Emerging Pest Alert

Hymenoscyphus fraxineus, causal agent of ash dieback: new hosts

Scientific Name:

Hymenoscyphus fraxineus

Describer: T. Kowalski, Baral, Queloz & Hosoya

Common Name: ash dieback


Hymenoscyphus fraxineus, causal agent of ash dieback: new hosts



Hymenoscyphus fraxineus, causal agent of ash dieback, infects Fraxinus spp. (ash) trees. Trees exhibit shoot and leaf wilting, leaf drop, bark necrosis, and dieback (Milenkovi? et al, 2017). Ash dieback has been reported in Europe from Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Guernsey, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Montenegro, Netherlands, Norway, Poland, Romania, Russia, Serbia, Slovakia, Slovenia, Sweden, Switzerland, UK, and Ukraine (EPPO, 2017). It has been reported in Asia from China, Japan, and the Republic of Korea (EPPO, 2017). Plants for planting (Kirisits et al., 2012) and wood (Husson et al., 2012) are considered likely pathways for long-range spread of Hfraxineus.

Ash dieback caused by Hymenoscyphus fraxineus has been highlighted in previous NAPPO-PAS Pest Alerts (https://www.pestalerts.org/nappo/emerging-pest-alerts/16/), as well as under the synonym Chalara fraxinea (https://www.pestalerts.org/nappo/emerging-pest-alerts/24/https://www.pestalerts.org/nappo/emerging-pest-alerts/45/https://www.pestalerts.org/nappo/emerging-pest-alerts/79/https://www.pestalerts.org/nappo/emerging-pest-alerts/144/).

Issues of Concern:

In 2018, the fungus Hymenoscyphus fraxineus was isolated from cultivated Phillyrea angustifoliaPlatifolia, and Chionanthus virginicus plants in the United Kingdom. This is the first report of PangustifoliaPlatifolia, and Chionanthus virginicus as hosts of Hfraxineus (DEFRA, 2018).


Synonyms: Hymenoscyphus pseudoalbidus Queloz, Grünig, Berndt, T. Kowalski, T.N. Sieber & Holdenr; Chalara fraxinea T. Kowalski



DEFRA. 2018. Ash dieback found on three new host species of tree in the UK. Department for Environment, Food & Rural Affairs (DEFRA). August 7, 2018. https://www.gov.uk/government/news/ash-dieback-found-on-three-new-host-species-of-tree-in-the-uk--2.

EPPO (2017) PQR - EPPO database on quarantine pests (available online). http://www.eppo.int

Husson, C., Cael, O., Grandjean, J.P., Nageleisen, L.M. and Marcais, B. 2012. Occurrence of Hymenoscyphus pseudoalbidus on infected ash logs. Plant Pathology, 61(5), pp.889-895.

Kirisits, T., Kritsch, P., Krauml, K., Matlakova, M. and Halmschlager, E. 2012. Ash dieback associated with Hymenoscyphus pseudoalbidus in forest nurseries in Austria. Journal of Agricultural Extension and Rural Development, 4(9), pp.230-235.

Milenkovi?, I., T. Jung, Z. Stanivukovi?, and D. Karadži?. 2017. First report of Hymenoscyphus fraxineus on Fraxinus excelsior in Montenegro. Forest Pathology DOI: 10.1111/efp.12359.