Or it could be a bacterial rot. In those cases, you need to take the plant out of its pot and cut out as much of the rot as possible. Cut off the black soft psuedobulbs, cut till you find green in the rhizome. Treat the wound with cinnamon. Or dunk the plant in a fungicide/bacteriacide. There are systemic products on the market used for roses that can be used on orchids. Always cut your plant with a sterilized tool. (propane torch flame the best).

Yes, I'm with Toyo on this. Don't jump to the conclusion it's a fungus. That assumption can kill your plant in a couple of days, and here's why:

You say it moves fast-- that's usually a sign of bacterial rots. Fngus rots move slower, so you have more time to deal with it.

Bacterial rots move very fast. From a spot on a leaf to losing the whole pb can happen in two days. And from then on it's moving fast toward the remaining pbs. So when it's fast moving and you aren't sure, treat for both right away, but for sure for bacterial.

I had one start on a C Bactia once, and I couldn't keep ahead of the rot. Even tho I cut into fresh tissue each time, the rot had gotten there first.

So rule #1 is act quickly-- time is on the other side in this.

The bacteria that start this sort of thing are always around, and opportunistic-- they take any chance they get. And chance is usually a cool, dim, wet period. If you can give the plant more air (set a fan at low speed on it) and more light, that will help prevent future outbreaks.

Treat as Toyo said.

Also, for the future, *sometimes* spots on the leaves can be stopped by cutting the spot out and treating with cinnamon, or if spot is small, without cutting and just rubbing cinnamon over the leaf on both sides.

Good luck.

OK, I get the message. So, tomorrow it's out with the cutting implements (will kitchen knife and scissors sterilised over a gas flame do?) and down to work cutting away at those pseudobulbs. I dread to think what I'll find in the potting medium. I know it will be wet, because it was still extremely damp after two weeks - and the weather has been warm and dry. Tomorrow will be an ezcellent day for this project as the forecast is for a hot, dry, easterly wind. Washing dries on the line in an hour! So, wish me luck!
Judy

Judy, don't cut into the pbs unless you *have* to to save the plant. I would wait for the black and softening to show on them before cutting into them, myself.

Can't tell you if that's "correct" or not, but it just makes sense to me to spare the pbs (and as much of the leaves as possible) if you possibly can-- there is so much stored energy in them, which the plant will need, especially if it loses a lot of leaf.

It's very possible that whatever your vendor drenched it with stopped it dead.

Use your good judgment, sparing as much of the plant as you can. If the damage is only what shows in the picture, just cut that triangle of black out of the leaf, leaving the rest, and watch closely to see if new black develops.

My cautions weren't meant to scare you into butchering your beautiful catt (and it is beautiful-- healthy fat pbs and leaves). They were meant just a caution against delay acting once you see that black, since it can be a really bad thing.

In the meantime, if you can turn a fan on it, moving air helps (since it's wet from the drench).

And I do wish you every good luck-- it's a beautiful plant. Sorry for the scare :(

It's OK, Mehitabel, I'll proceed with caution. Apart from some very small leaves that weren't going anywhere, and about 4 rotten pbs, that's all the damage there is. But
I'll have to repot because it isn't draining well. The expert who sprayed the plant noticed that the drainage hole seemed blocked, but told me not to touch the plant. I can't leave it like this, though, partly rotten and all clogged up. Today, the vendor will give me everything I need - potting medium, a clay pot and more fungicide - bactericide, but I'm not taking the plant to him, because travelling in this bad weather will stress it out too much. Instead, I'll show him the photo! Thanks again, and I'll re-activate this post to keep you informed of my success/ failure.
Judy

Hi all!
Promised to keep you informed of any developments. Well, sad to say, another pb started to turn black and its perfectly healthy looking leaf fell off yesterday. So, the cinnamon didn't seem to work and it looks as though the plant had started its road towards eventual demise. I will not repot a second time. My last resort is to spray the plant once more with fungicide and then banish it to the laundry room, where I will abandon it to fend for itself. What a shame!
Judy

I would have returned the plant immediately if they offered. Take it back and get your money back. Not worth spending time on trying to cure it.

Jane

Hi there, Jane,
Thanks for your concern and excellent advice. However I'm pretty stubborn, and also part of my approach to this new hobby is to fiddle around with an ailing plant and see what develops. For me, it's all part of the fun and the learning experience. If, in spite of all, the plant's a goner, it'll just take a bit longer. And optimistically, the chemical fungicide might just do the trick, especially seeing that most of the plant is still healthy and growing!!
Thanks once again,
Judy