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Bracken Spread

Bracken is a major problem, with in excess of 975,000 hectares of dense bracken bed in the UK. Bracken spread has the potential to expand by as much as 3% every year which equates to an extra 29,000 hectares per annum. With only approximately 6000 hectares treated via means of aerial application ( by helicopter ) each year in the UK, we are only scraping the surface!

The plant itself produces an extensively branched, underground rhizome system; one rhizome from a single plant can colonise a large area (to over 20 metres) by vegetative spread over several decades. The plant can also spread via spores, but by far the rhizomes are it’s main method of expanding. The quantity of rhizomes found under an established bracken stand will often exceed 100 tonnes/hectare.

The growth of bracken is dependent on aspect, exposure, seasonal weather conditions, altitude and latitude. Bracken is dormant over winter, producing new fronds from the active underground rhizome buds in late spring. These new fronds begin to emerge in May/June time. As each frond grows it depletes the food reserves in the underlying storage rhizomes.

Environmental And Economic Impact Of Bracken

Dense bracken has only one real benefit, the prevention of erosion, which may be useful on steep slopes that may be susceptible to landslides.

Benefits Of Bracken Control

  • Bracken has an array of 28 known groups of toxic, teratogenic and carcinogenic chemicals produced in its tissues. These toxins are thought to cause harm, to not only animals, but also to humans, with some academics reporting that the spores inhaled from the bracken plant, as well as spores getting into water courses, may be carcinogenic.
  • Bracken provides a favourable habitat for tick, with tick being responsible for diseases such as louping ill, tick-borne fever, pyaemia and lime , with the latter being a matter of public health concern. Though the health of the livestock is of major concern there is also the economic impact to both farmers and sporting estates.
  • Suppression of habitat by dense bracken beds can smother tree saplings, heather, grasses and other plants in its way, which in turn has a major impact on wildlife and the
  • Dense bracken beds within agricultural ground are classed as ineligible and cannot be claimed for in your IACS application resulting in loss of payments.
  • Bracken litter can be a fire risk.
  • Areas with dense bracken beds have a higher incidence of fly-strike.

Successful Bracken Control

There are many myths surrounding bracken control over the years. Some are true, more or less, and some, are nonsense. In reality, successfully controlling bracken is down to two things: application and timing.

Most bracken can be successfully controlled during a two month period from when the pinnae or fronds are fully extended until senescence. The bracken season will vary geographically and from year to year, but this two month period generally falls between early July and early September.

Between 30% and 50% of this time window ( this window has been getting shorter ) will be lost to, excessive wind or rain, so it is essential to maximise spraying opportunities during the 30 odd days that remain.

AirAgri achieves this by ensuring each helicopter targets its own geographical area, and each helicopter is supported by two mixing units. This allows AirAgri maximum flexibility, and also means that one team can support another if need be. This adaptability and capacity gives AirAgri the best possible chance of fulfilling client spraying requirements; this is crucial especially if the spraying programme is part of a grant aided scheme.

Bracken beds that have at least a 70% canopy tend to be the most suited for aerial bracken control.

This facilitates sufficient translocation of Asulox through the extended fronds down to the rhizomes below, and maximises control efficiency.


Following the ending of the approval to use Asulam for bracken control on 31 December 2012, temporary, annual arrangements have been put in place to allow the use of Asulam for bracken control to continue. Approval has been subject to the terms set out in Emergency Use Authorisations granted by the Chemicals Regulation Directorate of the Health & Safety Executive (CRD).

The continued availability of Asulam cannot be guaranteed, but the Bracken Control Group is working with all parts of the bracken control community to promote the value of Asulam for the control of this invasive species.

Asulam offers selective control of bracken and it has approval for aerial application.  These characteristics are unique to Asulam, which makes its use for bracken control very important.  Additional justification was submitted as part of the application for an Emergency Use Authorisation in 2015.

The support being provided by CRD, which is the relevant agency for the whole UK, is very gratefully acknowledged.

The Chemicals Regulation Directorate will issue a Notice of Authorisation in late April or early May 2016 and this will come into effect on 16 May 2016. The Notice will authorise the use of asulam in the form of Asulox to control bracken from 1 July 2016 until 12 September 2016.

There will be a further use-up period until 31 October 2016 that will permit the storage, disposal and use of stocks.  Note that during this period, the sale and distribution of stocks will not be permitted.

From 1 November 2016, it will be illegal to apply or store asulam.

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