I burned my ladies roots once adding too strong a dilution of H2O2 to my soil. (I don't do that any more) The leaves kinda looked (and felt) crispy, and looked just like yours. But since you mentioned none, I'm guessing that that isn't it, lol.
Does look like some sort of lockout, but doesn't look like the ph lockout I'm used to seeing.

I'd give what rhizome said some serious consideration. You might be over-micronuting them.
Any recent changes to your micronutes or their schedules?
Have you been attempting to foliar feed (or micro) them, in hopes of a recovery? (spraying stressed plants...?)

p.s. Nice molecule...cannabis perhaps?
Rusty Trichome Reviewed by Rusty Trichome on . Rapid Deterioration - Please Help Diagnose Aloha all. Over the past 36 hours I have noticed one of the ladies take a turn for the worse, and quite rapidly at that. I can't figure out what would cause problems in such a rapid way, but the plant has been flushed, cooled (taken out of the high heat it was in), and is receiving what would be called "general supportive therapy" if it were a patient in a hospital (eg it is getting as much TLC as possible). Three days ago, this plant was thriving and a beautiful healthy green, no problems Rating: 5