Bracken
Bracken is one of our largest native Ferns and can be found growing on a range of farmland habitats. While Bracken is particularly associated with woodland it also thrives on grasslands, rough moorland and coastal areas. Each year the plant dies back in the autumn and then new shoots emerge from the underground rhizome system in spring.
When left unmanaged Bracken can spread by spores and rhizomes to form tall dense stands that choke out other grasses and other plants by limiting the light and moisture available. Bracken also produces allelopathic toxins which are poisonous to other plants, further aiding its dominance.
Why is it a problem?
Whilst in some cases less dense stands of Bracken, particularly those that are being managed can provide cover for a range of birds, small mammals and invertebrates. The problem arises when the Bracken stands become dense, effectively shading out grasses and other plants and reducing both the agricultural productivity of the area and its value to wildlife.
Control methods
In recent years chemical control of Bracken with the herbicide Asulox has been the primary method of control, either by aerial application or ground based spraying. However, in 2023 the authorisation that covered Asulox was removed, and it is no longer available. In the absence of Asulox the remaining methods of control are:
- Glyphosate weed wiping – Glyphosate is one of the few approved herbicides known to control Bracken. As it is non-selective it will kill or damage any plant it touches. If the Bracken is clear of grasses and land conditions permit it may be possible to apply glyphosate via a weed wiper that only targets the Bracken. If weed wiping is possible it is the most effective control and will target the rhizomes.
- Cutting – Prevents energy being returned to the rhizomes. This continual process aims to deplete the rhizome energy reserves and slow regrowth.
- Rolling, brashing and livestock tramping – All aim to damage the stems of the Bracken causing the sap to bleed out. This reduces the vigour of the plant growth and the amount of energy being returned to the rhizomes. Trampling with livestock allows the Bracken litter on the ground to be broken up which then makes the rhizomes more susceptible to frost damage.
- Burning – Not recommended as this recycles nutrients and suppresses other vegetation that would compete with the Bracken. May encourage Bracken growth.
Due to their vast underground rhizome store Bracken control is a long-term process. Research has shown that control by cutting, brashing, rolling or trampling may take up to ten years to deplete the rhizomes to a point where plant growth is significantly reduced.
Before you undertake any control you should check if you are bound by any requirements from agri-environment schemes or conservation designations.
More information on Bracken control is available in the ‘Best Practice Guidance on Bracken Management’ which was commissioned by all of the UK nature conservation bodies.