These inaccurate stories are widely believed true. The evidence says otherwise. There is no ragwort plague.

Hansard Shona McIsaac (Cleethorpes): The ragwort plague, as it has often been described, was a serious problem throughout the 1990s, but less so during the '80s. There are many reasons for its increase, including changes made to farming practice over the years. Farming is becoming less labour intensive, which means that ragwort plants are not pulled up in and around paddocks and on verges and roadsides.

Daily Mail Story on Ragwort 5th August 2007
Each year, ragwort invades new land - its spread aided by the EU's long-running set-aside scheme under which farmland is taken out production and left to wild species.

Botanists estimate that the annual rate of spread is around ten per cent. ....

With the weed continuing its inexorable march across the countryside, it threatens to take its highest ever toll of Britain's horse population this summer.