Prioritization of plants species from the EPPO Alert List
In May 2026, the EPPO Panel on Invasive Alien Plants prioritised three alien plant species from the EPPO Alert List using the EPPO Standard PM 5/6 EPPO prioritization process for invasive alien plants. A summary for each species is detailed below.
Acalypha australis (Euphorbiaceae)
Acalypha australis is native to Asia and is recorded in several EPPO countries. Natural spread via seed can promote local spread of the species. However, it is unlikely that the seed can be spread over long distances as there is no evidence of seed being wind dispersed or spread by birds eating seed. A. australis has the potential to spread via agricultural practices including movement of machinery and equipment. The magnitude of spread was rated as high, and the potential impact on agriculture was rated as high. The result of the prioritization was that A. australis is transferred from the Alert List to the EPPO List of Invasive Alien Plants and, due to the potential for further entry and spread, it is a priority for a pest risk analysis.
Ambrosia grayi (Asteraceae)
Ambrosia grayi is native to North America (Mexico, USA) and it occurs in Israel as a transient species. In the USA, A. grayi can reproduce by both seed and rhizomes, with the latter extending up to 3 m deep in the soil. However, in Israel, sexual reproduction is considered unlikely to significantly contribute to the spread of the species. In Texas (US), A. grayi is considered highly competitive in crops such as cotton and grain sorghum. The magnitude of spread was rated as medium, and the potential impact on agriculture was rated as medium. The result of the prioritization was that A. grayi is transferred from the Alert List to the EPPO Observation List.
Aponogeton distachyos (Aponogetonaceae)
Aponogeton distachyos is native to South Africa and has a limited distribution in the natural environment in the EPPO region. It can be spread by natural and human assisted mechanisms. Ripe fruit can float for a short period of time before releasing negatively buoyant seeds which can move with the water body. Where it occurs, A. distachyos can form floating mats which can reduce light transmission and may alter the quality of the water body by reducing oxygen levels. Ecosystem services can be negatively affected, for example by reducing access to the water body or blocking irrigation channels. The magnitude of spread was rated as high and the potential impact on biodiversity and habitats was rated as high. The result of the prioritization was that A. distachyos is transferred from the Alert List to the EPPO List of Invasive Alien Plants and, due to the potential for further entry and spread, it is a priority for a pest risk analysis.
Sources
EPPO Panel on Invasive Alien Plants (2026-05).
EPPO (2012) PM 5/6 EPPO prioritization process for invasive alien plants. EPPO Bulletin 42, 463-474. https://doi.org/10.1111/epp.2592