Plant diseases and pests can be introduced from outside the EU in living plants, plant products or other items which are carrying certain pathogens, or even in soil adhering to them.
Intra-EU consignments of particularly harmful organisms, and also of plants, plant products, and other items that are, or could be, affected by such organisms come within the scope of phytosanitary legislation. Certain plants, plant products, and other items may, in principle, only be imported if special requirements (such as a certificate, import inspection) have been completed.
The Customs administration monitors intra-Community consignments crossing Germany.
You can find information about phytosanitary protection on the web sites of the Federal Ministry of Food and Agriculture (Bundesministeriums für Ernährung und Landwirtschaft) and of the Julius Kühn Federal Research Centre for Cultivated Plants (Julius-Kühn-Institut - Bundesforschungsanstalt für Kulturpflanzen).