Phytophthora

Phytophthora detected in soil from the rhizosphere of woody ornamental plants imported to Norway

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.

Table 1. Phytophthora species found in soil samples from woody ornamental plants imported to Norway in 2018 and 2019 (results from a total of 231 soil samples).

Phytophthora species

Host genera

 

Exporting country (no.

of pos. samples)

P. amenicola

 

Acer

The Netherlands (1)

P. cactorum

 

Fagus, Taxus, Tilia

Denmark (2), The Netherlands (1)

 

P. cambivora

 

Acer, Corylus, Fagus, Pinus, Prunus, Salix, Taxus, Ulmus

 

Belgium (1), Denmark (1), The Netherlands (8), Sweden (2), Germany (2)

P. chlamydospora
 

Ligustrum, Prunus

Denmark (1), The Netherlands (1)

P. cinnamomi

Cupressus, Pinus, Taxus

Italy (1), The Netherlands (4) 

P. citricola
 

Olea, Thuja

Italy (1), Germany (1)

P. cryptogea

 

Abies, Acer, Caprinus, Corylus, Fagus, Ilex, Juniperus, Larix, Magnolia, Pinus, Prunus, Rosmarinus, Tsuga

Italy (2), The Netherlands (6), Germany (1), Sweden (2)

P. gonapodyides

 

Abies, Betula, Chamaecyparis, Thuja

Denmark (1), The Netherlands (2), Poland (2)

P. gregata
 

Salix, Taxus, Thuja

The Netherlands (4)

P. hibernalis

 

Prunus

Denmark (1)

P. megasperma

Acer, Fraxinus, Magnolia, Prunus, Taxus, Thuja

Denmark (1), The Netherlands (4)

P. nicotianae
 

Prunus

The Netherlands (1)

P. occultans
 

Buxus, Chamaecyparis

The Netherlands (2)

P. palmivora
 

Olea

Italy (1)

P. parvispora
 

Citrus

Italy (1)

P. pini

Taxus, Thuja

Belgium (1), The Netherlands (1)

P. plurivora

 

Abies, Acer, Alnus, Betula, Chamaecyparis, Corylus, Fagus, Larix, Ligustrum, Liriodendron, Olea, Prunus, Pterocarya, Quercus, Syringa, Taxus, Thuja, Tilia

Denmark (6), Italy (1), The Netherlands (18), Poland (1), Sweden (2), Germany (2)

P. pseudocryptogeae
 

Fagus, Pinus

Belgium (1), Sweden(1)

P. syringae

 

Acer, Buxus, Ligustrum, Magnolia, Pinus, Prunus

Denmark (4), Sweden (1)

 

Publications

Abstract

I et oppdrag fra Mattilsynet, ble det i 2019 analysert totalt 101 prøver av jord fra importerte grøntanleggsplanter for nematoder og Phytophthora spp. Det ble gjennomført i OK-programmet «Nematoder og Phytophthora spp. i jord på importerte planter». Prøvene ble tatt ut av inspektører ved regionkontorene til Mattilsynet. Større trær til utplanting hadde førsteprioritet. Her rapporterer vi Phytophthora-delen av OK-programmet. Phytophthora ble funnet i 37.6 % av prøvene, totalt 13 arter. Plantematerialet kom fra Nederland, Italia, Tyskland, Danmark, Belgia, Sverige og Polen. To av disse artene er aldri rapportert fra Norge før (P. parvispora og P. occultans) og vi mangler kunnskap om hvor alvorlig risiko de utgjør for norsk natur. Ingen av de 13 Phytophthora-artene er karanteneorganismer, men flere av de gjør i dag skade både i grøntanlegg og norsk natur, spesielt P. cambivora på bøk (Fagus sylvatica) og gråor (Alnus incana). Kartleggingsprogrammet har nå pågått i to år og gitt verdifull informasjon om import som spredningsvei for Phytophthora. Neste skritt må være tiltak for å demme opp for videre innførsel av destruktive Phytophthora-arter for å beskytte norsk planteproduksjon og natur.