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Research article - Peer-reviewed, 2019

Diplodia Tip Blight on Its Way to the North: Drivers of Disease Emergence in Northern Europe

Brodde, Laura; Adamson, Kalev; Julio Camarero, J.; Castano, Carles; Drenkhan, Rein; Lehtijarvi, Asko; Luchi, Nicola; Migliorini, Duccio; Sanchez-Miranda, Angela; Stenlid, Jan; Ozdag, Sule; Oliva, Jonas


Disease emergence in northern and boreal forests has been mostly due to tree-pathogen encounters lacking a co-evolutionary past. However, outbreaks involving novel interactions of the host or the pathogen with the environment have been less well documented. Following an increase of records in Northern Europe, the first large outbreak of Diplodia sapinea on Pinus sylvastris was discovered in Sweden in 2016. By reconstructing the development of the epidemic, we found that the attacks started approx. 10 years back from several isolated trees in the stand and ended up affecting almost 90% of the trees in 2016. Limited damage was observed in other plantations in the surroundings of the affected stand, pointing to a new introduced pathogen as the cause of the outbreak. Nevertheless, no genetic differences based on SSR markers were found between isolates of the outbreak area and other Swedish isolates predating the outbreak or from other populations in Europe and Asia Minor. On a temporal scale, we saw that warm May and June temperatures were associated with higher damage and low tree growth, while cold and rainy conditions seemed to favor growth and deter disease. At a spatial scale, we saw that spread occurred predominantly in the SW aspect-area of the stand. Within that area and based on tree-ring and isotope (delta C-13) analyses, we saw that disease occurred on trees that over the years had shown a lower water-use efficiency (WUE). Spore traps showed that highly infected trees were those producing the largest amount of inoculum. D. sapinea impaired latewood growth and reduced C reserves in needles and branches. D. sapinea attacks can cause serious economic damage by killing new shoots, disrupting the crown, and affecting the quality of stems. Our results show that D. sapinea has no limitations in becoming a serious pathogen in Northern Europe. Management should focus on reducing inoculum, especially since climate change may bring more favorable conditions for this pathogen. Seedlings for planting should be carefully inspected as D. sapinea may be present in a latent stage in asymptomatic tissues.


carbon isotopes; dendroecology; water-use efficiency; latewood; earlywood; vascular wilt pathogen

Published in

Frontiers in Plant Science
2019, volume: 9, article number: 1818

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology
Adamson, Kalev
Estonian University of Life Sciences
Julio Camarero, J.
Consejo Superior de Investigaciones Cientificas (CSIC)
Castano, Carles
Universidad de Valladolid
Drenkhan, Rein
Estonian University of Life Sciences
Lehtijarvi, Asko
Bursa Technical University
Luchi, Nicola
Consiglio Nazionale delle Ricerche (CNR)
Migliorini, Duccio
Consiglio Nazionale delle Ricerche (CNR)
Sanchez-Miranda, Angela
Consejo Superior de Investigaciones Cientificas (CSIC)
Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology
Ozdag, Sule
Bursa Technical University
Oliva Palau, Jonàs
Swedish University of Agricultural Sciences, Department of Forest Mycology and Plant Pathology
Oliva, Jonàs
University of Lleida

Associated SLU-program

SLU Network Plant Protection

Sustainable Development Goals

SDG15 Life on land

UKÄ Subject classification

Climate Research
Forest Science

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