Bracken Control & Clearance

Understand bracken’s growth habit to understand its control

In some parts of the UK, particularly moorland areas, bracken is slowly but surely outcompeting heather required for game cover. In other areas the problem is one of bracken extending its occupation of land intended for grazing. In fact this gradual increase in bracken colonisation means that bracken is forecast to double the area of land it currently occupies over the next 50 years. Besides the problem of lost grazing and game cover, bracken also poses dangers though its carcinogenic and poisonous nature as well as harbouring sheep ticks that can spread disease (Lyme Disease) to both animals and humans.

Bracken control is not an easy matter. The only selective bracken herbicide available is ASULOX (containing asulam) from United Phosphorus Ltd and effective treatment must be part of a long-term strategy.

Why is bracken so difficult to control?

The problem is the growth habit and morphology of the bracken plant. Asulox acts on the frond buds along the bracken’s rhizomes, and this specific mode of action means that the level of control achieved after an initial application is not seen until the year following the initial spray treatment.

The fact that in any one year some buds on the rhizome remain dormant means that a single treatment will never manage to reach all the frond production sites along the rhizome, with a maximum of 90-95% control being achieved from a single herbicide treatment. The level of control achieved from a single spray treatment will depend on the number of buds that remain dormant in any one season. For this reason follow up applications of Asulox in consecutive years are needed to stop the bracken staging a recovery after the initial Asulox application. Failing to treat the re-growth from the dormant buds means that the bracken will be able to re-establish itself and within 5 years the benefit of the initial treatment will be lost.

It is worth noting that where bracken has previously been subject to a sulphonyl-urea herbicide (perhaps applied to the area to treat another weed present), or cultivation in an attempt to eradicate the bracken, or a “heather fire” it is likely to have a higher proportion of long-term dormancy buds along the rhizome, which in turn makes control harder.

When is the best time to spray bracken with Asulox?

The application treatment window is when there is maximum active growth – a period from mid-July, when the fronds are fully expanded, to late September / early October before the fronds start to yellow prior to winter die-back.

Applications made in subsequent years on any re-growth should be at the same time.

How to apply Asulox

Asulox may be applied by:

• Specialist helicopter contractors – particularly useful for large and inaccessible areas. Landowners must ensure they apply for permission to apply Asulox by air well ahead of the time that treatment is required. Applications need to be made to the Environment Agency or Scottish Environment Protection Agency (SEPA) by the beginning of June at the latest to allow time for paperwork to be processed. The application must be accompanied with a clear map of the area of bracken to be sprayed.
• Tractor, ATV or Quad mounted sprayers where ground access is possible
• Knapsack sprayer or hand-held Micron Ulva applicators for smaller areas or where mechanised access is not possible

Always follow buffer zone requirements (see Asulox label) for different application methods and ensure that spray is never allowed to contaminate water courses, stream banks, wet gullies and marshy ground or sites with rare plants, especially ferns.

Liaison with the Countryside Council for Wales, Natural England, or the Scottish Natural Heritage (SNH) may also be necessary if there are Sites of Special Scientific Interest (SSSIs) or other similar designated areas in or near the bracken to be treated.

For further information, please contact:
Richard Allen, UK Sales Manager, United Phosphorus Ltd email rallen@uniphos.com Tel 07831 346369 or alternatively telephone United Phosphorous on 01925 819999