Bracken Control: A Guide to Best Practice (SNH)

STAGE 3 - WHAT ARE THE CONTROL OPTIONS?

 MEASURE
 DETAILS
 PROS/CONS
USE OF LIVESTOCK

A balanced stocking regime with cattle and fewer sheep on badly affected areas, combined with other treatments is an option that may assist long-term bracken management.

Short-term high densities of livestock over winter can break up bracken litter and expose rhizomes to frost damage. This needs to be carefully managed to avoid damage to soils and vegetation. Feeding stock on badly affected areas will help concentrate impacts.

Pigs can produce similar effects to mechanical cultivation, and will eat rhizomes, but cause extreme ground disturbance and there is a risk of bracken poisoning.

May require fencing.

Bracken can be toxic to stock.

Potential damage to soil.

CUTTING/ CRUSHING/ BRUISING

For bracken control (rather than eradication) to be effective, it will be necessary to cut/roll/ flail bracken at least twice in the first year (in May/June and again in July/August) followed by at least one cut each year for the next five years. For bracken eradication, or where bracken is dense and vigorous, it may be necessary to cut/roll/flail up to three times per year. You should note that, where bracken control is carried out under the SRDP - Rural Priorities, it must be carried out according to the prescribed methods in force at the time. In 2008 these specify treatment three times per year.

Special rollers designed for crushing bracken are available.Whipping with thin metal or hardwood rods can be used to cut bracken where vehicle access is restricted or where bracken is not dense. Mechanical methods can be used in combination with chemical treatments. A noticeable reduction in bracken density can be achieved in time. Do not use this method if ground-nesting birds are present.

These options may not be appropriate in some areas because of steep slopes and difficult access. Vehicles should not be used on archaeological sites.

Care should be taken to avoid damage to reptiles, ants, butterflies including fritillaries, and their habitats, where these species are present.

Good for scattered bracken and if little damage is likely to the underlying vegetation. Can give good, but slow, control of dense bracken; breaks up litter layer. Eradication is rarely achieved.
PLOUGHING OR TILLAGE

Should be carried out by late autumn. Additional kill may be gained by exposing rhizomes to frost action. Must be followed up with further treatment of recovered bracken in subsequent years.

Not suitable on archaeological sites or where existing desirable vegetation may be excessively damaged.

Excellent control with litter broken up.

Soil erosion.

BURNING BRACKEN LITTER

Does not achieve bracken control but may be used as part of a control programme where deep litter prevents vegetation recovery. Not suitable on steep slopes. Carry out in autumn.

Not advisable on sites with standing stones.

Be aware of danger of erosion where there is no underlying vegetation.
BURNING HEATHER

Pre-control. Suitable for older heather where sparse bracken fronds are advancing as part of a control programme. These are vulnerable areas and burning will encourage thickening of the bracken. The bracken must be treated as soon as possible and within 2 years of the burn.

Not advisable on sites with standing stones.

Danger of bracken spreading rapidly unless follow-up control carried out.
CHEMICAL TREATMENT
AERIAL SPRAYING BY HELICOPTER

Suitable for primary treatment of large areas of dense bracken but not for small areas of scattered or patchy bracken, or where bracken is interspersed with other sensitive habitats such as pockets of woodland, scree, flushes and watercourses.

Ensure buffer zones are agreed and not over sprayed. Beware of spraying areas which are far too extensive to permit adequate follow-up treatment and aftercare. Treating smaller areas thoroughly is likely to be much more cost effective and have greater long term benefits.

Only approved herbicide: Asulam.

Good for areas inaccessible to ground vehicles.

Good control of dense bracken but no effect on litter.

Wasteful use of herbicide on scattered bracken.

TRACTOR/ATV WITH MOUNTED BOOM

Suitable for areas of shorter and/or scattered or patchy bracken stands on flat/even ground. Used for primary treatment.

Recommended herbicide: Asulam

Not suitable on archaeological sites.

Booms do not spray efficiently on rough land due to boom movement.

Significant run-off of chemical can occur.

Cheap and efficient use of herbicide. May be less effective as frond density and height increases.

TRACTOR/ATV WITH ROLLER WIPING GEAR (WEED WIPE)

Suitable where aerial spraying is deemed to be impractical. Buffer zones are smaller than for aerial spraying. Ideal for follow up treatment where ground conditions allow. Recommended herbicide: Glyphosate.

Not suitable on archaeological sites.

Cheap and efficient use of herbicide. May be less effective as frond density and height increases.
HAND-HELD SPINNING DISC SPRAYERS SUCH AS THE MICRON ULVA+

Suitable for large areas of shorter bracken or smaller areas of dense, tall bracken which are inaccessible to vehicles, in establishing woodland, or for treating missed strips.

Recommended herbicide: Asulam.

Waterless spraying (therefore light to carry) for difficult areas.
ATV OR QUAD BIKE WITH A SPRAY-LANCE

Necessary for follow-up over larger areas where wiping is not possible.

Recommended herbicide: Asulam.

Efficient use of herbicide on the scattered fronds left over after primary treatment.
SPOT-GUN SUCH AS THE 2ML ACCU-DOS

Essential where eradication is required: can treat fronds too small for any other method.

Recommended herbicide: Asulam.

Smaller volumes per squirt (0.5ml) avoids fatigue.

RELATIVE COSTS OF CHEMICAL AND MECHANICAL PRIMARY TREATMENT

Aerial spraying costs about the same as boom spraying by tractor or ATV. Most other treatments cost about a third as much for a single treatment (i.e. cutting twice per year will be about two-thirds of the cost of aerial spraying). The exceptions are knapsack spraying, which costs about three times as much as aerial or tractor spraying, and ULVA application, which costs about twice as much as aerial or tractor spraying.

HERBICIDES

Asulam (e.g.Asulox) - Although asulam is a selective herbicide, other non-target species may also be susceptible e.g. some ferns, young heather plants, western gorse and some grass and tree species. Seek advice if you need further details. Buffer zones are necessary to protect watercourses and wildlife interests.

Glyphosate (e.g. Roundup Pro Biactive) - This is not a selective herbicide (in contrast to asulam) and will damage or kill all green vegetation it comes into direct contact with. It is most appropriately used on very dense bracken where it forms an over-storey which acts to prevent the chemical directly contacting the other vegetation beneath. Buffer zones are necessary to protect watercourses and wildlife interests.

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