily be dumb luck. Fungal spores can be carried by air as well. Just happened to be that some spores may have been airborne and landed on that part of the leaf and germinated, idk.

[Orquiadicto]

It was watered on Saturday 23rd, so about ten days before the spot appeared. I don't think water got on the leave, but well, whatsoever. I did the surgery and hope this way it will just be one single episode.