Prioritising weed mapping & control, and preventing new problem weeds

Weeds are a major problem across the ACT and Southern Tablelands and we must prioritise how we manage different species to make the best use of available resources.

Figure 1. Weed Invasion Stages and Management Objectives shows the effort required to control weeds at the different stages of invasion. It is also shows why different approaches are needed to deal with the distribution and abundance of different weeds. As the area a weed occupies increases it becomes less likely that eradication is possible, and strategies need to move to containments and then protection of high value rural and environmental lands.

Figure 1. Weed Invasion Stages and Management Objectives

Priority 1: Prevention
Prevent any potential new species entering our region, and if they do appear in our region, eradicate them quickly - before they spread. When a new weed species first appears in an area, eradication is still possible because:
  • the area it occupies is very small;
  • the cost of eradicating it is very low; and
  • the return on investment is very high - for each $1 spent there is a $100 return on investment.*
Priority 2: Eradication
New weed species that have become established in a small number of localised population in our region, also need to be eradicated. This is achievable because:
  • the areas occupied by the weed is still quite small and contained;
  • the cost of treating the weed is still quite low; and
  • the return on investment is still quite high - for each $1 spent there is a $25 return on investment.

Priority 3: Containment
Weed species that have spread rapidly and have many populations that cover large areas and are becoming problem weeds that need to be contained. This category also includes sleeper weeds which have become established in the region and, whilst they are not currently spreading significantly, have the potential to do so. The priority is to stop the spread of these species into new areas. In these circumstances, complete eradication is unlikely, but containing the spread of these species is achievable. The return on investment means that for every $1 there is a $5 - $10 return on investment.
Priority 4: Asset based protection
Weed species that have become widespread and abundant across their range, such as serrated tussock or blackberry, should be managed as resources allow, with an emphasis on long-term management, ongoing suppression and protection of priority agricultural and environmental sites. Asset based protection has the lowest return on investment, but is also a significant and necessary tool in weed control. For every $1 spent on weed control, $1 - $5 is returned on investment.

All priority approaches have a role to play in weed management. It may be that all four priority approaches are applied to different weed species on the same area of land - whether it is a farm, a national park or another significant area of land.

* Return on investment - this refers to the present and future costs of controlling a weed. It costs far less to stop invasive plants from arriving than it does to remove them once they have established.

The weed lists provided in this portal (see the Weeds to watch for) have been grouped to encourage weedspotters to concentrate on identifying and reporting New weeds and Emerging weeds. More dedicated Weedspotters may like to familiarise themselves with the many Potential weeds that are not currently known to occur in this region, but may move into this region in the future.

Many species are also declared pest plants in the ACT under the ACT Pest Plants and Animals Act 2005 or noxious under the NSW Noxious Weeds Act 1993 and must be legally controlled as specified for each local area.