Integrated Weed Management Reduces the Environmental Impact of Urban Amenity Weed Control

Abstract Amenity weed control remains a contentious issue, requiring a balance between maintaining plant growth below acceptable thresholds while simultaneously reducing the use of synthetic herbicides such as glyphosate. The environmental impact of three weed control methods: (1) herbicide only (glyphosate), (2) integrated weed management – IWM (maximum 50% total glyphosate active ingredient applied to (1) + mechanical and/or thermal), and (3) zero-herbicide (mechanical and/or thermal alone) were evaluated. The herbicide only method consumed the least amount of fuel, had the lowest fossil resource depletion and emitted the fewest greenhouse gases of the three methods. Aquatic ecotoxicity was potentially higher, mainly due to the secondary metabolite of glyphosate, aminomethylphosphonic acid. The weighted aquatic ecotoxicity of IWM was 28% of that of the herbicide only method. Fossil resource depletion was 24% of the zero-herbicide method but increased by a factor of 1.5 relative to the herbicide only method although the zero-herbicide method increased by a factor of 6.2 compared to the herbicide only regime. Of the zero-herbicide methods evaluated, brushing and hot foam consumed the smallest quantities of fuel. Future weed control strategies should ideally focus on combined control methods that spatially target weeds for optimum control and low environmental impact depending on location. Weed control methods for amenity and environmental impacts in urban areas as part of an IWM strategy are discussed.