Giant rat's tail grass (Sporobolus pyramidalis)

Giant rat’s tail grass is an upright grass that grows in clumps up to 1.7 m tall. It can take over pastures and invade bushland.

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How does this weed affect you?

Giant rat’s tail grass is a weed in pastures and bushland areas, particularly on poorer soils.

Giant rat’s tail grass:

• invades pastures, replacing more productive grasses
• is tough and difficult for cattle to graze 
• reduces feed intake and animal production in cattle
• invades native grasslands, open woodlands, wetlands, replacing native plants
• can increase fire intensity.

What does it look like?

Giant rat’s tail grass is a perennial upright grass that grows in clumps up to 1.5 m tall. It has seedheads that look a bit like a rat’s tail when young and may branch to a elongated pyramidal shape when mature.

Where is it found?

Giant rat’s tail grass is common in coastal northern New South Wales. It was probably accidently brought into Australia in contaminated pasture seed.

It is native to Africa.

Maps and records

• Recorded presence of Giant rat's tail grass during property inspections (Map: Biosecurity Information System - Weeds, 2017-2023)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

Giant rat’s tail grass seeds become somewhat sticky when wet. Seeds spread:

• by attaching to animals, clothing and vehicles
• in water and mud
• in contaminated agricultural produce such as pasture seed and fodder.

More information

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Control

Herbicide options

See Using herbicides for more information.

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PERMIT 9792 Expires 30/11/2025
Glyphosate 360 g/L (Various products)
Rate: 3.3 L per 10 L of water
Comments: Wick wiper application. Apply when plant is actively growing.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Flupropanate 745 g/L (Tussock®)
Rate: 200 mL per 100L of water
Comments: Handgun application.
Withholding period: Spot spray: Do NOT graze or cut for stock feed for at least 14 days. Blanket spray: Do NOT graze, or cut for stock feed for at least 4 months. If stock are grazed in treated areas after required time has passed, remove stock from treated areas and do NOT slaughter or milk for human consumption until they have been on clean feed for at least 14 days.
Herbicide group: 15 (previously group J), Inhibition of very long chain fatty acid synthesis (VLCFA inhibitors)
Resistance risk: Moderate

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Flupropanate 745 g/L (Tussock®)
Rate: 1.5–2.0 L/ha
Comments: Boom spray. Best results during late winter and early spring when desirable species are semi-dormant. Four month withholding period for blanket spray application.
Withholding period: Spot spray: Do NOT graze or cut for stock feed for at least 14 days. Blanket spray: Do NOT graze, or cut for stock feed for at least 4 months. If stock are grazed in treated areas after required time has passed, remove stock from treated areas and do NOT slaughter or milk for human consumption until they have been on clean feed for at least 14 days.
Herbicide group: 15 (previously group J), Inhibition of very long chain fatty acid synthesis (VLCFA inhibitors)
Resistance risk: Moderate

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Glyphosate 360 g/L (Various products)
Rate: 10–15 mL per 1 L water
Comments: Handgun application for when plants are actively growing.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Glyphosate 360 g/L (Various products)
Rate: 6.0 L/ha
Comments: Boom application for pasture replacement/ improvement and best done as a split treatment. Apply when plants are actively growing.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
Greater Sydney	Regional Recommended Measure* (for Regional Priority - Prevention) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
Hunter	Regional Recommended Measure* (for Regional Priority - Asset Protection) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2023