I thought this was a bad case of mealies but upon unpotting, the
odor was a very strong mushroom mouldy type smell.

I call this stuff Flak but someone told me it is California snow mould?

I washed the plant removing all the bark mix from the roots, sprayed with a
solution of water &
Physan, trimmed the dead roots repotted.

Just thought you may like to see some of the nasty stuff.
Cheers Wendy