Hand Held Dibber (Oak)

I have been using slug banish for two years now and am delighted with the results. I also have used the bio-sterilant mustard and it appears to have have made an impact on the onion white rot which has ruined my onjon and garlic for the past two years. At the present time the onions and shallots are not showing any sign of disease, and the shallots will soon be ready to harvest. I wonder if anyone else has reported this?
G. Telfer, Swanley