Biosecurity Spotters logo

Job's tears (Coix lacryma-jobi)

Job's tears forms dense infestations in wet areas and can outcompete native plants. It can also alter water flows, restrict access to water and compete with crops such as sugar cane or rice.

Key facts

Type: Weed, grass.

Native to: Southern and eastern Asia.

Established in: QLD, NSW.

Other names: Chinese pearl barley, adlay rice, adlai rice.

Best time to act: Inspect downstream sites every four months and treat plants before they produce seed; flowers are produced during summer.

Identification

  • It is an erect, clumping grass that can grow up to 2 m tall.
  • The green, lance-shaped leaves have a white midrib, rough margins and can be up to 45 cm long and 2–5 cm wide.
  • Distinctive bead-like fruits are hard, smooth and shiny, usually oval to egg-shaped when mature, and white to blue-grey, sometimes reddish or black.
  • Thick, upright green stems are branched and often have prop roots near the base.

Where it grows

In Australia it grows in moist, humid areas and disturbed sites, often along waterways, in shallow water, at forest edges and in wetlands and swamps.

Why it matters

  • Dense infestations compete with native plants in and along waterways.
  • They can alter water flows and restrict access to water for people and livestock.
  • The weed can compete with crops such as sugar cane or rice.
  • Infestations can limit recreational activities such as boating.

How it spreads

  • Plants can produce up to 100 seeds per year, and may start producing viable seed after four months.
  • Seeds float and are mainly spread downstream by water.
  • New plants can grow from rhizomes, which may break off in floods and spread downstream.

Control options

  • Dig up small, immature plants where infestations are small, remove all roots, and take the plants from the site because rhizomes can regrow.
  • Collect all seeds when removing mature plants by hand, and contact the local council for disposal advice.
  • For chemical control, use an appropriate herbicide in accordance with its label and any permit conditions; take care near waterways and avoid spray drift or runoff into them.
  • Follow up after initial control, regularly reinspect treated sites and remove regrowth or new seedlings; notify the local control authority if the plant is found in the North Coast region.

Hygiene and washdown

  • Collect seeds from mature plants being removed and contact the local council for advice on disposing of plants and seeds.
  • Avoid allowing seeds or rhizomes to enter waterways, where they can be spread downstream.
  • 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.

  • 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

Sources