Variegated or nutrient deficient?

[SouthPark]

I would gently take the plant out of the pot and see what is really going on with the roots. It looks good but perhaps there is a problem.
If there are bad roots they can not absorb the nutrients that you are applying.

Good call on that one. Just in case.

And also check media/root temperature. Although, the interesting thing here is that this orchid is turning pale in the new leaves - while the other (I assume) many other phrags in that growing area are doing just fine (not behaving in this way) under the assumed same conditions and growing method.

 

[myxodex]

My money is on an S deficiency, the symptoms are classic and your fertiliser is short on S to begin with.
Epsom salts supplies both magnesium and sulphur, so you don't need plaster-of-Paris or gypsum (it comes with it's own complications).

 

[Phred]

Ok... here’s my experience on the subject. I’ve been growing under lights for 4 years now... there is a big learning curve. I started to have issues with parts of leaves or leaves turning yellow... old, new, tip and even some in the middle of the leaf. I tried magnesium sulfate and continued to lose leaves

 

[Phred]

I water each plant one at a time over the sink. I take the plant off the right end of the tray and as I water they all move to the right with the plant I took off first going back onto the tray at the left. This way they take turns directly under the light. As I was watering I noticed something odd. A leaf from one plant was resting on a leaf from the plant that was next to it. When I saw a darker spot where the one leaf was resting on the other I figured there was too much light.

 

[Phred]

So figuring there was too much light... and because I can’t adjust the height of my lights I added some shade material just under the lights. I continued to have problems so several months latter I added a second narrower piece of shade cloth under the light.

 

[Phred]

Over the next several months I stopped have trouble with leaves turning yellow. I noticed something else that at first confounded me. My Paphs, most of which are mini’s, were getting very long in leaf.
SEPTEMBER 2017

SEPTEMBER 2020

 

[Phred]

The lesson I learned...
Plants in high light need more nitrogen... and water and air movement.
Plant leaves grow longer than normal when plants are grown in too little light.
I took all the shade material off and increased my nitrogen substantially at each watering.
To my surprise I haven’t had any yellowing and all new growth and inflorescence length are normal size now.
More light, more nitrogen and more water means the plants are putting on more new growths faster also.

 

[SouthPark]

When I saw a darker spot where the one leaf was resting on the other I figured there was too much light.

A tan line for orchids! Nice!

Very nice information too Phred. Thanks for posting that. Also - are those leaves actually variegated? Or is that light-induced variegation? Very very interesting.

 

[Phred]

Citric acid also increases chlorophyll content in leaves. I make my own pH down by mixing 10 teaspoons of citric acid and I teaspoon of malic acid in a quart of distilled water. It's cheap and there are many ways you plants can benefit from some organic acids.

 

[Phred]

A tan line for orchids! Nice!

Very nice information too Phred. Thanks for posting that. Also - are those leaves actually variegated? Or is that light-induced variegation? Very very interesting.

Yes... it's a variegated Paph Paph insigne.

 

[NYEric]

Variegated! $5,000! Good luck.

 

[Djthomp28]

I had a similar but less severe issue a while back with a phrag. Jerry Fischer said acidicity was the problem. He thought my fertilizer was too acid. I found that my media had become acid also. Between change the media and being mindful of the solution pH, my phrag greened up in 6 or so weeks.

 

[Ozpaph]

Citric acid also increases chlorophyll content in leaves. I make my own pH down by mixing 10 teaspoons of citric acid and I teaspoon of malic acid in a quart of distilled water. It's cheap and there are many ways you plants can benefit from some organic acids.

what do you dilute that solution to?

 

[Phred]

what do you dilute that solution to?

I use it to lower the pH of my tap water which is about 7.3
If you didn't need to lower your pH you could mist with it. You would have to dilute it to an appropriate pH for misting.
There are a number of research papers online looking at foliar applications of citric acid.

 

[PeteM]

I use it to lower the pH of my tap water which is about 7.3
If you didn't need to lower your pH you could mist with it. You would have to dilute it to an appropriate pH for misting.
There are a number of research papers online looking at foliar applications of citric acid.

fascinating. Thanks for sharing this detail, I’ll be looking into this come growing season. Looks to also impact the blooms

https://www.frontiersin.org/articles/10.3389/fpls.2011.00106/full

 

[Happypaphy7]

Try moving the plant to the natural light near the window area for one week and see if it greens up at all.
I have Paphiopedilum Pink Sky doing this same thing. For some reason, I have two plants from the same batch, and only one plant exhibited this chlorosis, so it was very strange.
In about 7-10 days after being placed in the natural light, the plant started to green up. Some plants may not like artificial light, but why others are fine??

 

[Berthold]

It's some kind of metabolic disorder. There are many different options. Nutritional deficiency is only one of them, but certainly not in this case. One possible therapy is changing the substrate. The cause of the metabolic disorder can also be an infection in the root area.

 

[Ozpaph]

I use it to lower the pH of my tap water which is about 7.3
If you didn't need to lower your pH you could mist with it. You would have to dilute it to an appropriate pH for misting.
There are a number of research papers online looking at foliar applications of citric acid.

I added 1/4 teaspoon 'cooking/food grade' crystallized, citric acid to 8l water it reduced the pH from 11 to 5.5. (RO water + siO2), so Im intrgued by the seemingly high dose you use.

 

[Phred]

I added 1/4 teaspoon 'cooking/food grade' crystallized, citric acid to 8l water it reduced the pH from 11 to 5.5. (RO water + siO2), so Im intrgued by the seemingly high dose you use.

I didn't say how much I use... lol. The mix I spoke about is a stock solution. You can mix it however you want but I think 10 parts citric acid to 1 part malic acid is most beneficial. Once you have a stock solution you have to determine how much to use by checking the pH of what you're diluting it in as you use it. I mix 5 gallons of fertigation water at a time. I use 2 tbsp of my stock solution to lower my pH, after fertilizer is added, to 5.6 or so. I'm guessing I'm only using about 1/3 tsp of citric acid/5 gal. Depending on the silicon product you're using it can lower your pH also.

 

[Ozpaph]

That sounds much better. thanks