Obviously this issue begins in the roots, but if you see the leaves are wilted or your plant is doing poorly, you must check first the roots. if they are discolored, mushy or slimy. if you check these symptoms, probably is a root rot trouble. So, if you are not sure, then you can check the soil. When these ones have amounts of water, probably you are dealing with root rot or you are near to this risk.
This was the first step to prevent and treat root rot. If you need professional assistance please contact us.