[DadBear]

i dont think you should trim healthy plants, i got told when they are seedlings and sometimes they can start to rot from the tip,you should trim the rotting top off to stop it from spreading down the plant

I agree entirely, although it seems that if onions in particular get a bit 'leggy' a trim may well save them. I suppose we ought to be better gardeners and not let them get leggy in the first place ! Interesting subject plant pathology though !!!