The Highways Agency has pledged to focus its ragwort elimination programme on the verges of motorways and trunk roads that are close to grazing animals.
A Highways Agency spokesman said: Following the publication of new government guidance (a revised code of practice on how to prevent the spread of ragwort) we are taking this problem more seriously than ever, and we are assessing the risks in different areas.
A common method of eradicating the weed is to use herbicide at its leafy rosette stage, but it is often necessary to hand pull the plant when it comes into flower in July or August.
The spokesman added: We are continually looking at new, environmentally friendly techniques. Cutting is avoided as it encourages thicker growth the following year.
When ingested by a grazing horse ragwort acts as a cumulative poison, eventually destroying the liver. Each plant can produce up to 150,000 seeds with a 70% germination rate.
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