There is no doubt that weeds can have many adverse or undesirable effects in public areas: they can cause allergies and health problems, degrade hard surfaces like roads and pavements, damage infrastructure, decrease visibility along roadsides, invade areas of native vegetation preventing natural recovery after disturbance, affect sports field usage, and decrease the perceived visual amenity of public spaces.
Local governments and other government bodies and authorities develop weed management policies. Generally these cover the legislation applicable to the state and area and often provide lists of prohibited or restricted weeds and their method of management. This has come to mean the widespread use of pesticides with glyphosate the most commonly used. Its widespread use has been based on the twin fallacies of no or low impact on mammalian health and that it will readily break down in the environment. In common with other herbicides, its Chemical Registration does not take into account the unknown toxicity of the whole product or associated components – adjuvants, and wetting agents. Policies pay insufficient attention to the effects of using these synthetic chemicals on human and environmental health.
In Australia runoff into water or release into air remains unmonitored. Throughout Europe where the harmful effects of chemical runoff into waterways has long been known, the rules governing the use of chemicals are becoming ever stricter. As the resistance of ‘super weeds’ to repeated herbicide use increases, there is increasing recognition of the part played by Councils and other authorities to the problem. These are costs which should not be passed off as negligible and should always be included in any assessment or comparison of costs of different methods.
Public authorities, such as local councils and government agencies, are required under the Pesticides Regulation (2009) to notify the community, in accordance with a notification plan, when they use or allow the use of pesticides in public places that are owned or controlled by the public authority. However, it is generally the case that no notification for pesticide use applies for what they regard as the use of small quantities of pesticides (such as glyphosate) that are widely available in retail outlets.
Many urban sites are areas of high disturbance both because of the transformation from the original vegetation and because of high usage. In developing alternative treatment methods, more variables need to be taken into account than the simplified approach of ‘weed control’ so an effective result requires good planning. The presence of weeds is not usually an isolated problem and is often a sign that broader issues need to be addressed. Land management practices and activities need to be scrutinised to determine whether they could be contributing to new weed infestations or the spread of existing ones. Planners should include the type of situation and its degree of usage by the public, particularly by children or the ill.
A strategic cultural change may be required, to educate and assist Council, Council staff and contractors towards the best means of transition to chemical free management. It is advisable to extend this education to the general public through press releases, targeted resident information, and community groups.
Urban use covers a wide range of situations with differing needs and desired outcomes. For most sites the health and safety of recreational users and the general public is of paramount importance. This makes the movement toward reduction of chemical use even more important.
Road Verges and Road Reserves: Issues include:
- that vegetation growing in the kerb and channel and open water channels does not interfere with water flow;
- that there are clear lines of sight lines to street signage, reflective marker posts and minor streetscape assets as well as at intersections and roundabouts;
- That plant roots to not cause damage to the road surfaces, kerbs and channels,
Hard Surfaces, Car Parks, Pathways, including Easements Accessible to the Public: Issues include:
- as for Road verges;
- that footpath edges are not encroaching into the path of users or causing a trip hazard.
Parks, Garden Beds, and Playgrounds: Issues include:
- Lawns are well-maintained;
- Garden beds are full of healthy, thriving plants;
- Specimen trees have protection from machinery;
- Plant selection and planting design aids weed management.
Sportsgrounds: Issues include:
- sports field turf and amenity turf are maintained to a level which is fit for purpose.
Bush and Natural Areas: Issues include:
- Enhancement of biodiversity (threatened species and communities);
- bushland areas in good condition;
- partnership with Landcare volunteers to maintain local bushland.
Drains and Constructed Wetlands: Issues include:
Planning and Management
Planning should develop a co-ordinated, strategic approach which includes:
- A risk assessment and prioritisation on the basis of weed ecology and site characteristics;
- mapping of species particularly those within a ‘major pest’ category;
- a consideration of appropriate techniques including combinations of techniques for optimal results;
- recording of weed management efforts and results as a basis for future actions;
- a timeline for monitoring of management outcomes and to detect early invasions.
Planning should also include a community awareness program and the inclusion of all stakeholders.
Kingborough Council , Tasmania, provides a list of practices that should be considered in developing a management plan for effective weed treatment.
- A planned weed control program on an annual and seasonal basis;
- Prevention and early intervention; – Including accurate and up to date weed mapping;
- Up to date records of weed control; – Including date of treatment, treatment applied, weed(s) treated and area treated;
- Eradication of isolated outliers, which arrests one of the primary mechanisms of weed expansion;
- Identification and treatment of the source of reinvasion – looking beyond boundaries;
- A commitment to follow-up treatments, including revegetation;
- Improving hygiene – cleaning weed seeds from tools, equipment, machinery, vehicles, pets, clothing and boots contributes strongly to arresting weed spread;
- Catchment management – top down approach in relation to water movement, which can facilitate dispersal of weeds;
- Focussing on completing all stages of treatment (primary through to rehabilitation) of an achievable number of tasks;
- A commitment to integrated weed management methods to reduce the control effort required – for example: – Revegetation;
- Minimising site disturbance;
- Monitoring of primary treatments and prescribed responses to ensure appropriate and timely secondary treatment; – Including scouting to help to ensure new infestations are discovered early or to identify seasonal priorities.
- Working efficiently: maximising team effort by organising labour tasks;
- Optimising utilisation of equipment – consider sharing and hiring.