i unrooted my paph vanguard and found only 1 root section (about 2 inches long) was live and healthy
i removed all dead roots
should i treat with fungicide and repot?
Repot, yes. You can also continue to try to root it in sphagnum moss the way another poster suggested in the previous thread on this plant.
I don't treat with fungicide unless I am sure a fungus caused the problem, and I know that fungus is susceptible to the fungicide I have. In this case I wouldn't use a fungicide.
Try and keep the repotted plant warm. The room temperatures you mentioned before are much cooler than the plant would like when trying to form new roots.
__________________ May the bridges I've burned light my way.
Healthy tissue does not rot. If you are repotting into fresh medium, you are likely removing the majority of chance for rot - plus, sphagnum is relatively antiseptic, by itself.
Try treating the plant with KelpMax, if you want to stimulate root growth.
Another thing I thought of... healthy Paph roots look different from health roots of other orchids. They are brown and fuzzy. Sometimes people who haven't seen what they are supposed to look like think they're dead.
__________________ May the bridges I've burned light my way.