BIOSECURITY 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. Grass Broom is an aggressive pest plant, which is unpalatable to stock and will reduce stocking rates. It is an agricultural pest plant but Ground also causes problems in forestry, wastelands, along road and cover rail sides, braided rivers and protected natural areas. Broom is particularly a problem in the open tussock grassland of the North Island central plateau. Shrub Tree 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 Disposal 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. Bury deeply Report it Yellow broom ﬂowers. Broom • 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 gorse. • Broom has pliable, upright, ridged green stems that may have small leaves, but may also be leaﬂess. www.ew.govt.nz 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 www.landcareresearch.co.nz. 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 www.ew.govt.nz. controlled by further cultivation or heavy grazing. For more information on pest plants, check out Herbicide control www.weedbusters.org.nz. 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. GST. 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 www.ew.govt.nz Environment Waikato biosecurity factsheet series no. 13 (S1913-0509). Photos: Trevor James.