Noxious Weeds

Weeds are defined as plants that ‘don’t belong’. They can be plants from overseas or other parts of Australia that have been planted in the wrong place or escaped into bushland.

• Noxious Weeds (as defined by the Noxious Weed Act, 1993)
• Environmental Weeds as listed by Warringah Council
• Controling weeds

Noxious and environmental weeds threaten the biodiversity in the natural environment, impair ecological processes and impact visitor enjoyment of bushland areas. Some weeds cause severe land degradation while others produce vast quantities of seed, resulting in their out-competing or smothering native plants.

Weeds tend to penetrate bushland reserves along tracks, waterways, the urban fringe, and areas that have been disturbed. They are also spread by fire and birds and animals that eat weed seed. Weeds grow throughout the Warringah Local Government Area (LGA) on private properties and land managed by government authorities and agencies.

Noxious Weeds

Weeds are declared noxious if they cause a problem to human health, the environment, livestock or the agricultural industry. Noxious weeds legally must be controlled or removed. Warringah Council has a number of plants listed as noxious weeds under the Noxious Weeds Act 1993. A current list of species declared noxious in Warringah and their removal techniques can be found by clicking on the pictures below.

Trees and Shrubs

Privet	Green Cestrum	Lantana
Bitou Bush/Boneseed	Castor Oil Plant	Pampas Grass
Rhizomatous Bamboo	Rhus Tree	Ludwigia

         

Climbers and Scramblers

Turkey Rhubarb	Climbing Asparagus	Balloon Vine
Morning Glory	Blackberry	Cape Ivy
Cats Claw Creeper	Madeira Vine

Ground Covers

Asparagus Fern

Asthma Weed/ Pellitory

For a more comprehensive list of Warringah’s Noxious Weeds click on the link.

Warringah Council is a member of the Northern Sydney Noxious Weeds Committee. This committee assists Councils to work together in targeting noxious weeds that are particularly problematic to residents and the local environment. Warringah Council supports nationwide weed education programs such as Weedbuster Week.

 

Environmental Weeds

In the Northern Sydney region, the waterways and natural bushland are under threat due to the invasion of environmental weeds. These ‘introduced’ plants have few predators and usually produce large quantities of seed and can out-compete or smother native plants. This makes them vigorous invaders, especially in areas that have been disturbed and where soil nutrient levels are high, such as from stormwater pollution.

Environmental weeds usually begin life in someone’s backyard, and once these weeds take over an area, the character of the bushland changes, reducing habitat for native wildlife and altering fire regimes.

Crofton Weed	Moth Vine	Impatiens
Camphor Laurel	Cotoneaster	Fishbone Fern
Watsonia	Japanese Honeysuckle	Mother of Millions
Agapanthus	Fleabane	Formosan Lily
Ginger Lily	Mist Flower	Montbretia
Golden Wreath Wattle	Ochna

For a more comprehensive list of Warringah’s environmental weeds click on the link.

 

Controlling Weeds

Warringah Council has a comprehensive weed control program that involves private property weed assessment and public education. Through this program we aim to:

• Increase public awareness of weeds and their impact on the environment

• Reduce weeds on private and public land, particularly around bushland and coastal environments

• Provide detailed information about the extent of specific weeds in Warringah

Control Techniques

There are two ways to control weeds: physical removal and chemical removal.

As a general rule any weed should be controlled prior to flowering for effective results.

Any part of the plant capable of reproducing (ie tubers, rhizomes, seeds, berries or other propagules or the entire plant) should be placed in a suitable bag and removed off site. Other debris material can be mulched on site.

Physical Removal

When physically removing weeds the whole plant must be removed including stems, roots, bulbs and rhizomes to avoid regrowth. Most small weeds can be pulled out by hand or with the use of a mattock. When removing large plants from steep sloped or along waterways, it may be necessary to leave some rootstock to prevent erosion.

 

Hand Pull / Dig

Plants should be small enough to ensure the entire root is removed and should not be able to resprout from any remaining root system.

Tools: Gloves, knife, hand trowel or similar

Procedure: Rake back ground mulch. Insert knife or similar tool and loosen the soil around the plant roots. Keep soil disturbance to a minimum.

Grasp the stems or leaves of the plant at ground level and pull while freeing the roots with the knife. Remove the plant and shake off excess soil. Replace disturbed soil and any ground mulch.

 

Crown Cut

The underground meristematic (growing heart) part of the plant only needs to be removed, or above ground in the case of palm species. The plant should not be able to resprout from the remaining root system

Tools: Gloves, knife

Procedure: Rake back ground mulch. Grasp the plant at ground level gathering the stems or leaves together.

Insert a knife so as to cut the root system below the crown or underground stems. Remove the plant while cutting the lateral roots. Ensure the knife is used for cutting rather than levering. Replace the disturbed soil and ground mulch.

 

Rhizome / Tuber Trace

The plant has a root system of underground rhizomes, tubers or similar organs from which new plants can reproduce.

Tools: Gloves, knife, hand trowel or similar

Procedure: Rake back ground mulch. Grasp the plant at ground level gathering the stems or leaves together.
Insert a knife so as to cut the root system below the crown or underground stems. At ground level and using the appropriate tool, clear the soil from around the immediate root zone of the first rhizome or tuber. Trace the underground lateral stems / roots and remove any secondary rhizomes or tubers. Remove the roots, rhizomes, tubers and any attached soil. Replace the disturbed soil and ground mulch.

 

Chemical Removal

The use of herbicide is only recommended if physical removal is not possible. Always follow instructions outlined on the label for any herbicide use. Use reliable equipment, avoid direct contact with the chemical and wear protective clothing.

Herbicide such as glyphosate can be used on most weeds to assist with control. This chemical is marketed as Roundup, Zero or Glyphosate 360. Be aware that glyphosate will kill any plant if it comes into contact with the leaves or green stems.

 

Woody Weeds

The most effective way to use herbicide on woody weeds is the “cut and paint” method. This involves cutting the stem of the plant at a slight angle close to ground level and immediately applying herbicide to the freshly cut stem. Do not take any further action or disturb the plant until it is completely dead.

 

Vines

The most effective way to use herbicide on vines is to gentle scrape 15-30cm of one side of the stem and expose the moist layer below the bark. Apply herbicide immediately to the exposed area.

 

 

Herbaceous Weeds

Apply diluted herbicide to leaves with a weed wand or by spot spraying. If spraying, choose a warm day when the air is still and never spray near waterways.

Disposal and Follow-Up Weeding

When removing weeds, it is important to follow up the initial removal with further action to control regrowth and avoid re-seeding.

Weeds that are succulent, or that have large tubers, corms or bulbs, should be disposed of in domestic green waste bins or in Council vegetation clean-ups.  Other weed material that does not contain seeds or reproductive material can be used for composting.

Source: Information and images reproduced with the kind permission of the Sydney Weeds Committee.

More Information

• For more information on weed control programs and weed removal techniques, particularly in regard to the use of herbicide, call 9942 2111.
• If a weed that requires removing is a tree, call Council's Tree Management Officer on 9942 2111.