Heat / light stress or a deficiency?

[Kush]

Today I checked to see if the problem is getting fixed.
It seems that it isn't. The leaves are still yellowing and I expect them to show brown necrotic spots soon.
I don't understand why things are not getting better. The pH of the soil right after watering with my vinegar solution is 6.0 and I also gave the plant plenty of Phosphorus. I expected it to react positively to all of this. Alas, it is still sick and dying.
Maybe this is not a P deficiency I am dealing with after all? What else could it be?
Thank you for your help.

Photos from today:

 

[Waira]

-- P defc. for sure mate,... and indeed, that soil pH was too high; how exactly did you check it? Only way that's truly reliable is doing it in-pot with a good pH probe (Accurate 8 is a good one),.... And is your pH meter recently calibrated? If that reading is even close, you weren't out of availability range for P uptake,.... A note about pH adjusting: vinegar will work, but it breaks down fast in there, and stops being effective for this,.... citric acid is a bit better, and of course, the regular pH adjusters, though harsher, are more durable for effect,....
... this Kristalon NPK ratio is not good for this application, far too much K, not enough P,..... overload on K, and other defc. issues may start up, as well as nute burn,...just a caution here! I'd stay with the 4-6-6 until you can get a better balanced bloom nute going,.... what dilution/dosage did you do?

 

[Kush]

-- P defc. for sure mate,... and indeed, that soil pH was too high; how exactly did you check it? Only way that's truly reliable is doing it in-pot with a good pH probe (Accurate 8 is a good one),.... And is your pH meter recently calibrated? If that reading is even close, you weren't out of availability range for P uptake,.... A note about pH adjusting: vinegar will work, but it breaks down fast in there, and stops being effective for this,.... citric acid is a bit better, and of course, the regular pH adjusters, though harsher, are more durable for effect,....
... this Kristalon NPK ratio is not good for this application, far too much K, not enough P,..... overload on K, and other defc. issues may start up, as well as nute burn,...just a caution here! I'd stay with the 4-6-6 until you can get a better balanced bloom nute going,.... what dilution/dosage did you do?
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Thank you so much for your reply.
I noticed that vinegar loses its effect quickly, but this is all I have available for now. I assume that my soil probe is far from being accurate, will buy something more reliable in the future.
I used a 7.5 ml dose per 2 liters of water of the 4:6:6 fertilizer, as per the instructions on the label. I also added a teaspoon of brown Kristalon to the water which may have been overkill, but I figured if my other plant can take solid doses of Kristalon, then this sick plant would take it too, because it it is starving. I guess my logic is faulty, but I have nothing to lose at this stage, so I am just experimenting and hoping that things get better.
Now I am anxiously waiting for the lights to go on, so I can check the current state of the plant. It would be a pity to lose it because its young nugs feel so hard and dense to the touch. If it survives, it would deliver a great crop.

 

[Waira]

...color correction is unlikely at this point, but halting of progression of other symptoms is what to look for,.. it'll take couple days to start showing,....

 

[Kush]

I think the progression of the brown necrosis has slowed down a bit.
The leaves are yellowish and curled downwards, but there's only a few new brown spots.
Will check again this evening when the lights go on.

Is Tartaric acid going to be better than vinegar for lowering the pH? It comes in the form of powder or small crystals. I think I will give it a try - hopefully it will have a longer lasting effect than vinegar.

 

[razor]

Looks like P deficiency.

Plant also look little overwatered and she's clawing (high N).

Auto flowering need 20 /24 for best results some take a while to kick in I'd up the light if she's started flower

Sent from my SM-G903F using Tapatalk

 

[Kush]

Auto flowering need 20 /24 for best results some take a while to kick in I'd up the light if she's started flower

This plant converted to a photoperiod, so I am growing it under 12/12.
If I increase the light period, the plant will stop flowering and will just go back to vegging.

 

[Kush]

Photos from today. Things are not looking good.

 

[Kush]

It's all over, folks. The plant died today.
I tried my best to save it, but it would not react to whatever remedies I threw at it.

A pH measuring pen is on its way to me. Will make sure that this never happens again, although I think that it was just shitty genetics that caused my plant's demise (I have another plant growing under the same conditions and it is doing fine).

Anyway, thanks for all your help and advice.

 

[Waira]

sucky to hear mate,... I think the roots took a dive, and when that happens, very little can be done,....