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Cut-leaf mignonette (Reseda lutea)

In Australia, Cut-leaf Mignonette is a crop weed of particular concern in South Australia, where it can compete with cereals and contaminate harvested grain. Heavy infestations can reduce cereal yields by up to 60%, and the estimated cost to South Australia’s grains industry is about $2.2 million per year.

Key facts

Type: Weed, herb.

Native to: Southern Scandinavia and Siberia to the Mediterranean region and Asia Minor.

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

Other names: Cut-leaved Mignonette, Wild Mignonette, Yellow Mignonette.

Best time to act: Look for autumn-germinated rosettes before winter and target plants at the rosette stage, before flowering stems emerge in spring.

Identification

  • This hairless herb grows about 20–80 cm high and may sprawl or stand upright.
  • Young plants form a basal rosette; the stem leaves are deeply divided, commonly into 3–7 narrow lobes.
  • Numerous small yellow flowers grow in narrow, cylindrical spikes, mostly 10–25 cm long and occasionally up to 40 cm.
  • The roughly egg-shaped capsules are 8–13 mm long and contain mostly 20–30 small, brown, shiny seeds.
  • Look-alike: Other Australian Reseda species include Wild Mignonette (Reseda luteola), Sweet Mignonette (R. odorata) and Rampion Mignonette (R. phyteuma). Cut-leaf Mignonette has deeply divided leaves; Wild Mignonette has undivided leaves, while Sweet and Rampion Mignonette may have only one or two lobes.

Where it grows

In Australia it occurs in disturbed sites and croplands, especially across southern regions, and can grow in a wide range of soils, including calcareous and slightly saline soils.

Why it matters

  • It competes with crops for light and nutrients and can contaminate foliage and seed crops.
  • It is an effective competitor in cereal crops, where heavy infestations can reduce yields by up to 60.
  • Its seeds are difficult to clean from harvested grain, and contaminated crops may be downgraded, causing economic losses.
  • It can invade sandy coastal vegetation and roadside reserves.

How it spreads

  • It reproduces and spreads by seed and perennial rootstock.
  • Seeds can be moved by stock, contaminated produce, especially grain and hay, and vehicles; enough seeds survive digestion by stock to start new populations.
  • Cultivation can spread root fragments across paddocks, and ants may move seeds short distances.

Control options

  • Small infestations may be hand-pulled; cultivate larger infestations at the rosette stage and follow up as new seedlings establish to exhaust the soil seed bank.
  • Sowing competitive pasture species can provide good control, and heavy grazing kills seedlings.
  • Young plants are susceptible to some herbicides; use registered herbicides suitable for the site and follow label directions.
  • Slashing and mowing are not very effective, as plants can regrow from the base or deep root system; repeated treatments may be needed.

Hygiene and washdown

  • Prevent seed movement on vehicles and with contaminated grain or hay.
  • Avoid moving contaminated produce between sites.
  • 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: Declared plant. Depending on the declaration, it can be an offence to move it on public roads or sell it, and landowners may be required to control it on their land.
  • 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
  • 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