Clones dieing

Hey all,
I'm having some issues with my clones I don't quite understand. It appears after a few days of them sitting they will "bruise" at their base "just above the RW" and wilt over as if to die. I understand wilting is normal, though the bruising makes it seem a bit more then simple wilting.

1 inch RW cubes, also tried 3 inch squares- same result
5.5 ph water, also tried non ph'd water
currently 5.5 ph no super thrive- also tried with a 5.5 and superthrive all resulting the same.
NO heat mat in use.
Dome left on for 2 days, foliar sprayed 1-2 times daily, leaving the dome off for 2-4 hrs daily.

So what's happening here? This baffles me as I've had many successes in the past. ANYYYY advice would be greatly appreciated.


Thanks in advance

Yurmy

The only thing i can suggest is make sure no air is getting to the stem or make sure your rockwool cubes r not overwatered..

Humidity is the key to cloning! make sure its as humid as you can get it inside your chamber! no humidity, no roots, no plants