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Sorrel (Rumex acetosella)

Sorrel is widely naturalised in southern and eastern Australia and can become locally dominant in temperate pastures. Its extensive rhizomes make it difficult to eradicate, so it is best managed with an integrated approach.

Key facts

Type: Weed, herb.

Native to: Europe and north-western Africa.

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

Other names: Sheep Sorrel, Sheep's Sorrel.

Best time to act: Sorrel usually germinates in autumn or winter and flowers from spring to early summer.

Identification

  • It is a slender, upright perennial, usually 10–50 cm high, with an extensive rhizome system.
  • Leaves have short stalks and elongated, usually spear-head-shaped blades with basal lobes.
  • Plants usually bear either male or female flowers, which are small and arranged in loose clusters along the upper branches.
  • The conspicuous rusty-brown fruiting heads have three-sided nuts surrounded by three persistent, rust-coloured valves that are untoothed.
  • Look-alike: Sorrel is unlikely to be confused with other dock species: its slender, rhizomatous growth, unisexual flowers and untoothed fruiting valves distinguish it.

Where it grows

In Australia it grows in pastures, cultivated land and around settlements in cooler, high-rainfall areas, and also occurs in disturbed natural areas such as woodlands, grasslands and riverbanks.

Why it matters

  • It competes strongly in low-growing pastures, crops and other disturbed sites, but can be out-competed by taller, vigorous crops and pasture species.
  • It is unpalatable and seldom grazed, and may become locally dominant in temperate pastures.
  • It contains oxalates and is suspected of poisoning stock, although levels are generally unlikely to be high enough to kill them.
  • It invades a range of natural habitats, including heathlands, woodlands, grasslands, wetlands and alpine vegetation.

How it spreads

  • It produces numerous seeds and can spread rapidly over short distances through its extensive rhizome system.
  • Its small seeds commonly contaminate agricultural seed lots, and its introduction to Australia probably occurred accidentally with seed, fodder or agricultural equipment.

Control options

  • Cultivation and grazing practices, selective fertiliser use and taller-growing pasture species can control it more effectively than herbicides.
  • Manual removal is rarely successful because of the extensive rhizomes, and attempts can lead to greater infestations.
  • Registered herbicides can reduce sorrel but are unlikely to eradicate it; follow current product directions and local requirements.
  • The stem and root-boring moth Pyropteron doryliformis has been approved for release and is established in Australia, where it is known to impact Rumex weeds.

Hygiene and washdown

  • Sorrel seeds can contaminate agricultural seed lots; seed-cleaning equipment can remove them.
  • The species may have been introduced with contaminated seed, fodder or agricultural equipment.
  • 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: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • 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
  • 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