Managing weeds manually can be extremely specific, you don’t need to worry about herbicide drift hitting your desirable plants, or damage to soils or animals as with chemical weed sprays. Plants are usually completely dead and not standing to impede further work.
Remember, there are some underlining principles which we should aim for:
- Healthy plant stands are the best means of eradicating weeds – encourage healthy soil conditions
- Know your weeds and their control methods, otherwise things could get worse!
- In general, work from good areas to bad ones
- Work from upstream to downstream (to prevent seeds being washed down to newly cleared areas!)
- If the infestation is too big to eradicate, remove flowers and seeds to stop it from spreading
- If the weeds include wildlife foods and habitats, remove them gradually to allow the development of alternatives.
- Address any nutrient issues – enriched soils promote weed growth
- Consider runoff scenarios and take appropriate measures to address them.
The choice of weeding method and of implement depends in part on management goals or conservation targets at each type of site. Chapter 8 of the West Australia Coastal Planning and Management Manual has an excellent section on weeds and weed management.
Sometimes it is not so much a matter of removing weeds but of developing alternative management to avoid weed growth. Sometimes it is a matter of addressing our desire for cosmetic parks. We do not advise removing annuals or biennials in bush regeneration since they function to protect the soil and feed soil microbiology.
In a paper delivered to the National Conference on Urban Water Management in 2014 Jeremy Winer of Weedtechnics outlines holistic management for urban storm water catchments. He developed a matrix of techniques generally used against such factors as type and frequency of application, surface types, location, human or environmental harm, efficacy, and economic efficiency. The economic elements like purchase price, operating costs and labour requirements should always take into account human and environmental health including long-term chronic effects as well as short-term toxic ones.
Highly recommended reading:
- Bradley, Joan, 1988. Bringing Back the Bush. Reed New Holland, Currently out of stock but likely to be available in libraries. The Bradley sisters were the first to research manual methods for control of environmental weeds. They also set out principles which included: 1) Work outwards from good bush areas towards areas of weed; 2) Make minimal disturbance to the environment: and 3) Do not over clear. In general, these principles still hold.
- Marshall, Tim, 2010. Weed. ABC Books, Sydney, Australia. Tim Marshall has been a leader in the organic movement for some decades. Armed with this experience, his book is packed with information about weeds we are likely to meet and their control. There is a section on environmental weeds including how to deal with some which are listed as Weeds of National Significance.
- Wolff, A., 2012. The Weed Book. New Holland Publishers (Aust.) P/L, Sydney, Australia. This also includes extensive information on the biology of common weeds and a well-illustrated step-by-step guide to their manual removal. This book also has a section on ‘Using Herbicides’ for weeds he considers difficult although he does stress that ‘All herbicides must be used with great care and be considered to be potentially hazardous substances, and as such require careful handling.’
- French, Jackie, 1989. Organic Control of Common Weeds. Aird Books P/L, Flemington, Victoria. This is oriented more to gardening and farming but contains great information on many weeds and their management.
- Romanowski, Nick, 2011. Wetland Weeds: Causes, Cures and Compromises. CSIRO Publishing, Collingwood, Victoria. Excellent cover of wetland weeds and their control.
“The author takes a pragmatic approach to weed control, recognising that some weeds may not be possible to eradicate, and emphasising the need to assess the extent and future potential of any infestation before taking action…. A range of strategies for controlling wetland weeds are considered, from containment actions to prevent the development of a soil seed bank to physical removal, and biological approaches from biocontrol to shading, overplanting and use of turbidity. The widespread use of chemical controls is also discussed, with the warning that these are often only a short-term cure and can cause more harm to aquatic ecosystems than the weeds they are holding at bay.” CSIRO review.