Neonectria Canker on Subalpine Fir (Abies Lasiocarpa)

Neonectria canker on subalpine ﬁ r (Abies lasiocarpa) in Denmark

Venche Talgø1, Iben Margrete Thomsen2, Ulrik Bräuner Nielsen2, May Bente Brurberg1, and Arne Stensvand1

Norwegian Institute for Agricultural and Environmental Research

In June 2011, Neonectria canker was found on subalpine ﬁ r in Denmark in a provenance trial, a forest plantation and an arboretum. The disease is known from several conifer species in Norway.

Symptoms and signs Most trees in the Danish provenance trial investigated in June 2011 appeared healthy 1, but some dead and dying trees occurred 2. 1 Symptoms appeared in patches, which is typical for damage caused 2 by a pathogen. Typical symptoms were fl agging (dead branches) 3, canker wounds with dead tissue below the bark 4, heavy resin fl ow 5, and red fruiting bodies (perithecia) 6. Perithecia were present on the lower side of branches that had died the previous year (brown needles still attached). No perithecia were found on current year die- back or branches that obviously had been dead for a longer period. Perithecia were especial abundant where dead needles had accu- mulated 7 8. This was likely due to preservation of high humidity after rain- and dewfall, creating ideal conditions for fungal growth. Identifi cation 3 4

ITS sequencing of the rDNA from this Neonectria culture isolated from Danish subalpine fi r in the provenance trial showed that it was the same Neonectria species as earlier reported from conifers in Norway (Talgø et al. 2010). The isolates from subalpine fi r in the production fi eld and arboretum we sampled from, were also identical to the Norwegian isolates. In the future, this Neonectria sp. may be classifi ed as a new species. It is most similar to N. ditissima (syn. Nectria galligena), which is commonly found on broad leaf trees worldwide, but very different from N. fuckeliana, a well known canker causing fungus on Norway spruce (Picea abies). 5 6 Inoculation test On 15 July 2011, an inoculation test was performed. Leaders on 34 three year old subalpine fi r trees were inoculated with map pins coated with Neonectria mycelium and spores, and 13 trees were kept as control (autoclaved map pins). By 11 August 2011, needlecast and canker wounds occurred around the inoculation points 9 10 11. No canker was present on the control plants, only a slight discoloration of the tissue where the map pins had been inserted 12 13 14. The fungus was readily reisolated from the inoculated, dying shoots.

Reference Talgø, V., Brurberg, M.B. & Stensvand, A. 2010. Neonectria-canker on true ﬁ r and spruce in Norway. In: Proceedings of the 9th International Christmas Tree Research & Extension Conference (eds. 7 Hart, J., Landgren, C., & Chastagner, G.), Corvallis, Oregon, 14-18 September 2009. P 58-62. 8

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[email protected] Bioforsk www.bioforsk.no 1Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, Fr. A. Dahlsvei 20, N-1432 Ås Høgskoleveien 7, 1432 Ås, Norway, 2University of Copenhagen, Faculty of Life Science, Forest and Landscape Denmark, Hørsholm Kongevej 11, DK-2970 Hørsholm, Denmark Norway