Dot, here is what I have done in the past, sometimes they have worked and other times none of it has worked......
If you do not want to dig the plant up try pouring full strength bleach on the infected crown and you could pour some on the surrounding soil. I have done this with some success. Or if your not sure about full strength bleach, dilute it down. I pour it on every 2-3 days for a week or so just to make sure it's gotten all the rot. I have saved some this way.
Another thing is if I have a few fans together I will remove the rotted one. A lot of times it's already naturally seperated from the others and I just remove it from the soil and then disinfect the area around the rest with bleach or what I use now is Banrot.
I have head April talk about the liquid bandage, worth a try.
I also spray the soil and crown with an insecticide because some pests love to munch rotting stuff and I have noticed things crawling around and in the rotted crown and that may aggravate the damage. Another reason I do this is because some think that the bulb mite is one culprit to crown rot or at least they damage the crown so the fungus/bacteria that's naturally in the soil can get in.
