Phytophthora

In a surveillance program 2018 and 2019 financed by the Norwegian Food Safety Authority (Mattilsynet), the Norwegian Institute of Bioeconomy Research (NIBIO) analyzed 231 soil samples from imported, woody ornamental plants for presence of invasive exotic plant pathogens in the genius Phytophthora.

The sampling was carried out at ports of entry in several districts by inspectors from Mattilsynet. Larger trees were given priority when selecting material for testing. The exporting countries were The Netherlands, Italy, Germany, Denmark, Belgium, Sweden, Spain and Poland.

More than 1/3 of the samples contained one or two Phytophthora species and a total of 19 Phytophthora species were detected (Table 1).

Five of the species (P. amnicola, P. chlamydospora, P. hibernalis, P. parvispora and P. occultans) had never been found in Norway before. For many of the 19 Phytophthora species we lack knowledge of how serious a threat they pose to Norwegian plant production and natural environments. None of the 19 Phytophthora species were quarantine organisms, but many of them are already causing severe damage in Norwegian urban landscape areas and natural and semi-natural forests, e.g. P. cambivora and P. plurivora are among the responsible species for decline and mortality of Europe beech (Fagus sylvatica) in Norway.

This surveillance program revealed an alarmingly high degree of destructive Phytophthora species entering Norway via imported plants, even though all plants came with a phytosanitary certificate. This clearly calls for updated management strategies to protect Norwegian plant production and nature.