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Discussion Starter · #1 ·
Hello,
New to vivarium and this type of orchid. Is this a virus? should I be removing the plant from the environment? Since I took this pic some of the leaves are turning purplish and I see a few more of the black spots as well. I have it in a new setup. still figuring out light/humidity/temp/air flow.
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The black spots are often fungal or bacterial. Purple leaves are often from excessive light, but not so much light and heat that you're burning your plant. As for difinitive diagnosis and treatment, I'd be relying on Google, not experience. I know there are some people on here with a bunch or orchids in their tanks. Perhaps they can provide some advice.
 

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Viruses tend to be more ring-like but I couldn’t rule it out entirely. More likely fungal, and the genus Pleurothallis is very picky about air flow. Make sure the leaves are drying completely within an hour or two of misting, and if you have separated it from frogs you can try Physan 20 to treat.
 

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Discussion Starter · #4 ·
Viruses tend to be more ring-like but I couldn’t rule it out entirely. More likely fungal, and the genus Pleurothallis is very picky about air flow. Make sure the leaves are drying completely within an hour or two of misting, and if you have separated it from frogs you can try Physan 20 to treat.
I don't have frogs yet. Not getting any until I stabilize the environment so prob a few months. It was definitely not drying out as fast as you describes so I'll try not to wet it as much. I haven't found the right humidity balance. It either dries too quickly or stays humid all the time. I'm varying the opening on the top of the terrarium and I put in a small fan inside to help airflow a couple days ago.
 

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Sometimes, a droplet of water can act as a magnifying glass and create a burn spot in the plant tissue immediately below it. That's a possibility.

It could also be that a droplet may form frequently in the same spot, causing rot in that direct area simply due to the constant wetness. Given the amount of what looks like dried algae on the leaves, indicating water was sitting on the leaves for extended periods, I'm leaning towards a solution that includes increased airflow.

Edit: If you're tempted to use Physan, DO NOT put that chemical in the tank at all. This should go without saying, but we live in a world where people need to be told not to allow infants to play with plastic bags, after all. Remove the orchid from the tank, treat it outside the tank, give it time to recover, and thoroughly rinse the plant long before returning it to the tank.

In my opinion, that little spot looks pretty minimal, and Physan probably isn't necessary.
 

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In my opinion, that little spot looks pretty minimal, and Physan probably isn't necessary.
I thought the OP was talking about the yellow sections, but if they can be rubbed off then they’re just algae, hard to see in that pic. The single black spot definitely isn’t viral, it could be bacterial or fungal but doesn’t look very serious by itself. Some pleurothallids spot due to high temperatures, although that’s usually just small specks.

If the yellow stuff is indeed algae, then I hope those leaves weren’t removed from the plant, because otherwise those could be healthy leaves.
 

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Discussion Starter · #7 ·
The first picture (of the 3 leaves) I sent was from a few days ago. I had cut them off in fear that it was fungus. Here is the plant today so you can see the purpling and more of the yellow. I actually split it up and put it in different areas of the terrarium with a little less light to see if there is any improvement. I also unwound the small amount of sphagnum moss i had put around the roots and let them breathe in the air. I feel they may have been water logged due to the sphagnum moss as well. Now the roots can dry. I did that with a couple other orchids in the terrarium. Hopefully some of these live.
I ordered the Physan, but I am not sure I want to use it yet. I don't really have another spot for these orchids to grow if I remove them from the terrarium so I prefer to see how they deal with change of location and bare roots.
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As someone said above, purple (anthocyanins) is a response to high light. I have only ever seen it in orchids with red or purple flowers, but I still wouldn’t worry about it unless those purple sections are mushy.

Can you rub the yellow stuff off? Get a piece of paper towel, dip in rubbing alcohol, and gently massage the leaf. If the yellow comes off, it’s just algae and is not a problem for the plant. Bacteria and funguses aren’t an issue for orchids unless they have invaded the leaves internally, which causes pitting in various colors, often yellow, black or brown.

You should put a little sphagnum back around the roots, pleurothallids want consistent moisture to their roots but good air flow around their leaves. And then, if the yellow stuff comes off with alcohol, just leave it be for a couple months. You’ll do more damage by continuing to move, divide, cut leaves and generally fuss at it.
 

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Discussion Starter · #9 ·
As someone said above, purple (anthocyanins) is a response to high light. I have only ever seen it in orchids with red or purple flowers, but I still wouldn’t worry about it unless those purple sections are mushy.

Can you rub the yellow stuff off? Get a piece of paper towel, dip in rubbing alcohol, and gently massage the leaf. If the yellow comes off, it’s just algae and is not a problem for the plant. Bacteria and funguses aren’t an issue for orchids unless they have invaded the leaves internally, which causes pitting in various colors, often yellow, black or brown.

You should put a little sphagnum back around the roots, pleurothallids want consistent moisture to their roots but good air flow around their leaves. And then, if the yellow stuff comes off with alcohol, just leave it be for a couple months. You’ll do more damage by continuing to move, divide, cut leaves and generally fuss at it.
Thanks. I will buy some rubbing alcohol and try. All I have is peroxide and I'm guessing that's a no for using it. I will also add a tiny bit of moss around the roots.
 

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Discussion Starter · #11 ·
You could use a mix of vinegar and water, or just water. Peroxide might damage the leaves.
Thanks so much! I feel pretty stupid now. It totally rubbed off with water only. I am guessing it must have been algae from when I bought it that maybe discolored and turned yellow after the bleach solution. Hopefully they do OK now. :)
 
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