AusBonsai

I have a young cedrus libani growing on in a pot at home, after noticing yesterday a little trunk rot at the soil line i dug a little deeper to see the extent of the damage, to my horror i found the rot to get worse as i dug. The trunk below the soil line has rotted back to about one half to two thirds of the trunk size and the few roots i reached appeared very dark almost black.
Above ground the tree seems in good health it has been shooting for about two or three weeks now with plenty of vigour.
My question is do i ring bark above the rot and ground layer it while the plant still seems healthy or are there other options to remedy this?
I really hope i can save thiss one because i love the species and think it would make greAt bonsai.
Will post pics this arvo as i'm sure they will paint a better picture than what i have described.
Thanks, Mitch

Cut off and clear out rotted roots above level of rot.
Repot into free draining mix
Treat with fungicide (try asking at flower power or tims garden centre if your close by)
Try not to keep wet and cross those fingers

I'd love for there to be some roots above the rot, which is why i thought of ground layering and henerating a new set of roots then cutting the rot away from underneath. like i said earlier i'll post a few pics in a few hrs when i get home to give you guys a better idea of what i'm dealing with.

It may well have been some damage in the trunk and theus that section rotted away?

Rather than Layer above it, isi t possible to utilise the damage? maybe with a rock or stome in it place, or make a feature of it?

Ken