wilting broccoli

I always grow my own brassica plants from seed so if it is clubroot I've no idea where it came from. One small plus with my need to have 'cages' to grow them in is that I use 10mm net which also keeps out the cabbage white butterflies.

 

If you have club root it will be in the soil, not on the plant when you plant it out. My Father always said, brassicas need good stiff ground. By that he meant lots of compost or manure for a previous crop, firm soil as well. I always plant deeply, almost up to the first set of leaves and heel them in. Water very thoroughly in, but then no more for a week at least to encourage the roots to go down. In a dry year like this then I have watered weekly since. A foliar feed of seaweed TONIC is always good too.
You can get clubroot resistant varieties but note they are not totally immune.