Mission grass

There are two types of mission grass in the NT, perennial and annual.

Perennial mission grass is a declared Class B and Class C weed. Annual mission grass is not a declared weed in the Northern Territory, however it is recommended that both types be controlled at the same time.

The Latin names are Cenchrus polystachios (perennial) and C. pedicellatus (annual).

Mission grass - infestation

Identification

You should use this as a guide. There may be other plants or weeds that look similar.

If you are unsure, contact the Weed Management Branch.

Habit

These features describe the habit of this plant:

  • large, tough grass
  • forms a loose clump
  • perennial type grows to 3m tall
  • annual type grows to 1.5m tall.

Mission grass - habit (perennial) Mission grass - habit (annual)

Stems and branches

These features can identify the stems and branches:

  • slender and fairly straight
  • sometimes rooting at the lower nodes.

Mission grass - stems and branches (perennial) Mission grass - stems and branches (annual)

Leaves

These features can identify the leaves:

  • blades are hairy and elongated
  • up to 45cm long and 1.8cm wide
  • can have a reddish-purple colour, particularly when stressed
  • will stay green long after native grasses have dried.

Mission grass - leaves (perennial) Mission grass - leaves (annual)

Flowers

These features can identify the flowers:

  • flower heads appear in March
  • dense spike
  • 5-26cm long and 1.3-2.6cm wide
  • perennial type generally has a golden colour
  • annual type has a purple or pinkish tinge.

Mission grass - flowers (perennial) Mission grass - flowers (annual)

Seeds

These features can identify the seeds:

  • seeds are hairy on the lower half
  • ideal for dispersal by wind, and on animals and vehicles
  • flowering to seed maturity can occur in 14 days
  • perennial type has closely packed seeds
  • annual type has notable spaces between seeds.

Mission grass - fruit and seeds (perennial) Mission grass - fruit and seeds (annual)

Impact

By remaining green until the late dry season, this grass provides fuel for much hotter fires later in the year. It is also encouraged by repeated burning. The fuel load from this species can be three to five times that of native species.

Mission grass can have all of the following impacts:

  • competes with native species
  • occupies disturbed areas
  • provides fuel for hotter late fires
  • fires are detrimental to native species as well as property and horticulture
  • is encouraged by repeated burns.

Habitat and distribution

Mission grass is native to tropical Africa. It was originally introduced into Australia for testing as a pasture species. Naturalised plants were first noticed in the Darwin area in the early 1970s. 

Mission grass has since spread throughout the Darwin rural area and along many road networks. It also occurs in Arnhem Land and in the Katherine region.

Spread prevention

Mission grass is highly invasive, produces vast quantities of seed and has the capacity to spread into both disturbed and undisturbed areas. 

The light and fluffy seeds produced by mission grass are easily spread by wind, vehicles, machinery and animals. Contaminated hay is also a major source of seed spread.

You can prevent the spread of mission grass by doing all of the following:

  • map infestations to help develop a management plan
  • control plants before the seeds mature
  • control minor infestations, isolated outbreaks or seedlings first
  • designate wash down areas and actively work to prevent contamination of clean areas
  • spray any tussocks that grow along fencelines, fire breaks and roadsides or outside paddocks
  • make sure hay brought into clean areas for fodder or mulch is weed free
  • monitor areas that you have treated and watch for re-infestations.

Mission grass - spread 

Control

Annual mission grass can be controlled by slashing prior to seeding (repeated slashing may be required). Adult plants will not persist to the following year. Small infestations of perennial mission grass can be hand pulled. Slashing can prevent seed formation. Regrowth can then be treated with herbicide.

Chemical control

The best time to treat mission grass is from December to March. Below is a list of treatment methods that can be used.

Chemical and concentration Rate Situation, method and notes
Glyphosate 360 g/L
Various trade names and formulations
10 ml/L Seedling or adult - individuals or infestation:
Foliar spray - apply when actively growing

Non-chemical control

Hand pulling and grubbing

Weeds, including their roots, are physically pulled out of the ground by hand or using hand tools. This is an effective method of control for individual weeds and recent outbreaks that haven’t released seeds yet, but it requires a lot of labour.

Slashing

A brush-cutter, slasher or mower are used to cut weeds off above the ground level. This can be effective in suppressing flower and seed development.

Fire

Burning promotes further mission grass establishment. Fires should be followed up with herbicide application.

Last updated: 27 June 2017