Update on the situation of Phytophthora pluvialis in Belgium
Phytophthora pluvialis (EPPO Alert List) was first detected in Belgium in 2023 in the southern part of the country in watercourses and in samples from two Douglas fir tree (Pseudotsuga menziesii) stands (EPPO RS 2024/039).
In order to determine the status of P. pluvialis, the NPPO of Belgium conducted an official survey throughout Belgium in spring and autumn 2024 in watercourses and in samples of P. menziesii, Tsuga heterophylla and Larix sp. trees from nurseries and (semi-)natural environments in forests.
During this survey, P. pluvialis was detected in 4 additional watercourses crossing P. menziesii stands and in P. menziesii plants in a forest nursery that did not show any signs of damage. The watercourses were located in the provinces of Luxembourg, Liege and Namur (Wallonia, southern Belgium). The presence of the pathogen was confirmed by real-time PCR. P. pluvialis was not detected in Flanders Region, northern Belgium.
The NPPO of Belgium considers that P. pluvialis is established in forest areas in southern Belgium and cannot be eradicated or contained. As there are no symptoms on host plants, the NPPO considers that P. pluvialis does not qualify to be an EU quarantine pest or regulated non-quarantine pest.
The pest status of Phytophthora pluvialis in Belgium is officially declared as: Present, only in some parts of Wallonia.
Sources
NPPO of Belgium (2025-09).