Weed of the Week: Coolatai grass

Published on 06 December 2024

It’s week ten of Council’s Weed of the Week series for the 2024/25 spring and summer season. This series of articles provides our community with information and advice on new, emerging and established invasive plant species threatening our region.

Whether you live on the land, in town, or you’re just passing through – we all have a part to play in protecting our natural environment and agricultural land from weeds.

This week we look at Coolatai grass (Hyparrhenia hirta), another emerging weed threat in our region. Coolatai grass is an invasive drought, fire and herbicide tolerant tussock-forming perennial grass.

It is a summer-active perennial that grows to 1.5 metres tall and produces short rhizomes (underground stems) forming a dense grass tussock. It has greyish-green leaves that turn orangey-red in winter, particularly after frost. Its most obvious characteristic is its paired racemes (flower clusters) which adorn the plant in late spring through to autumn.

Coolatai grass is a major threat to nature reserves and national parks, as it is one of the few perennial grass species capable of invading undisturbed natural ecosystems. Pastures dominated by Coolatai grass can be productive, although the management requirements are higher than what is typically required.

Coolatai grass has many traits that closely reflect the locally abundant weed, African lovegrass. Both readily overrun disturbed pastures, thrive on summer rainfall, exhibit significant growth rates during the summer months, are frost, fire and drought tolerant and are of significant concern to fire authorities due to the abundance and flammability of their dry stalks and leaves.

Where is Coolatai grass found?

Coolatai grass is native to Africa, southern Europe and western Asia. It is a major invasive species in northern NSW and southern Queensland where it has invaded and dominated pastures. Locally, Coolatai grass has been identified at four sites on the Monaro Highway north of Cooma, where Council’s biosecurity staff have maintained an eradication program since it was first confirmed in 2016.

In southern NSW, Coolatai grass is most commonly found on roadsides where traffic and slashers readily transport it from one area to another.

Eradicating such a weed threat in its early stages of invasion provides significantly greater return on investment than trying to manage a well-established weed. For this reason, Council calls on community members to learn how to identify this species and immediately report suspected incursions to Council’s biosecurity team on 1300 345 345.

What should you do if you detect Coolatai grass on your land?

Due to its potential impact in the Snowy Monaro region and its limited distribution, the South East Regional Strategic Weed Management Plan 2023–2027 identifies Coolatai grass as a weed which should be managed with a containment objective. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value and should mitigate spread of the plant from their land.

Tips for managing Coolatai grass:

• Learn to identify Coolatai grass. Learn its preferred habitats and identify likely locations where this weed could establish itself on your property.
  
  
• It is critical to identify and control Coolatai grass sites before they can become fully established. If you identify suspected Coolatai grass, contact Council for confirmation and assistance.
  
  
• Maintain strong, competitive pastures to inhibit Coolatai grass establishment.
  
  
• Control all Coolatai grass before it produces seeds. One year of seeding means many years of weeding.
  
  
• Spot spraying is most effective for managing isolated or light infestations and minimises ground disturbance.
  
  
• Non-chemical options include digging or chipping out the plants. You can scatter grass seed over larger bare areas to help stop weeds from growing.
  
  
• Consider whether you have the time, equipment and ability to do the work yourself. It might be more practical and efficient to engage a contractor to do the work on your behalf.
  
  
• Coordinate your weed control efforts with your neighbours. You may be able to share resources and achieve more effective results.

Council is here to help. If you have questions about Coolatai grass, or any other weeds on your property, contact our specialist biosecurity officers for advice and assistance. Call 1300 345 345 or email council@snowymonaro.nsw.gov.au

Can’t identify a weed? Send in some photographs or arrange a free onsite inspection and one of our staff will promptly respond.

Download the free NSW WeedWise app for detailed information on how to identify and manage weeds. Visit www.dpi.nsw.gov.au/biosecurity/weeds

Visit the Department of Primary Industries (DPI) website for information on weed control methods – www.dpi.nsw.gov.au/biosecurity/weeds/weed-control

Visit our website at https://qrco.de/SMRCweeds for more information about weeds and biosecurity in the Snowy Monaro.

Image credit: "Hyparrhenia hirta plant11" © Harry Rose 2012, CC BY 2.0.