Complete name: Acacia dealbata Link
Taxonomy: Magnoliophyta » Magnoliophyta » Rosopsida » Fabales » Fabaceae » Acacia dealbata
Authors: Hélia Marchante
Last updated: October 9th, 2006

Silver wattle, blue wattle.

Acacia dealbata Link
Acacia decurrens Willd.
Racosperma dealbatum (Link.) Pedley

This fast growing tree can reach up to 30m in height. Leaves are greyish-green and segmented, leaf axis has glands only at the insertion of the pinnae. Flower heads are 5-6mm in diameter, pale yellow. Legume is compressed, scarcely constricted between the brown seeds.

• Dispersal Mechanisms
  • Seeds are dispersed by animals, namely birds and ants, and by sporadic strong winds. However, the majority of the seeds accumulate under the tree.
• Reproduction
  • It is a prolific seed producer. Seeds are triggered to germinate en masse following fires. It also has vegetative reproduction, forming new shoots from lateral roots.
• Known Predators/Herbivores
  • Palatable to livestock. In the native habitat several Coleoptera, Lepidoptera and Hemiptera attack this species.
• Resistant Stages
  • Large amounts of long-lived seeds can accumulate in the soil seed banks that can persist for around 50 years.

• Native (EUNIS Code)
  • C3-Littoral zone of inland surface waterbodies, G-Woodland and forest habitats and other wooded land (Grows in mountain forests and along watercourses and in dry sclerophyll forest on a variety of soils, often on slopes and creek banks, remaining shrubby under dry conditions.)
• Habitat Occupied in Invaded Range (EUNIS Code)
  • B1-Coastal dune and sand habitats, C3-Littoral zone of inland surface waterbodies, G-Woodland and forest habitats and other wooded land (mainly G1-Broadleaved deciduous woodland, G2-Broadleaved evergreen woodland, G3-Coniferous woodland, G5- Lines of trees, small anthropogenic woodlands, recently felled woodland, early-stage woodland and coppice), I1- Arable land and market gardens (specifically abandoned fields), J1-Buildings of cities, towns and villages, J4-Transport networks and other constructed hard-surfaced areas.
• Habitat Requirements
  • It prefers moist but not waterlogged soils, especially stream-sides. However, it tolerates drier soils. It also tolerates strong wind, moderate frosts and snow (down to -7 ºC).

It has been known in Europe since at least 1824. It is still planted for forestry, as an ornamental plant and for soil stabilization. In some areas is used for basket-work and extraction of essential oils.

• Native Range
  • Australasia - Australia (Victoria, New South Wales, Tasmania)
• Known Introduced Range
  • Europe: France, Spain, Baleares, Canaries, Portugal, Madeira, Italy, Corsica, Sardinia, Turkey; South Africa, New Zealand, California, India, Chile, Madagascar.
• Trend
  • >Native Range
    • Australasia - Australia (Victoria, New South Wales, Tasmania)

known distribution area (in CGRS grid squares; in countries; along coast)

	eradicated
	extinct
	not present; eradicated
	native distribution range in CGRS grid squares
	native range
	assumed native range
	infrequent distribution
	key distribution area
	not established

• Ecosystem Impact
  • It can form dense, almost impenetrable stands that compete with and prevent the development of other species. It has allelopathic properties. It is an N fixing species that increases N soil content. Dense thickets disrupt water flow and increase erosion along stream banks.
• Health and Social Impact
  • Allergies to its pollen are frequently reported.
• Economic Impact
  • Invasion of forests implies economic impacts with decreases in productivity. Control actions undertaken in several areas involve enormous economical costs, mainly due to the necessity of several follow up control actions.

• Prevention
  • Preserving natural woods with dense cover and preventing its commercialization will reduce the risk of invasion.
• Mechanical
  • Seedlings and very small trees can be pulled or dug out, but larger ones must be cut. These operations are more effective in humid soil to prevent root fragmentation. It readily re-sprouts both from the cut stump and from lateral roots connected to it, implying that steps must be taken to kill the stump and its root system. Cutting the stump level, close to the ground, and covering it with one or more layers to 10 mm black plastic, or follow up control must be assured to remove re-sprouts from lateral roots and/ or stumps. Ringbarking (i.e. bark removal from 1m high to ground level) is also effective and decreases resprouting.
• Chemical
  • Glyphosate application at the stump level is quite efficient. This must be conducted immediately after cutting to be effective. Foliar sprays can also be applied.
• Biological
  • Melanterius maculatus Lea (Curculionidae) is a seed-feeding weevil that destroys its seeds. This agent was released in South Africa and its establishment has been confirmed, despite the damage caused having not been quantified yet.

The following contributors have provided records in the DAISIE database for this species.

The following experts registered themselves as having knowledge about this species or its family.

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Campbell P (1993) Wattle Control. In Plant Protection Research Institute (ed) Handbook no 3. Pretoria

Marchante H, Marchante E, Freitas H (eds) (2005) Plantas invasoras em Portugal - fichas para identificação e controlo, Coimbra

Weber E (2003) Invasive plants species of the world - a reference guide to environmental weeds. CABI Publishing, Switzerland

Agricultural Research Council, Plant Protection Research Institute,Weed Research Division (2003) Biological and other control options - List of biological control agents released in South Africa. http://www.arc.agric.za/home.asp?PID=1000&ToolID=63&ItemID=2359 Cited 6 Sept 2006

Almeida JD (1999) Flora exótica subespontânea de Portugal Continental (Plantas Vasculares). Dissertation. University of Coimbra

Campbell PL, Bell RS, Kludge RL (1990) Identifying the research requirements for the control of sylver wattle (Acacia dealbata) in Natal. South African Forestry Journal 155:37-41

Carballeira A, Reigosa M (1999) Effects of natural leachates of Acacia dealbata Link in Galicia (NW Spain). Bot Bull Acad Sin 40:87-92

Dennill GB, Donnelly D, Stewart K, Impson FAC (1999) Insect agents used for the biological control of Australian Acacia species and Paraserianthes lophanta (Willd.) Nielsen (Fabaceae) in South Africa. African Entomology. Memoir 1:45-54

Franco JA (1968) Acacia Miller. In: Tutin TG et al (ed) Flora Europaea: Rosaceae – Umbelliferae, vol 2. Cambridge University Press, Cambridge, p 84

Holmes PM (1990) Dispersal and predation in alien Acacia. Oecologia 83:288-290

International Legume Database & Information Service (2005) Legume Web: Acacia dealbata. http://www.ildis.org/LegumeWeb?version~9.00&LegumeWeb&tno~245&genus~Acac.... Cited 2 Nov 2005

Luna I, Prober S, Thiele K (2006) Charles Sturt University Virtual herbarium - Acacia dealbata (Silver Wattle).http://www.csu.edu.au/herbarium/acacdeal_sws.html Cited 14 Sept 2006

Moore K, Hyland T, Morgan R (2002) A Plague of Plants: Controlling Invasive Plants in Santa Cruz County. 2nd edn. Wildlands Restoration Team, Santa Cruz http://www.wildwork.org/webdocs/Plague_of_Plants.pdf Cited 14 Sept 2006

Old KM, Vercoe TK, Floyd RB, Wingfield MJ, Roux J, Neser S (2002) FAO/IPGRI Technical Guidelines for the Safe Movement of Germplasm. No. 20. Acacia spp. Food and Agriculture Organization of the United Nations, Rome/International Plant Genetic Resources Institute, Rome

Sanz Elorza M, Dana Sánchez E, Sobrino Vesperinas E (eds) (2004) Atlas de las plantas invasoras alóctonas de España. Dirección General para la Biodiversidad, Madrid

Williams PA (1997) Ecology and management of invasive weeds. Conserv Sci Publ 7. Wellington

Wrigley J, Fagg M (1996) Australian Native Plants - Acacia section, 4th edn. Reed Books Pty Ltd, Australia