Q.overwatering ficus benjamina
I have two ficus benjamina in very similar positions and they have been quite happy there for over 18 months. Recently I noticed that one of them wasn’t absorbing its water. I stopped water, but the earth around the plant remained overwet. I have now taken it out of the pot, the earth is still completely wet … and there is a very strong rotting smell, maybe sulpurous. I wear silver rings and when stripping away some of the earth I noticed that the rings had discolored, which I believe is the effect of sulphur on silver. My plan is to repot … should I strip away all the remaining earth? Any ideas on why this plant is suffering like this, so that I can change its regime? It’s very puzzling as the other plant seems fine.
It does sounds like you have root rot fungus in your plant's soil. In this case, it would be a good idea to completely remove the old soil, wash the roots of the plant with plain water and wash the pot with a 10% bleach solution then allowing it to dry completely before replanting the plant. This should help kill the fungus that is causing the root rot.