There are two main species of privet in the Waikato region, tree privet and Chinese privet. Both invade the edges of forest and waste land, and can displace trees in our native forests. Privet’s leaves and berries are poisonous to people and animals, and its pollen can cause breathing problems for some people. Find out how to recognise privet and check out our tips for control.
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Privet is a woody tree or shrub that rapidly invades bush margins and waste areas. There are two types of privet in the Waikato region:
- Tree privet (Ligustrum lucidum).
- Chinese privet (Ligustrum sinense).
Privet were introduced to New Zealand as ornamental and hedging plants. However they are now both pests in the Waikato region.
Why privet is a pest
Privet rapidly invades bush margins and waste areas. Tree privet is capable of crowding out canopy trees in native forests, may impede native seedling germination and can eventually dominate an area of forest. Chinese privet can displace shrubs on the margins of native forests.
Privet leaves and berries are poisonous to animals and humans, and the highly scented flowers are commonly believed to add to respiratory problems such as asthma and hay fever. However, research shows privet is not a strong allergen for most people. A positive allergy test is therefore needed before the regional council can require a privet tree to be removed on health grounds.
How to recognise privet
Both types of privet are evergreen, meaning they keep their leaves all year round. They have strongly scented flowers and dark purple berries. Birds eat the berries and spread the seeds.
Privet tolerates a wide range of environmental conditions, for example, dry, cold and wet conditions.
- Evergreen tree – up to ten metres tall.
- Leaves are glossy and dark green above and lighter green below.
- Flowers appear from January to March.
- Flowers are small, cream-coloured and strongly scented.
- Evergreen tree or shrub – up to five metres tall.
- Leaves are small and dull green with wavy edges.
- Flowers appear from September to December.
- Flowers are small, white and strongly scented.
Responsibility for control
Landowners/occupiers are required to control privet on their property if Waikato Regional Council receives a valid health-related complaint from a neighbour, and the neighbour has a positive allergy test for privet from an approved medical laboratory. The privet causing the problem must be within 50 metres of the property boundary or in a public amenity area like a park, reserve, playground or walking track.
Privet is also banned from sale, propagation, distribution or commercial display.
How to control privet
There are two main ways to control privet:
- Pull out or dig up small plants. Make sure you remove the whole root system so the roots don’t re-grow.
- If cutting down larger trees treat the stumps with herbicide to stop them from re-growing.
- Regularly trim hedges to prevent them from flowering. This will reduce the impact of privet on asthma and hay fever sufferers.
- Plant areas where the soil has been disturbed with desirable plants such as native shrubs or grasses. This will suppress the germination of privet and other weed species.
There are three main methods for herbicide control:
- stump treatment
- cut and inject – for larger trees
- overall spray application – for smaller trees.
- Cut down the tree, leaving a stump no higher than five centimetres above the ground.
- Immediately paint herbicide over the entire stump surface, including the sides.
Cut and inject
- Use a machete or axe to make shallow downward cuts around the trunk of the tree. Make one set of cuts below the lowest branch and another set near the ground. Cuts should overlap each other all the way round the tree so that they effectively ‘ringbark’ it.
- Fill each cut with herbicide.
Overall spray application
- Most suitable for smaller plants, but hand-pulling may be cheaper and easier.
- Total coverage of leaf surfaces is required for effective control.
- Use ‘Pulse’ or another penetrant to improve the effectiveness of the application.
- Apply herbicide in fine weather during spring or autumn – during privet’s active growing season.
Disclaimer: Although this content has been prepared in good faith from a number of sources believed to be reliable, Waikato Regional Council does not give any warranty that all information contained is accurate or complete, or that advice given will be appropriate in all circumstances. Mention of product trade names implies neither endorsement of those products nor criticisms of similar products not mentioned.
Summary of herbicides and application methods for control
When using herbicides:
- read the instructions on the manufacturer's label closely
- always wear protective clothing
- always minimise the risk to desirable plants
- contact the supplier for further advice.
|Roundup G2® or Glyophosate
||Cut stem and inject
||Cut stem and inject
After the initial control, it’s important to:
- revisit the site at least annually to control re-growthf
- stop weeds invading by replanting with desirable plants (preferably natives) once re-growth is no longer a problem.
For further information and advice contact your local biosecurity plant pest contractor.
- Annual pollen calendar - details specific plants by month which may trigger your allergy
- Visit our Waikato Regional Pest Management Plan
- 'What makes a pest a pest? - A guide to Waikatos pest management future'. Pick up, download or order for free from our offices.
- 'Plant me instead - Plants to use in place of common pest plants'. Pick up or order for free from our offices.
- Download the National Pest Plant Accord.
- 'Poisonous plants and fungi in New Zealand - A guide for parents, schools and child minders'. Pick up or order for $15 from our offices.