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Buchan weed (Hirschfeldia incana)

Buchan weed is widespread in south-eastern Australia, especially in disturbed places, and can invade poor pastures, orchards and vineyards. In winter cereals it can compete with crops, interfere with harvesting and contaminate grain; if eaten by stock, it can taint meat and dairy products.

Key facts

Type: Weed, herb.

Native to: Mediterranean region.

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

Other names: Hairy Brassica, Hoary Mustard, shortpod mustard.

Best time to act: Seeds germinate through autumn, plants grow slowly until mid-winter, and flowering occurs from September to February, when plants are easier to identify.

Identification

  • An upright annual or biennial herb, occasionally perennial, growing up to 100 cm tall.
  • Stems and leaves are covered in stiff, simple bristle-like hairs.
  • Lower leaves are up to 350 mm long and deeply lobed; upper leaves become smaller and less lobed, with the highest leaves unstalked and toothed.
  • Many pale yellow, sometimes purple-veined flowers grow on branching stems; flowering is reported from September to February.
  • Fruits are usually hairy and held against the stem, with a small beak that usually contains one seed, giving them a clothes-peg-like shape.
  • Look-alike: It may be mistaken for yellow-flowered species of Brassica, Diplotaxis, Raphanus, Rapistrum or Sinapis; Buchan weed usually has stiffly hairy fruits held against the stem, with a small beak usually containing one seed.

Where it grows

In Australia it occurs across south-eastern regions, mainly in disturbed places such as roadsides and wasteland, and also in degraded pastures, orchards and vineyards.

Why it matters

  • It can form dense stands that replace or limit desirable pasture species and reduce available pasture.
  • It can compete with winter cereals, reduce yields, interfere with harvesting and contaminate harvested grain.
  • It can invade orchards and vineyards and is regarded as one of South Australia's top nine Brassica weeds.
  • If eaten by stock, it can taint meat and dairy products.

How it spreads

  • It reproduces by seed, which can be spread by water, particularly in riparian areas and on steep terrain where erosion and runoff occur.
  • Contaminated soil, fodder, vehicles and cultivation equipment can transport seed to new sites.
  • Seed can also spread through contaminated agricultural produce and roadside maintenance works.

Control options

  • Registered herbicides can control Buchan weed, but only a few herbicides provide effective control; check the Australian Pesticides and Veterinary Medicines Authority for chemical information.
  • Hand-pull individual plants, taking care to remove as much of the taproot as possible because plants can regrow from root pieces left in the soil.
  • Deep ploughing can control it by burying the taproot, but further cultivation may be needed to control emerging seedlings.
  • Sowing a vigorous pasture species can help prevent reinfestation; grazing and prescribed burning are not expected to be effective controls.

Hygiene and washdown

  • Clean vehicles and cultivation equipment, and avoid moving soil, fodder or agricultural produce contaminated with seed.
  • Take care during roadside maintenance, as seed can be dispersed along roadsides during this work.
  • 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: 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
  • 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

Sources