Feral olive (Olea europaea subsp. europaea)
Also known as:
European olive
Feral olive is a branching shrub or tree with clusters of creamy white flowers and purplish black fruits. It can outcompete native plants and dominate the understory of forests and woodlands.
Profile
How does this weed affect you?
Feral olive is an environmental weed that:
- outcompetes native plants
- dominates forest and woodland understorey, reducing native plant biodiversity
- may harbour diseases and pests of commercial olives
- increases the risk of fire.
What does it look like?
Feral olive is a perennial multi-branched evergreen shrub or tree usually growing 2–10 m tall, occasionally to 15 m. The crown is dense and rounded.
Leaves are:
- dark grey-green and glossy on the upper surface
- whitish or silvery underneath
- 3–7 cm long and up to 1 cm wide
- pointed (not hooked) at the tip
- on stalks up to 1 cm long
- in opposite pairs along the branches.
Flowers are:
- creamy-white
- tubular at the base spreading to 4 tiny petals
- in clusters of 10–40
- fragrant
- mostly present in spring.
Fruit are:
- purplish black and fleshy with one seed
- up to 3 cm long and 2 cm wide
- oval shaped.
- brown to black
- up to 1.5 cm long
- pointed
- hard.
Seeds are:
- brown to black
- up to 1.5 cm long
- pointed
- hard.
Stems are:
- greenish black
- covered with rough bark.
Roots:
- have a large taproot when young
- are woody and branched when mature.
Similar looking plants
Feral olive looks like another weed, African olive (Olea europaea subsp. cuspidata), which has larger leaves (6–10 cm long and 1–2.5 cm wide) with a hook at the tip and the leaf underside is green or yellowish brown.
Feral olive also looks like these native plants
- native olive (Olea paniculata), which is a much larger tree up to 30 m tall with broader leaves, up to 6 cm wide. The tops of the leaves are paler green, and the fruit is smaller (up to 1 cm long).
- mock olive (Notelaea spp.), which does not have flowers in branched clusters and the fruits are smaller (5–20 mm long).
Where is it found?
In NSW, feral olive has naturalised in the North West, Central West, Central Tablelands and Riverina regions.
It is native to North Africa and Europe. It is cultivated for its edible fruit.
What type of environment does it grow in?
Feral olive grows in semi-arid and warm temperate climates. In NSW, most naturalised plants are in areas with an average of 400–800 mm of rain per year. They tolerate drought but require winter and spring rainfall to produce fruit.
This weed can grow in many soil types but grows best in well-drained soils. It can tolerate mild salinity but not waterlogging.
Feral olive is found in disturbed areas including trails, forests, grasslands, shrublands, urban areas and parks.
How does it spread?
Feral olives are grown for fruit and oil in commercial orchards and home gardens. The risk of spread increases if plantations are abandoned and the fruit are not harvested.
By seed
Feral olive trees start producing fruit when they are 5 to 10 years old. Seed may remain dormant in the soil for up to 20 months. Seeds are spread by birds and other animals that eat the fruit and spread the seeds in their droppings.
References
Crossman, N. (2002). The impact of the European olive ( Olea europaea L. subsp. europaea) on grey box ( Eucalyptus microcarpa Maiden) woodland in South Australia. Plant Protection Quarterly. 17. 140-146.
Identic Pty Ltd. and Lucid central (2016). Environmental Weeds of Australia Fact sheet: Olea europaea L. . Retrieved: 17 April 2023 from: https://keyserver.lucidcentral.org/weeds/data/media/Html/olea_europaea.htm
Johnson, S., & Lisle, S. (n.d.) Issues posed by Feral Olives in New South Wales. NSW Department of Primary Industries.
Muyt, A. (2001). Bush invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South-East Australia. RG and FJ Richardson.
Parsons, W.T. & Cuthbertson, E. G. (2001). Noxious weeds of Australia. CSIRO publishing.
PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 8 August 2022 from https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=in&name=Olea~europaea~subsp.+europaea
More information
Control
Successful weed control requires follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.
Ensure that you have correctly identified feral olive before controlling the trees, as there are similar looking native plants.
Prevention
Harvest all fruit from planted trees and remove trees if the fruit are not being harvested.
Physical removal
By hand
Hand pull seedlings and saplings 3–10 cm tall when the soil is moist (so that the large tap root can be removed). Dig out small plants during drier times. For larger plants up to 1.5 m, use a mattock or chipping hoe.
Grazing
Grazing sheep can control feral olive plants.
Chemical control
Spot spraying
Spray plants up to 1.0 m tall. Apply to actively growing plants. Thoroughly cover all of the foliage with the herbicide mix. Resprouting trunks can also be sprayed.
Cut stump method
Cut trunks or stems of mature plants close to the ground (preferably less than 10 cm above the ground) and apply herbicide to the remaining stump within 15 seconds. For multi-stem plants, treat at least 80% of the stems.
Stem injection
Make a series of cuts 15-20 mm deep around the trunk using an axe or saw. Space cuts evenly with no more than a 20-40 mm gap between them. Within 15 seconds of making each cut, apply a 5 mm layer of gel over the lower surface of the cut.
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
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.
Glyphosate 360 g/L
(Various products)
Rate: 10 mL per 1 L water
Comments: Spot spray (smaller plants less than 1 m) For general weed control in domestic areas (home gardens), commercial, industrial and public service areas, agricultural buildings and other farm situations.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
Metsulfuron-methyl 75 g/kg + Aminopyralid 93.7 g/kg
(Di-Bak AM)
Rate: 1 capsule for every 10 cm of circumference
Comments: Capsule herbicide: See critical comments on the label for details on how to apply and seal the capsule into the sapwood layer of the tree trunk.
Withholding period: Nil
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors) + 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: High/Moderate
Picloram 44.7 g/L + Aminopyralid 4.47 g/L
(Vigilant II ®)
Rate: Undiluted
Comments: Cut stump for small plants: Apply a 3–5 mm layer of gel onto stems less than 2 cm diameter. Apply 5 mm layer on stems above 2 cm diameter. Stem inject trees: Make evenly spaced cuts 1.5-2 cm deep around the trunk. Apply a 5 mm layer of gel over the lower surface of the cut.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
Triclopyr 600 g/L
(Garlon® 600)
Rate: 4 L per 60 L diesel
Comments: Basal bark application up to 5 cm diameter at the base of the trunk. Cut stump application for plants up to or over 5 cm diameter at the base.
Withholding period: Not required when used as directed. If use is off-label check permit.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
Biosecurity duty
The content provided here is for information purposes only and is taken from the NSW 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 pest 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. |
For technical advice and assistance with identification please contact your local council weeds officer.
Reviewed 2025
