Thatch grass (Hyparrhenia rufa)

Also known as: Jaragua grass, thatching grass

Thatch grass grows in dense clumps and is up to 3 m tall. It outcompetes native plants and increases the intensity of fires.

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How does this weed affect you?

Thatch grass forms dense stands that can:

• outcompete native vegetation, especially in grasslands and the understorey of woodlands
• reduces habitat for native animals 
• competes with crops and contaminates the seed
• contribute to increasing frequency and intensity of bush fires.

What does it look like?

Thatch grass is an erect, densely tufted grass up to 3 m tall. Plants may be annual or perennial. Mature plants often retain clumps of brown, dry leaves that look thatched.

Leaves are:

• flat
• usually smooth with rough edges
• up to 60 cm long and 8 mm wide
• narrower at the base where it joins the leaf sheath

Seedheads:

• are 20–60 cm long
• are reddish 
• consist of stalks with many paired branches that form a ‘V” at the end - each branch is 1.5-5 cm long with 9-10 awns
• are usually present in summer.

Seeds:

• are hairy
• have a 2 cm long brown awn that is twisted with two bends.

Similar looking plants

• Coolatai grass (Hyparrhenia hirta ) is a weed that looks similar but only grows to 1.5 m tall. Each seedhead branch has 5-8 awns. 
• Tambookie grass (Hyparrhenia filipendula) is a native grass that looks similar, but it only grows to 1.5 m tall. Its seedhead branches are shorter, only up to 2.5 cm long and each branch only has 1-3 awns. 

Where is it found?

In NSW, most infestations have been found in the Hunter region. Thatch grass has also been found in the North Coast, North West, Central West, Greater Sydney and South East regions. 

It is native to tropical and southern Africa and Madagascar.

What type of environment does it grow in?

Thatch grass mostly grows in tropical and subtropical climates and does not tolerate frosts. Plants usually grow in moist environments with annual rainfall between 600 mm and 1400 mm. They tolerate waterlogging, temporary flooding, salinity, fires and up to six months of dry season. Although they can grow on a wide variety of soil types, they grow best on black clay soils and red soils.

Thatch grass grows in:

• grasslands and dry forest
• pastures 
• disturbed sites such as cultivated land and roadsides.

Maps and records

• Recorded presence of Thatch grass during property inspections (Map: Biosecurity Information System - Weeds, 2017-2024)
  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?

By seeds

The seeds have long awns which can attach to clothing, boots and animal fur. They are also spread by wind and by slashers, especially along roadsides. Germination often occurs after fires.

References

Identic Pty. Ltd. & Lucid. (2016). Weeds of Australia: Hyparrhenia rufa subsp. rufa (lucidcentral.org). Retrieved 7 March 2022 from: https://keyserver.lucidcentral.org/weeds/data/media/Html/hyparrhenia_rufa_subsp._rufa.htm

Northern Territory Government. (2024). Thatch grass (Hyparrhenia rufa) in A_Z Weeds List of the NT. Retrieved 7 March 2024 from: https://nt.gov.au/environment/weeds/weeds-in-the-nt/A-Z-list-of-weeds-in-the-NT/thatch-grass

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 15 March 2024 from https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Hyparrhenia~rufa

Rojas-Sandoval, J. & Acevedo-Rodríguez, P. (2014). CABI data sheet: Hyparrhenia rufa. Retrieved 7 March 2024 from Hyparrhenia rufa (Jaragua grass) | CABI Compendium (cabidigitallibrary.org)

Starr F., Starr K., & Loope L.L., (2003). Hyparrhenia rufa: Thatching grass. Plants of Hawaii. Haleakala Field Station, Hawaii, Hawaii: US Geological Survey, Biological Resources Division. 

Wagner, W. L., Herbst, D. R., & Sohmer, S. H. (1990). Manual of the flowering plants of Hawaii. In Manual of the Flowering Plants of Hawaii. University of Hawaii Press.

More information

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Control

Prevention

Ensure that fodder brought into clean areas is weed free.

Clean boots, clothing, equipment and vehicles after working areas with thatch grass.

Grazing

Thatch grass is grazed by cattle, therefore it is not a weed of pastures. 

Physical control

Small plants can be dug out by hand.

Chemical control

Spray

Check the labels and permits for the best time of year to spray as they vary between products.

Herbicide options

See Using herbicides for more information.

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PERMIT 9792 Expires 30/11/2025
Flupropanate 745 g/L (Tussock®)
Rate: 300 mL herbicide / 100 L water
Comments: Spot spray: for best results apply late winter to early spring. See permit for other critical comments.
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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PERMIT 9792 Expires 30/11/2025
Flupropanate 745 g/L (Tussock®)
Rate: 3 L /ha
Comments: Boom spray. Do not apply unless pesticide records indicate that no more than 3 L per hectare will be applied in any 12 month period. See permit for further critical comments.
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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PERMIT 9792 Expires 30/11/2025
Glyphosate 360 g/L (Weedmaster Duo)
Rate: 2 L herbicide / 100 L water
Comments: Spot spray. Optimal timing is late autumn to early winter, however applications outside this time have been satisfactory. See permit for further critical comments.
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.
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 2024