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Kochia (Bassia scoparia)

Kochia is not present in New South Wales, but infestations introduced in Western Australia and Tasmania were eradicated. It can reduce pasture and crop production and is toxic to livestock when eaten in large quantities.

Key facts

Type: Weed, shrub.

Native to: Eastern Europe and western Asia.

Established in: NSW, TAS, SA, WA.

Best time to act: Look for kochia in spring, when most seeds germinate, and report it immediately if found.

Identification

  • This annual shrub grows up to 1.5 m tall and wide, with a main stem and many branches that curl upwards.
  • Its leaves are up to 60 mm long and 8 mm wide, and change from green to yellow, red and then brown as the plant ages.
  • The striped stems are hairy when young, and the small, difficult-to-see flowers grow singly or in pairs on hairy spikes.
  • Its star-shaped fruits are about 2 mm in diameter and contain a single dull-brown seed about 1.5 mm wide.
  • Look-alike: The ornamental subspecies Bassia scoparia subspecies trichophylla, also called summer cypress or burning bush, has an oval shape, leaves only about 1 mm wide and no long hairs around the flowers.

Where it grows

Kochia is not present in New South Wales; infestations previously recorded in Western Australia and Tasmania were eradicated.

Why it matters

  • It competes with pasture grasses and crops, reduces pasture productivity and can contaminate and reduce crop production, including cereal crops.
  • Chemicals from its roots inhibit the growth of nearby plants, and it can host crop diseases.
  • Its pollen can cause hay fever, and it can increase fuel loads and alter fire regimes.
  • Kochia is palatable but can poison livestock in large quantities; deaths have occurred in cattle, sheep and horses.

How it spreads

  • Each plant produces around 14,000 seeds in late summer; in autumn, dead plants can break off at ground level and tumble in the wind, spreading seeds up to 3 km.
  • Most seeds germinate in spring when conditions allow; seeds are usually viable for up to one year, though some remain viable for up to four years.

Control options

  • If you see kochia anywhere in NSW, report it immediately to the NSW Biosecurity Helpline on 1800 680 244.
  • Do not attempt to treat or dispose of the plant yourself; NSW DPI will lead the initial treatment and disposal response.
  • For authorised treatment, listed spot-spray options include fluroxypyr, glyphosate and metsulfuron-methyl; follow current product labels and permit conditions.

Hygiene and washdown

  • Do not attempt to dispose of suspected kochia yourself; report it immediately so the response can prevent it spreading.
  • 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): National Environmental Alert List. One of 28 weeds named on the National Environmental Alert List as early-stage invaders with serious potential to harm the environment.
  • Queensland: Prohibited matter. Report it to Biosecurity Queensland on 13 25 23 within 24 hours and do not move or deal with it. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Prohibited matter. It is an offence to deal with it, and you must notify NSW DPIRD as soon as you become aware of it.
  • 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 (C1), prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. 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: Declared pest, notifiable, prohibited. It is a declared pest throughout the ACT. You must report it to ACT Biosecurity. Dealing with it, such as selling, moving or keeping it, is prohibited.

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
  • 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