Sheep can help fight the spread of an invasive and highly toxic plant, according to results of a four-year project in Aberdeenshire. Giant hogweed grows to heights of 5m (16ft) and the sap in its leaves and stems can cause severe skin burns. It is usually controlled by spraying it with herbicides or by removing flowering heads to prevent the spread of tens of thousands of seeds.

Researchers have found repeated grazing by sheep can kill the plant.

Since 2019, the Scottish Invasive Species Initiative (SISI) has been monitoring sheep in a giant hogweed-dominated area of woodland near the River Deveron at Macduff. The study suggests the animals’ feeding led to the plant’s taproot dying off. The researchers found the “woolly warriors” were unaffected by the toxic sap.

SISI said the trial could lead to sheep being used in other places where they could be left to graze safely.