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Also known as
Japanese privet, broadleaf privet
What does it look like?
A small to large evergreen tree that can grow up to 15m high, but can also be a dense shrub less than 10m. Can have distinctive warty lumps on stems. Dark green oval leaves (5-13 x 3-6 cm) glossy on upper surface, with pointed tips and smooth edges. Arranged in opposite pairs on the stems.
Produces long panicles or clusters of tiny cream-coloured, strongly scented flowers, from November to March, followed by bluish or purplish-black berry-like fruit (6 x 5 mm), coated with a powdery ‘bloom’.
Why is it a problem?
Fast-growing and very long lived (100+ years), with prolific, widely dispersed seed. Seedlings tolerant of both sun and shade means that it can invade both marginal land and intact forest. It replaces mid canopy trees (grows to the same height as species such as taraire, towai, pohutukawa) and completely dominates areas of forest if unhindered, forming very dense, tall stands. Leaves & fruit poisonous, pollen and perfume contributes to allergies and asthma.
Wide environmental tolerance; very tolerant of shade, frost, damage, grazing, all well-drained soil types, high to moderate temperatures, damp or drought conditions, salt and wind.
Threatens coastal and lowland forest types (intact and disturbed), shrublands, fernland, cliffs, and coastlines.
How does it spread?
Seed dispersed by birds, over long distances by Kereru. Vegetation dumping and soil movement also spreads seeds.
How much of it do we have on the Whangarei Heads Peninsula?
The core of the infestation at Solomon’s point and further north. South and east of this the infestations begin to reduce in frequency and density, to a point where there are only scattered individual trees and saplings, which occur less and less frequently.
What can we DO about it at Whangarei Heads?
Heaps! Privet is easy to kill with metsulfuron and if we approach it as a community, seeking out and removing the outliers and pushing back the boundaries of the worst infestations we can protect the rest of the peninsula from becoming what will otherwise be privet forest.
It is easiest to spot in peak flowering Jan-March so get in touch to get some advice and equipment to be ready and on the look out this summer.
Check out the control methods below:
How do I control it?
- Pull or dig seedlings. Leave on site with roots in the air to die and rot down, or mulch.
- Cut stump application: Cut at ground level and immediately treat stump with (5g metsulfuron/1L water). Metsulfuron works best, however (200ml Tordon Brushkiller®/1L water) or undiluted glyphosate can also be used (extra care is required when working with undiluted herbicides). Picloram gel can also be used, but is also less effective, especially for large trees). Cut stems can be left on site to rot down, or mulched.
- Frill and fill: Make deep downward cuts into the sapwood around the base of the tree, taking care not to ring bark the plant, and immediately saturate the cuts with (20g metsulfuron/1L water) to the point of runoff. Wait until the liquid subsides/absorbs and then apply again. Metsulfuron works best, however undiluted glyphosate or undiluted Tordon Brushkiller® can also be used, but extra care is required when working with undiluted herbicides. Picloram gel can also be used (less effective, especially for larger plants).
- Drill & fill: Drill (c.12mm drill bit) sloping holes into the sapwood at 10cm intervals around the base trunk, & immediately fill each hole with (20g metsulfuron/1 litre water). Metsulfuron works best, however undiluted glyphosate, or undiluted Tordon Brushkiller® can also be used but extra care is required when working with undiluted herbicide.
- Spray, best in spring & autumn, with (5g metsulfuron+10ml penetrant/10L water), or (100mls glyphosate/10 litres water).
Ensure correct identification. Easy to kill with metsulfuron. Follow up 6-monthly. Easiest to spot during spring flowering. Don’t replant until seedling regrowth ceases, as privet will grow through groundcover. If removing large adult trees and opening up an area to light, be prepared to treat the resulting seedlings that will germinate to prevent creating a thicket of saplings which are more labour intensive to control.
CAUTION: when using any herbicide or pesticide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
Click here for more information on the herbicides referenced in the control methods, or here for more information on the suggested techniques.
Photos of Tree Privet