I would soak it in a 20% bleach water solution for about an hour then let it dry. If you have comet you can put that on it before drying, some people use sulphur (the wettable/dustable kind). We usually let it dry for about 24 hours then pot it up. I would also soak the soil with the bleach solution that you plant it in and DO NOT reuse the same soil it was in. The rot bacteria or fungus resides naturally in the soil and it is obviously in that spot ( if it didn't come in with the plant) so replanting there would not be wise.
I would eventually invest in some Banrot fungicide to keep on hand, it works better than bleach. It is not 100% effective because sometimes it is caught too late and the rot is just too far into the crown to do any good, but it is good to have around It is not that expensive ($75-$85) and can be found on the internet
http://www.tampaagriculturalpr...
http://www.domyownpestcontrol....
You use 1/2 tsp. - 1 1/4 tsp. per gallon water; I usually use the higher rate
