Tree of Heaven

Ailanthus altissima

Family: Simaroubaceae

Type of weed:

Flower colour(s): ,

Priority Weed Local Priority Weed. (See more weeds of the class.)

Flowering Months: , ,


Tree of Heaven is a fast-growing deciduous tree to 20 m high with smooth, grey bark.

Large compound leaves are up to 1m long with many leaflets in opposite pairs, each with at least one small thumb like tooth near the base.

Flowers are in terminal clusters mostly 6–12 cm long; male and female flowers are on separate plants (dioecious). Male flowers emit an offensive smell that attracts insects. It flowers in summer.

The bark, leaves and flowers of this species are poisonous to humans and livestock and contact is known to cause dermatitis in humans. Drinking water contaminated with flowers has been reported to cause dermatitis and gastritis.

Don’t confuse with…

Tree of Heaven can be confused with Australian Red Cedar (Toona ciliate). The Cedar does not have the thumb like tooth on the leaf base, nor the distinctive smell.


Seed dispersed by wind, birds and animals; it suckers from the roots and can be spread by machinery.

Impact on bushland

Tree of Heaven suckers profusely and therefore forms dense stands of trees that are interconnected. It can out compete native plants for nutrients and light. It inhibits growth of other plants by creating a toxic soil environment.


, . Whole of Local Government Area, particularly Blaxland, Glenbrook, Springwood. Also Jenolan Caves and Cumberland Plains.

Alternative planting

Native plants

  • Christmas Bush (Ceratopetalum gummiferum)
  • Native Peach (Trema aspera)
  • Red Bottlebrush (Callistemon citrons)
  • Bleeding Heart (Omolanthus populifolius)

Council provides a tool, on its Mountain Landscapes website, to help you choose native alternative plantings. Choose your village, soil, vegetation community and the purpose of your planting, and the tool will give you suggestions.

There are native nurseries in several Blue Mountains villages, including Glenbrook, Lawson and Katoomba. Please also ask at your favourite local nursery.


  • Stem inject or frill
  • Scrape and paint

Chemical control

Note: Herbicides that may be used for this weed include Glyphosate.

Stem injection or frilling

Stem injection
Drilling holes at 45° and squirting poison into holes
Apply poison immediately after drilling

At the base of the tree, drill holes at a 45° angle into the sapwood (just under the outer bark) at two finger space intervals around the entire base of the tree. Repeat this process below the lowest branch


As an alternative to drilling, make cuts into the sapwood with a chisel or axe. Fill each cut/hole with herbicide immediately. Repeat the process at 3 cm intervals around the tree.


Plants should be healthy and actively growing. Deciduous plants should be treated in spring and autumn when leaves are fully formed. For multi-stemmed plants, inject or chip below the lowest branch or treat each stem individually. Herbicide must be injected immediately before the plant cells close (within 30 seconds before translocation of herbicide ceases.)

Scrape and paint

Using knife to scrape long gashes along stem
Scrape bark/outer layer away with a knife

With a knife, scrape up to a metre of the stem to reach the layer below the bark/outer layer. Immediately apply herbicide along the length of the scrape.


  • A maximum of half the stem diameter should be scraped. Do not ringbark.
  • Larger stems (over 1 cm in diameter) should have two scrapes opposite each other.

Specific control tips for this weed

Care must be taken when treating Tree of Heaven. Avoid contact with the sap.

Because of its vigorous ability to sucker, plants cannot be treated individually by hand removal or the cut and paint method. Follow up treatment of suckers and regrowth is required for a number of years. Tree of Heaven does not respond well to herbicide.

Every stem must be treated — regardless of size — both in the primary treatment and in follow up.

  • Thin stems should be scraped and painted. Scrape as far as possible along the leangth of each stem and paint.
  • Larger stems should be drilled and injected.
  • Scrape and paint or drill and inject exposed roots.

Refer to the NSW Department of Primary Industry’s WeedWise website for more information.

For key points on these techniques:

Local Priority Weed

Control measures:

  • The plant should be fully and continuously suppressed and destroyed.
  • Plants under 4 metres in height should be fully and continuously suppressed and destroyed.
  • The spread of this plant should be adequately contained to prevent spread impacting on priority assets. Weed notices will only be issued for these weeds under special circumstances.