When I used to have an allotment in england (God how old am I?) the old boy in the plot next to mine reccommended that the jeyes fluid was poyred in the planting hole 3 or 4 days before planting.
We used to use it against club root on cabbages.
It was very effective used as 1 part fluid 50 parts water applied with a fine rose watering can and give a thorough drenching in the hole and on the soil dug out which will go back in.
Hope this helps.
Steve