I have never seen either of those symtoms before. The burning in the second picture looks like a lock up of a micro element because the tips are not burned. It seems as if there was a lock up then it was fixed and new growth emerged healthily.

I would guess the first is a sativa that needs more lumens.
Chris Seekins Reviewed by Chris Seekins on . TIP CURL WHAT WOULD CAUSE THIS? I'VE SEARCHED, BUT NO CAN FIND. ALSO, WHAT CAUSES THIS YELLOW? I AM KILLING THIS PLANT ANYWAY, BUT JUST COURIOUS WHY JUST ONE PLANT DID IT. THNX Rating: 5