# Leaf collapse? Why??



## atlantis (Apr 3, 2014)

Hi everyone.

I´m writing here to know you opinion about these pictures that I´ve taken from some of my friend’s plants.

As you see, there is a kind of collapse on them. It appears only in a few plants (lowii, tranlienianum...) but the rest show no signs, and they stay close to the affected plants.

It appears in both old and new leaves, but it doesn´t seem to affect flowering capacity or plant development. It might be only esthetic (for the time being…).

My friend and I live in the same town. Our growing condition are similar (a bit warmer and brighter in her case) but I haven´t had this problem in any of my plants yet, even when they´re kept colder and drier.

The growing conditions are:
- Temps. around 15 ºC and 20 ºC in winter, and 25 ºC - 32 ºC in summer.
- Humidity around 65-75% in the day and 40-45% at night.
- Fed regime: 12-30-12 and 23-6-10 very diluted once every few waterings during growing period (almost no fertilizer in winter).
- Plants are kept moist but not wet. Dryer in winter. Water here is very soft.

What do you think? Genetic, culture issues, temps, pest?
Thanks in advance for your help


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## eteson (Apr 3, 2014)

Hi Alberto are the roots of the plants OK?
Seem to me dehydration.


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## orcoholic (Apr 3, 2014)

Same here. 

Roots killed by watering too often and/or not repotting enough.

Usually what happens is that the roots rot (due to watering too often) and the leaves begin to look floppy so everyone thinks they are not watering enough and give more water. That kills the roots faster.

Repot and water only after plant is dry.


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## eaborne (Apr 3, 2014)

I agree, looks like dehydration.


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## Paph_LdyMacBeth (Apr 3, 2014)

Can you fix this with re-hydration?


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## Stone (Apr 3, 2014)

I'm not sure its dehydration or the other plants would show similar symptoms wouldn't they? Also paph leaves don't really go ''floppy'' from what I've seen especially lowii. I could be wrong but the dehydration I have seen does not form pits. It begins with the leaf losing its shine and slowly becoming dryer and starts to curl inwardly.
I have seen this kind of thing after spraying with some pesticides. Some plants affected some not.
Look forward to seeing the answer to this problem!


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## ALToronto (Apr 4, 2014)

I have the same thing happening on a few of my phals, and only the phals. Some have suggested it's insects - false mites that cannot be seen without serious magnification. 

I've sprayed with SucraShield twice already, will do a third application this weekend. Of course, if it's insects, I won't see any results on the existing leaves, I'll have to wait for new leaves to come out to be sure if the remedy has worked.


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## tomkalina (Apr 4, 2014)

Looks similar to the mesophyll cell collapse we see in Phalaenopsis leaves when cold water is use for irrigation.


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## ALToronto (Apr 4, 2014)

tomkalina said:


> Looks similar to the mesophyll cell collapse we see in Phalaenopsis leaves when cold water is use for irrigation.



Tom, how warm should the water be? I use RO water, and the storage tank is in a poorly heated part of the house, so the water is probably at 10 degrees or less. Is this too cold? I do have the option of adding hot RO water to the sprayer.


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## tomkalina (Apr 4, 2014)

IMHO the water should be close to the temperature of the growing area. If you're watering with water that's 10C (50F) or less, and the growing area is around 20C (68F) mesophyll cell collapse may be possibility, especially in the strap leaved Paph. species/hybrids.


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## gonewild (Apr 4, 2014)

Ideally the water temperature should be the same as the leaf temperature, which may be higher that the air temperature.


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## NYEric (Apr 4, 2014)

tomkalina said:


> Looks similar to the mesophyll cell collapse we see in Phalaenopsis leaves when cold water is use for irrigation.



This.


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## Ozpaph (Apr 5, 2014)

I vote mesophyll collapse, as well. Often a temperature related phenomenon, I understand.


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## Rick (Apr 5, 2014)

Also humidity is low at night.

If roots are shot they are going to loose a lot of water if the humidity is low.

Humidity generally goes up at night. Why the drop?


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## atlantis (Apr 7, 2014)

Thank you all. I appreciate all you opinions a lot.

For those who bet for root problems, I have some recent pics taken last saturday:
- First photo shows the roots of an adult multigrowth P. lowii.


- Second photo shows a multigrowth P. Lady Rothschild also afected.





Stone said:


> I'm not sure its dehydration or the other plants would show similar symptoms wouldn't they? Also paph leaves don't really go ''floppy'' from what I've seen especially lowii. I could be wrong but the dehydration I have seen does not form pits. It begins with the leaf losing its shine and slowly becoming dryer and starts to curl inwardly.
> I have seen this kind of thing after spraying with some pesticides. Some plants affected some not.
> Look forward to seeing the answer to this problem!


*Stone*: that´s exactly my thought. A dehydration suggests that, if the watering schedule is similar for all the plants, most of them must be affected (well, considering they had exactly the same mix, root mass and pot size).
What about an individual tendency to dehydration? I.e. lowii seems more prone to be affected compared to other related species...



Paph_LdyMacBeth said:


> Can you fix this with re-hydration?


*Paph_LdyMacBeth*: No, I can´t. And it appears also in summer, when watering frequency is higher.



ALToronto said:


> I have the same thing happening on a few of my phals, and only the phals. Some have suggested it's insects - false mites that cannot be seen without serious magnification.
> 
> I've sprayed with SucraShield twice already, will do a third application this weekend. Of course, if it's insects, I won't see any results on the existing leaves, I'll have to wait for new leaves to come out to be sure if the remedy has worked.


*ALToronto*: that´s another good explanation we´ve been thinking about. Some of the affected leaves have a kind of path, but only some of them. We´ve never been able to see insects... but I think it´s a good idea to search for it using a microscope. Thank you  



tomkalina said:


> Looks similar to the mesophyll cell collapse we see in Phalaenopsis leaves when cold water is use for irrigation.


Tom: You´re right but, as she doesn´t water by irrigation I don´t think that is the problem. Moreover I asked her about the water temperature (just to discard some kind of temperature stress) and she is very careful with it.



Ozpaph said:


> I vote mesophyll collapse, as well. Often a temperature related phenomenon, I understand.


*Ozpaph*: we were asked about it too. Someone (I can´t remember who) suggested excess cold as possible cause, but I keep my plants in winter under lower temperature than she (maybe 3-4 ºC lower) and my plants don´t show any sign (well, I have to say that my only Phrag. is not very happy with this treatment )



Rick said:


> Also humidity is low at night.
> If roots are shot they are going to loose a lot of water if the humidity is low.
> Humidity generally goes up at night. Why the drop?


*Rick*: I find this input specially interesting because it´s something we haven´t thought about yet.
In our case, we grow our plants indoor (at home) and the humidity we have is what we can reach using foggers. We have cold dry winters (Humidity 30-35% outside) and extremely hot and dry summers (with less than 20% outside) so, when we switch off the foggers, the humidity drops to those low levels.

Thank you all again for your help!


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## Stone (Apr 9, 2014)

atlantis;477784
[QUOTE said:


> What about an individual tendency to dehydration? I.e. lowii seems more prone to be affected compared to other related species...



Being a true epiphyte, lowii should be more resistant to drying than just about any other paph. (except perhaps niveum and godyfroyae) Therefore I would say chemical damage or temp damage?


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## Ozpaph (Apr 10, 2014)

Also, it may not be absolute temperature range but sudden drops in temperature. Worth considering.


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## Rick (May 11, 2014)

Stone said:


> Being a true epiphyte, lowii should be more resistant to drying than just about any other paph.



A true epiphyte in Borneo and Philippines where air humidity rarely drops below 80% and it rains almost every day.

If we were talking about epiphytic Cattleya maxima I'd say no problem with the sparse humidity and watering regime.


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## Carper (May 11, 2014)

I've had this problem on a few of my plants which occurred last summer in the UK. It was an exceptional summer with many hot days. My plants also got extra light so a combination of heat and too much light may have been the cause. I tried to keep the temp in the gh down but they reached 95F at some points.

Gary
UK


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## ehanes7612 (May 11, 2014)

I water with 40 degree F water ( I watered with warm water in years past) and have no problem with any of my paphs developing pits( on this level anyway, except for lowii's whether it be warm or cold water)...this seems to be a common problem with lowii's...and none of the aforementioned theories fixed it when I grew them, so I gave up on them


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## Stone (May 11, 2014)

Rick said:


> A true epiphyte in Borneo and Philippines where air humidity rarely drops below 80% and it rains almost every day.
> 
> If we were talking about epiphytic Cattleya maxima I'd say no problem with the sparse humidity and watering regime.



Yes but if it doesn't rain for a couple of months - which can happen - roots will dry ( not desicate of course ) and all epiphytes have evolved to cope with this. but I agree it is generally a ''wet'' area. I was refering mainly to dryness at the root. I let my lowii almost dry out before I soak it and it seems to be doing well however I do spray the leaves almost every day.


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## Rick (May 11, 2014)

Stone said:


> Yes but if it doesn't rain for a couple of months - which can happen - roots will dry ( not desicate of course ) and all epiphytes have evolved to cope with this. but I agree it is generally a ''wet'' area. I was refering mainly to dryness at the root. I let my lowii almost dry out before I soak it and it seems to be doing well however I do spray the leaves almost every day.



Epiphytes have evolved to cope with very different conditions for different forests/climates.

All slippers are C3 plants while just about all Catts are CAM. That alone will tell you that the amount of water needed for any slipper (whether at the roots or in the air) is going to be quite a bit more (and continuous) than for a Catt.

I haven't seen any data on Mexipedium so maybe that will be the first CAM slipper discovered. But Paph parishii (also an epiphytic paph from the same subgenera as lowii, but with thicker leaves) was tested for C3/CAM capability and it came out C3 even though it probably comes from even dryer regime than lowii.

Compared to a CAM plant, C3 plants are water hogs with pores open at day regardless of temp and humidity.


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## Stone (May 12, 2014)

Rick said:


> Epiphytes have evolved to cope with very different conditions for different forests/climates.
> 
> All slippers are C3 plants while just about all Catts are CAM. That alone will tell you that the amount of water needed for any slipper (whether at the roots or in the air) is going to be quite a bit more (and continuous) than for a Catt.
> 
> ...



Yeah its not quite that simple. Phals are CAM and they grow in the same sort of humidity your talking about. Also CAM and C3 orchids were found growing on the same tree in Nth Queensland.


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## ALToronto (May 13, 2014)

My affected phals are now growing new leaves, and the new ones are flawless. At the same time, the temperature in my home, at the window, has gone up from nighttime lows of 16 degrees to 20-21. Could it really be a temperature thing?. The poor phals are exceptionally ugly right now, but one is in bloom, and 4 others just finished blooming.

What I find most interesting is that mature phals were affected much more than the 100 or so phal seedlings sitting right beside them. Of the seedlings, only 5 plants were affected. The seedlings were deflasked last July, and managed to grow through our brutal winter.


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## Rick (May 19, 2014)

ALToronto said:


> My affected phals are now growing new leaves, and the new ones are flawless. At the same time, the temperature in my home, at the window, has gone up from nighttime lows of 16 degrees to 20-21. Could it really be a temperature thing?.



Could be, and add humidity.

My night lows during winter are also around 16 C. But this year which is worse than the last 10, in that the day high in my GH may only have got up to 18C on cloudy days.

Overall that has to be a winter stress for stuff that normally stays above 21C.

I think you are under lights, what is your day length set too?


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## Rick (May 19, 2014)

Stone said:


> Yeah its not quite that simple. Phals are CAM and they grow in the same sort of humidity your talking about. Also CAM and C3 orchids were found growing on the same tree in Nth Queensland.



I also read recently that a Phal species was (I think amabilis or aphrodite) was determined to have CAM leaves and C3 roots. And even within CAM there are degrees of it.

Certainly quite a bit of complication, but just on a metabolic basis, C3 consumes a lot more water than CAM.


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## Stone (May 20, 2014)

Rick said:


> > Certainly quite a bit of complication, but just on a metabolic basis, C3 consumes a lot more water than CAM
> 
> 
> 
> Agreed


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## Happypaphy7 (Sep 5, 2014)

The mystery continues. 

I thought I have seen some pits on my paphs, but wow~ that looks quite serious! lol

I have asked people about this collapse, and basically no one knew what causes this.

I am dying to know for mainly curiousity's sake because almost all my paphs (over hundred) have varying degree of this kind of cell collapse and they all seem to do well. 
Some do not have any at all or very few in the shape of very very tiny hole, while some have quite a population of them in certain area on the leaves.
Then some have indentation that are much bigger, but all of them are confined to a small area of a leaf as opposed to the picture of the original thread starter. 

I see this occur both on old and new leaves.

I do not think it is water or temperature related.
My paphs are well watered, and these still occur.
I have been gone up to two weeks with no one coming in to water and I do not see sudden increase in numbers when I return.

I have very moderate temperature all year around in my apartment.

I think it could be those mites that are invisible? but no idea.

Apparently, the plants grow and flower fine.
So far, it's mainly just aesthetic, but I would love to know what it is and why it is happening.


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