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Hymenachne research project:

Ecological economic and social considerations of spray control for Hymenachne

What is this research all about?

Hymenachne, a Weed of National Significance, is an aquatic plant invading northern Australia's wetlands and waterways, including a considerable area of the Fitzroy Basin. The proliferation of this weed is associated with serious environmental damage and there are substantial costs associated with its control.

Researchers from CQUniversity have been provided with funding from Land and Water Australia's Defeating the Weed Menace program to examine the potential control options for Hymenachne, particularly methods using spray control. The aim of this research is to better understand the best ways to approach Hymenachne control, whilst satisfying environmental, social and economic concerns.

The research has two main components. The first part involves a social and economic study of both stakeholders and landholders, and is designed to document people's views about how Hymenachne should be controlled. This part of the research will involve contacting various people about their views and ideas, in order to find out ways to improve participation in management and control programs. 
The second part of the research is a scientific study that will investigate the environmental effects associated with controlling Hymenachne by the use of herbidical sprays. This will involve using different spray treatments and then monitoring the effects of this over time at various sites along creeks in central Queensland. Effects that will be investigated include those on aquatic plants, macroinvertebrates, fish and other aquatic biota.


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Hymenachne gets quite high and dense in some places

Project objectives:

  • to conduct scientific studies to address the information gap regarding the ecological effects associated with chemical control of hymenachne in aquatic situations
  • to develop a science-based best practice technique for spray control which minimises ecological damage to sensitive aquatic environments during spray events
  • to identify economic and social barriers to landholder participation in hymenachne control programs and to identify ways in which better cooperation and adoption can be encouraged
  • to estimate the opportunity costs and tradeoffs that landholders face for different control programs, and to identify the types of incentive programs and support actions that will trigger landholder involvement in control programs.

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Cutting Hymenachne to estimate the amount of biomas per unit area

Research partners:

Livingstone Shire Council

Contact: Ian Dare Tel. 4921 0573


Fitzroy River and Coastal Catchments

Contacts: Murray Bullock: Tel. 4921 3834 mbullock@frcc.org.au ; Chantelle James: Tel. 4921 0524 cjames@frcc.org.au

Contact details:

The following staff from CQUniversity are conducting the research and can be contacted for further information:

Primary project contact: Dr Susan Kinnear (s.kinnear@cqu.edu.au) Tel: 4930 9053 :

For specific information about the SCIENTIFIC component of the project contact:

Project leader: Dr Leo Duivenvoorden (l.duivenvoorden@cqu.edu.au) Tel: 4930 9570
Principal researchers: Wayne Houston (w.houston@cqu.edu.au) Tel: 4930 9087
Dr Susan Kinnear

For specific information about the SOCIAL AND ECONOMIC component of the project contact:

Project leader: Professor John Rolfe (j.rolfe@cqu.edu.au) Tel: 4923 2132
Principal researcher: Dr Jill Windle (j.windle@cqu.edu.au) Tel: 4930 9089

Other project staff:
Professor Bob Miles (b.miles@cqu.edu.au) Tel: 4930 9053


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Hymenachne taking over a creek in central Queensland

Related reports and fact sheets:

The following reports may be of interest:

Hymenachne Hymenachne amplexicaulis - Control methods and case studies
Produced by The Australian Government, Queensland Government Natural Resources and Water, CSIRO, Northern Territory Government and the National Hymenachne Management Group. August 2006 (855kb)

Facts: Pest series Hymenachne (Hymenachne amplexicaulis) - Declared Class 2
 Queensland Government Natural Resources and Water, August 2006 (206kb)

Hymenachne (Hymenachne amplexicaulis) in Queensland - Pest Status Review series - land protection
Queensland Government Natural Resources and Mines, 1999 (342 kb)

Towards a Farm Scale Best Management Practice for the Eradication of the Noxious Weed Hymenachne Amplexicaulis in Sandringham Lagoon, Mackay, Queensland
Produced by the Queensland Government Natural Resource and Mines and MackayWhitsunday NRM group, April 2005 (5681kb)

Project results:

The ffollwing reports are now available for downloading:

The final technical report / main report (3.1 MB)

Summary details are ailable in the Technical Summary and the Information Fact Sheet.

Results from the socio-economic component are also available as separate research reports (full details are included in the main report).

Socio-economic Research Report No 1: Social Considerations of the Control and Management of Hymenachne in the Rockhampton and Mackay Areas: Results from Extended Stakeholders Interviews.

Socio-economic Research Report No 2: Landholder's Opinions on the Control and Management of Hymenachne in the Rockhampton Area: Results from a Questionnaire Survey.

Socio-economic Research Report No 3: Identifying the Opportunity Costs of Hymenachne Control and Factors that may Influence Participation: Results from Landholder Workshops.

 Key findings in brief

The ecological results suggest that for central Queensland systems with very high Hymenachne cover, the use of either the half/half or full spray technique would be appropriate. This largely results from the fact that sites with heavy Hymenachne infestations (e.g., exceeding 70% cover) seem often associated with very low in-stream oxygenation levels. Hence, the application of sprays that create large beds of rotting matter - and consequent increases in oxygen demand - would typically make little difference to the ecological health of the system overall. Furthermore, since previous studies would suggest that allowing Hymenachne infestations to continue to grow would be likely to result in significant ecological deterioration, the use of spray control is far more desirable compared with the ‘do-nothing' approach.

Thesocio-economic results confirm that developing strategic and consistent control activities over wide areas will be very difficult because of the large variations in underlying economic and social drivers. However the analysis does identify some positive opportunities for improvement. First, there are a number of information gaps and evaluation mechanisms for both landholders and policy makers which are constraining the quality of decisions and investment being made, but these could be addressed. Second, the opportunity costs of control were generally found to be low, so targeted incentives and encouragement mechanisms have potential to improve rates of control activity. Third, participation in control activities is likely to be high where there are perceptions that control will be effective, suggesting that there is potential for a renewed focus on managing infestations in small catchments and isolated outbreaks. The use of regulatory mechanisms to ensure some minimum level of compliance may be appropriate in some situations. Together, these opportunities suggest that a more coordinated approach to weed management that addresses knowledge gaps, awareness, network mechanisms and appropriate incentives and controls is warranted.