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Stinking mayweed (Anthemis cotula)

Stinking mayweed is an introduced weed of agriculture, gardens, roadsides and other disturbed areas in Australia. It can contaminate crops and taint meat and milk, and may poison poultry, horses, dogs and cats or cause dermatitis in people.

Key facts

Type: Weed, herb.

Native to: Europe and North Africa.

Established in: QLD, NSW, VIC, TAS, SA.

Other names: Dillweed, Dog Daisy, Dog’s Camomile, Dog Fennel.

Best time to act: Look for seedlings during the main germination periods in autumn and spring, and treat individual plants ideally at the seedling stage.

Identification

  • It is an upright, bushy annual herb growing up to 60 cm tall, with densely branched stems.
  • The alternate leaves have no stalk and are finely divided into narrow segments.
  • Flower-heads have a yellow, raised centre and 10–15 white ray florets, and appear from October to April.
  • The reddish-brown seeds are 1–2 mm long and have no pappus.
  • The plant has a strong, foul smell when crushed, touched or brushed against.
  • Look-alike: Corn chamomile (Anthemis arvensis) has ascending or decumbent growth, smoothly ribbed fruits and is hardly aromatic when crushed.
  • Look-alike: Dyer’s chamomile (Anthemis tinctoria) is an upright perennial with yellow flower-heads that fade to cream.

Where it grows

In Australia it occurs in south-eastern Queensland, eastern New South Wales, parts of Victoria and Tasmania, with small infestations in South Australia and populations in the Donnybrook region of south-western Western Australia, mainly in disturbed sites, cultivation, pasture, crops, roadsides and wasteland.

Why it matters

  • It invades cultivated areas, pastures and paddocks, and can contaminate seed crops.
  • Its strong odour and bitter taste can taint livestock products, including milk, butter and meat.
  • It is poisonous to poultry and may cause poisoning in horses, dogs and cats.
  • Prolonged contact with the flower-heads and fruit is reputed to cause dermatitis and blister the skin.

How it spreads

  • It reproduces and spreads by seed, which can be carried as a contaminant in hay, chaff and pasture seeds.
  • Seeds can also spread in mud on hooves, wool, footwear, clothing, tyres, vehicles and machinery.

Control options

  • Plan an integrated control program to eradicate existing populations and prevent new infestations, with follow-up actions.
  • Hoe or grub out individual plants and small infestations, ideally while plants are seedlings.
  • Cultivate larger patches and follow up to control later-germinating seedlings; sow the area to pasture as soon as possible.
  • Use registered herbicides, with spot spraying for small patches and boom spraying for larger areas.

Hygiene and washdown

  • Avoid moving contaminated hay, chaff or pasture seed, and ensure machinery, equipment and vehicles coming onto a property are not contaminated.
  • Mud on hooves, wool, footwear and clothing can also spread the seeds.
  • 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: 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.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources