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Impacts of weeds

  • Degrade the natural values of an area
  • Displace native flora and fauna species
  • Threaten agricultural productivity
  • Decrease visual appeal of landscaped areas and paths
  • Degrade lawn quality
  • Pose a health and safety risk to humans, livestock and other animals
  • Generate an increased fire risk to vegetation and property

The control of weeds requires a lot of time, energy and money. By managing and containing the spread of existing weeds and preventing new weeds from establishing, together we can reduce the future costs of weed management.

How weeds are spread

Weeds are spread to new areas via a wide range of activities including:

  • Poor vehicle and machinery hygiene e.g. slashers and mowers
  • The dumping of garden waste
  • The planting of invasive ornamental garden plants
  • The movement of animals, vehicles and people through weed infested areas
  • The movement of soil through civil construction works
  • Birds eating fruit and depositing seeds in their droppings
  • Wind carrying air-borne or tumbleweed seed
  • Through the movement of water

Land owners and land managers are responsible for managing declared weeds on their property under the Weed Management Act 1999.

Declared weeds are weeds that have been listed under the Weed Management Act 1999 and have a legal status that requires land owners and land managers to contain and control, or eradicate them according to the statutory management plan for that particular species.

A list of declared weeds for Tasmania can be found on the Tasmanian Government Department of Primary Industries, Parks, Water and Environment website and declared weeds and prioritisation within Clarence specifically can be found in appendix 4 on pages 58-60 of the Clarence Weed Strategy 2016-2030.

Environmental weeds are weeds that are not declared under the Weed Management Act 1999 but are still a threat to natural values, and in particular natural bushland areas.

In the Clarence Weed Strategy 2016-2030 environmental weeds that threaten the natural values of Clarence are listed as the Clarence Local List (CLL). CLL species can be found in appendix 3 on pages 56 and 57 of the Clarence Weed Strategy 2016-2030.

Identifying weeds

Natural Resource Management South’s A Guide to Environmental and Agricultural Weeds of Southern Tasmania is a good guide to many of the weeds you might find on your property and garden within the Clarence municipality.

Hard copy versions can be obtained from the Council Offices or posted out to interested landholders as requested to assist in weed identification.

Alternatively, the Tasmanian Government Department of Primary Industries, Parks, Water and Environment have a weeds index of both declared and environmental weeds with information to assist in identification.

Weed management prioritisation on council managed land

Council manages and prioritises weeds across its bushland reserves, parks, public open spaces and road reserves within the Clarence municipality in accordance with the Clarence Weed Strategy 2016-2030 and requirements of the Weed Management Act 1999.

Declared weeds are given a priority rating based on their occurrence and distribution within the municipality, and whether management is aimed at control and containment, or eradication.

Environmental weeds from the Clarence Local List (CLL) are prioritised based on the context where they occur and their potential to impact on the natural, social and economic values of the area. Council also works in conjunction with other land management agencies and private land owners in managing priority weeds across the landscape.

Weed maintenance on your property

Important principles to follow for weed maintenance on your property:

  • Minimise soil and ground disturbance: Not all weed seed will germinate, but expose it to near the soil surface with access to light, warmth, water and without competition then you will get mass germination of weeds;
  • Minimise the introduction of new weeds to your property: Only use clean and reliable sources of soil, sand, fill and mulch; and practice good hygiene ensuring garden machinery (lawnmowers and brush cutters) are cleaned if used at another property, and boots, clothes and animals are free of weed seeds after visiting properties with known weeds; and
  • Integrated weed management: Use a variety of control methods that target various stages of the weeds life cycle and prevent weeds from establishing, flowering, seeding and regenerating a new generation of weeds.

Integrated weed management maintenance methods

  • Manual removal: Hand weeding or chipping out weeds as they are found is one of the most effective forms of control especially in sensitive areas and areas where herbicides shouldn’t be used – removing little but often is better than clearing large areas irregularly
  • Mulching and weed matting: Use mulches or woven weed matting to cover bare areas in garden beds and landscaped areas in order to smother and shade out future weed growth. Ensure weeds are removed or killed prior to laying mulch or weed mat. Lay mulch at least 5cm deep to prevent weeds from growing through easily. Don’t lay black plastic as a weed mat as it prevents infiltration of rainfall into the soil.
  • Competition: Establish lawn, pasture or native groundcovers to remove bare areas from your property that weeds love to exploit.
  • Topping (removing seed heads before they seed): Don’t allow weeds to go to seed. Some weeds are short-lived annuals and go to seed rapidly. By removing seed heads you prevent them from seeding and they will die shortly after.
  • Early detection and removal: Many weeds by nature are incredibly fast-growing and produce vast amounts of seed rapidly so early detection is important. Some weeds will blow in – e.g dandelion and some thistles – meaning you will get them regardless of controls mentioned above but usually only in disturbed sites. Detect these early when they are only broadleaf flat weeds or ‘rosettes’ and remove by digging out.
  • Non-chemical methods (heat, steam and solarisation): There are a range of commercial weed killing products such as steam weeders and flame weeders that can be purchased for non-chemical control of garden weeds, as well as homemade solutions such as solarising ‘cooking’ weeds under sheets of black plastic.
  • Herbicides: Herbicides are substances that are toxic to plants and are designed to kill undesirable plants – they can be derived organically or synthetically; can be selective (target groups of plants) or non-selective (kills everything); and can be residual (long-lasting) or non-residual. The weeds you target, timing of year and surrounding environment are all factors that will influence which type of herbicide you choose to use.
  • Organic herbicides: Non-selective knockdown control which can be oil-based such as pine oil e.g. Weed Blitz ® or plant acid based e.g. Slasher ® with the active ingredient pelargonic acid.
  • Synthetic herbicides: Can be selective – e.g. broad-leaf specific for lawn and turf situations; or non-selective – e.g. glyphosate for fast knockdown of all garden weeds. Synthetic herbicide control should only be used as the last line of defence and shouldn’t be used in parts of your garden where fruit and vegetables are grown or where children and pets play.

If you decide to use herbicides (organic and synthetic) then it is essential that you follow the label directions and use the recommended personal protective equipment when mixing and applying the herbicide. Even organic herbicides require safety precautions when mixing and applying.

General garden weed waste should be disposed of in the green waste bins and not dumped over back fences or on roadsides

Declared weed material should be double-bagged and disposed of at an approved waste management facility. Declared weed material should never be disposed of in green waste bins.