Green cestrum
Botanical name
Cestrum parqui
Family
Solanaceae (nightshade)
Where is it originally from?
Chile and Peru
What does it look like?
Smelly shrub (<1-3 m), with erect stems that become woody as it matures. Hairless, alternate leaves (20-120 x 5-30 mm) are foul-smelling when bruised. Dense panicles of greenish-yellow tubular flowers (15-23 mm long) with petal margins bent backwards and which are fragrant at nighttime, appear from November to June, followed by glossy, purplish black berries (7-10 x 6-8 mm).
Are there any similar species?
Cestrum elegans, C. fasciculatum, C. nocturnum, C. aurantiacum and many native shrub species, eg. Mahoe, are similar.
Why is it weedy?
Produces many long-lived, widely dispersed seeds, and forms dense, shady masses. Prefers damp conditions, is moderate to highly shade tolerant, and grows in most soil types, and hot or cold conditions. Deadly poisonous, not grazed.
How does it spread?
Birds, flooding, soil movement and vegetation dumping.
What damage does it do?
Forms dense (occasionally pure) stands in forest understorey, preventing the establishment of native plant seedlings. Poisonous berries and rotting vegetation may affect native fauna.
Which habitats is it likely to invade?
Disturbed and open forest and margins, streamsides and shrublands, potentially throughout New Zealand.
What can I do to get rid of it?
If you are in the Auckland region contact your regional council to determine the status of this species and responsibility for control. Otherwise report suspected findings to your local Department of Conservation office. Hard to distinguish from many native species (apart from foul smell), best controlled when in flower. Wear gloves when handling.
1. Physical removal - Hand pull small plants, or dig out entire plant including roots (all year round).
2. Cut and paste - Apply picloram gel (43g/l strength) to the entire cut stem. Do not use near desirable plants or overwater or wetlands. When a gel is inadequate apply a commercial formulation of (120g triclopyr/l of oil or product containing triclopyr and picloram 50ml/L water mix). Apply the mixture over the entire exposed surface of the cut stump, i.e. top and sides
3. Foliar spray - Apply Glyphosate (360 g/L active ingredient) herbicide (20ml/L) plus organosilicone penetrant (2ml/L) to cover entire plant Note: Non-selective, avoid overspray onto desirable plants OR Apply Triclopyr herbicide (600g/L active ingredient) at 6ml/L plus organosilicone penetrant (1ml/L) to thoroughly wet all parts of plant OR Apply Picloram/triclopyr herbicide (picloram 100g/l and triclopyr 300g/l active ingredient) at 6ml/L plus organosilicone penetrant (1ml/L) to thoroughly wet all parts of plant. Note: Triclopyr and picloram herbicides are ‘grass friendly’ but overspray will kill other (desirable) broadleaf plants. Picloram has residual activity in the soil which may leach through soil and kill other plants. Do not use under and around other (desirable) broadleaf plants.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and directions for the purchase, use and storage of the product, are followed and adhered to.
What can I do to stop it coming back?
Stems resprout. Reseeds into bared areas. Exclude stock at all times. Replant bared sites to minimise regrowth. Check for seedlings 6-monthly.
Images
