In Europe, the cultivation of genetically (living) modified (GM) Brassica napus is prohibited, but the import of GM B. napus seeds is permitted. Until March 2009 no GM B. napus was imported as reported by the consent holders. Since March 2009 several GM B. napus events are authorised for import. However, given this short period, no official records for seed imports into the Netherlands are available. and thus whether import of GM B. napus has occurred during the last 12 months is unclear. However, the bulk of the seed imports of B. napus are from within Europe. It is known that Brassica napus can become established outside cropped fields in the ruderal landscape and is able to cross with a number of other crucifers belonging to the Dutch flora, in particular Brassica rapa. These characteristics are taken into account in the environmental risk analysis for genetically modified B. napus. Data on the occurrence of B. napus in the Netherlands might aid in the refinement of the risk analyis for GM B. napus.
The existing impression that B. napus is widespread in this country is presently under discussion, because of the confusion surrounding identification of B. napus and its closest relative, B. rapa. As a result, the current distribution of the species in the Netherlands is poorly understood. In this study we examine the morphological differences between B. rapa and B. napus and the presence of B. napus in the ruderal landscape to establish a baseline for its distribution. Against this background, recommendations are given how these results may be incorporated into the monitoring plans of (un-)expected adverse environmental effects as the results of the commercial releases of GM B. napus as required by EU directive 2001/18/EC.