Indentations on Phal leaf

[The Mutant]

I noticed this today on one of my Phal's leaves. What the heck is it? It's not soft or anything like that and it's only on the top side of the leaf.

The Phal is already isolated due to the very yellow leaf tip it has on one of its older leaves. I know that they normally lose their older leaves, but the yellow colouration was so very sharp on this leaf that I decided to isolated and keep it monitored.

[Val]

I suspect mesophyll cell collapse:
PP265/PP265: Physiological Disorders in Orchids: Mesophyll Cell Collapse

[Wynn Dee13]

I think the indentations on the top of the leaf could be a burn from light or cold. I wouldn't worry about the yellow leaf tip.

[The Mutant]

Originally Posted by Val

I suspect mesophyll cell collapse:
PP265/PP265: Physiological Disorders in Orchids: Mesophyll Cell Collapse

I thought something similar and after reading the article you linked to, I think it could have been caused by the fluctuation in the temperatures (I haven't had low enough temperatures for it to be caused only by that) since there has been some drastic differences between day and night temps in my flat during the last month or so. The fact that this guy might be sensitive to too much of a gap between day and night temps, doesn't make it any better I think.

Thank you for the link, I feel much calmer now.

Originally Posted by Wynn Dee13

I think the indentations on the top of the leaf could be a burn from light or cold. I wouldn't worry about the yellow leaf tip.

That's what I though too, but since the temperatures haven't been low enough I got worried. Thanks to Val's link, I think this might be the cause anyway, so I feel less worried now. But I think I'll keep my little guy in the room with more even temperatures so as to prevent this from happening again.

It is my little mutant after all so I really don't want to cause it unnecessary stress.

One of my newly purchased small phals has several spots like that on one leaf and I was going to throw it away thinking it was some kind of disease. Good thing I came across this thread.
We probably need to watch that it doesn't get bigger.

[silken]

It's likely just stress, but there is that contagious Phal disease that results in sunken areas on the leaf also. Usually it starts first with yellow spots or streaks which yours doesn't have. But better to isolate and be cautious. I would consider giving it a spray of Physan also just to be safe.