European hackberry (Celtis australis)

Also known as: nettle tree

European hackberry is a deciduous tree with a wide spreading crown. It competes with native plants and forms dense stands along waterways.

Profile

How does this weed affect you?

European hackberry has escaped from gardens and become a weed that:

  • competes with native plants
  • dominates the edges of waterways and can restrict access to water
  • reduces water quality when leaves drop in autumn
  • invades pine plantations.

What does it look like?

European Hackberry is a deciduous tree up to 20 m tall.  It has a single straight trunk and a wide canopy. It is often planted as a shade or street tree. It can live for hundreds of years.

Leaves are:

  • dark grey-green, turning yellow in autumn
  • oval – spear shaped with serrated edges
  • 4-10 cm long and 1-4 cm wide
  • rough on the top and hairy underneath
  • alternate along branches.

Flowers are:

  • very small and difficult to see
  • greenish yellow
  • in the base of leaf stalks
  • are either male (in clusters) or bisexual (single flowers) on the same tree
  • present in spring when leaves are emerging.

Fruit are:

  • round with one seed
  • green then orange, and purplish-black when ripe.
  • 1 cm wide on a stalk about 3 cm long.

Bark is:

  • smooth but sometimes wrinkled when older
  • blue grey, somewhat warty 

Where is it found?

In NSW, European hackberry is mainly a weed in the southern tablelands. It also grows in the Australian Capital Territory.

It is native to the Mediterranean region including parts of southern Europe, northern Africa and western Asia.

What type of environment does it grow in?

European hackberry grows best in full sun on well drained soils. However, it can grow in a wide variety of soil types including clay, loam or sandy soils, acidic to slightly alkaline soils and low nutrient soils. It tolerates drought, frost and salty air. It has been found:

  • along waterways (rivers and creeks)
  • in woodlands and forests
  • in pine plantations
  • in urban areas, spreading from garden and street tree plantings.

How does it spread?

By seeds

European hackberry trees produce seeds that are viable for several years. The fruit is eaten by birds, foxes and other animals that spread the seeds in their droppings. Seeds are also be spread by moving water and by people dumping garden waste.

References

Agriculture Victoria (2020) Victorian Resources Online: European nettle tree (Celtis australis). Retrieved February 2021 from: http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/weeds_european-nettle-tree

Blood, K. (2001). Environmental weeds: a field guide for SE Australia. CH Jerram & Associates.

Brodie, C.J., Kellermann, J. & Lang, P.J. (2016). Cannabaceae (version 1). In: Kellermann, J. (ed.), Flora of South Australia (ed. 5). 8 pp. (State Herbarium of South Australia: Adelaide). Retrieved 2018 from: www.flora.sa.gov.au/ed5

Gilman, E.F. & Watson, D.G. (1993). Fact Sheet ST-137 Celtis australis Mediterranean Hackberry. Forest Department U.S. Department of Agriculture. Retrieved 2018 from: http://hort.ufl.edu/trees/CELAUSA.pdf

Juan, T., Sagrario, A., Jesús, H., & Cristina, C. M. (2006). Red fox (Vulpes vulpes L.) favour seed dispersal, germination and seedling survival of Mediterranean Hackberry (Celtis australis L.). Acta Oecologica, 30(1), 39-45.

Magni, D. & Caudullo, G., (2016). Celtis australis in Europe: distribution, habitat, usage and threats, In The European Atlas of Forest Tree Species: modelling, data and information on forest tree species. Eds: De Rigo, D., Caudullo, G., Houston Durrant, T., & San-Miguel-Ayanz, J.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 22 February from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Celtis~australis 

Queensland Government (2016). Weeds of Australia, Biosecurity Queensland edition Fact sheet: Celtis australis L.. Retrieved 2018 from: https://keyserver.lucidcentral.org/weeds/data/media/Html/celtis_australis.htm

More information

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Control

Physical removal

Hand pull or dig up small seedlings.

Large trees may be cut down and the stump dug up and removed. Care should be taken to avoid moving fruit to uninfested areas when manually removing mature trees.

Disposal

Check with your local council for information about safely disposing fruit or plant parts.

Chemical control

Cut stump

Cut trunks or stems and apply herbicide within 15 seconds.

Basal barking

Apply herbicide mixed with diesel to cover all the way around the lower stem or trunk.

Stem injection.

Drill or make cuts into the sapwood in a ring all the way around the trunk. Fill each cut or hole with herbicide within 15 seconds.

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


PERMIT 9907 Expires 31/03/2025
Fluroxypyr 200 g/L (Comet® 200 herbicide)
Rate: 35 mL per L diesel/kerosene
Comments: Basal bark
Withholding period: Do not graze failed crops and treated pastures or cut for stock feed for 7 days after application. See label for further information.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


PERMIT 9907 Expires 31/03/2025
Fluroxypyr 333 g/L (Staraneā„¢ Advanced)
Rate: 21 mL per L diesel/kerosene
Comments: Basal bark
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Various products)
Rate: One part product to 1.5 parts water
Comments: Cut stump, drill, frill axe or injection
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L with Metsulfuron-methyl 600 g/kg (Various products)
Rate: 1:1.5 glyphosate to water + 1 g metsulfuron to 1 L water
Comments: Stem injection
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area Duty
All of NSW General Biosecurity Duty
All plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.

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For technical advice and assistance with identification please contact your local council weeds officer.
For further information call the NSW DPI Biosecurity Helpline on 1800 680 244 or send an email to weeds@dpi.nsw.gov.au

Reviewed 2021