Type of weed: Woody weed
Flower colour(s): Pale Blue, White
Priority Weed State Priority Weed. (See more weeds of the State Priority Weed class.)
This is a Weed of the Month for October
Flowering Months: September, October, November, December
An erect perennial shrub growing 3m x 3m. It is characterised by its woody, thorny growth. The stems are rigid, very branched and the main stems have spines up to 15cm. The long thorns are a distinctive feature.
The leaves are smooth, fleshy and up to 3.5cm long. The plant is drought resistant and in times of moisture stress can shed its leaves, making it look dead. In some locations plants can be deciduous.
Flowering generally occurs in spring and early summer, but it may occur at any time of the year provided the conditions are right.
The flowers have five petals; white with pale blue markings and are fragrant.
Fruit set generally occurs in autumn but, again, it can occur at any time of the year depending on conditions. The berries are green when young and orange-red when ripe. Each berry contains 35–70 seeds. Seeds can germinate at any time of the year if there is adequate moisture and warmth.
This plant can be confused with Native Blackthorn (Bursaria spinosa subsp. spinosa).
Spread by seed. Fruit is commonly eaten by foxes and birds. Seeds may also be spread by water, machinery and in dumped garden waste or contaminated soil.
Impact on bushland
The plant is an aggressive invader of bushland and waterways. It has an extensive, deep, branched taproot that will sucker and produce new growth if broken. Early root growth is rapid to allow seedlings to compete with other plants. It also provides habitat for native birds, so replacement planting of native species needs to occur as a follow-up to control treatments.
Lower Blue Mountains. Lower Mountains such as Glenbrook (and Cumberland Plain)
Local provenance Grevilleas, Banksias and Hakeas make great hedge plants and habitat for native birds. Spiky bushes that provided shelter and protection for small native birds include:
- Hakea teretifolia
- Lambertia formosa
- Leucopogon lanceolata
In the lower Mountains, plant Bursaria spinosa subsp. spinosa.
Council provides a tool, on its Mountain Landscapes website, to help you choose native alternative plantings. Choose your village, soil, vegetation community and the purpose of your planting, and the tool will give you suggestions.
There are native nurseries in several Blue Mountains villages, including Glenbrook, Lawson and Katoomba. Please also ask at your favourite local nursery.
- Hand remove
- Remove flowers, fruit, pods or seeds
- Stem inject or frill
- Cut and paint
Grasp stem at ground level. Rock weed backwards and forwards to loosen roots, then pull out gently. Carefully tap the roots to dislodge attached soil. Replace disturbed soil and pat down.
- Leave weeds so that roots do not make contact with soil; on a rock, for instance. A small amount of debris may be hung in a tree or removed from the site.
- Vary the position of your body to avoid fatigue when removing plants by hand over extended periods.
Remove seeds, pods or fruit
Gently remove any seeds, pods or fruit and carefully place in a bag.
Note: Herbicides that may be used for this weed include Glyphosate.
Stem injection or frilling
At the base of the tree, drill holes at a 45° angle into the sapwood (just under the outer bark) at two finger space intervals around the entire base of the tree. Repeat this process below the lowest branch
As an alternative to drilling, make cuts into the sapwood with a chisel or axe. Fill each cut/hole with herbicide immediately. Repeat the process at 3 cm intervals around the tree.
Plants should be healthy and actively growing. Deciduous plants should be treated in spring and autumn when leaves are fully formed. For multi-stemmed plants, inject or chip below the lowest branch or treat each stem individually. Herbicide must be injected immediately before the plant cells close (within 30 seconds before translocation of herbicide ceases.)
Cut and paint
Useful for small to medium sized woody weeds up to 10 cm in diameter.
Make a horizontal cut as close to the ground as possible with secateurs or loppers, and immediately apply concentrated Glyphosate to the exposed stump surface. Do not allow the surface to get covered with soil.
Specific control tips for this weed
Seedlings can be hand pulled if all the root can be removed.
- More established small plants will need to be cut and painted using herbicide.
- Larger plants can be stem injected.
Because the berries are bird spread, it is best to treat plants before they fruit; if not bag the fruit and treat in a hot compost. Other parts of the plant can be spread to dry out off the ground and it will break down, or compost if you prefer.
For key points on these techniques:
State Priority Weed
- The plant must be eradicated from the land and be kept fully and continuously suppressed and destroyed; and the land must be kept free of the plant.
- If the weed is part of a new infestation of the weed on the land, notify the local control authority as soon as practicable.