^I agree with all you guys, but have to add one warning....
....I've had this happen, and it took me a handful of grows to figure out. I run my humidity a little lower than alot of guys, and also used to run my temps quite high(around 85-90*), with a oscillating fan going constantly. Well, it took me forever to figure out why my plants on the outer edges would get "the claw", like a nitrogen overdose, even though I knew they weren't overfed. Then I thought it was something to do with the light being weaker around the edges...wrong.lol Finally, I realized that they were in the exact spot where the fan stopped, before changing direction, and as mentioned, they over-transpired(if that's a real word.lol), and ended up looking claw-like. It didn't effect all the strains, either, just the Crystal, which made it more confusing. Well, I moved the fan a little, and the problem has never come back. So, my only conclusion, is that it was indeed, the cause of the problem. Whoulda thunk it?