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False yellowhead (Dittrichia viscosa)

False yellowhead is an introduced weed on the National Alert List for Environmental Weeds and is spreading along roadsides and walking trails in south-western Western Australia. It produces many seeds and can affect people, animals and native bushland.

Key facts

Type: Weed, shrub.

Native to: Southern Europe, the Mediterranean, Turkey, the Middle East and northern Africa..

Established in: VIC, WA.

Other names: Aromatic Inula, Sticky Fleabane.

Best time to act: Flowering occurs from December to April, and control is best carried out before flowering and seed set.

Identification

  • An erect to spreading, much-branched perennial sub-shrub or shrub, usually 50–150 cm high and about 1 metre wide.
  • The plant is sticky, soft-wooded and camphor-scented, with glandular and non-glandular hairs.
  • Its leaves are stalkless, alternate on the branches, and 25–100 mm long by 8–30 mm wide.
  • Yellow, daisy-like flower heads, about 15–20 mm across, are clustered in pyramidal groups on the flowering stems.
  • After flowering, it produces small, hairy, one-seeded fruits with a bristly pappus.
  • Look-alike: It is similar to the related annual Stinkwort (Dittrichia graveolens); false yellowhead is a perennial sub-shrub or shrub.

Where it grows

In Australia it is recorded in Victoria and Western Australia, mainly in disturbed places such as roadsides, railway lines, firebreaks and walking trails, and can grow on clay or sandy soils.

Why it matters

  • Oil on the leaves and stems can cause contact dermatitis, itching and blistering in people, especially when the plant is in flower.
  • It can cause health problems in animals and taint milk and meat, although stock do not usually graze it.
  • In bushland, infestations can detract from natural and aesthetic values and may reduce tourism appeal.
  • It can invade parks and gardens and is a weed of roadsides and other disturbed areas.

How it spreads

  • It spreads by seed, and the hairy pappus can catch the wind or assist flotation.
  • Seed can be moved with soil during road making or grading, or when attached to machinery.
  • Germination generally follows rainfall and can be prolific when fire or mechanical disturbance creates bare ground.

Control options

  • Report new outbreaks promptly to your state or territory weed management agency or local council, and do not attempt control without expert assistance.
  • Before flowering, isolated plants or small patches can be hand-pulled with gloves or removed with a fork, while minimising soil disturbance.
  • Registered herbicides can be used, with spraying before seed set; seek expert advice and consult the Australian Pesticides and Veterinary Medicines Authority for chemical information.
  • Plants cut or slashed in bud or flower can still form seed, so bag and dump the material or place it in heaps and burn it.

Hygiene and washdown

  • Seed can be spread when attached to machinery or moved with soil during road making or grading.
  • 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): National Environmental Alert List. One of 28 weeds named on the National Environmental Alert List as early-stage invaders with serious potential to harm the environment.
  • 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: Not a priority weed. Not a state or regional priority weed in NSW. 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: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • 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: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

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.

  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources