[grinling]

Had about 10 onions with rot, they came out of the ground very easy unlike the rest of the crop which looked alright. I binned the offending onions as well as taking a scoop of the soil. I saw only the start of the white fluffy part, with lots of roots still on.
Should I dry the alright onions or should I cut up and freeze instead?

Looked at previous posts and read the one about using crushed garlic in a watering can over the area...has anyone tried this and if so what success.
Hoping the leeks will survive.

[cadalot]

See bottom of the post here http://www.growyourown.info/page173.html

[grinling]

done all of that, but the onions hadn't even started to rot. Shallots fine and so were the silverskin I took out today. None of the infected onions were next to each other with no problems with the leaves.
Might start freezing the onions.

[Ivor Backache]

The rot travels from root to root on contact. If your onions are spaced well apart so that there is no contact then your remaining onions should be OK.
With regards to crushed garlic I have read a few threads with good intentions but never seen any results.