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Posted in Chemical

Gamba grass

Gamba grass, Darwins worst weed or most destructive weed due to fire and its spread.  Fast growing and furious a bit like the 1 minute video, this is an artistic combination of weed control, Mad max and Pulp fiction rolled into Darwins worst weed, Gamba grass hell.

Another take on Gamba grass, both videos using the same them to explore the ideas of the urban fringe as infested and destroyed by the dreaded African plant.

Gamba Grass Genus Andropogon sp. gayanus

History Gamba grass: Is native to the tropical and sub-tropical savannas of Africa, from Senegal on the west coast to Sudan in the east and south to Mozambique, Botswana, and South Africa.  Was first introduced to the Northern Territory in 1931 for testing as a pasture grass. It has naturalised in the east Kimberley region of Western Australia, in the northern parts of the Northern Territory, and in coastal and sub-coastal areas of North Queensland.

Gamba grass is a large tufted perennial grass to 4 m high but more usually around 1.3 m tall. The stem and leaves are hairy. The inflorescence is held above the leaves and is loosely branched. The individual spikelets are hairy.  Flowers/Fruits: Mainly April – August.  Habitat: Creek lines, floodplain fringes, degraded areas, roadsides, pastures, and Eucalyptus savanna in areas where rainfall is over 600mm per year.

All property owners and occupiers must install a 15m gamba free buffer as follows:

  • around entire property boundary
  • around all infrastructure
  • along either side of all tracks and driveways.

If you have a small amount of gamba or if you are in the Class A eradication zone, you must be working towards removing all gamba plants from your property.  Darwin Chemical Course Dates

Chemical Control of Gamba grass

The best time to treat gamba 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
10mL / 1L Seedling or adult (individuals or infestation):
Foliar spray - apply when actively growing (Dec-Mar)
Use surfactant

Effective chemical control of gamba grass relies on spraying the entire plant.  For optimal uptake of the herbicide and high mortality rates gamba grass should be sprayed when actively growing and young (leaves should be at least 40cm long).  Spraying plants prior to reaching full height will reduce time and herbicide requirements.  Gamba grass is still sensitive to herbicide when flowering. Once gamba grass is seeding and the leaves are drying out herbicide will not work.

Always Read the Chemical Label - SAFETY DIRECTIONS for Glyphosate 360:

Product will irritate the eyes and skin. Avoid contact with eyes and skin. When preparing product for use wear elbow-length PVC gloves and face shield or goggles. When using controlled droplet applicator wear protective waterproof clothing and impervious footwear. After use and before eating, drinking, or smoking wash hands, arms, and face thoroughly with soap and water. After each day’s use, wash gloves, face shield or goggles and contaminated clothing.  Darwin chemical courses online

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 have not released seeds yet, but it requires a lot of labour.


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.  Slashing will not eradicate gamba grass, but it can reduce the biomass, prevent seeding, create an opportunity for more desirable species to establish and provide improved access to control by other means.


Fire as a management technique is most effective when it is used together with other methods. It is useful for mass seedling control if there is a sufficient fuel load. Burning will not kill gamba grass, but low intensity fires, undertaken in the wet season, can remove rank growth improving access for slashing or spraying. Plants may need to be treated with herbicide prior to burning to create enough dry matter to carry a fire. Fire may have the ability to carry seed in hot air currents, therefore avoid using fire as a control method while plants are seeding.


In areas within the Class B declaration zone gamba grass may continue to be used in established pasture areas, however there is a requirement to disallow any further spread. Gamba being used as a pasture should be grazed with enough stock to keep grass height below 90cm. Above this height tussocks may be avoided by stock and allowed to produce vast quantities of seed. After lightly grazing pasture in the early wet season, a stocking density of four to five head per hectare is required to control growth for the remainder of the wet season. Increase grazing pressure if the grass nears 90cm. Gamba grass is not recommended for cattle production on smaller properties as it requires high stocking densities to keep it low and palatable.

Spread prevention:

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

  • spray/destroy any tussocks that grow on fence lines, fire breaks and roadsides or outside paddocks
  • slash infestations in the early dry season before seed matures
  • avoid driving through seeding plants
  • clean vehicles and equipment that come into contact with gamba seed
  • in areas where gamba grass can be legitimately used for pasture, graze it intensively to prevent seeding.

You can do a herbicide user course course online, the focus is 100% Darwin weeds and chemical use.  We are the only providers of the online AusChem chemical course that is 100% based on the Northern Territorys weeds, pest insects and chemicals that are used in the NT. You can select to be tested on 1080 Wild Dog labels or herbicides labels. The legislation is 100% Northern Territory Government. You do not need to be a IT guru, the learning materials, books, tests are provided to you via the online website is designed to be user friendly and easy to drive.  Have a look at Weed Control Courses Online

Gamba grass