Rhus tree (Toxicodendron succedaneum)

Rhus is a deciduous shrub or small tree with bright red leaves in autumn. All parts of the plant are toxic and can cause severe dermatitis.

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How does this weed affect you?

Rhus tree can:

• cause dangerous allergic reactions in people
• invade natural areas.

Human health

Rhus tree contains a toxin that causes severe skin reactions. Some people can have a reaction just from standing under or near a rhus tree.

Touching the plant, sap or resin and contact with smoke from burning rhus tree can cause painful reactions including:

• severe dermatitis with a rash, redness, severe itching and blisters
• localised swelling of the face, arms and legs
• increased sensitivity to the plant over time.

The oily resin (toxicodendrol) can stay on shoes, tools and other items for up to a year.  

Symptoms take between 12 hours and 7 days to appear and last for 10–14 days.

What to do if a person is poisoned:

• If the patient is unconscious, unresponsive or having difficulty breathing dial 000 or get to the emergency section of a hospital immediately.
• If the patient is conscious and responsive call the Poisons Information Centre on 13 11 26 or your doctor.
• If going to a hospital take a piece of the plant for identification (carefully bag a sample of the plant without touching it) or take a photo and take it with you to the hospital.

What does it look like?

Rhus is a small, deciduous tree 5–8 m tall. If unpruned it forms a spreading crown on a single trunk. Trunks are covered in smooth, grey bark.

Leaves are:

• 20–35 cm long
• divided into 9–15 leaflets (mostly 11)
• leaflets are:
  • bright green on top
  • often greyish underneath because of a waxy bloom on the leaf surface
  • bright red in autumn
  • lance to oblong shaped gradually tapering to a point
  • 4–10 cm long and 2–3 cm wide
  • in opposite pairs with a single leaflet at the end.

Flowers are:

• small
• creamy white, creamy yellow, or yellowish-green
• in large clusters 8–15 cm long
• present among new leaves in spring and early summer.

Trees have either all male or or female flowers. 

Fruit are:

• pale brown or fawn
• hard with a papery skin and contain one seed
• 5–11 mm in diameter
• in clusters
• present through autumn and winter, falling in spring.

Seeds are:

• dark brown
• round
• 3–5 mm in diameter

Similar looking plants

Rhus looks like Chinese pistachio (Pistacia chinensis). You can tell them apart by the number of leaflets at the end of the leaves. Rhus leaves end in a single leaflet while Chinese pistachio leaves end in a pair of leaflets. Chinese pistachio is also taller, with more upright leaves and branches.

Rhus is closely related to North American poison ivy (Toxicodendron radicans) and poison oak (Toxicodendron diversilobum). 

Where is it found?

Rhus tree is generally found in gardens and nearby bushland. It was common in the Sydney and Central Coast regions and became a problem in the Sydney region in the 1980s. It has been removed from most areas.

Rhus is native to Japan, China and northern India.

What type of environment does it grow in?

Rhus grows in temperate regions on a wide range of soil types. It grows in woodlands and disturbed areas such as roadsides.

Maps and records

• Recorded presence of Rhus tree during property inspections (Map: Biosecurity Information System - Weeds, 2017-2023)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

Rhus trees have either male or female flowers, therefore at least two trees are needed to produce fruit. Trees are at least 2 years old before they produce seed. The seeds can be viable for many years. Most seedlings are found close to a parent tree and very large numbers of seedling have been found under trees. Seeds are spread:

• by birds and other animals that eat the fruit and excrete the seeds
• in garden soil
• by people dumping garden waste with seeds in bushland.

References

Frohne, D. and J. Pfander. 1984. A Colour Atlas of Poisonous Plants. Wolfe.

Hosking, J. R., Sainty, G. R., Jacobs, S. W. L. and Dellow, J. J. (draft), The Australian WEEDbook, Industry & Investment NSW, Orange.

Johnson, A. and Johnson, S. (2006), Garden plants poisonous to people, Primefact 359, NSW Department of Primary Industries, Orange.

McKenzie, R. (2012). Australia's poisonous plants, fungi and cyanobacteria: a guide to species of medical and veterinary importance. CSIRO.

Parsons, W. T. & Cuthbertson, E. G. (2001), Noxious weeds of Australia, Inkata Press, Sydney.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 2020 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Toxicodendron~succedaneum

Slaughter, R., Beasley, M., & Schep, L. (2017). Dermatitis due to Toxicodendron plants: a common occurrence during autumn. Dermatitis, 130(1451).

More information

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Control

Successful weed control relies on 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.

 To manage rhus:

• take extreme care to avoid skin contact with both living and dead plant 
• control trees as soon as practical
• check for and control regrowth or new seedlings.

Physical removal

Physical removal carries a high risk of allergic reaction. Wear personal protective equipment such as overalls, hat, eyewear, dust mask and gloves.

Dig out the entire plant to discourage suckering. The best time to remove plants is in winter because the sap levels are lowest when the tree has no leaves. If cutting down trees, treat the stump with herbicide to prevent regrowth. Clean tools afterwards to remove sap.

Disposal

Bury or dispose of all plant material to landfill. Do not mulch or chip any part of the plant. The toxic resin remains active for months, even after weathering. Do not burn any part of the plant as the smoke is toxic. 

Chemical Control

Cut stump method

Cut trunks or stems and apply herbicide to the stump within 15 seconds of cutting. Bag and dispose of any brushes used to paint the stumps.

Stem injection

When: In summer when the tree is actively growing.

Drill holes or make cuts into the sapwood and fill with herbicide within 15 seconds. Once treated, leave the tree in place to die. Dispose of dead plant material carefully as it is still toxic.

Herbicide options

See Using herbicides for more information.

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Glyphosate 360 g/L (Various products)
Rate: Undiluted (1–2 mL per cut)
Comments: Stem injection technique, as per label.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Glyphosate 360 g/L (Various products)
Rate: 1 part glyphosate to 1 part water
Comments: Cut stump application.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Picloram 44.7 g/L + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut stump application: Apply a 3–5 mm layer of gel for stems less than 20 mm. Apply 5 mm layer on stems above 20 mm. Stem inject application for trees: 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. 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

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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 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.
Hunter	Regional Recommended Measure* (for Regional Priority - Eradication) Notify local control authority if found. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2023