Prevent gamba grass spread
Gamba grass is a highly invasive weed.
The seeds are produced at the end of the wet season and can be carried by wind, vehicles, animals and people.
Gamba dries out later in the dry season and burns up to 8 times hotter than native grasses.
If you don’t manage gamba grass, you risk:
- further spread by seed
- invasion of natural habitats
- increased fuel loads for bushfires that threaten lives, homes and assets.
Spread prevention
You can prevent the spread of gamba grass by doing all of the following:
- Spray or destroy tussocks that grow on fence lines, fire breaks, roadsides or outside paddocks.
- Slash infestations in the early dry season before seeds mature.
- Avoid driving through seeding plants.
- Clean vehicles and equipment that come into contact with gamba seed.
- Remove all seeds and mud. Mud may contain seeds.
- In areas where gamba grass can be legitimately used for pasture, make sure to graze it heavily so it doesn't produce seeds.
Find out more about preventing weed spread in the NT.
All property owners and occupiers must also install a 15m gamba-free buffer (an area free of gamba grass) as follows:
- around the entire property boundary
- around all infrastructure
- along either side of all tracks and driveways.
Read more about landholder responsibilities.
Report problem gamba
Control gamba grass
If you're a landholder in the Northern Territory (NT), you must control gamba grass on your property.
Find out about your responsibilities as a landholder.
To learn about how to plan and manage gamba, read the gamba management guide PDF (1.1 MB).
You can also watch the videos below on applying and mixing herbicide.
The best time to treat gamba is from December to March. That's when the grass is actively growing.
Treatment methods include chemical control and non-chemical control.
Chemical control (spraying herbicide)
The most common way to treat gamba grass is by using the glyphosate herbicide.
Glyphosate comes in different brand names and types.
The recommended concentration and rate for glyphosate 360g/L are 10mL per 1L of water.
Apply it as a foliar spray when the grass is actively growing. Use a surfactant to make sure it works well.
Find out how you can get free herbicide for gamba grass.
To chemically control gamba, follow the steps below.
Step 1. Plan to spray your property
Before you spray
You should consider the following when you are planning to spray your property:
- spray only when leaves are green and at least 40cm long - glyphosate can be absorbed only by growing leaves and stems
- spray early in the wet season, before it reaches full height - this gives better results for less herbicide and effort
- before spraying, consider removing tall, dry grass stems and encouraging new growth of mature gamba grass - controlled burning or slashing may help with this
- allow time for slashed, mown, grazed or burnt gamba grass to grow new leaves before spraying
- always spray before seeding
- gamba grass is still susceptible to herbicide when flowering.
Where to prioritise
You should prioritise fire risk areas.
All gamba grass within 15m of roads, tracks, property boundaries, houses, sheds and other infrastructure must be controlled.
Control all gamba grass in fire access trails. This also prevents spread to adjoining properties.
Eradicate isolated plants and outbreaks to prevent establishment in new areas.
Control plants which are likely to cause further gamba grass spread, such as on the edge of tracks.
Ensure your control efforts do not contribute to unintended seed spread.
Step 2. Read the herbicide label and learn about safety
Under the law, you must follow instructions on the herbicide label.
Read the safety data sheet of any herbicide you use for information including:
- potential health effects
- first aid
- personal protective equipment
- spill and disposal procedures.
Follow these guidelines for safe herbicide use:
- don't spray plants other than declared weeds as glyphosate can kill plants other than gamba grass if it comes into contact with them
- don't spray in windy conditions as spray drift can damage plants you are not targeting
- don't contaminate dams, waterways or sewers with glyphosate.
For more advice on using herbicides, go to page 8 of the NT Weed Management Handbook PDF (1.3 MB).
Step 3. Mix herbicide (with video)
Watch a gamba grass mixing herbicide demonstration below.
You must dilute the glyphosate before you apply it to gamba grass.
When you dilute glyphosate, you must use only the described ratio of water to herbicide.
For glyphosate 360g/L , mix 1 litre of concentrate with 100 litre of clean water for a 1% ratio.
Ratios that are:
- too strong can burn leaves and may not kill the whole plant.
- too weak may not kill the plant.
You must do all of the following:
- mix herbicide with rainwater, tap water or good quality bore water
- not use creek or dam water that may contain clay or organic matter
- consider adding a wetting agent to help the glyphosate get through the hairy surface of gamba grass leaves
- consider using a marker dye to show if you missed any weeds.
Step 4. Spray herbicide (with video)
Watch a gamba grass spraying demonstration below.
The following is a checklist for how and when to spray:
- Adjust your nozzle to produce medium to heavy size droplets so you can get full coverage of the plant while reducing spray drift.
- Coat the entire plant - each stem of a gamba grass tussock is an individual plant, if any stems are missed the plant can recover.
- Spray until herbicide drips from the leaves to make sure it gets through the fur on the leaves.
- Don't spray in windy conditions to avoid damage to non-weed plants nearby.
- Use only aquatic approved glyphosate near watercourses to avoid harming plants and animals in the water.
- You should spray in the mornings, and at least an hour before rain as it takes an hour for plants to absorb the herbicide.
For best results, you should spray:
- every part of the plant
- when actively growing and young (when leaves are at least 40cm long)
- before they reach full height - this 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.
Step 5. Follow-up after spraying
If plants have not wilted and yellowed within 4 to 7 days, you will need to spray again.
Check all treated areas for missed plants, regenerating plants and new seedlings.
You may need 3 or 4 rounds of spraying for good results in the first year of control.
Follow-up control in subsequent years will also be necessary.
Poisons advice
For advice in case of a medical emergency, contact the Poisons Information Centre on 131 126.
Non-chemical control
You can control gamba without using any chemicals in 4 ways.
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.
Slashing will not eradicate gamba grass, but it can:
- reduce the biomass
- prevent seeding
- create an opportunity for more desirable species to establish
- provide improved access to control by other means.
Fire
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.
You should treat plants with herbicide before 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.
Grazing
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 4 to 5 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.
For general methods of weed control used all around the world, read types of control methods.
Contact
If you have any questions, contact the Weed Management Branch.
Check your gamba grass risk
If you're a landholder with gamba grass on your land, you're legally responsible for controlling it.
To get advice on what you should do to manage gamba grass, check your risk rating below.
The calculations below use the compliance rating system - it's the same system that weed officers use when measuring gamba control on properties.
Read each statement below and select all relevant boxes.
Gamba grass is:
Report gamba
You can now report a concern about unmanaged gamba grass.
Managing gamba grass and landholder responsibilities
If you're a landholder in the Northern Territory (NT), you must take all reasonable measures to prevent gamba grass from spreading on your land or to other people's land.
Different requirements apply to the zone you're in. If you're unsure, check your declaration zone.
What you must do
If your property is in the class A zone, you must destroy all gamba on your property by July 2023.
If your property is in the class B zone and it's:
- less than 3 ha (7.4 acres), you must destroy all gamba by July 2023
- bigger than 3 ha (7.4 acres), you must:
- have a 15m wide gamba-free area around your property boundaries, driveways and infrastructure
- actively reduce gamba plants every year
- destroy all outlier gamba grass plants and infestations as soon as possible.
These are requirements under the weed management plan - 2020 to 2030 PDF (2.0 MB). Read about the management plan.
Mitigation and compliance
The Weed Management Branch and the Gamba Fire Mitigation Unit are responsible for checking that you're doing what you should about your gamba.
The Gamba Fire Mitigation Unit addresses areas where:
- unmanaged gamba grass is creating high fuel loads
- there's non-compliance with the Weeds Management Act 2001 and the Bushfires Management Act 2016.
The Weed Management Branch address gamba in other areas of the NT.
For more information, read the:
- gamba fire mitigation: compliance policy PDF (1.5 MB)
- Weeds Management Act: compliance policy PDF (1.1 MB).
As a part of this compliance process, your property may be inspected for gamba grass. This will be done by weed management officers.
If you don't comply, you may receive a management order or fine.
See the below image for an example of how you can comply.
Bushfire planning and mitigation strategies
To test a range of bushfire planning and mitigation strategies relevant to gamba grass on rural residential blocks, check out the Darwin rural fire simulation.
Contact
If you have any questions, contact the Weed Management Branch.
Free herbicide for gamba grass
To help control gamba grass in the Northern Territory (NT), you can get free herbicide, spray equipment loans and weed management advice.
This is also called the Gamba Action Program.
The Gamba Action Program will open on 1 December 2023.
What you'll get
The herbicide you'll get is called glyphosate.
The 2 brands stocked through the program are:
- Kenso Agcare Ken-Up Aquatic 360
- Relyon Glyphix 360 Herbicide.
Both products contain 360g per litre of glyphosate as the active ingredient.
View the product labels or safety data sheets (SDS):
- Relyon Glyphix 360 herbicide SDS PDF (575.7 KB)
- Ken-Up Aquatic 360 e-label PDF (453.4 KB)
- Glyphix 360 herbicide e-label PDF (649.9 KB)
- Ken-Up Aquatic 360 Herbicide SDS PDF (277.0 KB)
Read more about the herbicides on the Kenso Agcare or Relyon websites.
How to use
Always refer to the label on the bottle before mixing herbicide.
You must correctly use herbicides as they can cause immediate and long-term illnesses.
There are laws and instructions you must follow when using herbicides, these include:
- NT law, read the Agriculture and Veterinary Chemicals (Control of Use) Act 2004
- Commonwealth law, go to the Australian Government website.
For a step-by-step guide on how to use herbicides, read controlling gamba grass.
Get free herbicide or spray equipment
Location | Address | Opening hours | Contact |
|---|---|---|---|
Freds Pass Sport and Recreation Reserve Slip-on spray tanks available | 20 Bees Creek Road | Monday and Friday - Every second Saturday from 2 December - 8am to 12 noon | |
Adelaide River Fire and Rescue Response Group | 132 Stuart Highway | Call for details | |
Coomalie Community Government Council | 141 Cameron Road | Fridays only 8:30am to 3pm | |
Dundee | 4250 Fog Bay Road | Call for details | 0429 407 520 - John Trott |
Daly River | Wooliana Road | Call for details | 0447 585 572 - Tony Schultz |
Katherine Weed Management Branch depot | 11 Crawford Street | Call for details | |
Labasheeda Volunteer Bushfire Brigade | 645 Parkin Road | Call for details | 0427 760 383 or therese.taurus@gmail.com - Therese Balanztegui 0409 286 439 - Terry |
Milne Volunteer Bushfire Brigade | 165 Bynoehaven Road | Call for details | |
Territory Wildlife Park | 960 Cox Peninsula Road | Monday to Friday - 9am to 2pm | |
Wagait Shire Council | 62 Wagait Tower Road | Call for details |
Contact
If you have any questions, contact the Weed Management Branch.
Gamba grass declaration zones
Gamba grass is a declared weed under section 7 of the Weeds Management Act 2001.
It has a split declaration based on its known distribution and density.
There are 2 declaration zones:
- class B - growth and spread to be controlled
- class A - to be eradicated in all areas of the NT except where it's classified as class B.
For information on the declaration zones, read the 2014 gazette notice PDF (1.7 MB).
Contact
If you have any questions, contact the Weed Management Branch.
Gamba origin, habitat and distribution
Gamba grass is originally from Africa. It was introduced to the Northern Territory (NT) as a pasture species in the 1930s.
Research and trials resulted in widespread plantings in pastoral and agricultural areas of the Top End.
Read more about its origin on the Australian Government's weeds in Australia website.
Habitat and distribution
It needs at least 600mm of rain each year.
It usually flowers in April and produces seeds from May to August.
If there's an early wet season, it might also produce seeds again in November.
Gamba grass can survive in tough conditions such as drought, fire, and poor-quality soil found in north Australian savannas.
It can grow in most Top End soil types except heavy clays.
Distribution in the NT
Gamba grass has already affected up to 15,000km2 of the NT. However, it can potentially affect up to 380,000km2.
Most infestations are north of Katherine.
To find out more about where gamba grass is spreading, read the annual reports on the Department of Environment, Parks and Water Security website.
Plans and strategies for gamba grass
Under section 10 of the Weeds Management Act 2001, the weed management plan for gamba grass outlines the legal requirements of land owners about gamba grass control.
It also describes required management actions by all owners and occupiers of land and everyone in the Northern Territory (NT).
Read the weed management plan for gamba grass 2020 to 2030 PDF (2.0 MB).
Consultation
An extensive community consultation occurred to develop the plan.
To find out the process for developing it, read the gamba grass weed management plan discussion paper PDF (16.3 MB).
Mapping and monitoring program for class A zone
As part of the plan, a mapping and monitoring program for the class A eradication zone has been developed to understand the distribution of gamba grass across this eradication zone.
The program outlines:
- properties with known gamba grass in the class A zone
- the methods proposed to assess gamba grass on each of these properties.
- the methods for monitoring gamba grass in the class A zone to assess progress towards eradication.
Read the mapping and monitoring program for class A (eradication zone) PDF (1.6 MB).
Performance and reporting
You can read the gamba grass annual report and snapshot on the Department of Environment, Parks and Water Security (DEPWS) website.
Contact
If you have any questions, contact the Weed Management Branch.