Based on this PRA, Ageratina adenophora was added to the EPPO Lists of pests recommended for regulation as quarantine pests in 2023.

Ageratina adenophora presents a high phytosanitary risk for the endangered area with moderate uncertainty. Ageratina adenophora is locally established in Algeria, Croatia, France (French Riviera, Corsica), Greece, Italy, Morocco, Portugal (including mainland, Azores and Madeira) and Spain (including mainland, Canary Islands). The overall likelihood of further entry of A. adenophora into the EPPO region is low with a moderate uncertainty. Several pathways were assessed in the PRA but there was no strong association with any pathways. The EWG note that the pathway plants for planting (horticultural use) is not currently active, however, this may change in the future. The likelihood of further establishment outdoors is very high with low uncertainty. Habitats are widespread within the EPPO region and further establishment is likely in regions where habitats and climatic conditions are conducive for establishment. Likelihood of establishment in protected conditions is very low with moderate uncertainty. Temperature within protected conditions would be suitable for the establishment however, other conditions, e.g., the intense crop management, are likely to reduce the likelihood of establishment. The potential for spread within the EPPO region is high with a moderate uncertainty. Ageratina adenophora can spread both naturally via wind dispersed seed, and plant fragments via waterways, and via human assisted spread (e.g. contaminant of travellers equipment). The magnitude of impact in the current area of distribution (excluding the EPPO region) is high with a moderate uncertainty. A. adenophora has negative impacts on native biodiversity, ecosystem services and has been shown to have socio-economic impacts on managed forests and crop yields. The EWG considered that the potential impact in the EPPO region is moderate with a moderate uncertainty. Similar types of impacts are expected though the moderate rating reflects the lower impact observed and the moderate uncertainty reflects the unknown severity in the EPPO region. Based on high likelihood of spread (moderate uncertainty) from existing established populations in EPPO region, and high impacts (mod uncertainty) the overall risk appears correct.