Weeds are one of the major threats to the natural environment, as well as to agricultural production. They are destroying native habitats, threatening native plants and animals and choking our natural systems including rivers and forests. They compete with native plants for space, nutrients and sunlight, they can change the structure and composition of our natural bushlands, and they often replace the native plants that animals use for shelter, food or nesting.

Some of the weeds species that pose a serious problem in the South West region include Paterson’s Curse, Cape Tulip, Watsonia, Bridal Creeper, Blackberry, Cottonbush, Arum Lily and African Lovegrass.

Weed control is a shared responsibility between landholders, grower groups, biosecurity groups and the Department of Agriculture and Food, Western Australia (DAFWA).

DAFWA provides many services in relation to weeds as below:

  • works with landholders, grower groups, community groups and biosecurity groups.
  • regulates weeds under the Biosecurity and Agriculture Management Act 2007.
  • provides a weed identification service.
  • provides a predictive simulation tool called weed seed wizard.
  • provides information on weed control, crop weeds, regulated/declared plants and herbicides.
  • contributes to social science through weedwatcher.

If you need advice on weeds, please see DAFWA’s website at www.agric.wa.gov.au

Weeds and Climate Change

The effect of climate change on weeds will mostly likely only see them increase. Native species stressed by climate change will become more susceptible to destruction or displacement by weeds. Transformed ecosystems composed largely of weeds and vigorous native species may result as a result of a changing climate.

AdaptNRM have developed a Technical Guide “Weeds and Climate Change: Supporting weed management adaptation” which can be accessed here. Key messages from this guide include:

  • Weeds are one of the main threats to biodiversity and agriculture but under climate change, management of this threat will be an increasing challenge in two ways:
  1. the suite of weed species will change
  2. some weeds will become more invasive.
  • The main drivers for climate change impacts on weeds include increased temperatures, changed rainfall, increased CO2 levels, more extreme weather, more frequent frosts, changed phenology and changed land use. The rate of response of invasive plants and weeds is expected to be faster than for other plants, including native species and crops. Secondly, climate change is likely to foster the appearance of a new set of weed species.
  • One of the main effects of climate change is its influence on species’ distributions. There is extensive modelling of species distributions for southern Australia, mostly indicating a southern shift.
  • A major adaptation response to climate change is increased landscape connectivity, but this presents a major opportunity for increased weed invasion. Adaptation responses include quarantine and filtering methods to monitor species displacement.
  • The national level of biosecurity threat is not expected to increase with climate change. Instead, the main threat of species migration is from neighbouring regions in Australia.
  • Novel ecosystems are already a reality in the Australian environment. The new species assemblages due to changed distributions of both alien and native species will lead to the formation of novel ecosystems. A new management approach will be needed.

The Technical Guide develops an outline of the vision, strategy and weed management plan elements that are required to address climate change adaptation. The plan is also connected to other planning approaches such as asset based and resilience thinking.

Examples are given for adaptation responses for the main weed management techniques of quarantine barriers, eradication and containment, biological control, herbicides and other control methods. Examples are also given of maladaptation, that is,management responses to climate change that may prove to be detrimental.

The Technical Guide concludes with suggestions for strategic,research and communication needs. In addition, the Guide provides an extensive list of information sources, and data repositories of supporting materials and maps of use in developing a weed management plan adapted to climate change.


  • DAFWA website – www.agric.wa.gov.au
  • Weeds and Climate change factsheet – Invasive Species Council (www.invasives.org.au)
  • Scott, J.K., Webber, B.L., Murphy, H., Ota, N., Kriticos, D.J. and Loechel, B. (2014) AdaptNRM Weeds and climate change: supporting weed management adaptation. Available at:www.AdaptNRM.org