First report of Phytophthora pluvialis in Douglas fir plantations in Belgium

Abstract

Following a report of Phytophthora pluvialis in the United Kingdom in 2021 (Pérez-Sierra et al., 2022), surveillance for this forest pathogen started in 2023 in southern Belgium. Douglas fir (Pseudotsuga menziesii) was surveyed as it is an economically important conifer species and a major host for P. pluvialis. Fifteen Douglas fir plantations close to streams were visited between May and October. Two monitoring methods were used: checking trees for symptoms of the disease (shoot dieback, resinous cankers, needle loss) and baiting in streams using a qPCR detection method developed by McDougal et al. (2021). Baiting was done using Western hemlock (Tsuga heterophylla) twigs placed in cheesecloth bags attached to the riverbank which were left floating on the water surface in the river for two weeks.F I G U R E 1 Morphological features of Phytophthora pluvialis: a) colony on carrot agar after10 days; b) hyphal swellings on carrot agar; and c) oogonium and amphigynous antheridium This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.