Biosecurity factsheet 13 - Gorse and Broom.indd by zhangyun


Biosecurity series – pest plant factsheet                                                                                             FACTSHEET

Gorse and broom
Ulex europaeus and Cytisus scoparius

                                                                                                                                     Plant type
Why they are pest plants
Gorse is widespread throughout the Waikato region, reducing the                                                                        Aquatic
area available for grazing by livestock on pasture land and
invading naturally open spaces. The foliage of gorse can become                                                                        Fern
dry, making gorse stands susceptible to fire.
Broom is an aggressive pest plant, which is unpalatable to stock
and will reduce stocking rates. 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.

How to recognise these pest plants                                         Gorse flowers produce 1800 seeds per bush, which can
Gorse is a deep-rooted woody perennial that can grow up to four                    remain viable in the soil for 16 years or more.
                                                                                        Eradicate gorse before seed is produced.       Vine
metres high.
                                                                       Identifying features                                            Scrub
Broom is a deciduous shrub most recognisable by its distinctive        Gorse
upright green stems. Broom normally grows in areas of high             •   Leaves of gorse take the form of sharp spines.
rainfall and can tolerate a wide range of soil conditions.             •   The plant can grow up to four metres tall.
                                                                       •   Gorse’s yellow pea-like flowers grow into
All land occupiers in the                                              •
                                                                           brownish black flattened seed pods.
                                                                           Seedlings initially have more conventional

Waikato region are required                                                leaves, which are trifoliate (three leaflets).               Burn

to destroy all gorse and                                                                                                               Compost

broom plants within 20 m                                                                                                               Herbicide

of their boundary.         Gorse.

                                                                                                                                       Report it

                                                                                                           Yellow broom flowers.

                                                                       •   Broom is an erect deciduous shrub growing up to
                                                                           2.5 metres in height.
                                                                       •   Flowers are large, yellow and bloom from
                                                                           October to November. Seed pods are similar to
                                                                       •   Broom has pliable, upright, ridged green stems
                                                                           that may have small leaves, but may also be
Responsiblity for control
All land occupiers in the Waikato region are required to destroy all gorse and broom plants     Manaaki Whenua – Landcare Research runs a
within 20 m of their boundary. All quarries and road and rail verges must be kept completely    national biological control programme. Environment
clear of gorse and broom.                                                                       Waikato supports this programme and maintains a
                                                                                                local biological control programme for the Waikato
Gorse and broom are declared total control plant pests for all quarries and road and rail       region. For more information on bio-control agents
verges, requiring all plants to be destroyed in these areas. The sale, propagation or           visit
distribution of gorse and broom is prohibited throughout the Waikato region.

How to control gorse
Mechanical control
A hand slasher or scrub cutter can be used on isolated bushes but if the stump is not treated
with a herbicide (see stump treatment below), re-growth will occur. Large areas of slashed
stumps can be left to grow to 0.5 metres in height and then sprayed.

Herbicide control
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 such herbicides as Grazon®, Tordon Brushkiller, Escort® and Roundup® or
stump treated with Vigilant™ gel.

Hard grazed gorse or recently slashed gorse is difficult to control because of reduced foliage                                                   Broom.
to take up herbicide. Active growth is more susceptible to spraying. Your biosecurity pest
plant contractor can give you advice on the timing and method of application best suited to     Important contacts
your situation.                                                                                 Biosecurity pest plant contractors in the Waikato
                                                                                                region – 0800 BIOSECURITY (0800 246 732).
How to control broom
Mechanical control                                                                              For more information on pest plants or the use of
Young plants can be hand pulled or grubbed. This method of control should be carried out        agrichemicals phone Environment Waikato’s
before seeding. Small bushes can be slashed and the area cultivated. However, this will         freephone 0800 800 401 or check out
produce a seedbed suitable for the establishment of seedlings. These areas should then be
controlled by further cultivation or heavy grazing.
                                                                                                For more information on pest
                                                                                                plants, check out
Herbicide control
Chemical control is effective. A ‘blanket’ spray during the full leaf stage (spring to early
summer), followed by maintenance spraying of any further growth is effective. All the
herbicides suggested for controlling gorse (above) can be used to control broom. The use of     More information
penetrants may increase effectiveness of control. Your biosecurity pest plant contractor can     Regional Pest Management Strategy (RPMS).
give you advice on the timing and method of application best suited to your situation.
                                                                                                What makes a pest a pest? – A guide to the Waikato
Summary of herbicides for control                                                               Regional Pest Management Strategy (free).
When using herbicides:
• read the instructions on the manufacturer’s label closely                                     Plant Me Instead – Plants to Use in Place of
• always wear protective clothing                                                               Common Pest Plants (free).
• always minimise the risk to desirable plants
• contact the supplier for further advice                                                       The New Zealand Pest Plant Manual (National Pest
• for aerial and boom application rates contact the supplier.                                   Plant Accord Identification Guide) – $10.00 incl.
Biological control of gorse and broom
Six separate biological control agents for gorse have been released within the Waikato          Poisonous Plants and Fungi in New Zealand – A
region. The most successful of these has been gorse spider mite. Four broom agents have         Guide for Parents, Schools and Child Minders
been released including the broom seed beetle, broom twig miner and broom psyllid.              ($15.00 incl. GST).

Environment Waikato, 401 Grey Street, PO Box 4010, Hamilton East 3247

For more information call Environment Waikato’s freephone 0800 800 401 or visit
Environment Waikato biosecurity factsheet series no. 13 (S1913-0509). Photos: Trevor James.

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