The project, led by Scottish & Southern Electricity Networks, is part of the East Coast 400kV Phase 2, aimed at modernising the electricity grid.

According to Ian Thornton-Kemsley of property consultancy Galbraith, the planned series of 187-foot pylons between Kintore and Tealing traverses prime agricultural land, posing a significant threat to farming.

The senior chartered surveyor, who is advising several landowners along the route, said SSEN must do more to properly address biosecurity dangers.

Ian Thornton-Kemsley, a consultant at the firm, said: “Despite landowners identifying the risks, SSEN appears to have delayed addressing the threat to the agricultural industry.

“Biosecurity measures outlined by SSEN and its contractor Balfour Beatty in August 2023 do not adequately address risks associated with potato cyst nematode (PCN), a microscopic pest that attacks potato roots, potentially leading to significant crop failures, nor clubroot, a soil-borne disease affecting crops including brassicas such as cabbage and oilseed rape, causing swollen and deformed roots - both potentially significant for a route passing through prime agricultural land. Biosecurity measures proposed by the contractor Balfour Beatty are more suited to grazing areas than prime agricultural land.

“Despite recognising that protection is essential against soil-borne pathogens, the proposed measures omit mandatory steam cleaning of machinery and comprehensive soil testing before and after work - both potentially critical in avoiding disease spread.”

According to Galbraith, SSEN appears to be prepared to use powers available to it under the Electricity Act to enter land without prior testing for PCN and clubroot. After the contractor Balfour Beatty asked landowners in the Mearns and Angus to detail their concerns, the landowners produced a protocol of suggested biosecurity measures required.

SSEN has instructed contractors not to sign the protocol, though it has yet to explain its concerns about the document, Galbraith added.

The second-biggest economic threat to potatoes after late blight, PCN has affected crops across numerous countries, sometimes causing yield losses exceeding 70% depending on soil type and potato variety. The UK loses some £26 million annually from PCN, rising to more than £60m when taking into account the cost of yield protection measures.

PCN cannot be eradicated and can survive in soil for up to 20 years. Infected land can no longer be used to grow seed potatoes, a vital part of Scotland’s £4.5 billion potato supply chain. A significant addition of PCN-infested land would threaten the industry’s sustainability.

Clubroot, a further cause for concern, can reduce yields of oilseed rape by 10% and in severe cases cause complete crop failure.

“These lands are crucial for Scotland’s agricultural output, particularly for high-value crops such as potatoes and daffodils - key crops along the chosen route,” said Mr Thornton-Kemsley, who owns a property along the route. “The potential spread of soil-borne pathogens along this route could have long-term economic and environmental consequences for Scottish agriculture.”

Galbraith is recommending a series of actions by landowners potentially affected, including testing for PCN and clubroot and recording the condition of land prior to entry, and the adoption of strict hygiene protocols covering vehicles, equipment and footwear, maintaining detailed records and action logs, and undertaking regular inspections during works.