What is this a disease, a deficiency…? Please give me some thoughts
Possibly light stress, have you been cranking the new LED directly above it?
I notice that the leaves themselves are quite dark green. It could also be burn from too much fertilizer. Did you change anything about the fertilization schedule?
Nope. Same as I’ve used for years…these leaves roll all the way up like a joint an turn brown dead n brittle.
Yeah that leaf curling is common sign of light or heat stress, I thought going to the LED may have been too much for them. What are your temps like? HPS could just be cooking them
Here’s an interesting article that I found:
Heat stress and nutes…something has something locked out. What’s ur ph in and out?
It could also be both, that’s true
Yeah my first thought was the cat peed in the dirt. Check the pH and then the temperature at canopy hight and try to eliminate that first,
I keep a little thermometer hangin right under light at canopy lvl n kt stays between 77-78. I check ph every feedin. 6.5 6.8. That one plant is ths only one doin it really. Its been beside 3 others. They aint doin it.
You all think ill be be a big deal switchin to that led tomar?
Nope they’ll love it
Yeah shouldn’t matter on the light.
I really don’t know about the other thing, if you figure it out tho, let me know. I see these kinds of things, and I normally assume that it’s got to be something in the environment, but what? Since it’s only the one plant, that to me suggests that it’s contained in the pot, some..thing.. isn’t right 
I also tended to think it was some kind of surplus or deficit
Id like to know if it was tops bottom or all over! That’ll help to @RidgeDandy
From what I could make out in the pictures, it looked to me like it was right in the middle of things
Ahhh seems like it was all over but worse on top. I removed all the damaged leaves, double garbage bagged em lol.