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Rhus tree (Toxicodendron succedaneum)

Rhus is an introduced tree found as a weed in parts of New South Wales and Queensland, including disturbed areas and urban bushland. Its sap can cause severe allergic dermatitis, and all parts of the plant are toxic.

Key facts

Type: Weed, tree.

Native to: Japan, China and the Himalayan region.

Established in: NSW.

Other names: Japanese Tallow Tree, Japanese Wax Tree, Scarlet Rhus, Wax Tree.

Best time to act: Winter, when the leaves have fallen, is the preferred time for physical removal.

Identification

  • It is a small to medium-sized deciduous tree, usually 2–5 metres tall but sometimes reaching 8–10 metres.
  • Its alternate, bright green leaves have 9–15 leaflets, including a terminal leaflet, and turn scarlet or crimson in autumn.
  • The lance-shaped to egg-shaped leaflets are 5–10 centimetres long, with smooth edges and hairless surfaces; the underside can be greyish.
  • Creamy-white to yellowish-green flowers grow in branched clusters, and the pale brown fruits are round to egg-shaped and compressed.
  • Look-alike: Chinese pistachio (Pistacia chinensis) mostly lacks a terminal leaflet, and its leaf undersides are not greyish.
  • Look-alike: Scentless rosewood (Synoum glandulosum) and ribbonwood (Euroschinus falcatus) have similar leaves and berry-like fruits, but do not change colour in autumn or lose their leaves in winter.

Where it grows

In Australia it occurs as a weed around Sydney and on the Central Coast of New South Wales, and in and south of Brisbane, mainly in temperate areas, disturbed woodland, roadsides, waste places and urban bushland.

Why it matters

  • Sap causes severe dermatitis, and all parts of the plant are toxic.
  • Allergic reactions can begin 12 hours to 7 days after contact and may include rash, redness, itching, blisters and localised swelling.
  • Reactions usually last 7 to 10 days, but can be more extreme or last longer for sensitive people or chronic sufferers.
  • It can invade disturbed forests, open woodlands and urban bushland, and is also a weed of roadsides, gardens and waste areas.

How it spreads

  • Rhus mainly reproduces by seed, with occasional local vegetative spread by suckers.
  • Birds and other animals disperse seed, and spread has also occurred through commercial nurseries.
  • Seed can be moved in garden soil and remains viable for many years.

Control options

  • Wear protective clothing whenever handling Rhus, as physical removal carries a high risk of poisoning.
  • Stem injection of herbicide, also known as cut stump, is described as the safest chemical control method; use approved methods.
  • If removing trees physically, winter after the leaves have fallen is preferred, and most of the root system should be removed to minimise suckering.
  • Do not burn Rhus, as its allergen is especially harmful as an airborne oil.

Hygiene and washdown

  • Avoid moving soil from places where Rhus has grown, as its seeds can remain viable for many years.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Regional priority in 1 of 11 regions. Regional priority weed in Hunter. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Declared plant. Depending on the declaration, it can be an offence to move it on public roads or sell it, and landowners may be required to control it on their land.
  • Western Australia: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • Australian Capital Territory: Declared pest, notifiable, prohibited. It is a declared pest throughout the ACT. You must report it to ACT Biosecurity. Dealing with it, such as selling, moving or keeping it, is prohibited.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development

Sources