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Wild mignonette (Reseda luteola)

Wild mignonette is generally a minor weed in Australia, occurring mostly as scattered plants and small patches in crops, roadsides and disturbed areas. It can compete with crops and contaminate cereal grain, and there is some concern that it may be toxic to stock.

Key facts

Type: Weed, herb.

Native to: Central and southern Europe east to Afghanistan.

Established in: NSW, ACT, VIC, TAS, SA, WA.

Other names: Dyer's Rocket, Dyer's Weed, Weld, Yellow Weed.

Best time to act: Look for rosettes after seeds mainly germinate in autumn and treat at the rosette stage before spring shoots flower from November to March.

Identification

  • An erect, hairless annual to perennial herb, usually up to 1.5 m tall and rarely reaching 2 m.
  • Young plants form a basal rosette of oblong leaves with toothless, often crinkled margins.
  • The leaves remain undivided throughout the plant.
  • Numerous pale yellow or cream flowers grow in narrow, elongated spikes that can reach 60 to 80 cm long.
  • The fruits are small, nearly globular, ridged capsules; the seeds are brown, shiny and about 1 mm long.
  • Look-alike: Other Australian Reseda species include R. lutea, R. phyteuma and R. odorata; unlike these, wild mignonette has undivided leaves throughout the plant.
  • Look-alike: The upper leaves of R. odorata and R. phyteuma may have one or two lobes, while those of R. lutea are deeply divided into several narrow lobes.

Where it grows

In Australia it occurs mainly on roadsides, disturbed sites and in crops, and can also persist in native vegetation along watercourses, swamp margins and other areas prone to occasional inundation.

Why it matters

  • It is generally confined to scattered plants and small patches and is not regarded as a high-impact agricultural or environmental weed in Australia.
  • In crops, it competes for light and nutrients and may reduce productivity.
  • Contamination and degradation of cereal grain value are concerns.
  • There is some evidence that it may be toxic to stock, and it is considered to have little forage value in Australia.

How it spreads

  • It reproduces by seed and is most likely spread through contaminated pasture or crop seed.
  • Agricultural and road machinery, road vehicles, stock and fodder may also spread it.

Control options

  • Hand-pull small infestations.
  • Cultivate larger infestations at the rosette stage and follow up new seedlings to exhaust the soil seed bank.
  • Repeatedly slash or mow plants before flowering and continue beyond the flowering period.
  • Rosette-stage plants are susceptible to registered herbicides, while mature plants are to some degree resistant; consider the possibility of poisoning if grazing young plants with sheep.

Hygiene and washdown

  • Check and clean agricultural and road machinery and vehicles after working in infested areas.
  • Avoid moving contaminated crop or pasture seed and fodder.
  • 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: Restricted weed. Where it is a restricted weed, trade in it (including the plant, its seed or contaminated material) is prohibited.
  • 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: 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: 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.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • 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
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources