Splitting phal leaf theory

[GiovannaD]

I have this theory. I'm not sure if someone somewhere has expressed the exact theory before...And cjcorner's previous thread on stained leaves got me thinking and observed my phals a bit closer.

In the last month, I've started misting the leaves with water and a bit of fertilizer (at 1/4 strength and maybe less). I've noticed that a considerable amount of residue builds up on the leaves, in the form of leaf stains. I remove these regurarly with a moistened cotton pad and a droplet of lemon juice.
Even though I clean them once or twice a week, I'm beginning to notice some leaves are splitting at the tip. RH is not a problem. I monitor the RH levels with a digital meter and it's usually at 45-55% and at times 60%. Spring in Athens is mild with temps from 16-25 C (61-77F) and the grow area (inside the house) usually reads 21 C (70F).
I'm growing my phals in s/h using water at 6.0PH (not RO water) and diluted liquid urea free orchid fert at 1/4 the strength.
I'm thinking that splitting leaves is a result of a chemical burn from the evaporating fert residues.
Feel free to express your opinion.

[Mehera]

It sounds like you are being very careful and attentive. I know that I have backed off from handling my phal leaves very much; they are fairly brittle and easy to crack.

[uncasteeb]

You could be right that the misting is causing the leaves to split.I have noticed on some paphs that they get a line in the middle of the leaf which looks like sunburn.Maybe a small amount of water on the joint of the leaf
is causing the burn under my HPS setup & this would cause the leaf to split eventually.

[GiovannaD]

I tend to pamper my phals mostly because my collection is very small and I have the luxury of time (for now).
However the end splitting leaves started to develop when I added a bit of fert to the water bottle. I had heard of this (the splitting leaves) before from other growers but it was considered an issue relative to low humidity.

[clintdawley]

I'm with Lynda. I don't think the ferts have caused the problem but maybe the dabbing and cleaning up has.

I have foliar fed phals for ages without these kinds of problems...

[Gin]

I read somewhere the extra humidity/ water on the leaves could over load the leaf cells causing them to split . Don't know about this for sure as I just feed the roots . Gin

[Kerry]

The only phal leaves that i have noticed splitting, are those that are very long.

I had assumed that this would be something to do with lack of humidity, as when the leaves are less turgid, they do not support themselves and stand up as straight as they could.

Mind you, I don't really mist mine. I may well do more of this in the summer as it gets hotter continually.

[AlessandraS]

Gin, the cells only split when they are growing, they burst when the cells are overloaded with water, but this shows up as a hematoma, not splitting, and it's not dangerous.
Personally, I don't believe leaf splitting is caused by too much water or misting. It seems as if it has to do with drying more than too much water.

[wetfeet101b]

I do not think that the leaf split is entirely due to fertilizer exposure, or foliar misting. They could be contributing factors, but not the main cause.

Taking a cross section of a leaf, we will see these main sections (simplified):
1. Epidermis
2. Mesophyll layer
3. leaf veins

The leaf veins are relatively pliant and can expand and contract significantly depending on water content.
The mesophyll layer simply moves around, filling in any gaps within the leaf structure.
In some plants, the epidermis tends to be less pliant than the other parts.

Now picture this scenario:
1. The leaf is growing in a period of low water content. It could be several days, or several weeks. I dont really know.
2. The plant has conditioned the leaf to have the epidermis grow and harden at a predetermined rate, based on how much water and nutrients it is getting.
3. Then the plant is given a lot of water. That water ends up in the leaves.
4. The root veins expand due to the water content - but no cellular rupturing happens. The root veins are designed to hold water.
5. Instead, it is the epidermis that could not flex fast enough to cope with the sudden expansion of the interior and ruptures physically at the seams.


Fertilizer exposure, sunburn, etc, they could have contributed to this by weakening the leaf's epidermis and making it more prone to this rupturing.

A similar phenomenon happens to citrus fruits when they are overwatered after going through a dry spell.

Why does this happen to phals more often than other plants? Perhaps it is for the same reason that this happens more to "thin skinned" citrus fruits than others.
The epidermis may just be significantly thinner or less pliant (or both) on these species compared to others.

~John

[Cjcorner]

I have to chime in....just because I am obsessed with Phals...lol. I water my orchids from above...like the rain. Then before I take them in, I dab their leaves with a paper towel so they aren't left with water in the crowns and so that there isn't too much moisture left on the leaves. So far.....no cracks. I also mist because I have sicko's that need to grow new roots. I have alot of time on my hands, some days I mist because I'm bored. lol So far even the baby dendrobiums dont seem to mind. I have developed a theory about Phal's of my own....
They are moody creatures and do what they want in their own time. If they want to crack up....let them. lol If they want to hang sideways out their pot instead of standing up like a normal Phal would...let them.
Connie