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Types of Noxious Weeds Found in NSW and How to Deal with Them

You may find it odd to see plants in your garden that aren’t supposed to be there. Weeds are plants that grow arbitrarily. They aren’t planted nor wanted in any land because they multiply uncontrollably and compete with other plants for water and nutrients. 

The NSW council frowns upon noxious weeds, in particular, because of their invasiveness and ability to spread fast. These plants pose a threat to the economy, community, and the environment. As a result, it is imperative to control these noxious plants throughout NSW before they become unmanageable and disastrous.

Types of Noxious Weeds in NSW

The local council and agricultural experts consider a lot of weeds noxious in NSW. The Minister for Primary Industries regarded these plants as such because they are harmful to agriculture and plants, ecosystems, animals, and humans. Below are the types of noxious weeds based on their class.

Class 1 (State Prohibited Weeds) 

The entire state orders the eradication of noxious weeds that fall under this class and keeping of the state free of the plant. It is essential to notify the local council if ever you spot class 1 noxious weeds so that they can perform measures to control the said weeds.

Some examples of class 1 noxious weeds found in NSW include:

  • Horsetail (Equisetum spp.)
  • Parthenium weed (Parthenium hysterophorus)
  • Siam weed (Chromolaena odorata)

Class 2 (Regionally Prohibited Weeds) 

The parts of the state that prohibits class 2 noxious weeds must eradicate and keep the region free of the plant. Like in Class 1, you should also notify the local council for any discovery of class 2 weeds so that they can regulate them. Some examples of class 2 noxious weeds found in NSW include:

  • Water hyacinth (Eichhornia crassipes)
  • Salvinia (Salvinia molesta)
  • Kudzu (Pueraria lobata)

Class 3 (Regionally Controlled Weeds)

The region should fully and continuously suppress and destroy class 3 noxious weeds to reduce and confine the negative impacts of the infestation. Some examples of class 3 noxious weeds found in NSW include:

  • Alligator weed (Alternanthera philoxeroides)
  • Boneseed (Chrysanthemoides monilifera)
  • Green cestrum (Chromolaena odorata)
  • Pampas grass (Cortaderia species)

Class 4 (Locally Controlled Weeds)

The local community must control the growth of these noxious weeds to reduce their numbers, spread, and incidence and to inhibit their proliferation continuously. The locality should also aim to minimise the negative impacts of class 4 weeds on agriculture, community, and environment. Some examples of class 4 noxious weeds found in NSW are:

  • Blackberry (Rubus fruticosus agg. species)
  • Lantana (Lantana camara)
  • Serrated tussock (Nassella trichotoma)
  • Rhus tree (Toxicodendron succedaneum)

Class 5 (Restricted Plants)

NSW restricts weeds that haven’t been established in the state yet or only have rare occurrences. The state also prohibits selling weeds that were initially garden or aquarium plants but have the potential to become noxious weeds. The MPI created this class to prevent the introduction and spread of these potential weeds throughout NSW. Examples of class 5 noxious weeds are:

  • Dodder (Cuscuta spp)
  • Artichoke thistle (Cynara cardunculus)
  • Fountain grass (Pennisetum setaceum)

How to Deal with Noxious Weeds. 

Since weeds can grow anywhere, it wouldn’t be surprising to find some in your garden. When these unwanted plants appear in your garden, you need to take measures to control their growth and proliferation immediately. Some ways on how you can deal with them are listed below.

Prevent weed growth

Preventing noxious weeds from growing in your yard is more straightforward and cost-effective than getting rid of existing ones. While it is impossible for you to avoid undesirable plants, you can still use weed killers to intervene during their early stages of development. Applying selective weed killers can hinder the growth and spread of noxious weeds while keeping the desirable plants safe. 

Cover soil with mulch

Mulching is an effective way to inhibit weed growth. Covering the ground with mulch hinders the seeds of noxious weeds from germinating due to lack of sunlight. It also helps nurture the significant plants since mulch allows moisture and nutrient retention as well as temperature moderation. 

Take the weeds out

The best way to get rid of noxious weeds is to pull them out manually. The trick is to pull the entire plant to take out the root so that the weed stops regrowing. You can ensure that you’ve included the roots by pulling from the base and digging the soil using a spade or fork. Watering the soil is also a good idea so that you can easily slip the weeds out. 

Cultivate high-quality plants

High-quality, desirable plants and weed-free crops can outcompete noxious weeds. These plants can hoard all the nutrients, water, and sunlight that the weeds also need, thereby preventing the unwanted plant from flourishing. 

Apply herbicides 

Chemical application of herbicides is a surefire way to kill existing noxious weeds in your yard. It is also an excellent treatment for your garden soil when you remove your old lawn. Just make sure that you read and follow the directions so that you can safely apply the chemical.


Noxious weeds are undesirable plants in your garden because they endanger other plants, animals, and people. Thus, you should remove them immediately if you notice any seed or sprout in your yard so that they don’t thrive. That is, however, an exhausting task. You may also find it frustrating to stop and limit the proliferation of weeds in your garden. More so when you notice your precious plants and lawn die of weed infestation. 

Trees Down Under can help you deal with weed problems in your garden. Throughout our more than 30 years of service in the Sydney area, we have remained to be your number one partner in garden and tree removal services. Our expert gardeners and plant experts have the right tools and expertise to ensure that your yard is free from any noxious weeds. Contact us now at 0475 463 597 to get a free quote.

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