The law on ragwort is the Weeds Act 1959. This is a piece of legislation, that mentions the control of ragwort. A rare legal order may be made forcing someone to control ragwort, but in the absence of this legal order there is no requirement to do anything.
It is important for landowners and other people to understand that they have no automatic legal obligations to treat and remove ragwort from their land. It is simply the case that there is nothing in the legislation that says that you automatically must eliminate ragwort from land. It is similar to legislation creates orders for traffic such as yellow lines. It is not automatic but only happens where there is problem.
This law where Ragwort is mentioned is the Weeds Act 1959. This is what the Act says
"(1) Where the minister of Agriculture fish and food (in this act referred to as ' the Minister') is satisfied that there are injurious weeds to which this act applies growing upon any land he may serve upon the occupier of the land a notice, to take such action as may be necessary to prevent the weeds from spreading.
(2)This act applies to the following injurious weeds, that is to say-
spear thistle
creeping or field thistle
broad leaved dock
ragwort"
It is commonly claimed that this legislation forces landowners to control ragwort or that it places an obligation on them to do so. As can clearly be seen from the actual contents and text of the act this is not the case. It is not unknown for even such august bodies as local councils to get this matter wrong. This is the text of the act and this is what it says. The rest of this rather short act of parliament is about procedure and powers but has no bearing on the legal obligations and requirements placed on landowners in general. For completeness a copy is available here. The Weeds Act 1959
The Weeds Act has been subsequently amended by the Ragwort Control Act 2003. but this has no real effect on the legal information given on this page since it only provides for some guidance to be created.
The Weeds Act as a piece of law gets criticism from conservationists because it conflicts with modern policies dealing with the biodiversity crisis. In fact the Weeds Act actually wasn't debated in parliment in 1959 and merely repeates part of legislation from 1920, which weas created to give the ability to landlords to force their tenants to keep their land tidy. This was before modern intensive agriculture caused so much trouble for biodiversity.
There is also another legal myth that ragwort is a "Notifiable Weed" that must be reported to someone in authority. Since this is the only piece of legislation that can place an obligation on anyone and it does not say that it is notifiable this is clearly a myth. There is no requirement in law to nofify, inform or tell anyone of the occurence of ragwort anywhere. There is another article on this site where this legal myth is explained as false by a government minister in a parliamentary answer. See Notifiable weed
It is also important to remember that it is a criminal offence to uproot any wild plant including ragwort without the landowner or occupiers permission, unless you are one of a list of specified officials. The full details are here Ragwort and the Wildlife and Countryside Act.
There are also separate pieces of legislation in Northern Ireland , The Isle of Man , and the island of Jersey . They say the same thing in essence as the Weeds Act 1959.