Common Gorse (Ulex europaeus) is a spiny shrub from the Mediterranean region of Western Europe. Introduced to other countries, this shrub competes very successfully with native vegetation, and is ideally-suited to mild maritime climates. It readily competes for well-drained areas where the soils have been excessively disturbed or are naturally poor, and has become increasingly prevalent on roadsides, disturbed sites and on farmland.
Gorse is a valuable plant for wildlife, providing dense thorny cover ideal for protecting bird nests, however, there is concern that gorse is spreading and posing a threat to forests and other resources.
How can I identify gorse?
Gorse grows to 2-3 metres tall, and spreads widely.
Young seedlings produce normal leaves for the first few months, resembling a small clover leaf.
The shoots and leaves then become modified into green spines, 1-3 cm long.
The flowers are yellow, 1-2 centimetres long, with a typical pea-flower structure. These are produced throughout the year, but mainly in the early spring.
The fruit is a 2 cm long pod, dark purplish-brown, partly enclosed by the pale brown remnants of the flower. Each pod contains 2-3 small blackish seeds, which are released when the pod splits open in hot weather.
Why is gorse a problem?
Gorse thrives in poor growing areas and conditions including drought, it is sometimes found on very rocky soils where many species cannot thrive. Gorse is a weed and invasive species due to its aggressive seed dispersal and has proved very difficult to eradicate.
It can quickly become established on disturbed sites within its range where a lack of moisture and nutrients limits the establishment of native vegetation.
Gorse seed can scatter when its pods burst and eject the seeds, and can be spread by animals, water and machinery. Seeds can be dispersed by vehicles that pick them up in mud and gravel along roadsides and then distribute them along roads adjacent to forest land.
Seeds are also readily transported by water as the hard seed coat provides protection in the water.
Gorse readily becomes dominant in suitable conditions, and where this is undesirable for agricultural or ecological reasons control is required, either to remove gorse completely, or to limit its extent.
How can I prevent gorse establishing itself?
Early detection and prompt control of gorse in new areas is preferable to trying to eradicate an established infestation.
Sites prone to gorse infestation should be planted with preferred vegetation immediately following disturbance.
Do not plant gorse. Be aware of its methods of spreading.
On removal of gorse from a location, plant alternate vegetation immediately, fertilise and water if necessary to help new vegetation become established. Use native or less aggressive vegetation adapted to the site conditions.
How can I get rid of it?
Gorse is not killed by cutting or burning the top growth. It catches fire easily, but re-grows from the roots after the fire. The seeds are also adapted to germinate after slight scorching by fire.
Effective eradication requires, in most instances, a combination of treatments to remove it from a site. Control methods include:
Cutting or chopping – followed by fire, grazing or herbicides
The gorse is cut manually, or with mechanical implements such as bulldozers. It is then burned to remove the mature vegetation and to encourage sprouting.
The resprouts can be treated with herbicides.
Cutting followed by seeding
The gorse is cut to ground level and the site is seeded to a cover crop such as grass. The site is monitored periodically for gorse sprouts, which are removed by cutting or application of a selective herbicide.
Several herbicides have proven effective in controlling gorse. This is best done by an experienced technician.