Trade off between costs and environmental effects of weed control on pavements

An actor-participative project on sustainable weed control on pavements was started in 2000 in the Netherlands. The aim of the project was to develop a new concept of weed management that provides cost-effective and environmentally sound weed control. Early in 2002, practical guidelines were drawn up in support of decision making by managers of pavements, and weed control contractors. The guidelines are focused mainly on reduction of herbicide use and emission thereof. The new concept was tested in 2002 and 2003 in nine Dutch municipalities on defined urban areas of 5–25 ha, which formed units from a construction, hydrology and management point of view. Use of herbicides (mainly glyphosate) was reduced by 11–66% compared to standard practice. Levels of weed control remained good and ecological threshold concentrations in surface waters were not exceeded. Monitoring showed a glyphosate emission factor via the sewage water system of 2% on average. Costs of weed control with the new concept were higher (10–25%) compared to the standard practice control of weeds (using herbicides) on pavements, but much lower compared to alternative (non-herbicide) weed control systems. It is concluded that the new concept provides a useful framework for finding a good trade off between economical and ecological aspects of weed control on pavements.