Base of stems seem eaten off cant find problem

Base of stem seems bitten off a lil and is brown there were some small bug/beetles I have been chopping heads off as they are not effected by neem karanja and rosemary oils rotating (not many) but them mostly seem to have been on leaves seems like this happened to alot of my plants maybe a disease?

Looks more like a stem rot to me. Given the discharge into the neoprene disc.

Thanks, I'll look into that