You may have noticed the problems that the present ‘War on Weeds’ has encouraged: soil microbiomes and waterways poisoned, replacement by other weeds, erosion, faunal habitat and their food supplies destroyed, etc. We often are unaware of the impact of our methods and have even been encouraged in Landcare to use pesticides when we understand little about their effects. We need to get toxic chemicals out of public spaces and develop our restoration programs on the basis of a much broader knowledge to ensure no additional damage.
While what we call pests includes a wide range of organisms – insects (like ants and termites), animals (like rats and mice), fungi, viruses and bacteria, weeds – here we focus on plants.
Options for control include cultural and physical control, biological control, plant choice (matching species to the site), and chemical control. While many government departments and authorities advocate IPM it is still often a long jump between the theory of reducing pesticide use and the practice – in both our public spaces and conservation areas, we often see ‘business as usual’ cloaked in new words.
So what strategies do we need to think about before starting to ensure reduction or removal of dangerous chemicals?
Firstly, what is the overall weed management aim? This will differ depending on whether your purpose is for ecological, urban, or agricultural weed control. We will deal with only the first two. There is plenty of excellent information available on weed control in organic agriculture. In the natural environment we intend to move towards a functioning sustainable ecosystem; in urban environments, we are maintaining a disturbed environment.
Some overall guidelines:
- Consider the environment as a whole – micro-organisms, invertebrates, birds and mammals, orchids, fungi, grasses etc. Soil health is of primary importance;
- Avoid the urge to rush into a “crisis” situation, and instead, take time to plan;
- Identify the threatening pressures (they may not only be the weeds);
- Do not plant exotic species which are difficult to control. If a plant moves, don’t plant it (seed dispersal, runners). (We need to prohibit the trade of such species);
- Reduce weed control for ‘cosmetic’ purposes, i.e. those which aim to ‘improve the appearance of’ or keep neat non-agricultural green spaces;
- Determine whether control methods are contributing to new weed infestations or the spread of existing ones;
- Have appropriate timing of follow-up control. In some cases, repetitious seasonal programs may be necessary, in others weed management reduction may be possible through a longer term view of site rehabilitation.