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Annual mission grass (Cenchrus pedicellatus)

Annual Mission Grass is a problematic weed in grain sorghum crops and can invade disturbed areas, degraded pastures, waste sites and native vegetation. It is naturalised in tropical parts of Western Australia, the Northern Territory and Queensland.

Key facts

Type: Weed, grass.

Native to: Tropical Africa.

Established in: QLD, WA, NT.

Other names: Hairy Fountain Grass, Deenanth, Annual Pennisetum, Denath Grass.

Best time to act: It flowers from April to June and produces seeds from April to July, so look for it and treat it before mature seeds form, when growth is high.

Identification

  • This is a tufted annual grass with slender stems, growing up to 1.5 metres tall.
  • Stems are usually more or less straight, but may root at the lower nodes.
  • Leaf blades grow up to 45 centimetres long and 1.8 centimetres wide, and may be hairy or hairless; a ring of hairs occurs at their base.
  • Dense, cylindrical flowering heads grow above the leaves and are cream-coloured with a purple tinge; they are usually 5 to 15 centimetres long, sometimes reaching 20 centimetres.
  • The seeds have bristles and dense, woolly hairs.

Where it grows

In Australia it occurs in northern Western Australia, many parts of the Northern Territory, and northern and eastern Queensland, especially on disturbed sites such as degraded pastures, cultivated land, roadsides, waste sites and creeklines.

Why it matters

  • It is a problematic weed in grain sorghum crops.
  • It invades disturbed areas, degraded pastures and waste sites.
  • It can also invade native vegetation.

How it spreads

  • Its light, fluffy seeds can be carried by wind and water, and transported by people, birds, other animals, vehicles and machinery.
  • Seeds can also spread as contaminants in hay and grain.

Control options

  • Treat small, isolated infestations in native vegetation before large infestations, taking care to minimise damage to native plants.
  • Dig out seedlings and small plants before they have mature seeds.
  • Use registered herbicides when plant growth is high but before seeding.
  • Follow up in subsequent years to prevent regrowth or invasion by other weeds.

Hygiene and washdown

  • Practise appropriate weed hygiene to prevent seeds being moved to uninfested areas, particularly on vehicles and machinery.
  • Avoid spreading seed-contaminated hay or grain.
  • 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): Key threatening process. Listed under the EPBC Act, with a national threat abatement plan for invasion by five invasive grass species.
  • 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. Listed on the NT A to Z weed list but not declared under the Weeds Management Act 2001.
  • 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)
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources