Onion Rot???

[Sprocket]

Help
I have two different types of white onion hung up in the garage, but one has started to rot and is covered in a fungus which is sliver in colour and is in large silver blobs. Why is this happening to one and can I prevent it spreading??? Have just been throwing the ones away that have gone so far but they just keep rotting

[Snadger]

I have onion white rot in a couple of veg beds. Mine rot if left to mature but even when dug early they won't store. If you wanted to save them I can only suggest cutting up and freezing the unaffected bulbs you have left!