The Federal Plant Variety Office is responsible for the maintenance control of listed and protected varieties. The breeder is responsible for maintaining the variety unchanged. The Federal Plant Variety Office monitors propagating material from the breeder or from the seed marked. The samples are tested in a growing trial and are compared with the standard sample or the variety description. Standard samples for each variety are stored at The Federal Plant Variety Office keeps a standard samples for all seed propagated varieties. If a variety does no longer fulfil the necessary requirements for protection or listing, national listing and/or plant breeders’ rights are revoked by the Office.