Jordan, N., Agronomy and Plant Genetics Department, University of Minnesota, St. Paul, MN, United States
Schut, M., Knowledge Technology and Innovation, Wageningen University, Wageningen, Netherlands, International Institute of Tropical Agriculture (IITA), Kigali, Rwanda
Graham, S., School of Social Sciences, The University of New South Wales, Sydney, NSW, Australia
Barney, J.N., Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA, United States
Childs, D.Z., Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
Christensen, S., Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
Cousens, R.D., School of BioSciences, The University of Melbourne, Melbourne, VIC, Australia
Davis, A.S., Global Change and Photosynthesis Research Unit, USDA ARS, Urbana, IL, United States
Eizenberg, H., Department of Plant Pathology and Weed Research, Agricultural Research Organization (ARO), Newe Ya'ar Research Center, Ramat Yishay, Israel
Ervin, D.E., Institute for Sustainable Solutions, Portland State University, Portland, OR, United States
Fernandez-Quintanilla, C., CSIC-Institute of Agricultural Science, Madrid, Spain
Harrison, L.J., Environment Department, University of York, York, United Kingdom
Harsch, M.A., Department of Biology, University of Washington, Seattle, WA, United States
Heijting, S., Agrosystems Research, Wageningen University and Research Centre, Wageningen, Netherlands
Liebman, M., Department of Agronomy, Iowa State University, Ames, IA, United States
Loddo, D., Institute of Agro-environmental and Forest Biology, National Research Council, Legnaro, Italy
Mirsky, S.B., Sustainable Agricultural Systems Laboratory, USDA-ARS, Beltsville, MD, United States
Riemens, M., Wageningen University and Research Centre – Applied Plant Research, Lelystad, Netherlands
Neve, P., Agroecology, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
Peltzer, D.A., Landcare Research – Ecosystems and Global Change, Lincoln, New Zealand
Renton, M., School of Plant Biology, University of Western Australia, Crawley, WA, Australia
Williams, M., Michael Williams & Associates Pty Ltd, Sydney, NSW, Australia
Recasens, J., Department of Horticulture, Botany and Landscaping, ETSEA, Universitat de Lleida – Agrotecnio, Lleida, Spain
Sønderskov, M., Agroecology, Aarhus University, Slagelse, Denmark
Schutte, B., Las Cruces, NM, United States

Transdisciplinary weed research (TWR) is a promising path to more effective management of challenging weed problems. We define TWR as an integrated process of inquiry and action that addresses complex weed problems in the context of broader efforts to improve economic, environmental and social aspects of ecosystem sustainability. TWR seeks to integrate scholarly and practical knowledge across many stakeholder groups (e.g. scientists, private sector, farmers and extension officers) and levels (e.g. local, regional and landscape). Furthermore, TWR features democratic and iterative processes of decision-making and collective action that aims to align the interests, viewpoints and agendas of a wide range of stakeholders. The fundamental rationale for TWR is that many challenging weed problems (e.g. herbicide resistance or extensive plant invasions in natural areas) are better addressed systemically, as a part of broad-based efforts to advance ecosystem sustainability, rather than as isolated problems. Addressing challenging weed problems systemically can offer important new leverage on such problems, by creating new opportunities to manage their root causes and by improving complementarity between weed management and other activities. While promising, this approach is complicated by the multidimensional, multilevel, diversely defined and unpredictable nature of ecosystem sustainability. In practice, TWR can be undertaken as a cyclic process of (i) initial problem formulation, (ii) ‘broadening’ of the problem formulation and recruitment of stakeholder participants, (iii) deliberation, negotiation and design of an action agenda for systemic change, (iv) implementation action, (v) monitoring and assessment of outcomes and (vi) reformulation of the problem situation and renegotiation of further actions. Notably, ‘purposive’ disciplines (design, humanities and arts) have central, critical and recurrent roles in this process, as do integrative analyses of relevant multidimensional and multilevel factors, via multiple natural and social science disciplines. We exemplify this process in prospect and retrospect. Importantly TWR is not a replacement for current weed research; rather, the intent is to powerfully leverage current efforts. © 2016 The Authors. Weed Research published by John Wiley & Sons Ltd on behalf of European Weed Research Society