Pest control hub
What does it look like?
There are four species of privet in New Zealand: tree privet (Ligustrum lucidum), Chinese privet (Ligustrum sinense), privet (Ligustrum ovalifolium) and common privet (Ligustrum vulgare). Tree and Chinese privet are common in Northland and both are pests.
Tree privet is a small to large evergreen, hairless tree up to 15m tall with distinctive lumpy warts on the stems. It has dark green leaves (5-13 x 3-6cm) that are glossy on the top surface and arranged in opposite pairs on the stems. Tiny fragrant, cream coloured flowers are produced from November to March, followed by bluish or purplish to black berry like fruit (6 x 5mm).
Generally present in or near sites of human habitation, where they have been planted as hedges or specimen trees. Tree privet inhabits most coastal and lowland forest types (intact and disturbed), shrublands, fernland, cliffs and coastline.
Why is it a problem?
Privet produces many highly viable seeds in widely dispersed berries. It is very dominant, spreading dense carpets of seedlings that displace native shrubs and prevents native plant regeneration. Privet is very tolerant of shade, damage, frost, grazing, all well drained soil types, high to moderate temperatures, damp or drought conditions, salt and wind. Tree privet is long lived while Chinese privet is short lived but constantly replaced.
These species flower at different times of the year between July and March, with the flowers followed by berries that contain high numbers of viable seeds. These berries are dispersed through the autumn and winter months by birds or by falling from the tree. The seeds can germinate without the removal of berry flesh, but have a relatively short seedbank and are not likely to be viable after a year.
- Pull or dig seedlings out all year round. Leave on site to rot down.
- Cut low and treat stump immediately (all year round) with: 250ml glyphosate (360g/l) per 1L water or 5g metsulfuron-methyl (600g/kg) per 1L water.
- Drill and fill (all year round): Using a 10-12mm drill bit, drill one downward sloping hole every 200mm around the base of the trunk and fill with undiluted glyphosate or 20g metsulfuron-methyl (600g/kg) per 1L water. Extra safety precautions must be taken if using undiluted herbicides.
- Frilling: With a sharp chisel or axe, make a deep cut into the sapwood at regular intervals around the base of the tree, taking care not to ring-bark the plant. Immediately saturate the cuts with 250ml glyphosate per 1L water or 5g metsulfuron-methyl (600g/kg) per 1L water.
- Spray (spring-autumn): 5g metsulfuron-methyl (600g/kg) + 10ml penetrant per 10L water or 100ml glyphosate (360g/l) + 10ml penetrant per 10L of water.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.