Opinion of the Scientific Panel on Plant Health on the pest risk analysis made by EPPO on Lysichiton americanus Hultén & St. John (American or yellow skunk cabbage)

Abstract

Following a request from the European Commission, the EFSA Scientific Panel on Plant Heath was asked to deliver a scientific opinion on two pest risk analyses made by the European and Mediterranean Plant Protection Organization (EPPO) on invasive alien plants (American skunk cabbage and floating pennywort). The Panel was in particular asked a) whether these organisms can be considered as harmful for the endangered area of the European Community and thus potentially eligible for addition to the list of harmful organisms in the plant health Directive 2000/29/EC, and b) whether the identified management options are appropriate through an evaluation of their efficacy, feasibility and impact. This document presents the opinion of the Panel on Plant Health on the pest risk analysis made by EPPO on Lysichiton americanus Hulten and St. John. L. americanus is a yellow-flowered herbaceous perennial plant known as American skunk cabbage or yellow skunk cabbage. It can be terrestrial, semi-aquatic and even aquatic. It has been introduced into Europe intentionally as an ornamental garden plant. It is naturalised in several European countries including Ireland, Germany, Norway, Sweden, Switzerland and UK. However, invasive behaviour has been reported in parts of Europe, with local species extinction reported in Germany. L. americanus is considered an invasive alien plant by EPPO and is included on the EPPO Action List (pests which EPPO recommend member countries to consider for inclusion in their phytosanitary regulations), with the entire EPPO region considered an endangered area. In delivering this opinion the Panel conducted a detailed review of the EPPO pest risk analysis provided, using the internationally accepted standard for pest risk analysis for quarantine pests ISPM No 11. The available information shows that Lysichiton americanus can be considered an invasive species with potential to cause environmental damage to ecologically vulnerable wetland habitats. However, the factors contributing to invasive behaviour are not well characterised and thus the endangered area cannot be clearly defined. Despite the presence of L. americanus in at least nine European countries, clear evidence of environmental damage has been found only in restricted areas of Germany. A more detailed analysis is required to identify the key factors contributing to invasive behaviour. Although the Panel recognises that invasiveness of a plant in one area can be a signal for its invasiveness elsewhere, it concludes that the information provided in the EPPO document is insufficient to confirm that L. americanus qualifies as a quarantine pest for the EC. The Panel considers that the significant knowledge gaps identified in the pest risk assessment stage of the pest risk analysis preclude a detailed evaluation of management options at this stage. The Panel suggests that further work, including monitoring and surveillance, is needed to address the areas of uncertainty identified in the EPPO document, in order to identify the areas of the European Community at risk and enable management options to be considered. These include: a) the effect of abiotic factors on the establishment, development, reproduction, survival and dispersal of the plant in both the native and introduced range; b) the population dynamics of the plant in areas where it is present but not invasive; c) the volume of trade in L. americanus as an ornamental plant entering and moving within the EC, including further analysis of the pathways through which it can reach natural water bodies; d) the nature and occurrence of areas within the EC where conditions result in invasiveness of the plant, supported by the use of modelling and geographic information system (GIS) tools. the environmental damage caused by the plant in areas where it is invasive.