Chlorotic Leaf Issue, Again!!

[Happypaphy7]

Last year, I posted Paphiopedilum Pink Sky with bleaching leaves.
I have three Pink Sky and the other two are fine under the same conditions.
After I moved it out of the artificial light, it immediately started to return green and now the plant is completely green after a few months with some very small patches of white area here and there.

http://www.slippertalk.com/forum/showthread.php?t=41906&highlight=bleaching

Now, I am posting a new plant with a similar issue.
The plant is Paphiopedilum Dolliroth, a primary between henryanum and rothschildianum.
Someone posted a beautiful example of this hybrid in the past. The plant was purchased from Orchid Limited.
I looked up and they had very limited stock, so I got one in December 2016.
It has been a terribly slow grower working on second leaf since its arrival.

I have grown this under T8 like many of my other plants.
The first new leaf under my care came out near cream white, which then turned brown and now completely dead shown in the picture.
The second leaf is coming out completely cream white also.
There are two growths, and both are doing the exact same thing.

If it wasn't so rare, I would have just tossed it.
I would love to see it flower one day! It is a small plant in 2inch pot (now repotted in 4 inch pot in the photo), and supposedly a blooming size or near blooming size.

I wonder what in the artificial light might cause this on some plants and not on most others?

I moved the plant out of the artificial light two weeks ago. Still white as the phot was just taken today after watering.

 

[Ray]

I really doubt that has anything to do with lighting. The intensity on those leaves are only barely different from that hitting the others.

I'd look more to a disease or poisoning that is affecting them.

 

[SlipperFan]

My thoughts also. I'd check the roots.

 

[Stone]

Perhaps a physiological problem stemming from mixing genes which were never meant to be mixed. Most hybrids can give vigour but some turn out very weak or susceptible to one thing or another.

 

[Hien]

I think the same of what Mike said above , the leaves coming out randomly green or white , some will be white , and perhaps the white leaves don't have a way to make energy without chlorophyll, so eventually ,it turns brown and dies . Just guessing.

 

[Dandrobium]

I had a Macodes do that from an iron deficiency. Not sure if thats the case here or not

 

[Happypaphy7]

I really doubt that has anything to do with lighting. The intensity on those leaves are only barely different from that hitting the others.

I'd look more to a disease or poisoning that is affecting them.

Right, but light is the only thing I can think of.
It happens under artificial light only and once taken to natural light, the green color returns.

Very strange.

 

[Happypaphy7]

My thoughts also. I'd check the roots.

Recently repotted. Good roots.
On my Pink Sky, amazing roots.

 

[Happypaphy7]

I had a Macodes do that from an iron deficiency. Not sure if thats the case here or not

The fertilizer I use contain iron.
The pH is not out of wack, so I wouldn't think it's the iron deficiency.

 

[Happypaphy7]

Perhaps a physiological problem stemming from mixing genes which were never meant to be mixed. Most hybrids can give vigour but some turn out very weak or susceptible to one thing or another.

This is what I think, also.

 

[gego]

The fertilizer I use contain iron.
The pH is not out of wack, so I wouldn't think it's the iron deficiency.

Unless you boosted up your micronutrients, diluted pre mix fert may not have enough of them. Light could trigger the deficiency.

 

[myxodex]

My guess is that Ray has come up with the most likely causes, infection or toxicity.

A macronutrient issue that should still be ruled out is sulphur, as this is the classic symptom and some fertilisers are rather limited in S because of precipitation problems with Ca. Maybe the plant has genetic issues with S metabolism or transport. The bit of doubt I have with this is that S deficiency usually only shows up like this in rapidly growing plants, in paphs we might expect a more gradual yellowing of the newer leaves. It still might be worth increasing the amount of S in your feed, ... but the problem would be that the affected leaves might be too far gone to be able to reduce SO4 in the first place.

There are carbamate type fungicides like Mancozeb that come with complexed Mn and Zn. There is another type that has Cu. The point is that this compound degrades in light to a reduced S compound from which the plants can get reduced S and at the same time you might (?) be combating any infection. I think Bjorn has used mancozeb to boost micronutrients. Bear in mind that the S requirement of plants can be increased when they are fighting infection which is why S deficient plants are more prone to infection in the first place. Heavy metals and other free radical generating poisons can also increase S demand in a plant. So there could be a combination of issues going on here. A foliar spray with some reduced S compound like the amino acid cysteine could also be worth a try.

 

[Happypaphy7]

A new leaf is coming out and it is green.
Two "white" leaves are slowly greening up also.

This is exactly the same thing that Pink Sky did.
The only thing changed was the light.

This hybrid and Pink Sky are extreme cases, but I had quite a few paphs and other orchids that showed bleaching under T8 light.
Once they were moved out of the artificial light, the green always returned to normal.

 

[Ray]

If the light is absolutely the only thing that changes when you move the plants to natural light, it sounds like there is something grossly amiss with your artificial light source.

Frankly however, I have a hard time accepting that, as I've grown under 50/50 (wattage wise) incandescent and cold white fluorescents long before there were plant light phosphors, MH, HPS, fluorescent plant lights, and LEDs of all types of spectrum, and have never seen such issues.

It's baffling.

 

[Happypaphy7]

I know, but the light is the only thing changed.

Note that I didn't say ALL the plants. Quite a few bleached, and not just Paphs.
Majority seem fine.

 

[Ray]

I know, but the light is the only thing changed.

Note that I didn't say ALL the plants. Quite a few bleached, and not just Paphs.
Majority seem fine.

Looking at this from the perspective of someone trained in problem solving, I really doubt it's the "only" thing that changed.

That does not mean, however, that discerning what else might have changed will be easy.

 

[Happypaphy7]

I know. It seems very strange. But it is true.
Please read all I wrote.

While majority of the plants are fine under the light, quit a few bleached and two showed extreme bleaching.
All returned to green once out of the artificial light.
Simple as that.

 

[Chicago Chad]

Happy you are not alone with this. I recently bulked up my collecting habits over the past year. Most plants I buy will be in sets of 3 to 6. From this year I have a set of sangii which are all potted together so they receive the exact same treatment. One plant in the bunch has decided to throw up a leaf lacking the proper pigment being completely white. I have not seen this in 10 years of growing paphs. It has since grown a new one with proper color but only after I separated the pot from the artificial light source. I believe it is a genetic problem which is exasperated by some aspect of my culture, particularly with the lighting which is LED.

During the time it occurred my plants were also growing far too brightly so I believe it was the volume and spectrum of those LEDs.

 

[Happypaphy7]

Good to know!
Thanks for your input.

I always wonder if the light on for many hours at consistant level might stress these plants?
The way I understand is that they are usually shaded by taller plants and trees, so they receive dappled light.
Direct sun might shine on them but not for too long if at all.

 

[Ray]

I think one needs to think in terms of the sum of photons hitting the plants.

If you look at natural sunlight, the intensity over the course of a day is sort-of a bell curve - zero at dawn, max at noon, returning to zero at dusk. If you simulate that with a triangle, the area under that curve is 1/2 base (day duration) times height (peak intensity), and that number represents the "volume" of light it is exposed to.

Where artificial light growers often go wrong is reading that their plants should get "2000 foot candles" (for example), so expose their plants to that for 12 or 14 hours. However, that "triangle area" will tell you that for the same "volume of photons", they really should be providing roughly half that intensity for that constant duration.