Red cestrum
Botanical name
Cestrum elegans and Cestrum fasciculatum
Family
Solanaceae (nightshade)
Also known as
Cestrum purpureum, Cestrum newellii
Where is it originally from?
Chile and Peru
What does it look like?
Smelly shrub (<2-4 m) with erect stems that are densely covered with purplish hairs when young and become woody as plant matures. Hairy leaves (40-150 x 15-75 mm) are foul-smelling when bruised and are arranged alternately on the stems. C. elegans has dense clusters of tubular magenta to deep crimson scentless flowers (15-25 mm long) with petal margins bent backwards (Jan-Dec). Flowers on C. fasciculatum are scarlet (Aug-Mar). When produced, berries (7-15mm diameter) are crimson to dark red.
Are there any similar species?
Cestrum aurantiacum, C. nocturnum and C. parqui are all similar as are many native shrub species, eg. mahoe.
Why is it weedy?
Produces many long-lived and widely dispersed seeds and forms dense, shady masses. Moderate to highly shade tolerant, and grows in most soil types, damp or dry conditions, and hot or cold temperatures. Poisonous, not grazed.
How does it spread?
Birds, flooding, soil movement and vegetation dumping all spread seeds.
What damage does it do?
Forms dense (occasionally pure) stands in forest understorey and shrubland. Prevents 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, shrublands, and dry gullies.
What can I do to get rid of it?
If you are in the Gisborne region contact your regional council to determine the status of this species and responsibility for control.
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 Triclopyr herbicide (600g/L active ingredient) at 6ml/L plus organosilicone penetrant (1ml/L) to thoroughly wet all parts of plant. Note: Triclopyr herbicides are ‘grass friendly’ but overspray will kill other (desirable) broadleaf plants. Do not use over or near water bodies or wetlands and use only as directed on label.
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.
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