Guy wrote:Quarantine the plant and soil from all others -----not sure, but if only the in-ground section is affected I would air layer a couple of inches up the trunk then discard the cut off lower section (bin or burn)----keep in quarantine for a couple of years until the roots show how effective the treatment.If the pot is important I would clean(preferably over a bin) then perhaps soak in bleach for a period .
is air layering above ground level not a possible solution?