Is this how the plant looks now? Because it seems quite healthy to me - maybe it's stalled because of another cultural condition that is missing?

I agree with Calvin - you have a new growth just starting off the old black pbulb and a new growth at the front of the pot almost full grown - which will probably give you a sheath.

I'm not convinced the old black pbulb is even a problem. Sometimes old pbulbs turn very dark before they expire and sometimes they just turn tannish brown color.

The systemic fungicide, tebucanozole will only be absorbed through live viable roots. I would have to ask my husband if when absorbed, would the fungicide "go" backwards to the backbulb or only up and through the area with the live roots. My gut says no. It is a topical fungicide too so maybe you have that area covered by pouring it through the mix.

If this were my plant, I would severe the old black pbulb with the new growth and treat it like Richardol does for propogating old pbulbs. Again I'm guessing about the way my catts grow, the new growth will grow roots soon. By removing it, you will catch any problem before it creeps up the rhizome and effects the rest of your plant. And most importantly, it will relieve your mind. You should be able to cut through the rhizome and seal it with cinnamon without repotting.

Do not over water this plant so the roots search out all available moisture from the fungicide. Two applications should be ample to treat the plant.

Remove the dried sarongs on your plant. A gentle washing with soap and water will eliminate some great hiding places for bugs. Be careful when stripping them away to not damage any growing points.

I think you have a healthy plant - give it as much sun as you can without burning it and don't be surprised when you get sheaths in those new growths.

Brooke

Calvin, Brooke - thank you both for your prompt replies.
Calvin - That's my main problem and my hope. The plant LOOKS perfectly healthy. However, the black pseudobulb happened overnight. The day before, it was green and plump with a healthy-looking leaf attached. The leaf dropped two days later - it was still firm and green, as were all the other leaves that dropped after the original diagnosis of fungus.
Brooke - Thanks for all the practical advice. I really doused the plant with the fungicide, as well as spraying all the leaves. So I'll be using latex gloves while I handle the plant!
First, I'll remove the dried sarongs from the healthy pbulbs. I didn't know whether this was good practice. I'm learning all the time.
I was dying to remove the backbulb but it seemed to be too firmly attached to the rest of the plant. Now I have expert assurance I can go ahead. But I'll have to reread Richard's instructions very carefully.
I've been keeping the plant in near-drought conditions -even I know that fungus needs water to flourish. And my "isolation ward"(the top of the washing machine)is right up against a west-facing window with a milky glass pane, so it's getting plenty of light, without danger of sunburn.

So, you both think there's hope for this plant. Thank you so much for your kindness. It has cheered me up immensely and given me the reassurance I need to continue treatment and care.
Will keep you informed of future developments.
Judy

Judy the other thing you can do with a suspicous pbulb is cut through the rhizome completely and insert a piece of plastic between it and the good part. If you do have an infection, it cannot grow into the good area.

Yes, the black pbulb is firmly attached to the other part by the rhizome and you can't pull it out until it is cut.

Can you take a close up pic from the other side?

Brooke

If it blackness is spreading overnight, then the quick progression suggests to me that you have a bacterial infection not a fungus - is the PB squishy?

jemsta Judy first posted about this a month ago. The loss of leaves happened fairly fast after she got the plant. If it was a bacterial infection, I think the plant would show additional losses or be dead by now.

The original photo almost looked like freeze damage. The new growth on the old pbulb, with a bacterial infection, should have been the first to die as it spread through the rhizome.

This of course is pure speculation on my part from seeing the two photos. It is hard to diagnose something by the written word and two pictures. What I see in this photo is a nice growing catt with a discolored pbulb. I've had a hard black pbulb on one of my catts and it is totally healthy.

Brooke

Brooke,

I did read the old thread when it was posted. I agree that it is difficult to judge. I just wanted to point out that it's possible that the original damage (whatever it was) has recently caused a secondary bacterial infection which is spreading from the leaf down into the PB. It just seems to me that the best course of action in this case is not necessarily to treat with dangerous (to humans) chemicals especially if the first fungicide did not work. If the rot/fungus/whatever is spreading from one particular PB then cutting off that PB should be sufficient to stop its progress.

I also agree with you that the catt looks perfectly healthy from this side and that it's quite possible to have a healthy dark colored PB. However, Judy said the change happened in just 1 day, that doesn't sound normal to me. Of course, I could be wrong :)

Anyway, my (somewhat poorly articulated) point is that Judy should check whether the PB is squishy, if not then that probably rules out a bacterial infection. Just wanted to make sure we touched all the bases.

I probably should have made that clear from the start :)
~Jem

Transferring the plant to a pot with side slits will greatly improve its chance at survival. Air supply to roots is essential for orchids which grow naturaly with roots exposed to air. Since a new growth has started, I would assume that the mancozeb WAS effective! More light and a dose of epsom salts would add strength to both new growths.

Don't throw it away. And I doubt fungus or bacteria is the problem. A sudden turning color suggests exposure to cold. The leafless pb still looks firm though.

In the meantime, be sure you are not overwatering it, because the stuff it's potted in looks moisture retentive, which combined with that deep pot could easily spell trouble. As soon as I saw new root nubs from any new growth, I'd get it out of the tall pot into an azalea type pot (pref. clay) and medium bark.

My two cents,

J

I seem to be causing a lot of trouble. Of course it is difficult to make a diagnosis from a photo. But you are all helping me overcome this crisis, and strengthening my resolve to nurse the plant back to health.

Here's the sick plant from the back:

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and here's how it looked a month ago:

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Exposure to cold? An interesting idea. However, it was a particularly hot and dry day when I bought the plant. And even with the changeable weather, the house has always remained warm. Maybe it suffered from too much air- conditioning before I acquired it?
The pb is as hard as a rock.
When I repotted, the original medium was wet and mushy with a smell of mildew. The central mass of roots were all rotten and there was a swarm of tiny winged insects in the medium that escaped into the room when disturbed. Still not a fungus? (When the last leaf fell off two days ago, it left a ring of powdery black stuff where it had been attached.)
There was a layer of styrofoam packed so tightly at the bottom of the plastic pot that it was barely allowing moisture to drain. The new clay pot is exactly the same size as the original plastic, and even if the medium is less than ideal, it is still draining a lot quicker than before.
I would rather not repot again at this stage, as I don't want to subject the plant to further stress. For the same reason, I've decided not to tamper with the black pb. especially as I don't know where exactly in the plant the fungus (or whatever) is centered.
The second smaller shoot has grown about half a centimeter over the past few days. If I remember, these two shoots were on the plant, but dormant, when I acquired it. There hasn't been any entirely new growth at all,as far as I can tell.
So, that's the whole story. You all seem to think that the plant is basically healthy. That's so encouraging. No, I won't toss it now. It deserves another chance.
Judy

The plant still looks pretty healthy. But if there is a black, mushy leafless pseudobulb, remove it (cut it out with a sterile cutting tool). The main thing I notice is the new growth looks small. The reaon it's languishing is that it's not getting enough strong light.

I agree with everyone else, your plant does not look that bad. It is just recovering from overwatered/broken down media that killed its roots. I wouldn't worry about using fungicide, because any problem is bacterial. One of the best ways to fight fungus/bacteria is to change the cultural conditions that caused the problem in the first place. You have done that. Fungus and to some extent bacteria are secondary symptoms of an underlying problem.
I would give it a little more light then the photo, but wouldn't put it into too highlight until you are satisfied that your plant is healthy. You can worry about blooming it once you have good healthy roots.

Painterart: Thanks for your comments. You saved me the job of answering Toyo.
However, I don't want to cast aspersions on any of you. You have all been so kind, helpful and encouraging.

That was a terrible photo, wasn't it? My fool-proof mini-pocket-digital-toy decided that there was enought light not to warrant use of the flash, and in addition, the light outside had a yellowish tint because of the yellow dust coming in from the Sahara (lol). Yesterday was cool and damp, today was hot and dry, tomorrow's forecast is for cooler, damper weather etc. That's spring in this part of the world.
Actually, I'm a bit mystified about how little light my orchids seem to need to feel comfortable and to grow. My "nursery" now has four plants, arranged in a diagonal row, facing an east window. They are not in the direct path of the sun, but parallel to it. First in the row is the Epicatt, which has already bloomed early this year and is producing a new sheath. Next in line are the Miltonia (just finished blooming and now producing new growths -2 sheaths and a leaf, I think) and the Beallara (just finished flowering and now recovering from being repotted) and last is a phal which still has a few blooms, but is now past its prime. Do you think the high light could be caused by reflection off the nearby buildings which are all faced with white stone???
About the small new growth on the left - I have another theory. When I repotted, I had to cut away a lot of rotted roots below this shoot. Then I gave it a too-liberal dusting of cinnamon (it still smells like my peanut-butter cookies every once in a while). So it's probably still working on producing some new roots, instead of growing taller.
I'm rather dazed at the amount of interest this poor little catt. is provoking. Let's hope it was all worth it.
Judy