mould /fungus help

Hi, just been down to water my plot and noticed a white mouldy fungus around the base of some of my veg cabbage and swede but seems indiscriminate bits everywhere.  I have brought some home and checked all my books, Alan, RHS, encyclopedia, even consulted the allotment oracle ( my grandad) he told me the soil needed air and just to hoe round.... fair enough but does anyone have any suggestions.  This allotment is new hasn't been touched for 35 years and consequently was a bit of a mess when I took it on in March.
any help greatly appreciated. 

Possibly I did chuck lots of well rotten manure in before I cultivated it should I try and remove affected soil or just hoe it in
Thank you for you help