Umm...little latex caulking?

Seen em keep pumping water for a while- don't forget, if you went to a weak nute solution, the osmotic pressure across the root wall is very high.

They should dry up and leave a little sorta dried-pumpkin-vine-ish appendage in not too long- if you wanna staunch the flow, treat it like any other vascular system. Usually die back as far as the node below the cut.

Seriously, if it's got you freaked out, you can use whatever to bandage/tourniquet the flow- rubber cement, cling wrap and rubber bands, string tied tightly enough to constrict phloem, whatever.

Oh- I'm pretty sure that Serenade is Bacillus Subtillus- copper just don't smell that bad.