Hill farmers fear that the crucial annual authorisation for Asulox – the selective herbicide used to control bracken – will not be granted this season.

The situation is increasingly desperate as controlling bracken is one of the critical methods to stop the tragic rise of Lyme disease which has jumped from dozens, to thousands of human cases in the last few decades.

Bracken litter provides ideal breeding habitat for sheep ticks and Lyme disease is one of several tick-borne diseases that are of increasing concern to public human health officials.

Typically, the spraying of the selective herbicide Asulox happened from the start of July when bracken develops, until the plants die back, which can be as early at the start of August, depending on weather.

Meanwhile, the product, which is only manufactured in India, takes at least six weeks to arrive following an order. Also, those requiring helicopter application will also need to obtain an aerial spray permit, which can take weeks to clear.

Approval for the use of Asulox in Scotland during 2023 is being considered by the Minister for Green Skills, Circular Economy and Biodiversity, Lorna Slater – a member of the Scottish Greens.

An application for the use of Asulox was submitted in November, last year, but no decision has been made yet.

A spokesperson for the Scottish Government said: “HSE, the UK regulator of plant protection products, considered an emergency authorisation application for the use of Asulox for bracken control in 2023. The Scottish Government, alongside the other UK administrations, is currently considering HSE’s recommendation and a decision will be communicated, by HSE, in due course.

“The Scottish Government recognises the difficulties associated with bracken control, particularly in Scotland and the role that Asulox has played over recent years.

"We continue to work closely with stakeholders and NatureScot to consider options for sustainable bracken management. The Biodiversity Minister recently wrote accepting an invitation from the Bracken Control Group to visit a site with established bracken and looks forward to the opportunity to discuss impacts and control options.”

To cover the area of bracken that is required to meet commitments under AECS, it is essential to employ the high work rate of helicopters. Even so, the full period from July 1 until bracken die back occurs is required – especially if the weather is unfavourable.

Industry specialists pointed out that to ensure that supplies of the herbicide will be available and aerial permits obtained to allow a start of spraying, approval to use asulam – the active ingredient – needs to be granted no later than mid-May.

The willingness of Lorna Slater to attend a site visit was welcomed by the Bracken Control Group, but it added that the use of Asulox in 2023 cannot wait until for this to happen until the bracken is fully grown this year. A decision is needed in the next few weeks.

A number of SNP MSPs have been lobbying behind the scenes to speed up the process of getting a permit for Asulox. In a letter to the minister, they jointly stated that in 2018 there were estimated across Scotland, Wales and England to be 1900 known diagnosed cases of Lyme disease but by 2022 these have risen to 7800.

In the letter, the MSPs explained that bracken if left untreated formed an ideal habitat for sheep ticks to thrive. These then act as hosts to pass on Lyme disease to humans and animals.

The MSPs argued that only control of bracken by Asulox could provide the appropriate scale to counter this serious risk to human and animal health which is growing exponentially.

The letter quoted expert scientific analysis which stated that the evidence that the chemical is linked to endocrine disease is minor/negligible in comparison with the proven major substantial risks of failing to treat bracken.

Hill farmer, Andrew McGillivray, who runs a company which organises helicopters to control bracken, said: “The clock is ticking on getting the chemical approved. If we leave it until the minister has time to visit developed bracken plants then it will be too late to get everything organised for the short window of application.

"This will affect everyone, from helicopter applications to knapsack sprayers and all in between. There are no other commercial options for controlling bracken.

"If we lose Asulox, then there will be little to stop bracken taking over hundreds of thousands of hectares of hill ground, not to mention the grave threat it will have to public health.”

In Scotland, hill farmers pointed out that funding for bracken control had been removed from AECS for new applications in 2023, while in England, Defra had substantially increased the capital rates payable in the first year for treatment under Countryside Stewardship from £170 per ha to £270.90 per ha.