Weeds on small farms

Weeds are just one of the many challenges that small farmers face. A weed is any plant which grows in an area where it is unwanted - weeds are often termed ‘invasive’ as they invade natural ecosystems. Weeds have varying definitions and uses on small farms, for example some farmers see any plant outside the species they have sown as a weed, while other farmers view weeds that aren’t noxious or poisonous as an important part of the farms overall biodiversity.

What is a weed?

A good example of this is barley grass (Hordeum leporinum) which is a common annual grass weed found in the drier parts of the east coast. This weed provides valuable feed for livestock through autumn and winter, however once the plant sets seed in spring it produces sharp seeds which can contaminate wool/hair and pierce skin of livestock. Another example is during periods of drought where a weed may be the only plant growing, in this case it may not be considered a weed (as long as it is not listed as noxious) as its removal will result in bare ground and a worse environmental situation.

Noxious or not

Weeds can be divided into 5 main groups:

Small farm owners should be aware that not all weeds can be managed and that by law some must be controlled, these weeds are declared noxious. The Noxious Weeds Act (1993) outlines the role of government, councils, private landholders and public authority roles in the management of noxious weeds. For a complete copy of the noxious weeds act, click here.

Each council has a list of noxious weeds, most are similar, however for those specific to your local area contact your relevant council authority. In the case of owner occupiers of private land, noxious weeds must be controlled as required under the control class or classes (section 12, Noxious Weeds Act). For a complete list of noxious weeds in NSW, including classes and required control measures click here.

Native or introduced

Not all weeds are introduced species; some serious weeds include native species like the Cootamundra wattle (A.baileyana). Introduced species however do pose the greatest threat to agriculture.

Introduced or native species can become naturalised in regions where they adapt so well to the local environment that they spread, out compete other local species and become a weed. Weeds can be divided into a number of groups including:

  • Annual and perennial grass weeds
  • Annual and perennial broadleaf weeds
  • Woody weeds

Weed attributes

Weeds have unique attributes which enable them to adapt and survive in environments where other plants will not. Some of these attributes include:

  • Prolific seeders, weeds are often annual and set huge quantities of seed.
  • High hard seed content, seeds can last for a number of years.
  • Mechanisms to travel, weed seeds often have spikes or small hairs which enable them to travel on livestock, machinery and waterways.
  • Resistances to feeding, weeds often have spikes, are unpalatable or contain toxins which deter feeding by livestock and pests.
  • Fast establishment; compete strongly with other plants during establishment.
  • Tolerance to extreme weather conditions, native plants are adapted to survive in harsh environmental conditions.

Since European settlement native vegetation has been removed and the application of fertiliser has increased, this has reduced competition from deep rooted native plants and increased nutrient levels enhancing the environment for weeds to grow. The level and type of weed infestation on any farm will be influenced by previous land management, frequency of droughts and floods, proximity of the farm to roads and stock routes and the level of native vegetation removal. 

What’s the cost?

Weeds have a significant impact on farms by increasing competition, reducing crop and pasture yields, animal production and overall farm productivity. It is estimated that weed control measures cost Australian farmers $1.5 billion dollars per year and that weeds cost $2.5 billion dollars per year in lost agricultural production. Apart from agriculture the environment is also at risk as introduced species compete with native plant species, the cost of weeds to the environment is estimated to be a similar if not higher level than agriculture1.

Is your farm at risk?

If you are considering purchasing a property you should evaluate and understand it’s current and future weed risks. Prospective property purchasers can write to their local council and request a certification on the property regarding:

  • Outstanding weed control notices on the property.
  • Outstanding fees or charges in relation to weed control notices.
  • Charges against the land resulting from previous weed control notices.

To have a farm certification conducted ranges in price from $40-$80; contact your local council for further information.

This certification does not guarantee existing or future weed situations on the farm. Therefore, it is advisable that you contact your local council weeds officer and undertake a property inspection. Local weed officers can outline your basic requirement of duty under the Noxious Weeds Act along with respond to particular problem weed concerns.  

Unfortunately you may have already purchased a farm with weeds, if so don’t panic the time to act is now. Contact your local weeds officer, carry out an inspection of the farm, correctly identify any problem weeds, write up a management plan and decide whether you can eradicate or simply control the weed.

Where to from here?

If you would like a practical guide to establishing successful weed management programs to improve the quality of your land. Develop preventative strategies and the best mix of chemical and non-chemical control options to receive a high return on your crops and pastures. Click on the image below to purchase a copy of Agguide: Managing weeds.

Agguide: Managing weeds


  • Weed: Any plant which grows in an area where it is unwanted.
  • Unpalatable: Not readily eaten or desired by livestock.
  • Eradicate: To totally remove.
  • Noxious: Weeds which have the potential to spread causing harm to individuals and the community.


1. Thorp, J.R, Wilson, M. 1996, Weeds Australia
2. Thanks to North West Weeds for some of the general information contained in this article.

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