yellow leaves on paph. gigantifolium

[musa]

Hello,
my gigantifolium is getting yellow leaves what makes me realy nervous.
On the first two fotos taken under grow lights it is obvious. For comparison it stands between kolopakingii (left) and platiphyllum (right). The last two fotos are done under normal light withour flash.
I already repotted it, it's in orchiata with a bit of marble gravel. Rootsystem is not perfect but there are four growing root tips. For some weeks it gets an extradose of epsom salt. How should I go on?
I really appreciate your help!

 

[GuRu]

Michael, I think you potted the plant a bit too dep in the potting medium. Therefor the very low leaves are rotting at their base.

 

[Ozpaph]

probably no roots

 

[musa]

Thank you both.
I'll take away some potting media to give room to the lower leaves.
With four growing root tips roots are not too good but I didn't imagine it would have such an effect. I already repotted it, what else could I do to induce root growth?
Thanks

 

[Martin]

I heard that a fertilizer with high K Help root growing. There is one called Plantstarter, which has about 40 K

 

[masaccio]

Is there a chance that you are over-lighting? The plant on the other side of the kolopakingii also looks a little yellowed.

 

[musa]

Thank you both!
They are under two tubes 36W growlight of OSRAM. I non't think that is excessive, but I cut the light down 1,5 hours per day.
What you can see on the far left is intaniae. You are right, massaccio, that it is a little light, too. However the gigantifolium is worse and I'm most worried about.
Martin I'll keep the K in mind and will see to to find some extra.

What I'm worried about as I can't explain it are the little dark green dots on the leaf in the second foto (post1). Might there be some kind of infection?

 

[masaccio]

These are LED tubes? I don't know about OSRAM. They have a wide array of products so it's difficult to deduce your particular product. The red flag for me was 35 watts of LED light. I use 26 watt LEDs (2600 lumens) Sylvania spots for growing Cattleyas and those are roughly 20" away from leaf TIPS. For paphs, its 19 watt CREE spots (1500 lumens), which are almost three feet away from horizontal leaves on roth crosses. But my PPFD ratings are quite satisfactory. I run them 12 hours a day. I don't mean to be bulldoggish about this, not knowing anything about how long you've been growing, your rate of success, how long you've had the plant in question, etc. I just wanted to suggest that the plant, if generally stressed by excess light (which is a common error for for LED growers - including myself), it could be suffering from more than one sort of malady but from a common cause. Good that there are living root tips. Best.

 

[terryros]

I agree that knowing the light intensity (the peak photon flux density) helped me a lot. I don’t buy cheap plants and found that the cost of the Apogee full spectrum meter that measures the PPFD in the PAR range is about the cost of 1-3 plants I might by. I don’t have 30 years of growing left to just use trial and error to find out about the right light levels. You can’t tell with your eyes. I haven’t wanted to just raise or lower lights and wait months to see if there is a change In the right direction. I know my approach would be different if I were young and on a tight budget.

 

[masaccio]

I agree that knowing the light intensity (the peak photon flux density) helped me a lot. I don’t buy cheap plants and found that the cost of the Apogee full spectrum meter that measures the PPFD in the PAR range is about the cost of 1-3 plants I might by. I don’t have 30 years of growing left to just use trial and error to find out about the right light levels. You can’t tell with your eyes. I haven’t wanted to just raise or lower lights and wait months to see if there is a change In the right direction. I know my approach would be different if I were young and on a tight budget.

I found your recent posts (and several earlier ones) brilliant and so helpful to my struggle. Bookmarked forever. I"m ordering the Apogee myself in 4 days, and counting. Thanks so much.

 

[GuRu]

Is there a chance that you are over-lighting? The plant on the other side of the kolopakingii also looks a little yellowed.

Of cause, overlightning can be one of the reasons of yellow leaves......but in this case I would say by my experience.....it isn't. Overlightning would have affect to almost all leaves and the upper leaves, which are the closest to the light source, would be affectect more than the lower ones. But here the upper leaves seem to be healthy and only the lower leaves are turning to yellowish.

 

[musa]

Thanks a lot for your help, I hope the following is kind of useful.

Just by my feeling I'd say light isn't the problem as I brought many paphs, mainly coryopedilum, from seedlingsize to bloom. Some issue I had with gigantifolium, and anitum. I grow under the same light conditions from the beginning in 2012.
But of course might light be the trigger to the problem of my gigantifolium.

Nevertheless I tried to find some more information on my lights:
Osram fluora 77, flourescent tube, 36 watt, length 120 cm, 1400lm. That is official.
In an other forum I found the following:
6,48 PAR Watt, 29,1 µmol/s PAR PFF

Per shelf 25 cm x 40 cm I have 2 flourescent tubes at a distance to the tips of the leaves of about 18 cm. I had them running 14,5 hours a day, now I cut it back to 13 hours.

Unfortunately I do not have a full spectrum meter.

 

[GuRu]

.......Just by my feeling I'd say light isn't the problem.........

Michael, I want to insist to my post #2. You wrote you removed some potting media. Did you look closely to the base of the lower leaves? Was there a zone with a width of aproximately 2-4 mm like a ring with brown decayed tissue?

 

[masaccio]

Of cause, overlightning can be one of the reasons of yellow leaves......but in this case I would say by my experience.....it isn't. Overlightning would have affect to almost all leaves and the upper leaves, which are the closest to the light source, would be affectect more than the lower ones. But here the upper leaves seem to be healthy and only the lower leaves are turning to yellowish.

Absolutely. I stand corrected. It appeared to me from the first photo that all the leaves were yellowish. I"ve enclosed a photo here that may illustrate the problem you are describing. I found it on my recently arrived Prince Edward of York.

 

[GuRu]

.......I"ve enclosed a photo here that may illustrate the problem you are describing. I found it on my recently arrived Prince Edward of York.

Exactly, that's what I ment.

 

[hamiltons]

Hi Musa
First I would like to say thats its cool that you have got this rare plant, P.gigantifolium, its not so easy to get and its very expensive in this size which is the only size to benefit from, its a very slow growing species, so getting young plants of it will take years and years to bloom...Next I think I will give Guru right, it seems that the plant and maybe other of your fine species are potted too deep so the lower leaves first turns yellow and next rot and fall off, due to the very moist/wet media around the roots, which will also get wet and soggy and eventually rot and in the end the plant will have almost no roots and therefor the plant will be in grave danger of simply slowly dying and its very difficult to get it back...I have myself grown slipper species for more than 25 years, close to 30, and have tried almost all kind of medias to grow in, bark, sphagnum, gravel etc. and is now growing all my orchids (except for thick rooted plants like Catts and Rhyncostylistylis etc) in a special produced rockwool mix for orchids called greenmix, produced here in Denmark, a blend of water resistant and water absorbant rockwool/grodan added with a small bit of lime gravel, considering species etc. and I have been growing in this for more than 25 years now and its the best damn mix I have ever used, is good to use whether you grow in greenhouse or windowsill, the only problem is that it is not good to keep too wet and cold for warm growing types, roots will stay to cold and die if too wet too...So regarding your gigantifolium and other fine paphs, try to repot it and keep it a bit higher in pot, not so roots will be above pot edge, but just so it stays in the pot top line, and if you like the media you have your plants in, of course continue with this, but I would recommend that you try to get a portion of the rockwool "Greenmix" for orchids and experiment with maybe a couple of not so valuable plants and see how it goes, its a media easy to work with, it shall not be pressed hard into the pot but just be put carefully into the pot around roots and softly packed, and thus carefully wtered with clean water and kept fairly moist but not wet...I have all my paphs and other orchids in a small 3 x 3,5 m greenhouse on our balcony, and in winter I use a small electric heater with thermostate to regulate temperatures and in summer whatever temperature the outside weather generates, in hot days I use a fan to ventilate the air, and I shade quite much as the sun gives much light and heat, so temps will get very high sometimes if not shaded and ventilating, Summer temp. app 28 degrees in day and 20 degrees at night, and in winter the temps. should be about 5 degrees lower over all, and in winter it gets quite dark outside, but my paphs still just get what they can from outside, except for a couple of hours in the late afternoon where I turns on a large "plug and grow" tube that is mounted into the middle of the ceiling in greenhouse, this I do from November to february and then natural light again...For watering I use natural rain water and in periods when not raining so much I use cleaned water from a reverse osmosis aggregate, and I use a fourth of the amount recommended fertilizer and fertilize every time I water in summer (may to September) and then set the fertilizer down to only once a month or not when watering...I hope that this is a bit helpful to you and maybe also to others, we all have different growing conditions and methods and should of course stick to that if it works, all this here is just an example of how I do, and with a few tips too...Hope it was helpful and have a continued great day and merry holidays soon I will try to attach a few photos of my greenhouse/plants

 

[musa]

Thanks a lot, your advice is most appreciated.

I just removed the top layer of the potting media and discovered brown spots (Foto 1 and 2), but then I realized that it was the rest of an old leaf which I could remove (Foto 3 and 4). On the 5th foto you see how the plant is now leveled in the potting mix.
As you can see I keep it a bit on the drier side, the top of the pot dries out before watering while the lower pot is keept moist all the time. On the last foto you can see growcubes which are added in the top layer of the pot. I think theese are what you mentioned, hamiltons.
I could remove the oldest leaf which has a slight brown hue at the base but I don't think it is a good idea. What is your opinion on spraying a copperbased fungicide?
One other thing is temperature, it is quite high. At the moment I have 28°C, at night it is about 21°C. Might this be a problem?
Humidity is 50%.

 

[Ozpaph]

i would not use a fertilizer with K=40.

 

[musa]

As it it recently repotted and roots are already growing I won't. In fact it'll get low fertilizer for some days, till It has established again.

 

[musa]

As suggested elswhere I covered a leaf partially with paper for over a week, but there war no change in colour where the paper has been. Rules that out too much light, or is stress by overlightening still possible?
The new growing leaf is darker, but still on the light side; I can see still four active root tips like in december and they are growing. That's not overwhelming but at least there is a working root system.
The base of the plant is now higher in the media and there are no signs of rot.
Thank you very much for your help!