How to assess and manage risks of plants as pests?

Invasive alien plants can pose serious threats to cultivated and wild plants. This provides the basis to regulate them as ‘plant pests’ within the framework of plant health. To assess if a regulation would be appropriate, necessary and effective, and to identify available options for measures to reduce a possible risk, the revised International Standard on Phytosanitary Measures No. 11, “Pest risk analysis for quarantine pests including analysis of environmental risks and living modified organisms” by the International Plant Protection Convention or the more operational decision support scheme for pest risk analysis by the European and Mediterranean Plant Protection Organisation, present useful tools. One of the challenges to assess the risks of alien plants to other plants and the environment is the identification of the plant’s potential for invasiveness. In addition, the approach to the economic impact assessment is different in comparison to the ‘traditional’ plant pests. The level of uncertainty is often greater in the assessment of environmental risks than in risks to cultivated plants, and also management options in particular for intentionally introduced plants can differ significantly from those for traditional pests. This article focuses on risk analysis beyond traditional plant quarantine, and elucidates the features with regard to the assessment and management of invasive alien plants.