clubroot

when we took over this plot some twenty years ago we planted brassicas on the plot but we found it was rife with clubroot so we had to grow all our brassicas on our other plot but I'm now thinking about trying brassicas on that plot

so does anyone know if after twenty years clubroot would still be in the ground? I suppose one could say plant brassicas on it and see but I thought I would ask the question before jumping in feet first planting brassicas I remember you could buy a clubroot powder but that has since been banned?

I know I could try growing clubroot resistant brassicas but not sure about those? so any info or advise would be very much appreciated

Yorkie's strategies work up here.