Can i cut the roots of completely and root the stem with some rooting powder as a cutting?

take a couple clones and start over again.

AFAIK you'll risk the cuttings having pythium also (if it's sytemically infected the original plant)...

I'd be inclined to start-over with clean stock...

ATB

Stan

I had caught it very early on, it just infected the lower roots so I trimmed (pic of roots i left on diary), and nice white clean roots have grown back to so thankfully it wasn't affecting the stem, and i couldn't take cuttings becouse of how small she is bless her