Interception of invasive alien plants as contaminants in potted plants from China
Contamination of potted plants by invasive alien plant species is a known pathway for entry within the EPPO region. Both Parthenium hysterophorus (Asteraceae: EPPO A2 List) and Polygonum perfoliatum (Polygonaceae: EPPO A2 List) have been intercepted by the Dutch NPPO as contaminants of potted plants (see EPPO RS 2016/020). Following the implementation of the EU Regulation 1143/2014 on Invasive Alien Species, and the establishment of an EU list of Invasive Species of Union concern, inspection efforts targetting potted plants at Dutch ports has increased. In 2018, a shipment of Podocarpus macrophyllus and Pseudolarix amabilis bonsai plants from China were inspected and several non-native plant species were identified. These included two species currently on the EU list of Invasive Species of Union concern (P. perfoliatum and Alternanthera philoxeroides (Amaranthaceae: EPPO A2 List)), as well as Humulus scandens (Cannabaceae - EPPO A2 List) which is currently being considered for listing as a species of Union concern. In the case of the latter, two small plants were collected from the potted plants and raised in the greenhouse of the Plant Protection Service at Wageningen (NL). Both female and male plants were present as contaminants and both were grown to maturity where they flowered and produced seed which aided identification. This is the first report of H. scandens entering the EPPO region via the pathway ‘contaminants of potted plants’.
Sources
Personal communication: J. van Valkenburg, Q-bank http://www.q-bank.eu/
Q-bank interactive key: http://keys.lucidcentral.org/keys/v3/bonsai/