Weed definitions & FAQs
Weeds are often classed in broad groups depending on their characteristics and impacts. The main groups of weeds are:
- Noxious weeds
- Environmental weeds
- Agricultural weeds
- Weeds of National Significance (WONS) and
- National Environmental Alert List Weeds.
Many weeds can be classified in more than one of these groups. For example, blackberry can be classed as a noxious weed, environmental weed and agricultural weed, depending on its situation and is also listed as one of Australia’s Weeds of National Significance (WONS).
Noxious Weeds
Some serious weeds are required by law to be controlled by all landholders in an area. These are known as noxious weeds and the law that controls these in NSW is the Noxious Weeds Act 1993.
Weeds that are declared noxious are those weeds that have potential to cause harm to the community and individuals, can be controlled by reasonable means and most importantly, have the potential to spread within an area and to other areas.
A weed is declared noxious because its control will provide a benefit to the community over and above the cost of implementing control programs.
Many ‘bad’ weeds do not meet the criteria for declaration. Noxious weeds will have limited distribution with the potential to become more widespread and will cause impact on agriculture, human health or the environment.
In New South Wales the administration of noxious weed control is the responsibility of the Minister for Primary Industries under the Noxious Weeds Act 1993. The Act is implemented and enforced by the Local Control Authority (LCA) for the area, usually local government.
The Act imposes obligations on occupiers of land to control noxious weeds declared for their area.
There are five classes of noxious weeds identified in the Act (see Table 1). All Noxious Weeds in NSW are listed in the Noxious Weeds database.
Table 1 Control classes of noxious weeds
| Control class |
Weed type |
Example control requirements |
|---|---|---|
| Class 1 |
Plants that pose a potentially serious threat to primary production or the environment and are not present in the State or are present only to a limited extent. |
The plant must be eradicated from the land and the land must be kept free of the plant. The weeds are also "notifiable" and a range of restrictions on their sale and movement exist. |
| Class 2 |
Plants that pose a potentially serious threat to primary production or the environment of a region to which the order applies and are not present in the region or are present only to a limited extent. |
The plant must be eradicated from the land and the land must be kept free of the plant. The weeds are also "notifiable" and a range of restrictions on their sale and movement exist. |
| Class 3 |
Plants that pose a potentially serious threat to primary production or the environment of a region to which the order applies, are not widely distributed in the area and are likely to spread in the area or to another area. |
The plant must be fully and continuously suppressed and destroyed.* |
| Class 4 |
Plants that pose a potentially serious threat to primary production, the environment or human health, are widely distributed in an area to which the order applies and are likely to spread in the area or to another area. |
The growth and spread of the plant must be controlled according to the measures specified in a management plan published by the local control authority.* |
| Class 5 |
Plants that are likely, by their sale or the sale of their seeds or movement within the State or an area of the State, to spread in the State or outside the State. |
There are no requirements to control existing plants of Class 5 weeds. However, the weeds are "notifiable" and a range of restrictions on their sale and movement exists. |
NOTE: All Class 1, 2 and 5 weeds are prohibited from sale in NSW.
* In some cases the following wording has also been inserted "the plant may not be sold, propagated or knowingly distributed."
Environmental weeds
Environmental weeds are plants that represent a threat to the conservation values of natural ecosystems. They invade native plant communities and out-compete them causing a reduction in plant diversity and resulting in a loss of habitat for native animals.
Some examples of environmental weeds are bridal creeper, bitou bush, boneseed, blackberry and lantana.
Environmental weeds can also be native Australian plants that are not local (indigenous) to the area they are growing in. They have the potential to displace and out-compete plants within the local plant community. Examples of native Australian plants that are doing this are sweet pittosporum and coast wattle.
Agricultural weeds
Agricultural weeds are plants that represent a threat to agricultural production. They reduce the area available for agricultural activities, interfere with agricultural practices and affect the quality of produce.
Some examples of agricultural weeds are serrated tussock, thistles, blue heliotrope, St John’s wort, Paterson’s curse and blackberry.
Weeds of National Significance
Under the National Weeds Strategy, 20 introduced plants were identified as Weeds of National Significance (WONS).
These weeds are regarded as the worst weeds in Australia because of their invasiveness, potential for spread, and economic and environmental impacts.
The weeds are:
More information: Weeds of National Significance (www.environment.gov.au)
National Environmental Alert List Weeds
Under the National Weeds Strategy, 28 environmental weeds were identified National Environmental Alert Weeds. Alert Weeds are non-native plant species that are in the early stages of establishment and have the potential to become a significant threat to biodiversity if they are not managed.
The weeds are:
More information: National Environmental Alert List (www.environment.gov.au)
FAQs
- For answers to frequently asked questions about weed management.