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  Services » Regional Services » Plant and animal pests » Pest plants » Gorse and broom

Gorse and broom

Gorse and broom

Sustained control

Gorse and broom

Sustained control

Keep gorse and broom from affecting nearby land

Why they are pest plants

threat

Identifying Features
Identifying Features
Production threat Environmental threat Public threat

Identifying features- Gorse

Gorse is a deep-rooted woody perennial that can grow up to 4m high.

Flower

  • Yellow pea-like flowers.

Fruit/seed

  • Brownish-black flattened seed pods.
  • Seeds are ejected from their pods to up to 10m away.

Leaf

  • Seedlings’ leaves are initially made up of three ‘leaflets’.
  • Later, the leaves of gorse take the form of sharp spines.

Identifying features- Broom

Broom is a deciduous shrub which grows up to 2.5m tall. It is most recognisable by its distinctive upright green stems. Broom normally grows in areas of high rainfall and can tolerate a wide range of soil conditions.

Flower

  • Large yellow flowers.
  • Flowers bloom October to November.

Fruit/seed

  • Brownish-black flattened seed pods – similar to gorse.
  • Seeds are ejected from their pods to up to 10m away.

Leaf

  • Pliable, upright, ridged green stems that may have small leaves.
  • However, broom stems may also be leafless.

Gorse is widespread throughout the Waikato region, reducing the area available for grazing by livestock on pasture land and invading naturally open spaces. The foliage of gorse can become dry, making gorse stands susceptible to fire. Gorse’s ability to fix nitrogen in the soil can lead to adverse effects on water quality. Gorse is widespread throughout the Waikato, affecting pasture, roadside verges, scrub land, forest margins and coastal habitats.

Broom is an aggressive pest plant, which is unpalatable to stock and will reduce stocking rates. It shades out pasture and inhibits its growth. Large thickets of broom can also prevent stock from getting at any grass surviving underneath. It is an agricultural pest plant but also causes problems in forestry, wastelands, along road and rail sides, braided rivers and protected natural areas. Broom is particularly a problem in the open tussock grassland of the North Island central plateau south of Tokoroa.

 

Broom Infestation

 

Responsibility for control

All landowners/occupiers in the Waikato, on complaint from an adjoining neighbour, are responsible for controlling gorse and broom within 20m of their property boundaries and are required to work with Waikato Regional Council in areas where control programmes are in place. Gorse and broom are also banned from being sold, propagated, distributed or included in commercial displays.

How to control gorse and broom

Many herbicides are not effective on gorse because of the shape of the ‘leaves’ and the thick cuticles on the spines, which help prevent absorption of herbicides. However, gorse can be killed using herbicides like glyphosate, metsulfuron or triclopyr/ picloram mix or stump treated with picloram or glyphosate gel.

Physical control

Physical control includes removing plants by hand, with machinery or by burning. It has been found that when the plants are big, cutting at the base (at flowering time) and fraying the stump causes the stump to lose moisture and generally kills the plant. As with many scrub weeds, gorse/ broom soon regrows from dormant buds on stumps if shrubs are cut with chainsaws or slashers without prior herbicide treatment. Regrowth from buds can also occur after fires. The cheapest treatment for large blocks of gorse/broom may be to fence it off and wait for it to revert to native bush. On less steep land, ploughing or repeated rotary slashing can be used.

Herbicide control

Basal treatment of trunk

The basal treatment X-Tree® can be applied with a low pressure sprayer using solid cone nozzle or a paintbrush. Liberally treat the full circumference and at the base of the shrub or tree trunks so the spray thoroughly wets at least 2-3 times around the diameter of the lower stem or trunk including the root collar area.

Cut stump treatment

A hand slasher or scrub cutter can be used on isolated bushes but if the stump is not treated immediately with a herbicide, regrowth will occur. Large areas of slashed stumps can be left to grow to 0.5m in height and then sprayed.

Gorse and Broom image

Spray application

As mentioned, gorse can be killed using herbicides like glyphosate, metsulfuron or triclopyr/picloram mix or stump treated with picloram or glyphosate gel. Hard grazed gorse or recently slashed gorse is difficult to control because of reduced foliage to take up herbicide. Active growth is more susceptible to spraying. Your biosecurity pest plant officer can give you advice on the timing and method of application best suited to your situation.

Safety when using herbicides

  • Follow the instructions on the manufacturer’s label.
  • Always wear protective clothing.
  • Always minimise the risk to your other plants.
  • Contact the supplier for further advice.

Disclaimer: Any product names mentioned below are not an endorsement nor are they a criticism of similar products not mentioned.

Summary of herbicides and application methods for control

Herbicide

Application


Picloram gel Cut stump treatment.
Glyphosate Spray application and cut stump treatment
Glyphosate gel Cut stump treatment.
Metsulfuron Spray application and cut stump treatment.
Triclopyr/picloram mix Spray application and cut stump treatment.
Triclopyr Spray application and cut stump treatment.
X-Tree ® Basal treatment of trunk.
Herbicide rules will apply. You may need to notify neighbours if spraying. The Waikato Regional Plan explains the agrichemical (herbicides) use rule in section 6.2

Management

After initial control, it’s important to:

  • clean out the site again at least annually to control regrowth
  • stop weeds invading by replanting with non-pest plants (preferably native plants) once regrowth is no longer a problem.

Biological control of gorse and broom

Six separate biological control agents for gorse have been released within the Waikato region. The most successful of these has been gorse spider mite. Four broom agents have been released – the broom seed beetle, broom twig miner, broom gall mite and broom psyllid.

Landcare Research runs a national biological control programme. Waikato Regional Council supports this programme and maintains a local biological control programme for the Waikato region. For more information on biocontrol agents visit www.landcareresearch.co.nz.

More information

Advice

  • For advice and additional information on control methods, call our pest plant staff on freephone 0800 BIOSEC (0800 246 732).
  • Chemical company representatives, farm supply stores and garden centres can also be good sources for advice.

Publications

View, download or order the following publications  or call our freephone 0800 800 401.

  • National Pest Plant Accord (Manual of plants banned from sale, propagation and distribution) ($10.00 plus GST)
  • Plant Me Instead! (Plants to use in place of common pest plants) (free)
  • Waikato Regional Pest Management Plan (RPMP) (free) (Section 5.23, page 83)
  • Waikato Regional Council pest guide (free)
  • What makes a pest a pest? A summary of the Waikato Regional Pest Management Plan (free)

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