Weed management: preventive and curative methods to optimize street scene conditions

Sustainable weed management on pavements remains a challenge to many cities and municipalities in Flanders. To protect surface water, there has been a legal ban on the use of herbicides in public spaces in Flanders since 1st January 2004. The transition period in which this zero use requirement can be waived subject to motivation expires in 2015. In the Brussels Capital Region and in Wallonia the legislation follows a similar trend or at least is preparing to adopt a similar view. However, knowledge on the effectiveness, the ideal scenarios for application and the environmental impact of non-chemical weed control techniques is still limited. Moreover, adequate design and proper construction of the pavement can help to prevent weed growth, but clear directives and recommendations are still missing in this respect.

That is why BRRC, with support from the Flemish Agency for Innovation by Science and Technology (IWT) and in cooperation with the Plant Production Department of the Ghent University, started a four-year research project on “optimum” weed control on pavements (VIS-CO project 070670) in August 2008. The object was to take stock of the available preventive (design, type of pavement, joint seals, etc.) and non-chemical curative methods (sweeping, brushing, burning, treatment with hot air, with hot water, etc.) and to evaluate them for effectiveness, cost, and environmental impact.

Relevant knowledge was gained in four areas: inventory of weed flora depending on the environment and the application, effectiveness of weed-repellent joint seals and paving materials, effectiveness of curative weed control techniques and, finally, eco-efficiency and cost analysis. This approach made it possible to map out both the preventive and curative aspects of weed management on pavements.

The results from this research project have led to practical recommendations for ecologically and economically sustainable weed management to optimize street scene conditions, which have been bundled in a new code of good practice published by BRRC (R84/12, for non-chemical weed control and management on pavements in small modular elements).

With this reference work BRRC intends to assist field actors (designers, public and private road managers, paving block manufacturers, suppliers, contractors, and even ordinary citizens) in making the right choices to arrive at a sustainable, integrated and non-chemical weed management system. In addition, a handy appendix synthetically and schematically represents the process of weed control on pavements. It also contains a decision tree developed for that purpose, as a practical decision support tool for field operators.

For more information, see the code of good practice R84/12 and Dossier 10 Gestion préventive des mauvaises herbes sur les revêtements (annexe au Bulletin CRR n° 86).

Of course, the BRRC staff involved remains at your personal service for additional guidance and assistance in the field of non-chemical weed management on pavements.