Poster: Diseases of Plants: Disease Detection & Diagnosis
Fusarium canker on holly in Norway
G. STRØMENG (1), V. Talgø (1), A. Stensvand (1), J. Razzaghian (1) (1) NIBIO, Norway
Holly (Ilex aquifolium) thrives well in the mild and wet costal climate of southwestern Norway, where it is commonly harvested for Christmas decorations. During the last decade, a Fusarium sp. has frequently been found to damage both natural and cultivated stands, causing leaf drop, dead twigs, canker wounds and berry rot. The most severe outbreaks of the disease ever occurring were observed in late autumn 2015. Isolates of the fungus are most similar to F. acuminatum (97% identical TEF sequences). On one occasion, the fungus was detected on dead shoots of Nordmann fir (Abies nordmanniana). Inoculation tests proved it pathogenic to both host plants. Many holly stands are no longer intensively cultivated, and they have become very dense and overgrown by other vegetation, thus creating an ideal microclimate for fungal pathogens. In an investigation in a natural stand in 2006-2009, the quality of the holly improved by letting more air and light into the dense plantation by different combinations of pruning, thinning, clearance of unwanted trees and bushes, and grazing with sheep. Thus, it is possible to gain control with the disease by sanitation and proper management, and thereby increase both the quality and quantity for marketing. There is a potential market in other Nordic countries where the climate is too harsh for holly, but earlier attempts of export fell through due to quality issues.