And then there are the health costs. Weeds cause health problems for both humans and livestock. Parthenium, for example, can cause severe allergies, asthma and dermatitis. If you live close to State forest or bushland, be careful when buying plants. Seek advice on what species are problems in your area.
Different plants are problems in different areas.
Better still, join Weedbusters in October. Organisations involved in Weedbuster Week include Landcare, the Scout Association of Australia, Greening Australia, Weed Societies in each state and primary industries organisations. Weedbuster activities include field days, displays and weedclearing. Bushland regeneration dreaming. The Bush Next Door.