Prioritization of alien plant taxa for EPPO Pest Risk Analysis
In 2024/25, the EPPO Panel on Invasive Alien Plants conducted a horizon scanning study. Experts from the Panel suggested alien taxa for prioritization for Pest Risk Analysis (PRA) from their country or sub-region based on two criteria: (1) taxa were not already on any of the EPPO lists, (2) there are known negative impacts on plant health or the environment or the species shows invasive behaviour (spread outside of planted area/spread into agricultural habitats, forms monospecific stands, etc.). This initial work resulted in a list of 89 plant taxa, and this list was further reduced by a consensus ranking based on (1) the species is not a priority for prioritization or (2) the species is a priority for prioritization. This resulted in a list of 25 plant taxa which were prioritized using the EPPO Standard PM 5/6 EPPO prioritization process for invasive alien plants. The results of the prioritization work included six plant taxa being added to the EPPO List of Invasive Alien Plants, 16 plant taxa being added to the EPPO Observation List of Invasive Alien Plants and three species being added to the List of Minor Concern. Of the six plant taxa included on the List of Invasive Alien Plants, three were considered a priority for PRA. The Panel further assessed the literature for these three species and concluded that a PRA should be conducted on Senecio angulatus in 2026. S. angulatus is a prolific climbing perennial species native to South Africa. It can spread by seed and stem fragments and has the ability to form dense infestations in open and disturbed habitats, where it negatively impacts native biodiversity and ecosystem services. It can grow in open woodland where it can have a negative impact on tree regeneration.
Table 1. Twenty-five species prioritized using the EPPO Prioritization Process (PM 5/6)
Species | Family | Origin | EPPO List | Priority for PRA |
Acacia pycnantha | Fabaceae | Australia | Obs. | |
Agave fourcroydes | Asparagaceae | Americas | Minor | |
Artemisia verlotiorum | Asteraceae | Asia | Obs. | |
Arundo donax | Poaceae | Asia | L IAP | |
Austrocylindropuntia subulata | Cactaceae | S. America | Minor | |
Bothriochloa barbinodis | Poaceae | Americas | Obs. | |
Cenchrus longisetus | Poaceae | Africa, Asia | Obs. | |
Chasmanthe floribunda | Iridaceae | South Africa | Obs. | |
Claytonia perfoliata | Montiaceae | N. America | Obs. | |
Dactyloctenium aegyptium | Poaceae | Africa, Asia | Obs. | |
Eleocharis bonariensis | Cyperaceae | Americas | Obs. | |
Leucaena leucocephala subsp. glabrata | Fabaceae | Americas | L IAP | Yes (High) |
Lonicera japonica | Caprifoliaceae | Asia | Obs. | |
Melia azedarach | Meliaceae | Asia, Oceania | Obs. | |
Paraserianthes lophantha subsp. lophantha | Fabaceae | Australia | Obs. | |
Parkinsonia aculeata | Fabaceae | Americas | L IAP | |
Pterocarya fraxinifolia | Juglandaceae | C. Asia | L IAP | Yes (High) |
Salpichroa origanifolia | Solanaceae | S. America | Obs. | |
Senecio angulatus | Asteraceae | South Africa | L IAP | Yes (High) |
Sinacalia tangutica | Asteraceae | Asia | Obs. | |
Spiraea alba | Rosaceae | N. America | Obs. | |
Spiraea japonica | Rosaceae | Asia | Obs. | |
Telekia speciosa | Asteraceae | Europe | Obs. | |
Zantedeschia aethiopica | Araceae | South Africa | Minor | |
Zea mexicana | Poaceae | N. America | L IAP |
Where L IAP = EPPO List of Invasive Alien Plants; Minor = EPPO List of Minor concern; Obs. = EPPO Observation List of Invasive Alien Plants.
Sources
EPPO Global Database: https://gd.eppo.int/
EPPO (2012) PM 5/6 EPPO prioritization process for invasive alien plants. EPPO Bulletin 43, 463-474. https://doi.org/10.1111/epp.2592