Boneseed
Boneseed is a rapidly growing perennial shrub and a prolific seed producer. Thriving in bare land, boneseed quickly invades areas of native vegetation posing a threat to the sustainability and biodiversity of native ecosystems.
What is boneseed?
Boneseed is a perennial, woody, erect shrub with a shallow root system which usually grows up to 3 metres tall, however, it can occasionally develop into a small tree reaching up to 6 metres high. Its bright green leaves are waxy and broad with jagged edges and a downy white underside, while the flowers are bright yellow and look like daisies.
Boneseed produce fruit in the form of dry berries that turn from green to black before flaking off to show a white inner coat. This is where it gets the common name boneseed from. Boneseed primarily reproduces is by seed which is spread by contaminated soil or water, or by animals that eat the fruit. Germination is promoted by fire, soil disturbance, weathering and ingestion of seeds by animals and once germinated, its growth is rapid.
Where is boneseed found?
Boneseed is not restricted by climate and tolerates most soil types, invading bushland and displacing native vegetation. It is well adapted to fire but will not tolerate waterlogged soil or prolonged drought. It can be found along the Murray River, waterways, roadsides, and mallee scrub.
There are known infestations scattered throughout the Murraylands and Riverland region.
Recorded boneseed outbreaks in the Murraylands and Riverland region*
What are the impacts of boneseed?
Boneseed is a threat to native vegetation, establishing readily on disturbed sites such as cleared, cultivated or burnt land. Invasive due to its rapid growth, large seed store in the soil, and the ability to regenerate after fire, boneseed poses a significant issue to native fauna affected by the loss of habitat and food sources.
What is the declared status of boneseed?
Boneseed is declared in South Australia and is subject to the following restrictions:
- Land owners and managers to take reasonable steps to kill plants and prevent their spread,
- Plants must not be sold or traded in any way, including as a contaminant of anything,
- Plants must not be transported on a public road, including as a contaminant of anything,
- Plants must not be imported into the region.
When is the best time to monitor for and control boneseed?
Boneseed is easily detected when it flowers in late winter and early spring, producing bright yellow daisy-like flowers. Landholders should also be on the lookout before flowering, for old plants to prevent seeds from setting, and should check areas of previously known infestations for new incursions.
Be careful not to confuse boneseed with the native species twin-leaf (Roepera apiculata) which also produced small yellow flowers at the same time of year. Twin-leaf often grows in similar environments to boneseed but tends to be a lower growing shrub and often grows with other native species. Twin-leaf has smooth-edged leaves, that are a paler green in colour than boneseed. They can also be distinguished from boneseed as their leaves don’t have a downy underside.
How should boneseed be controlled?
Boneseed is relatively easy to control. As a shallow-rooted plant, simply pulling it out of the ground is an effective way to kill it. After being hand-pulled, boneseed plants can be left where they grew to breakdown, limiting the risk of spreading seeds to un-infested sites.
To control boneseed, landholders should:
• treat mature plants to limit seed production
• check for regrowth and new seedlings
• kill young plants before they are 1 year old to prevent seed set (most plants do not flower until 18 months old)
• keep checking for new seedlings each year - seeds can be dormant in the soil for up to 10 years.
More information about control options, including specific herbicide rates, can be found on the PIRSA website.
How can boneseed be prevented?
It is important to keep uninfested areas clear of boneseed by identifying and addressing existing or potential sources of this plant before it invades natural ecosystems. Once an infestation is established, preventing its spread into surrounding areas should be a priority:
- Remove isolated plants before they reach the age of seed production and pile pulled plants where it has been removed, and monitor for germination.
- Quarantine an area to stop movement of seeds in mud on vehicles may also be required.
- Don’t move or use soil contaminated with seeds.
- Destroy all seed material by safe disposal or burning.
- Prevent entry on to your property by ensuring your stock, machinery and purchases of seed, soil and fodder are free of weed seed.
- Quickly identify and treat weeds using the recommended measures and continue follow up treatments until the weed is killed.
What to do if you suspect a boneseed outbreak
If the plants are actively growing on your land, remove and destroy the plant or treat with chemicals until plant is killed. Always follow up after the initial efforts.
For support in identifying and controlling boneseed, contact your local district officer.
This project is supported by the Murraylands and Riverland Landscape Board with funding through the landscape levies.
*Map provided as a guide only. Mapped outbreaks are not necessarily current or comprehensive.