Steve,

You've done something very wrong to those poor plants. And, without better pics (probably with them, too), I'd have to agree with Weedhound that the last change you made is to blame. That is, unless you've made more than one change in the last little while.

Flush, flush and flush, and back off on the lights, because something is killing those babies dead.

IOW, growhead Weedhound has it covered, I think.

So, I guess the only *new* advice I can give you is to give the plants a thorough foliar rinse, too. Hose them off real good. It might help. Oh, and bigger pictures, too.