I've got two tracks going in my mind:

A. A slight Mg deficiency compounded by bright LEDs.
B. An Mg deficiency you remedied, then you locked out potassium.

Then there's the third track:

C. I took two, totally wrong wild stabs.

What are your roots like Frank? Or Phosphorus if not roots.

Is this a cutting or from seed plant?

Ph swing?

i think this little guys taking all the food away from the weed jk jk

Transplant it. Feed it. See what happens.

FuriousStyles said:

Is this a cutting or from seed plant?

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From seed. It's a mystery seed that came from a jar of various highs. Everything popped had a rating of 25% and above.

All good suggestions. I have to agree with the first in some respect.

mysticepipedon said:

I've got two tracks going in my mind:

A. A slight Mg deficiency compounded by bright LEDs.
B. An Mg deficiency you remedied, then you locked out potassium.

Then there's the third track:

C. I took two, totally wrong wild stabs.

Click to expand...

Your on track, and well could be correct, I'll try and explain below my line of reasoning.

chemistry said:

What are your roots like Frank? Or Phosphorus if not roots.

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Correct also, and the same. It's both actually, IMO.

Mr.GreenthumbOG said:

Ph swing?

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Possible, but highly unlikely. I've had pretty decent control over ph, although it's a possibility on some level yes.

So here's my line of thinking on this one. Calcium Excess is the culprit, and maybe a little too much light, as was also suggested. I was certainly pushing them hard and fast with the LED's.
But I have started using calcium hydroxide to balance my pH, and if I'm correct here, that's the culprit. It's attempt at pushing the calcium out of the tips...

Too much calcium can lead to severe consequences. The most obvious problem with calcium additive is leaf burn. The cannabis plant is reacting to excessive Ca+ and is trying to push it out from the leaf tips. This causes necrosis (death) of the tips, they will turn yellow/brown.

Besides causing leaf burn, excess calcium doesn’t actually create symptoms as a deficiency. Instead, too much calcium actually lead to problems in other nutrients, such as magnesium and potassium. This situation is a frustrating problem. Too much calcium will lock out magnesium or potassium, the only way to correct is by first dealing with the calcium issue.

So, you’re experiencing potassium and magnesium related symptoms, the actual root problem is too much calcium. Excessive Ca+ doubles or triples your work by making it necessary to try and fix your magnesium and potassium issues. It can you astray chasing other nutrients, while Ca+ remains unresolved.

I'm changing up, so lets see if this comes around or not. Flush a little, then same mix with only single adjustment. Instead of balancing with calcium hydroxide, I'll use a little potassium hydroxide this time around.

Things look a little greener in the core today, also appears a bit more engaged, so I'm encouraged.

Have the roots bottomed out the cups? A transplant into good soil could fix everything.

mysticepipedon said:

Have the roots bottomed out the cups? A transplant into good soil could fix everything.

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certainly not what I would like, quite yet, but I'm looking now, and there praying nicely again, so I might have some discoloration at the end of this along some bottom edges, but I think they'll pull out of it. Personally, I think much of this has been a combination if issues, certainly calcium is at the top of the list for me, but I think some of those cool nights getting perhaps too low, the ol lady leaving the doors open, and it being 60f in here, with strong LED's on them, and I've got the humidity down some, cause I got others in flower, so the (vdp) vapor deficit pressure too. Certainly the flower room is much warmer in there. Note to self; I'm going be cool in here, keep the humidity very low. I need to move this mess into the 2 x 4 again, need to put it back up. Maybe tonight.



So pushing them plus, the nutrients. Look at the original photo's, and note the flatness, how the leaves are all level and low. Now there v notched, greener, and wings in the air. Transpiration is restored, so the dead and necrotic will simply fall away, but I will leave it on for now, because it's able to feed and cannibalize it to some extent.

Dude, I was going to say old calcium excess damage, that's why I was asking about cutting or seed. I did not think you would have an overfeeding issue with a seedling, but a cutting...???
I have seen all kinds of crazy stuff that they just have to grow through to the new.

You seem to be on the right track nice catch!

edit. IMHO it had to be an excess, there is no leaf yellowing on the damaged leaves. Which would have been a sign of a deficiency from cannibalization.

FuriousStyles said:

Dude, I was going to say old calcium excess damage, that's why I was asking about cutting or seed. I did not think you would have an overfeeding issue with a seedling, but a cutting...???
I have seen all kinds of crazy stuff that they just have to grow through to the new.

You seem to be on the right track nice catch!

edit. IMHO it had to be an excess, there is no leaf yellowing on the damaged leaves. Which would have been a sign of a deficiency from cannibalization.

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Yea, it basically went from good to necrotic with no real in between, and so mysterious, so I tend to agree. No doubt these things are complex issues, so it's difficult to nail down, and/or replicate. I think when your dealing with excesses like this, especially in the micro's; the ratio's at play, and some of the environmental factors (temps/humidity/lighting lend enough variance to the outward appearance, that it doesn't always follow a distinguishing pattern, but more of a generalized symptomology.

Everything's looking big and lush today, so the necrosis remains, but the new growth has cannibalized much of that into the upper fauna.