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Rough corn bedstraw (Galium tricornutum)

In Australia, Rough Corn Bedstraw can form dense, tangled growth and cause considerable yield loss in crops, including wheat, barley, field peas, chickpeas and faba beans. Its seeds contaminate grain and fodder, and it hosts a stem nematode that is a serious pest in lucerne crops.

Key facts

Type: Weed, herb.

Native to: Europe through to central Asia.

Established in: NSW, VIC, SA, WA.

Other names: Three-horned Bedstraw, Three-horn Bedstraw, Three-cornered Bedstraw, Corn Cleavers.

Best time to act: Seeds generally germinate in autumn and flowering peaks from August to January, so look for plants then and remove them before they set seed.

Identification

  • It is a scrambling, coarse annual with four-angled stems that can grow up to 1 m long.
  • Small backward-pointing hairs or prickles line the stem edges.
  • Leaves grow in rings of six to eight and are mostly 1–5 cm long.
  • Small, inconspicuous white flowers grow in loose groups, followed by paired, joined fruits about 2–3 mm across.
  • The fruits are rough with small bumps or papillae and do not have hooked hairs.
  • Look-alike: Cleavers (*Galium aparine*) is similar, but its fruits have hooked hairs; Rough Corn Bedstraw’s fruits are roughened by small granules and lack hooks.
  • Look-alike: Native *Asperula conferta* and *Asperula euryphylla* can also have leaves in rings of six or more and hooked stem hairs, but their fruits are smooth.

Where it grows

In Australia it occurs patchily in New South Wales, Victoria, South Australia and Western Australia, mainly in crops and fallow paddocks on heavy alkaline soils.

Why it matters

  • Dense, tangled growth can compete with crops and cause considerable yield loss at high densities.
  • It can be troublesome in wheat, barley, field peas, chickpeas and faba beans, and difficult to control in other pulse crops.
  • Seeds contaminate fodder and grain.
  • It hosts the stem nematode *Ditylenchus dipsaci*, a serious pest in lucerne crops, and can invade riparian and disturbed open vegetation.

How it spreads

  • Seeds spread by water, wind, animals, machinery, clothing and contaminated agricultural produce.
  • Contaminated crop seed or stock fodder is a likely pathway for its spread.

Control options

  • Hand-pull small infestations while plants are young and before seed set; the plants are weak-rooted and can be removed readily.
  • Use registered herbicides suitable for the crop situation, following current label directions.
  • Control is more difficult in canola, pulses and legume-based pastures than in cereal crops and grass pastures.
  • Limit spring tillage where appropriate, as even minor tillage can promote recruitment of the related Cleavers.

Hygiene and washdown

  • Clean machinery to reduce the risk of moving seeds between sites.
  • Use certified seed and clean tillage, and avoid spreading contaminated crop produce or stock 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: 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: Declared pest (C2), prohibited. C2 Eradication: present in limited areas and targeted for eradication. It must not be brought into WA (prohibited organism).
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • 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
  • 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