These myths are extremely common. Here are examples of Council bodies getting the law wrong. All these statements are factually incorrect see Ragwort Law
Ryedale District Council
The Ragwort Control Act became law in 2004 and landowners now have a legal obligation to remove the weed or face a fine.
http://www.ryedale.gov.uk/Default.aspx?page=10657&theme=textonly
Cornwall County Council
"The Ragwort Act(sic) means that landowners in general have a responsibility in relation to control of the plant and should consider whether the law requires them to take action."
http://www.cornwall.gov.uk/index.cfm?articleid=33203
PULBOROUGH PARISH COUNCIL
A Meeting of the Recreation and Open Spaces Committee was held at the
Sports Pavillion on Thursday, 13th July 2006 at 8.30 pm.
URGENT MATTERS RAISED BY COUNCILLORS
Mr Denison requested that a letter be sent to the Diocese of Chichester
requesting that the East Glebe Field be cut. It was also stated that it should
be brought to their attention that it is illegal to let ragwort grow and flower.
www.pulboroughparishcouncil.gov.uk/docs/minutes/y2006/r060713m.pdf
NORTH DORSET DISTRICT COUNCIL
MINUTES OF THE MEETING OF THE COUNCIL HELD ON FRIDAY, 30 JULY 2004 IN THE COUNCIL CHAMBER, NORDON, SALISBURY ROAD, BLANDFORD FORUM AT 10.00AM
The Chairman proposed the following motion, seconded by Cllr Jeffery:
" A law has recently been passed by Government (not before time) making it a criminal offence to leave, or allow to grow, ragwort on all land throughout the UK.
This Council strongly supports this law and will do its utmost to remove any ragwort growing on land owned by the Council and ensure that it keeps free of this noxious and poisonous weed in future.
Further that the County Council be advised that we expect them to remove this weed from all verges and land owned by them within North Dorset and to keep this land free of ragwort in the future."
http://www.north-dorset.gov.uk/index/about_your_councils/north_dorset/committees/
minutes_and_agendas/council_minutes_30_july_2004.__council-30.07.04.doc
This myth has also led to complaints to the advertising regulator. See British Horse Society and Advertising Standards Authority
It has also occured on a facebook forum discussing Ragwort Awareness Week