Biosecurity Spotters logo

Red sprangletop (Leptochloa chinensis)

Red sprangletop is not naturalised in Australia and is not recorded in any Australian state or territory, although it is listed as a declared weed in the NT. Overseas it can establish in waterlogged crops before they take hold and has shown herbicide resistance in Thailand.

Key facts

Type: Weed, grass.

Native to: Tropical Asia.

Established in: .

Other names: Feathergrass, Asian sprangletop, Chinese sprangletop.

Identification

  • It is a tufted annual or perennial grass with upright or bent stems up to 1.5 m tall.
  • Stems often root at the lower nodes, and the plant also has rhizomes.
  • Its flat or folded, linear leaves can grow up to 50 cm long and 1 cm wide.
  • The narrow, branched flower head is 10–60 cm long, with unstalked groups of 3–7 green to reddish flowers.
  • Its brown seeds are 6–9 mm long and may be smooth or wrinkled.
  • Look-alike: It can be confused with Leptochloa panicea. Red sprangletop lacks the scattered, long, fine tubercle-based hairs found on that species and has 3–7 florets per spikelet.

Where it grows

It is not recorded from any Australian state or territory and is not yet naturalised in Australia.

Why it matters

  • In waterlogged conditions, it can establish and grow profusely before crops take hold, suppressing crop growth.
  • Overseas it is a weed of rice, sugarcane, vegetables, cotton and corn.
  • It is a serious grass weed in seeded rice systems in Thailand and is reported as a serious threat to rice production in Sri Lanka.
  • It has shown resistance to some herbicides in rice fields in Thailand.

How it spreads

  • Seeds can be dispersed by animals or water.
  • It can spread by rhizomes.
  • Clumps or rootstock can regrow after division during tillage or incomplete weeding.

Control options

  • Use seed hygiene because red sprangletop seed can contaminate rice seed.
  • In sown rice, increasing the paddy water layer to 8–10 cm has been found to prevent seedling emergence.
  • Herbicides can be spot-applied to grass weeds in rice crops, but resistance has been reported in Thailand.
  • Check the Australian Pesticides and Veterinary Medicines Authority for current chemical information and use registered herbicides.

Hygiene and washdown

  • Maintain seed hygiene, as red sprangletop seed can contaminate rice seed.
  • 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: Declared weed. Weeds Australia lists it as a declared weed in the NT under the Weeds Management Act 2001. Check the NT declared weeds list for its class and what it requires.
  • 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.

Sources