Based on this PRA, Chionaspis pinifoliae was added to the EPPO A1 List of pests recommended for regulation as quarantine pests in 2022. Measures for host plants for planting and cut branches (including Christmas trees) are recommended

Main conclusions 

Entry: Several EPPO countries already prohibit the import of most host plants for planting and cut branches (including Christmas trees) (e.g. Abies, Cedrus, Juniperus, Larix, Picea, Pinus, Pseudotsuga, Taxus and Tsuga in the EU). However, there are EPPO countries where the import of these host plants is not prohibited. Therefore, the likelihood of entry in the EPPO region was considered as high with a high uncertainty; the highest rating being for host plants for planting (except seeds, tissue cultures, pollen) and cut branches of hosts (including Christmas trees) into countries where there is no import prohibition.

Establishment: As climatic conditions appear to be suitable, the likelihood of establishment of C. pinifoliae outdoor in the EPPO region was considered very high with a low uncertainty. Chionaspis pinifoliae is not known as a pest under protected conditions, but it was considered as able to establish and difficult to control in greenhouse production, as is the case for other scale insects.

The magnitude of spread was considered moderate with a moderate uncertainty. The pest is mostly sedentary but could spread long-distances either naturally via wind, or with human assisted spread. The ability to reproduce parthenogenetically when there are no males around allows a single female to potentially establish a new population, which greatly increases its spread capacity. Chionaspis pinifoliae is known to have been moved with plants for planting and cut branches of hosts (including Christmas trees), a phenomenon which is expected to increase the spread rate.

Impact (economic, environmental and social) was considered high with a moderate uncertainty. Host plants are major forest, ornamental, and nursery trees in the EPPO region. Chionaspis pinifoliae only occasionally kills trees, but is difficult to control, especially on ornamental trees (e.g. in urban environment) and in nurseries. Pinus sylvestris and P. mugo, which are native to the EPPO region and widely distributed, are reported to be particularly susceptible.

Phytosanitary measures to reduce the probability of entry: The EWG considered that phytosanitary measures should be recommended for all host plant genera. Risk management options are considered for host plants for planting (except seeds, tissue cultures, pollen) and cut branches of hosts (including Christmas trees).