Cattleya leaves with "blisters"

[CoolPhrog]

I am almost positive that someone has posted this question before....but...

This appears to be afflicting my C. Netrasiri Waxy 'Jairug' with some concern, it's on two older "growths" and isn't on any of the other leaves...Is this serious?

[Ross]

Looks like sunburn damage to me. Not sure tho.

[susiep]

I have seen that many times before on my orchids. Mainly catts. I asked a grower at a show once what it was and he said it can happen from too much water after too little water. Kind of like some of the cells burst and what you see is scar tissue. It looks like cancer to me, but it never gets worse or spreads.

[Becca]

Like Ross said, looks like sunburn, is it in direct sun? What ever it is it doesn't look good. If it isn't sunburn, I would be chopping those parts of the leaves off in a hurry! But then again, if it isn't spreading at all like mentioned by susie, I would just watch it closely!

[CoolPhrog]

WHEW!!! I'm concerned about the water thing though...all of my plants are watered consistantly...hmmm...

Thank you all of your repsonses (and comfort)

[wetfeet101b]

I agree. Those are sunburn blisters from too much sunlight.

Overwatering while the plant is exposed to very warm conditions could also cause this (minus the scorch marks). The plant tries to take as much water as it can from the roots and pseudobulbs, and transpirate at the leaves. But sometimes it results in a buildup of water on the leaves faster than it can transpirate and results in damage to cell walls.

This seems to happen more to "thick leaved" orchids like some cattleya alliance and some dendrobiums. I guess in part because these are the orchids typically exposed to brighter/warmer sunlight.

[Ray]

1) Forget the watering thing. Plants aren't gluttonous like people, but absorb by osmosis. They will never take in more water than they need. If that affect was valid, any plant grown hot in s/h culture would exhibit that. In 35+ years of growing, I have never seen such an occurrence.

2) A pure burn will turn dry and parchment-like. Plants do not blister like we do.

3) On the other hand, if some damage was done, and then water stood on the damaged area, that could lead to a fungal- or bacterial infection that could cause blisters.

[susiep]

At the risk of . The spots that I am talking about are not due to bacteria or virus or water sitting on the leaves and possibly not even to "sunburn". I have been growing for 35+ years down here in south Florida and I have seen this many times before. As a matter of fact I have at least 10 examples in my orchid house right now. One old catt of mine has had the same ugly spot for years because that is how old that leaf is. It has never gotten worse (but of course not better either). It is a scar that looks like a melanoma. Now my is this occurs when a hard, thick leaf (catt, for example) gets dehydrated. It can't "wilt" in the usual way because of it's fiborous structure, but inside the cells are damaged. Then you flood the plant with water and all that water flowing into those damaged cells just break the cell walls. However this damaged area is still contained by the rigid structure of the rest of the leaf and the remaining good cells. Over time the dead area hardens up and forms a scar. Down here too much heat (dehydration) and then deluges of water (rain) are cyclic. That is why we see it much more here. Just my . Here is a of a spot on Ctna Mem Henry Goldberg (Why Not 'Roundabout' x Keith Roth) and it's new flowers!

[CoolPhrog]

Thank you everyone for your responses.

The "scars" on my catt where there when I bought it...it might be possible that it was getting a great deal of light (though not direct) based on it's location in the greenhouse where it was purchased. I know the grower and I'm not sure how often he waters but I certain it's at least weekly and he also has a misting system in use....since it's been with me, it gets misted daily (including the leaves) and gets watered/fed weekly)....as you stated, Susie, it hasn't gotten worse but it hasn't gotten better either....Ray, how do I determine if this is an infection?

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[susiep]

Yes, that is a very good question! This debate has made me very concerned about spots that I would otherwise ignore. Is there a way to test?