Originally from Europe, gorse and broom were brought to our country by settlers in the 1800s for use as hedge plants. They soon spread from these original plantings and began invading the landscape.

Gorse and broom are pests as they produce massive numbers of long-lived seeds, mature and grow rapidly, and are able to establish in a range of habitats. These pests can form thick groups of bushes, outcompete native vegetation, prevent stock from grazing and are generally seen as a threat to economic and environmental values. They can tolerate a wide range of temperatures and rainfalls, and can withstand wind, salt, damage, grazing pressure, and can grow in most soil types.

Gorse and broom seeds are dispersed by explosive seed pods, water and human-mediated activity through contamination of vehicles, livestock and machinery. Seeds are long-lived and can remain dormant in the soil for 40-80 years.

Gorse and broom will grow well across habitat types anywhere in Otago. Thankfully, large areas of Central Otago and the Queenstown Lakes are mostly clear of infestations. Gorse and broom are only considered pests under our pest plan in the gorse and broom-free areas and rural-zoned properties.

Broom

• Woody perennial shrub that grows up to 3 m tall.
• Leaves are sparse, small, hairy and grouped in threes.
• Flowers are bright yellow with a dark pinkish streak near the base and are visible in spring and summer.
• Seed pods are hairy and green-brown, maturing to black. 
• Root system has one main stout taproot. 
• Habitats include lowland and montane areas, shrublands, grasslands, steep slopes, open forests, riparian areas, riverbeds, wastelands, disturbed habitats, pastures, and plantations.

Gorse

• Sharp, spiny, woody perennial shrub that grows up to 4 m tall.
• Leaves are reduced to a sharp, spine-like tip.
• Flowers are bright yellow and are visible from May to November.
• Seed pods are hairy and green-brown, maturing to black.
• Root system has taproots very deep with extensive lateral roots.
• Habitats include grasslands, shrublands, forest margins, plantations, hill country, coastal habitats, sand dunes, and wastelands.

The goal of the pest plan is to sustainably control gorse and broom, to ensure that land that is free of, or that is being cleared, does not become infested. This is to prevent negative effects on both production and economic values.

To achieve this Otago Regional Council (ORC) slightly extended the gorse and broom-free areas from our last plan. These areas are mainly Otago’s unique high country and tussock grasslands that have never had a major history of these pest plants, and where an invasion of these plants would greatly affect grazing, biodiversity and the landscape. In total, the gorse and broom free areas cover over 50% of Otago.

Click here to see a map of the gorse and broom free areas in our pest plan

The rules in the Otago Regional Pest Management Plan (2019-2029) simplified include:

• Everyone within the gorse and broom-free areas must eliminate gorse and broom on the land that they occupy. For those in the new gorse and broom-free areas this rule will not be enforced until March 2024. ORC will give advice and information to anyone in the new areas to make sure they are ready for this rule to come into effect.
• Everyone outside the gorse and broom free areas on rural-zoned land, must eliminate gorse and broom 10m from their property boundary where the neighbouring property is eliminating gorse or broom 10m on their side of that boundary.

For a more detailed explanation of the programme and rules, see pages 48-52 of the Otago Regional Pest Management Plan (2019-2029).

Physical control:

• Hand pull seedlings and small plants, or for larger shrubs, cut trunk into manageable sections to be dug out. Ensure you dig out the roots for effective removal.

Chemical control:

• Cut down the plant and treat the stump near the ground using a suitable herbicide gel containing either metsulfuron, triclopyr or glyphosate
• Spray when the plant is actively growing using suitable herbicides such as Tordon or Grazon.

Caution: When using any herbicide or pesticide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.

Disclaimer: Mention of product trade names does not endorse these products nor imply criticism of similar products not mentioned. The Otago Regional Council does not give any warranty that the information is accurate or complete or that it is suitable for all circumstances.

Biocontrol agents:

Biocontrol agents for both gorse and broom are present throughout Otago.

Otago Regional Council has carried out a number of releases of the broom gall mite across Otago with successful results for reducing broom infestations. Broom gall mite is a microscopic organism that colonises and feeds on broom, gradually forming white galls on the plants that can stunt their growth and eventually kill them. As its name suggests, the mite only attacks broom, making it an effective weapon against the invasive bush while protecting our native plants.

If you have gorse or broom, you can check for the presence of biocontrol agents (more detailed information is available on Landcareresearch.co.nz):

Gorse Biocontrol agents

• • • • Gorse colonial hard shoot moth
      • Gorse pod moth
      • Gorse seed weevil
      • Gorse soft shoot moth
      • Gorse spider mite

Broom Biocontrol agents:

• • • • Broom gall mite
      • Broom leaf beetle
      • Broom psyllid
      • Broom seed beetle 

Gorse colonial hard shoot moth

Gorse pod moth

Gorse seed weevil

ORC has a number of broom gall mite release sites around Otago that are providing good results. Broom gall mite is a microscopic organism that colonises and feeds on broom, gradually forming white galls on the plants that can stunt their growth and eventually kill them. As its name suggests, the mite only attacks broom, making it an effective weapon against the invasive bush while protecting our native plants.