Boneseed is a threat to low coastal vegetation, where it can rapidly take over and replace native plants. It is a fast growing shrub that can produce up to 50,000 seeds a year. Boneseed is a ‘containment’ pest, requiring the removal of all plants. Find out how to recognise this plant and check out our tips for control.
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Why boneseed is a pest
Boneseed (Chrysanthemoides monilifera) is also known as salt bush or bitou bush. It threatens low coastal vegetation, where it can rapidly replace native plants. Boneseed shades out seedling trees like pohutukawa that need a lot of light to survive. Its thick growth can also restrict people’s access to beaches.
Boneseed can be difficult to control because of the large numbers of seeds it produces. Seeds can also remain dormant in the soil for up to 10 years. Birds and possums eat the fleshy fruit and spread undigested seeds into neighbouring shrub lands and coastal forests.
How to recognise boneseed
Boneseed is a fast growing shrub that produces up to 50,000 seeds every year. Seed germination is stimulated by fire. Boneseed grows best in dry sunny conditions in coastal areas, cliffs, sand dunes and wasteland. It doesn’t like heavy shade and wet soils.
Identifying Features
- Bushy shrub up to three metres tall.
- Leathery, paddle-shaped leaves, with toothed edges and a powdery surface.
- Yellow daisy-like flowers from September to February.
- Clusters of small fruit that turn from green to black when mature.
- Seeds are bone-like in colour and extremely hard.
Who is responsible for control?
A native of South Africa, boneseed was first brought to New Zealand as an ornamental plant but is now a ‘containment pest’ in the Waikato region, requiring the removal of all plants (total control). Infestations have been found around Waihi, Raglan and the Coromandel Peninsula.
All landowners/occupiers are required to work with Environment Waikato in areas where control programmes are in place. Boneseed is also banned from sale, propagation, distribution or commercial display.
How to control boneseed
There are two main ways to control boneseed:
- physical control
- herbicide control.
Physical control
- Small plants can be easily pulled out.
- Plants without seeds can be composted or mulched but those with seeds should be buried deeply or taken to a refuse transfer station.
- Larger plants usually need to be treated with herbicide, as they will re-grow.
Herbicide control
There are two main methods for herbicide control:
- stump treatment
- spray application.
Stump treatment
Cut stems at ground level and cover the whole stump with herbicide.
Spray application
Cover all leaf surfaces with herbicide where stump cutting is not practical. Best results are achieved from spring to autumn.
Follow-up management
Removal of adult boneseed plants can assist seed germination, so it’s important to:
- follow up control methods with regular seedling removal
- stop weeds from reinvading by replanting the treated area with desirable plants. For example fast growing native shrubs like taupata, akeake and hebe (Hebe salicifolia).
Summary of herbicides and application methods for control
When using herbicides:
- Always 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.
| Herbicide |
Application |
Method |
| Roundup® Renew |
Stump treatment |
200 ml / litre of water |
| |
Spray application |
100 ml / litre of water plus 20 ml ‘Pulse’ as penetrant |
| Escort® |
Stump treatment |
5 grams / litre of water plus 10 ml ‘Input’ as penetrant |
| |
Spray application |
5 grams / 10 litres of water plus 10 ml ‘Input’ as penetrant |
| Grazon® |
Stump treatment |
1 part / 12 parts water |
| |
Spray application |
60 ml / 10 litres of water plus 10 ml ‘Boost’ as penetrant |
| Vigilant® |
Stump treatment |
Use undiluted |
| Banvine® |
Spray application |
120 ml / 10 litres water |
Disclaimer: Although this content has been prepared in good faith from a number of sources believed to be reliable, Environment Waikato 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.
Further information
For further information and advice contact your local Biosecurity Plant Pest Contractor.
Related publications
Visit our Waikato Regional Pest Management Strategy.
'What makes a pest a pest? - A guide to Waikato's pest management future' download (730 kb, 104 seconds to download, 56k modem), order or pick up for free from our offices.
Pick up or order 'Plant me instead - Plants to use in place of common pest plants' for free from our offices.
Download the National Pest Plant Accord.
Pick up or order 'Poisonous plants and fungi in New Zealand - A guide for parents, schools and child minders' for $15 from our offices.