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Environmental Weeds in Knox

What is an Environmental Weed?

Environmental weeds are non-indigenous (not locally native) plants that impact on indigenous vegetation by competing for space, nutrients, water, light and pollinators.

Some of the effects of environmental weeds include the following:

  • Suppress and exclude indigenous vegetation
  • Prevent regeneration of indigenous species
  • Reduce habitat and displace native fauna
  • Provide favourable conditions for introduced pest animals such as rabbits and foxes
  • Disrupt ecological and physical processes such as fire regimes, hydrology and nutrient cycles
  • Increase fire risk

Some weeds are also termed ‘noxious’. The definition of ‘noxious weed’, varies between states and territories. In Victoria, noxious weeds refer to those that are declared under legislation (Catchment and Land Protection Act, 1994) and impact on natural areas, primary production or human health.

The Sites of Biological Significance study for Knox (2010) identifies environmental weeds as the greatest threat to nature and biodiversity in Knox.


Download a sample of environment weeds found in Knox

Dispersal Methods

The majority of environmental weeds threatening our natural bushland areas have spread from residential gardens, tracks or roadsides. The ways in which environmental weeds spread into bushland include seeds moved by wind, water flow, by birds eating fruit or seed, the dumping of garden rubbish and sometimes slashing or mowing. Once established, they grow vigorously because they have few natural competitors or diseases to control them and subsequently, impact on native vegetation and wildlife habitat.

Methods of Removal


Suitable for small infestations, in areas where other techniques may cause disturbance. Manual removal includes hand pulling, digging using shovels, rakes, chisels, knives, forks or mattocks.

Disadvantages include excessive soil disturbance, spread of seeds, fruits and plant material.

Slashing and mowing

Slashing and mowing can be an effective method of limiting the spread of some invasive species. Equipment used includes mowers, brush cutters and tractor-mounted slashers, depending on the area to be treated. However, these methods can also spread seeds, bulbs and ripe fruits. It is important to treat areas before fruit or seed develop.


Suitable for trees and large shrubs that do not sucker or re-shoot when damaged. Use an axe to cut away the bark and sapwood in a 5-10cm wide band below any branches around the lower trunk. Make sure that the cuts penetrate into the heartwood of the plant.

Herbicide use

  • Cut and paint - Suitable for climbers, creepers, shrubs and trees. Use a handsaw, chainsaw or secateurs to cut the plant as close and level to the ground so the herbicide will not run off. Apply concentrate herbicide to the outer rim of the stump within 30 seconds.
  • Drill and fill - Suitable for shrubs and trees. Drill a 5cm deep hole at a 45° angle into the sapwood as close as possible to the base and below any branches.
  • Inject herbicide into the hole. Repeat around the base of the plant with holes placed at 3-5cm.
  • Frilling - Suitable for larger shrubs and trees. Use a sharp knife or chisel to frill away the bark below any branches to expose the sapwood, no higher than half a metre from the base. Apply herbicide within 30 seconds. Repeat around the base 5-10cm apart.
  • Stem-scrape - Suitable for vine species. Use a sharp knife to scrape back the bark 10-20cm and apply herbicide within 30 seconds using a paintbrush or dabber bottle.
  • Spraying - Suitable for herbaceous and grass weeds. Labelled instructions and herbicide rates should be adhered to. Care is required for herbicide use within areas containing non-target plants.


  • Surfactants are used to aid the uptake of herbicide on target plants, particularly those with waxy leaves. Adding a household detergent to the herbicide mix will assist the herbicide to adhere to foliage and penetrate the leaf surface.


Cover area of weeds on the ground with a thick cover of material that is difficult to penetrate, e.g. mulch, or wet cardboard or newspaper with a layer of mulch on top.


It is important to dispose of the various parts of weeds safely and in a way that limits further spread. Seed free foliage can be safely composted. Seed-heads, stem portions, bulbs and plants with persistent root systems should not be placed in the green waste bin to avoid spread through unscreened mulch.

Replanting after Weed Removal

An important part of managing environmental weeds is to replace them with plants which do not pose a problem. By choosing indigenous plant species grown from seed collected within the region (local provenance), residents can create a habitat for local animals and birds, and contribute to our local landscape. The ‘Gardening with indigenous plants in Knox’ brochure provides some locally native plant options. A more extensive list of local native plants is available on Council’s website under Indigenous Plants in Knox

Gardens for Wildlife Program

Watching birds and animals interact in your newly established garden adds a special dimension to the garden. Just by planting local species, you will attract local fauna.

To find out more about the Gardens for Wildlife Program, visit or contact Knox City Council on 9298 8000.

Knox Environment Society (KES) Community Nursery

KES is located next to the Ferntree Gully Library on Burwood Highway between Glenfern Road and Brenock Park Drive, Ferntree Gully (Melway ref: 74 A5). The nursery is open Thursdays, Saturdays and Sundays, visit the KES website for specific opening hours.

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