The draft guidance from the agency is out for consultation until June 14 and is based on FSA-funded research into the presence of Ecoli, salmonella and listeria in farm manure. Those crops that are unlikely to be cooked before consumption are most vulnerable to contamination by the bugs, which could cause food poisoning.

The guidance has been drafted by the UK's agriculture departments and representatives from the horticulture and food sectors including the organics lobby.