Weeds - Phase 1 - Research Highlights

Serrated tussock

Protecting Australia's agricultural grasslands from herbicide-resistant serrated tussock

What the report is about

This project highlights the importance of investigations into biological control of serrated tussock and supports the continuation of this work.

Where are the relevant industries located in Australia?

Land managers in New South Wales, the Australian Capital Territory, Victoria and Tasmania will benefit from this research by learning how to recognise, manage and prevent serrated tussock herbicide resistance. It is their management practices, along with the nature of the inheritance, the breeding system and the amount of gene flow that will determine the spread of serrated tussock flupropanate resistance.

Background

Serrated tussock is an unpalatable South American perennial grass that is a Weed of National Significance in Australia because of its severe agricultural and environmental impacts.

Aims/objectives

This report aims to inform landholders about how to how to recognise, manage and prevent serrated tussock herbicide resistance.

Methods used

Detailed surveys of the extent of serrated tussock's resistance to flupropanate have been conducted in the Armidale region of New South Wales and at Diggers Rest in the Rowsley Valley in Victoria. Serrated tussock samples were also received from two properties near Goulburn in southern New South Wales.

This report provides an assessment of the extent of serrated tussock resistance occurring in 100 regions of one square kilometre surrounding three known locations of resistant serrated tussock in Australia.

In addition, workshops with affected farmers and other land managers were held in Sunbury (30 participants) and the Rowsley Valley (26) in Victoria and in Armidale (16 participants) and Goulburn (82) in New South Wales.

Results/key findings

The report found that all locations surveyed have sites with flupropanate-resistant serrated tussock more than two kilometres from the properties initially identified with resistance. This suggests that flupropanate resistance has probably already escaped from the original sites to surrounding areas.

This shows that serrated tussock's resistance to flupropanate is becoming widespread, which has implications for further serrated tussock invasion, increased herbicide use, and higher management and labour costs for farmers.

As a result of the survey findings, a national awareness campaign dealing with serrated tussock resistance has been undertaken which includes producing brochures on how to recognise, manage and prevent serrated tussock herbicide resistance and distributing 10 000 to land managers in New South Wales, the Australian Capital Territory, Victoria and Tasmania.

Workshop participants also received detailed information about resistance in their localities and information about how to deal with the problem in future.

Implications for relevant stakeholders

As a result of this research it is obvious that land managers are increasingly going to have to deal with flupropanate-resistant serrated tussock, and the possible loss of flupropanate as a control tool will severely limit the options.

Recommendations

It is crucial that weed management authorities wishing to contain serrated tussock resistance to flupropanate understand the current extent of resistance infestations. If the resistant tussock is confined within a very small area (that is, a single property), the resistance can be nominated for management using government assistance for direct control costs and compliance. If the resistance is widespread, management becomes more problematic, and government assistance is likely to be directed at extension and advice promoting integrated control.