Implementing isolation perimeters around genetically modified maize fields Yann Devos, Dirk Reheul, Olivier Thas, Eva M. De Clercq, Mathias Cougnon and Karl Cordemans Agron. Sustain. Dev., 27 3 (2007) 155-165 Published online: 13 March 2007 DOI: 10.1051/agro:2007005