Blc black spots/dropped leaves, to rescue or to trash? fungus?

[stefpix]

Hi
I got this Blc at Parkside.

A couple of days ago i noticed the base of the leaves was black and fell off.
pulled out of the medium and it smelled a bit mold-like.

i rinsed in peroxide cleaned etc.

some PB are not too firm.
is it a fungus?
was wondering if it is worth to try to rescue or it could spread disease and then would be just better to dispose.
my small catts are doing well. new roots etc. So i do nit understand why this got sick.

Maybe the plastic pot instead or clay that I use for most?
I bought also some Daconil spray fungicide but it is very dense so hard to apply inside from a close range.

Is neem oil a good fungicide?
Anywa is this rot due to fugus?
thanks
stefano