Can you post a photo? Sounds like damp-off a fungus disease with several different soil-borne causal agents that strike in cool, overly-wet soil. Most common in young plants but can really strike at any time. Sadly it is terminal.

Dave

Lost a bed of 98 plants to this over two weeks. The roots seem healthy. I am on very sandy soil so have had no root fungal diseases that I know of. We did have warm weather and then very cold for about two weeks.

So since it is something I have never seen in twenty years of growing here, I am guessing it must be in the soil brought in by something, seed borne, or something that is always out here in the world but the perfect weather conditions allowed it to live long and prosper. If it only affected the cauliflower do you think I can assume it might be seed borne? Brocolli, kale, kohlrabi and cabbage were all grown in adjoining beds and up to this point not affected.

Rhizoctonia seems most likely. Thank you for the help. I can only hope it was weather related and I will not see it again.