Paph with brown spotted undersides
 

This is a Paph who is developing dark spots on the undersides of its leaves. The aren't the harmless little speckles that I'm used to seeing. They're large and more menacing. The upper leaves on the plant are entirely free of this. Almost all of the undersides are affected. Can anyone help diagnose these? Thanks much. :)

https://live.staticflickr.com/65535/...d6a1959a_n.jpg20210624_162748

https://live.staticflickr.com/65535/...978dd2c8_n.jpg20210624_162813

https://live.staticflickr.com/65535/...efc57127_n.jpg20210624_154512

Here's a pic of the topside of the leaves.

https://live.staticflickr.com/65535/...97634533_n.jpg2021-06-24_04-58-48

What are your growing conditions? How are you watering? How long have you had it? When was it last repotted?

It looks very dessicated, like it has been underwatered for weeks. Paphs should never dry out during the growing season, and only a few tolerate it during winter. Either it hasn't received enough water or the roots are dead.

Underwatering can cause spotting like this. So can spider mites. Check for those.

If you zoom in on the picture one can see the roots are all brown and hollow, squeezing them would confirm they have died but it looks that way.

I've had it for a year, I've never repotted it, and it grows indoors under lights.

Watering? Hmm. The plant's been under "husband care" for the last 7 months. I got really sick in November, and my husband took over everything at that point. He says that he's been watering following my instructions...which were to every day check how damp it was by checking the stake that I keep in the pot.

It does look really desiccated (like many of mine now). The exposed roots on top are probably dead. I didn't know that underwatering could cause spots like this.

I can't say for sure but I would consider these spots to be a sign of stress. If a plant is stressed it has to show it somehow, usually by getting infected by something. So any stressful situation whether getting watered too much or too little can cause problems but you can never predict what it will look like, if something does not look right then you have to start playing detective and more often than not it is the rootzone that is the culprit. If the roots have gone bad they will cause soggy conditions in the pot so they need to be pulled away if they are soft and pull away easily, if they are firm then they are still alive. Don't be too hard on your husband, it is really hard to follow a watering schedule someone else has been following, it takes time to get a feel for it but rotting roots indicate things were probably not drying out sufficiently between watering which again is a very common mistake. The best tip I have for your husband is to look at the bottom of the pot, water sinks to the bottom so as long as there is moisture in the bottom of the pot which shows as condensation then the pot can still go without watering for longer. It's nothing that can't be saved but I'd start by getting your husband to learn how to clean some roots ;)

You're right, and my husband has been the best.:bowing He's been so conscientious. I'm beginning to take back the orchid care from him. I think I need to do some repotting...or at least check the roots on a few plants!

I'm sorry you've been ill, and hope you recover soon.

Given that history, I'm fairly sure the spots are from underwatering. The stake method is not useful for plants in chunky bark; there isn't enough contact between bark and stake,. Just water Paphs every 2-3 days. If the medium is in good shape they do well.

It would benefit from repotting. Paphs are like Phals in that repotting almost doesn't affect them. Medium bark would be a better choice, but if you only have large bark, use that.

Hold the plant gently, turn the pot upside down, and ease it out of the pot. Shake off only the old medium that falls off easily. Don't cut any roots.

Set the plant down on the table. Clean the old pot with soap and water. It's the right size for this plant.

Put a little of the new medium just on the bottom of the pot.

Hold the plant with one hand, suspended, with roots dangling in the pot, and the leaf base just below the pot rim.

Use the other hand to backfill with new medium. The root zone should wind up just below the new surface of the medium.

Set in a bowl. Fill with water to an inch below the rim. Let it soak 8-12 hours.

Put back in its spot. Put a saucer under it. Water heavily every day for a week, leaving a half inch of water in the saucer. New bark doesn't hold water well.

Then water heavily every time the water in the saucer is gone.

After a few weeks it should look a lot better.

Paph roots don't look at all like roots of other orchids. They are normally mid to dark brown, and fuzzy. People here on OB have not known this, and cut off all their normal Paph roots because they thought they should look like Cattleya roots. They don't.

If you'd like to learn more on Paphs, here are some notes from a lecture given by the orchid curator at the Huntington Gardens in Los Angeles.

Thank you, ES, awesome post. I will tackle this tomorrow morning.

ES, can I use this same method for a cattleya? Thanks.