if leaves inside the canopy are the same, then its not what i was refering to with spraying with water... if the light is too much, and you spray, the water will create a lense and burn the shit out of your plants... when you spray it with water, do you see webs over the sections? like super fine spider webs?
only other thing i think it could be, is Blight if its not the other 2, or, as richinweed said, salt buildup, which will burn the shit out of them too... you can do as he says to test them, or flush them heavily and see what happens on the new growth..