Large black spots on pleurothallis

[clintonsparsons]

I received this pleurothallis two days ago from a vendor. Is this a fungal or bacterial infection?

Cut off affected leaves and medicate? I have azoxystrobin on hand as a systematic antifungal, and physan 20 as a bacteriocide.

[SouthPark]

Were the spots already there when it arrived?

As usual - avoid water-logging of roots ----- ensure good air-flow to the whole plant (roots, media, and all). Good drainage pot.

If light intensity is too high, then do something to cut down on any burning or scorching.

If it is fungal - or spreading, then some orchid-recommended fungicide (mancozeb - non systematic) would be beneficial. Your systematic fungicide could help. It just depends on the actual situation.

If the spots were there already - then it might be a good idea to chat to the vendor - to see what they say about it.

If those spots are dried and hard, and not growing or spreading, then just maintain good air-flow to the whole plant (roots, media, leaves and all), and provide all the other necessary conditions (good temperature, suitable lighting level and duration).

[Roberta]

Unless the spots are spreading and are soft, you don't need to do anything... thin-leaved orchids that live in a moist environment (like pleurothallids) tend to get blemishes on the leaves - may be fungal, but if it doesn't spread not really a problem. When you water, try not to hit the leaves (especially if it is cold) It might just be the photo, but the leaves look on the yellow side, indicating that the plant would prefer a bit less light. These do tend to be low-light plants.

[aliceinwl]

I think this is a fungal infection based on what I’ve looked up. My outdoor orchids tend to get it when exposed to cold wet conditions (a cold rain). It seems to be mainly cosmetic. In cases where I’ve brought an affected keiki inside where it is warm and dry, the spots never spread and no new spotting occurs. The existing spots are there to stay, but as long as the existing foliage and pseudobulbs are kept dry, I wouldn’t expect to see any new spots develop.

[Ray]

Probably a result of water droplets standing on leaves becoming microbe incubators.

You might consider regular use of a probiotic rather than curative measures, after-the-fact. Both Quantum Orchid and Concentric Ag’s Inocucor Garden Solution will work, but the latter is far more of a broad spectrum product (and my price includes shipping).

[clintonsparsons]

I only received the plant two days ago. I dont know how the vendor was watering it or what light they kept it in.

I will look into those products ray!

In the meantime, I'm go ij ng to go ahead and remove the offending leaves and treat with a fungicide. I am paranoid.

[SouthPark]

Originally Posted by clintonsparsons

In the meantime, I'm go ij ng to go ahead and remove the offending leaves and treat with a fungicide. I am paranoid.

There appears to be lots of those spots and patches among all the leaves. So it is probably better to just apply a systematic fungicide (orchid-recommended on) to the whole plant.

And give this plant good air-flow all around it - leaves, roots, media, stem and all.

Removing too many leaves could weaken the plant.

Also - if the spots were already on there when it arrived, then a chat with the vendor would be a good idea. You can see what they have to say about it first.

If it does turn out to be fungal, and if it spreads and becomes terminal - then at least the vendor could possibly help you by sending you a replacement.

But if you begin to do surgery on this plant when the issue is of no fault of your own, then that could become a disadvantage.