Winter cauliflowers left standing in the vegetable garden managed to survive thre fairly harsh freezes but I noticed two today that were keeling over, the green heads were still surviving but their stalks, barely hanging on by a thread, had been hollowed out. I have never had this before. It is the first time growing these in my new allotment but I grew them for the previous five or six years in another allotment without too many problems (leaves attacked by some blueish insects but managed to control them and attacked by pigeons in early spring, dispelled by wire netting).
See pictures. Any idea what the beast is that did this damage please?
Anton