1. Second Annual Conference of Ethiopian Weeds Science Society (EWSS), 15-16 December 1994, Addis Ababa, Ethiopia.
2. Pflanzenschutz in den Tropen und Subtropen: Arbeitskreistreffen, 7-8 July 1998, Hattersheim/Frankfurt, Germany. The Conference was organized by the Deutsche Phytomedizinische Gesellschaft, Institut fuer Pflanzenkrankheiten, Bonn.
3. Plant Production and Agroecology: Thoughts about the Future, A symposium in honour of Prof. Dr. Werner Koch, 24 July 1998, University of Hohenheim, Stuttgart, Germany.
4. The Fourth International Workshop on Orobanche Research, 23 September 1998, in Albena, Bulgaria.
5. Parasietendag (Parasitic day) on 2 November 1998, at the Royal Tropical Institute, Amsterdam, The Netherlands.
6. Tropentag 98, “Stabilisierung und nachhaltige Entwicklung land- und forstwirtschaftlicher Systeme in den Tropen, 3-4 Dezember 1998“, Tropenzentrum, Georg-August-Universität, Göttingen, Germany.
7. X International Symposium on Biological Control of Weeds, 4-14 July 1999, Bozeman, Montana, USA.
8. „Fusarien – Symposium“ , 02.12.1999, Universität Hohenheim, Stuttgart, Germany.
9. „ V International Bioherbicide Group Workshop“, 5 – 6 June 2000, Foz Do Iguacu, BARAZIL.
10. Third International Weed Science Congress – IWSC“, 6 – 11 June 2000, Foz Do Iguacu, BARAZIL.
11. „Symposium 2000, Adapted Farming in West Africa: 15 Years of Research Results Offering New Perspectives for the Future“, 5 – 7 July 2000, Universität Hohenheim, Stuttgart, Germany.
12. „Deutscher Tropentag 2000“ International Agricultural Research: A Contribution to Crisis Prevention, 11 – 12 October 2000, Universität Hohenheim, Stuttgart, Germany.
13. Workshop: Host-Parasite Interactions in Parasitic Flowering Plants, 7. February 2001, University of Hohenheim, Stuttgart, Germany.
14. Arbeitskreis Mykologie / Wirt-Parasit-Beziehungen, 15-16 March 2001, University of Hohenheim, Stuttgart, Germany.
15. 7th International Symposium on Parasitic Weeds, 3-8 June, 2001, Nantes, France.
16. NATO Advanced Research Workshop: Enhancing biocontrol agents and handling risks, June 9-15, 2001, Hotel Villa Pitiana, Donnini, Florence, Italy.
17. The practice of biological control: importation and management of natural enemies and agents, August 2-5, 2001, Montana State University, Bozeman, Montana, USA.
18. 12th European Weed Research Society Symposium, June, 2002, Wageningen, The Netherlands.
19. 2nd joint meeting of working groups 2 and 4 of COST Action 849, Parasitic plant management in sustainable agriculture, June, 2002, Obermarchtal, Germany.
20. XI International Symposium on Biological Control of Weeds, 27 April- 02 May 2003, Canberra, Australia.
21. VI International Bioherbicide Group Workshop“, 27 April 2003, Canberra, Australia.
22. Biological control working group (WG2) of COST 849 action meeting entitled “Synergistic use of biocontrol agents for parasitic plant management“, 27-29 February 2004, Rome, Italy.
23. SAFE Consortium “European Excellence in Food Safety” Seminar Series 5 entitled “Contaminants and influence of agricultural practices – mycotoxins; chemical contaminants; microorganisms” March, 18-19, 2004, Brussels, Belgium.
24. 4th International Weed Science Congress – IWSC – 20-24 June 2004, Durban, South Africa.
25. 1st International Parasitic Plants Society (IPPS) Workshop, 25 June 2004, Durban, South Africa.
26. Jahrestagung 2005 der Alexander von Humboldt Stiftung, 30 June- 02 July 2005, Berlin, Germany.
27. „Deutscher Tropentag 2005“ The Global Food & Product Chain – Dynamics, Innovations, Conflicts, Strategies, 11 – 13 October 2005, Universität Hohenheim, Stuttgart, Germany.
28. Einführungstagung der Alexander von Humboldt Foundation, 13-15 October 2005, Mainz, Germany.
29. 23rd German Conference on Weed Biology and Weed Control, March 7th – 9th, 2006, Universität Hohenheim, Stuttgart, Germany.
30. FAO regional technical meeting within FAO Striga project TCP/RAF/3008 for West African Countries (Atelier sous-régional sur la gestion intégrée durable en agriculture des espèces du genre Striga) on Striga control, 25-27 April 2006, Cotonou “Le Chant d’Oiseau”, Benin.
31. Deutscher Tropentag 2006 “Prosperity and Poverty in a Globalized World – Challenges for Agricultural Research”, University of Bonn, Germany, 11 – 13 October 2006.
32. International Symposium on Integrating New Technology for Striga Control: Towards Ending the Wicht-hunt. November 5-11, 2006, Addis Ababa, Ethiopia.
33. XII international Symposium on Biological Control of Weeds, 22-27 April 2007, Montpellier, France.
34. VII International Bioherbicide Group Workshop (VII IBGW), 22 April 2007. Montpellier, France.
35. “9th World Congress on Parasitic Plants”, June 3-7, 2007. Omni Hotel, Charlottesville, Virginia, USA.
36. Deutscher Tropentag 2007 “Utilisation of diversity in land use systems: Sustainable and organic approaches to meet human needs”, Witzenhausen, Germany, October 9-11, 2007.
37. 5th International Weed Science Congress “Weeds – local problems/global challenge” Vancouver, Canada, 23 – 27 June 2008.
38. Deutscher Tropentag 2008 “Competition for Resources in a Changing World: New Drive for Rural Development”, University of Hohenheim, Germany, October 7 – 9, 2008.
39. “10th World Congress on Parasitic Plants”, 8 to 12 June, 2009 Kusadasi, Turkey.
40. 2nd International Conference on Applied Biotechnology “Biotechnology for Sustainable Human Society”, October 25-27, 2010, Khartoum, Sudan. African City of Technology, Sudan.