The aim MASCOTE program is to evaluate the collectives and individual strategies of collection firms to ensure co-existence between GM and non GM production. This evaluation is made using two kind of criterions: collection cost and the ratio of GM in the non GM production collected. The model proposed calculates the localisation of GM fields taking into account farmer economics and agronomics variables in different scenarios of collection governance. These scenarios are based on an analysis of (i) the determinant of the collection firms collectives strategies and (ii) the collection organisation. A link with the MAPOD model allow to evaluate these territorial and organisational configuration with the ratio of GM in non-GM batches.