Onion white rot

I used to have a plot with serious white rot on it.Decided to grow brassicas on area and found out I also had clubroot in same area. Both fungal diseases I could have done without. I often think white rot is brought to soil by alliums.especially onion sets grown on infected land. I have also had a sooty mould on garlic linked to white rot methinks? Thankfully neither white rot ofr clubroot on present site...............touch wood!