Week 5 Flowering - Bronze/Brown leaves w/ curling tips upward...

This started about 2 weeks ago and has slowly progressed ever since. It looked like a magnesium deficiency to me, but I've been giving it plenty of Mg so I'm lost at to what it could be.
It's an organic grow... see the setup here: https://www.rollitup.org/led-other-lighting/795905-organic-led-multi-strain-medical.html

The strain in question is Blueberry.
The leaves near the bud-sites have been turning an orange/bronze color from the tips inward and curling upward. The edges are also spiky and have necrosis.

Does anyone know what this could be?
Thank you.

Not enough fluids. Water more often/lower the temps at the canopy level/raise the light a bit. All three of these answers go hand in hand with your problem.

MOISTURE STRESS! (lack of).

I might ask what are the plants in? How often do you water and what's the temps in the room AT the canopy level?

Dr. Who said:

Not enough fluids. Water more often/lower the temps at the canopy level/raise the light a bit. All three of these answers go hand in hand with your problem.

MOISTURE STRESS! (lack of).

I might ask what are the plants in? How often do you water and what's the temps in the room AT the canopy level?

Click to expand...

The plant is in a 5 gallon fabric pot with organic soil.
I water every 3-4 days once the soil dries a little bit. The LED lights are 24 inches above the canopy. Canopy temps are 72 during the day, 66 at night..
Humidity is around 50-55% throughout both night and day.
To me, it seems I'm giving them ideal conditions but I could be wrong.. All the other plants in my flowering tent are under the same conditions and don't show these symptoms.

Thanks for your help!

The cupping and curling point to moisture stress (needs more).

All of that above brings me right back to the soil and the smart pots (fabric).

That particular plant is wanting to be watered more often! In pots, the root ball can become so dense that you can get what is called the "umbrella effect". This problem can only get worse with "fabric" pots. You water and it appears to soak in and flow through. What happens is that the root ball deflects some of the water off the root ball like an umbrella. If you don't leave the plant and pot in the catch tray, in the "flow through" water for a few minutes, allowing the "dry" area under this root ball to soak up the excess water to get everything wet enough. You don't get a completely watered plant. (some of the plant has enough to get through, but some runs low to soon and can't get enough from the other parts of the plant to transpire correctly = cupping and curling).

I water a measured amount (enough to carry it 24hrs) of feed/water every day at lights on, for every plant. This puts the oxy o2 to the roots everyday and is a good thing! I would go out to your grow and everyday stick your finger into the soil on that plant, up to your first knuckle. Feel damp? = don't water. Feel dry? = water.

I have used smart pots. They work well. BUT, I don't care for how they "need" to be watered "more". I like my plastic pots with the vented "cones" in the bottom...I get NO umbrella effect from them.

Let your plant sit in the flow through from your watering for like 3 -5 min. and I'll bet your problem goes away!