Considering the European regulations, a product needs to be labelled as containing GM when the adventitious presence of GM material exceeds 0.9%.  During collection, crops from many fields are combined to fill a silo.  Three management strategies to avoid the risk of mixing GM and non-GM crops were identified by a descriptive work based on cases studies in various region of France: defining GM and non-GM silos and production zones; specifying the timing of GM and non-GM crops delivery at silos; or using local management rules at each stage of the supply chain.  To evaluate these strategies and to compare them to the actual supply chain management we propose a model of elevators' supply chain management.  The allocation of specific silos to GM and non-GM crops allows all the non-GM production to be segregated, but with a 700% increase in transportation cost.  Specifying the timing of GM and non-GM crops deliveries allows all the non-GM crops to be segregated without any cost increase.  Using local management rules does not allow more than 50% of the non-GM crops to be segregated without an increase in costs.