Leaf 'delamination' ? ... severe curling, in parts.

[Yozhik]

Strain: ... Sweet Seeds Cream Mandarine XL Auto
Plant Age: ... 18 Days
Medium: ... Plagron Lightmix
Environment Temperature: ... Min. 24.9 ºC ... Max. 27.1 ºC
Environment Humidity: ... Min. 46 RH% ... Max. 54 RH%
Lighting: ... HPS 600W @ ~ 50cm
Nutrient Feeding: ... Advanced Nutrients Sensi Grow A+B, CalMag, Voodoo Juice, B-52
Feed pH: ... 6.3
Feed EC: ... 1.9

16 plants [various strains] in the tent.
1 plant showing the following on lower leaves.

Multiple pics to show the condition on multiple leaves.
Closest description I can think of is a delamination of the upper leaf area.
Also severe curling of leaf in parts.
Where curling is severe, leaf is also 'crispy'.
Can't see any signs of creepy crawlies.

New growth appears to be unaffected and 'normal'.

Any ideas?
I've looked through all of the 'deficiency' guides, but can't see anything similar.

 

[namvet25]

To young to have any deficiencies and only on one plant my only thought would be some sort of leaf minor.If you have a magnifying glass check the bad leaves both tops and underneath for insects than remove the effected leaves and dispose them outdoors or burn them.Keep an eye on them and let us no in a few days how there doing

 

[Yozhik]

To young to have any deficiencies and only on one plant my only thought would be some sort of leaf minor.If you have a magnifying glass check the bad leaves both tops and underneath for insects than remove the effected leaves and dispose them outdoors or burn them.Keep an eye on them and let us no in a few days how there doing

Hmmm ... I can't see any little critters ... time for the loupe.

Should I remove the affected leaves?
I can't see them being of any benefit in their current state.

Or just let them fall off au naturale?

 

[Waira]

Hey Yoz! --this is weird, and almost certainly not a defc. issue, or vermins, or bacterial/fungal.... looks more like physical damage to me, but from what? It's going pale and crispy that fast, ay? I can see in the great pics (thanks) that the pale zones are collapsed,... has there been a cold breeze on them by any chance? I've only seen it once here, causes by a cold draft directly on the lower leaves, causing mesophyll cell collapse (mesophyll are the cell in the center zone of leaf),... overly strong nute' soln. splash can cause something kinda similar, as can lensing burn from HID light and droplets left on the surface... but these are lowers, so that makes no sense in this case,... Any idea what the soil pH is? In hydro, sometimes coco, a sudden wild, even temporary, change in pH can cause patchy necrosis as well,... I'll see if I can get other eyes on this,... is it spreading still, and did it happen suddenly? Let the leaves be, maybe advancing symptoms will offer a clue....

 

[namvet25]

Get rid of them outside now.

 

[namvet25]

Ok,I just told him to get rid of those leaves just incase they contain eggs.

 

[Yozhik]

Hey Yoz! --this is weird, and almost certainly not a defc. issue, or vermins, or bacterial/fungal.... looks more like physical damage to me, but from what? It's going pale and crispy that fast, ay? I can see in the great pics (thanks) that the pale zones are collapsed,... has there been a cold breeze on them by any chance? I've only seen it once here, causes by a cold draft directly on the lower leaves, causing mesophyll cell collapse (mesophyll are the cell in the center zone of leaf),... overly strong nute' soln. splash can cause something kinda similar, as can lensing burn from HID light and droplets left on the surface... but these are lowers, so that makes no sense in this case,... Any idea what the soil pH is? In hydro, sometimes coco, a sudden wild, even temporary, change in pH can cause patchy necrosis as well,... I'll see if I can get other eyes on this,... is it spreading still, and did it happen suddenly? Let the leaves be, maybe advancing symptoms will offer a clue....

Suggestion elsewhere is that it may have been caused by the leaves resting on freshly watered soil ... which does make sense.
I do remember that this plant, did have some low lying leaves, and there is a very distinct possibility that they have have been low enough to rest on the soil, if not slightly immersed.

I can't specifically remember it happening, but cannot write it off.
It 'feels' like a very probable answer.

Would this be consistent with your analysis?

 

[Yozhik]

UPDATE:

Hmmm ... Houston, we have a problem.



It seems to have spread from lower leaves on this plant, to a couple higher up.
Initial signs appear to be a yellowish spot, which then spreads into this general 'delamination' appearance.
Will try and grab some pics and post later.

What is even more concerning is I have noticed similar signs on a couple of other plants in the tent now - restricted to lower leaves only - and very similar to the photos posted above.



I'm going to:

• Remove all the affected leaves - to be destroyed outside.
• Look at repotting/transplanting into new pots, with new medium, just in case it was as a result of a rogue bag of soil.
• Will also reposition the oscillating fans just in case it is something as simple as cool air being blown directly onto the leaves [as previously suggested] - although having said that, Patient Zero was at the back of the pack, and never would have taken the full brunt of any instance of cool air. There were other plants at far greater risk of cool air damage, if that were a contributing factor.

Other than the affected leaves, the plants give the general appearance of being healthy and growing unimpeded.
They're all doing the pre-flower and stretch thing right now, so growth is accelerated rates, and also at a critical juncture.
Damn - this is doing my head in.



The initial signs of nute burn, I can deal with very simply.
The expression of heat stress from being too close to the HPS due to an unanticipated growth spurt overnight is easily also rectified.

But this physical damage of delamination?

 

[Yozhik]

Patient Zero Pics

It's amazing what you can see with the camera, that you don't pick up with the naked eye.
I'm now wondering - given the photos suggest that issue seems originates from the leaf tip - could this just be some exotic expression of nute burn, in a plant which might have some hypersensitivity.

Lower leaf issue on otherwise healthy plant

New growth unaffected

... and so it begins

... and so it spreads

... and spreads

... is it an exotic expression of nute burn ??

 

[Waira]

Yoz, again, we need an in-soil pH for sure,... this is not a leaf on the soil surface issue, or pests, or an infection, or very likely, a defc. issue either.... your excellent pics show the progression very well, but alas, I can't pin the problem down, at least not until we have a proper soil pH reading.... do you have a soil probe, like an Accurate 8? If you have to do a run-off test, use this guide ( https://www.autoflower.org/threads/...-testing-and-ph-estimation.41733/#post-928975 ) ...the run-off method is prone to measurement errors, but this one at least helps address those some,...it still looks most like the sudden pH shift symptoms I usually see in hydro, sometimes coco,... your EC, how much of that is the water, or are you using RO/DI? ...... I'm looking at the color of the dead tissue, and how fast it happens, how it dries out quickly, so much so that sometimes a little chlorophyll is still present,... I'm recommending a flush in any case, so do that improved r-o test first,.. make sure you have some RO/DI water for part of that test!