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Broad-leaved dock (Rumex obtusifolius)

Broad-leaved dock is an aggressive agricultural and environmental weed that can dominate pastures and compete with crops and native plants. Dense infestations can reduce grazing capacity and crop yields, and the species is best managed with an integrated control program.

Key facts

Type: Weed, herb.

Native to: Europe and South-west Asia.

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

Other names: Broadleaf dock, Bitter dock.

Best time to act: Established plants usually start growing from the rootstock in winter and flower and fruit by early summer, so look for plants before their fruits mature and detach.

Identification

  • It is a tap-rooted perennial herb, usually 60–120 cm high, with branches that spread or grow more or less upright.
  • It forms a basal rosette of leaves, usually with stalks longer than the blades; the blades are broad, up to 25 cm long and about 12 cm wide, with round-lobed bases.
  • Numerous flowers grow in dense clusters along the branches, and the flower stalks are slender and jointed.
  • When fruiting, the heads become rusty-brown; each fruit is surrounded by three persistent valves, each 3.5–6 mm long and with 2–5 teeth on its side margins.
  • Look-alike: Fiddle dock has flower clusters spaced farther apart, an obvious leafy bract, and thickened flower stalks about as long as the valves; broad-leaved dock lacks the obvious bract and has slender stalks that become at least twice as long as the valves.

Where it grows

In Australia it is recorded in the ACT, NSW, SA, TAS, VIC and WA, in places including pastures, cultivation, orchards, roadsides, gardens, riverbanks and seasonally damp grasslands and woodlands.

Why it matters

  • It competes with pasture, crop and native species for space, light, moisture and nutrients, and can become the dominant herbaceous plant, particularly in irrigated production areas.
  • Dense infestations can reduce grazing capacity, cause pasture yield losses, infest irrigated orchards and other plantation crops, and obstruct irrigation and drainage channels.
  • It produces about 60,000 seeds per plant, and its root system can extend to 2 m, depleting soil nutrients and moisture.
  • It can replace native species in natural grassland, woodland, riverbank and other plant communities; it contains oxalates and is suspected of poisoning stock, although levels are generally unlikely to be high enough to kill them.

How it spreads

  • It spreads by seed: mature fruits detach from dried branches when brushed by people, animals or equipment, and their toothed valves aid dispersal by wind, water, animals and people.
  • The crown and upper taproot can regenerate from fragments created by cultivation equipment.

Control options

  • Deep hoeing or grubbing can control single plants; slashing and mowing are not effective.
  • For larger infestations, a combination of cultivation and registered herbicides is effective; check current registration and application advice with your state or territory weed management agency or local council.
  • In pastures, infestation can be reduced using the spray/graze technique.
  • The clearwing moth, Pyropteron doryliformis, is an established biological control agent; it provides almost total control in WA and good control in approximately 50% of infested areas in VIC and NSW.

Hygiene and washdown

  • Check and clean equipment after working in infested areas because mature fruits can be carried by equipment.
  • Avoid moving crown or upper taproot fragments on cultivation equipment, as they can regenerate.
  • 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: 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.

  • 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