Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2024
Authors
Ari Hietala Wilson Lara Henao A. Kolsgaard S. Seljegard Nina Elisabeth Nagy Isabella Børja Tor Arne Justad Yngve Rekdal Even Bergseng Halvor SolheimAbstract
Forest grazing by free-roaming livestock is a common practice in many countries. The forestry sector sees the practice as unfortunate owing to several reasons, such as damages inflicted by grazing in young plantations. Concerning Norway spruce forests, a tree species known to develop wood decay with high frequency followed from stem bark damage, there is a strong perception among foresters that the trampling damage caused by livestock on the superficial root system of this tree leads to decay. Because of the very limited scientific documentation available on this topic, we pursued a clarification by investigating three 38- to 56-year-old Norway spruce forests used for silvopasture. Two types of injuries were observed on exposed roots: bark cracks characterized by resin exudation, and injuries involving localized bark peeling and exposure of the underlying wood. These injuries occurred up to 250 cm away from the root collar, with the sector 50–150 cm away from the root collar showing the highest incidence of injuries. In two of the forest stands, wood within the injured root areas was primarily colonized by the wound parasite Corinectria fuckeliana or species of the order Helotiales, fungi that do not cause wood decay. Wood colonization of injured roots by Heterobasidion species, the most frequent wood decay fungi of Norway spruce, was common in the third stand, but only in a few cases it was possible to deduce that the colonization had probably initiated via trampling injuries on roots. In a few cases, an injury was located at stem base at the root collar height along paths used by animals, and in such cases, it was obvious that stem colonization by Heterobasidion species had initiated via the wound. The relatively small amount of data warrants caution when drawing conclusions. Considering the high establishment frequency of decay via stem bark wounds of Norway spruce observed in previous studies, our data would suggest that roots are generally better equipped to defend themselves upon infliction of superficial wounds than stem of this tree species. The likelihood of trampling injuries leading to decay may vary considerably between different stands, this presumably depending on the level of local propagule pressure by pathogenic wood decay fungi and the frequency of damages close to root collar.
Abstract
No abstract has been registered
Authors
Jorunn Børve Katharina Pampus Tuuli Haikonen Andrea Podavkova Gaute Myren Roland W. S. WeberAbstract
Ascospores discharged at rainfall and dispersed by wind can provide long-distance spread of the European canker fungus, Neonectria ditissima. Ascospores are produced by perithecia which are the sexual reproductive stage. Diffuse knowledge exists on the seasonal pattern of perithecium formation under different climatic conditions. Therefore, the development of perithecia was observed for several successive seasons at five sites in three Northern European countries. In Norway and Finland, ripe perithecia were commonly recorded throughout the year, and on individual cankers continuously for up to 28 months. In contrast, asexual reproductive structures (sporodochia) were confined to the growing season in both countries. In Northern Germany an average of 51% of cankers developed ripe perithecia by late winter, and perithecial senescence ensued in late spring. On average, ripe perithecia were present on cankers for 22 weeks. In contrast, sporodochia were observed all year round. The timing of perithecium maturation correlated with the number of days with > 2 mm rainfall in July–September. The presence of mature perithecia and sporodochia for different lengths of time in different countries has implications for regional disease management strategies.
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No abstract has been registered
Abstract
No abstract has been registered
Authors
Håvard Kauserud Tor Arne Justad Yngvild Vindenes Ine-Susanne Hopland Methlie Jørn Henrik Sønstebø Inger Skrede Sundy MauriceAbstract
Wood-decay fungi are adapted to growth under different climate conditions and on various host tree species, but little is known about intraspecific variation in growth, substrate specificity and decay rates under different climatic conditions. Such knowledge is relevant to understand how wood-decay fungi will respond to climate change. Here, we investigate whether populations of the widespread brown-rot fungus Fomitopsis pinicola grow at different rates under different temperatures and water availabilities and whether the decay rate of the two wood substrates, Alnus incana and Picea abies, differs across populations. We isolated 72 cultures from fruit bodies collected in nine geographic localities across Norway, representing different climate conditions and substrates. We conducted in vitro growth experiments to assess the level of intraspecific phenotypic variability in temperature-dependent growth. All populations showed a strong but similar response in mycelial growth rates to different temperatures and water potentials. There were no consistent differences between populations in growth rates across temperatures, but larger variation between populations at the higher temperatures. Similarly, we observed no significant differences in wood decay rates across the nine populations and no signs of substrate specific adaptation to P. abies and A. incana. Our results indicate that local adaptation to different climates or substrates, as revealed by in vitro growth experiments, has to a limited extent, taken place during the few thousand years Fomitopsis pinicola has been present in this area.
Authors
Theresa Weigl Jorunn Børve Emily Follett Ingunn Øvsthus Carl Gunnar Fossdal Hanne Larsen Siv Fagertun RembergAbstract
No abstract has been registered
Authors
Dalphy Ondine Camira HarteveldAbstract
No abstract has been registered
Authors
Dalphy Ondine Camira HarteveldAbstract
No abstract has been registered
Abstract
Tip rot of carrot significantly reduces root quality and contributes to the high-level rejection during sorting and packaging in Norway. The rot can be dry, or wet, and vary in colour from light brown to dark brown. Diagnosis of a plant disease involves close examination of the symptoms, detection and identification of the causal agent(s), and confirmation of pathogenicity. The objective of this study was to identify the causal agent(s) of tip rot in carrot. Fungi and bacteria were isolated from multiple carrots with tip rot symptoms and used for inoculation of healthy carrots to determine pathogenicity and also for DNA extraction, sequencing of commonly used genes for identification and barcoding genes and DNA metabarcoding. For isolation and inoculation, we developed a method allowing individual carrots to remain upright without touching each other within an incubation box. For morphological identification of causal agents, we found that a combination of methods such as isolation on potato carrot agar, disinfection of infected tissue followed by moist incubation, and inoculation followed by incubation at room temperature for 24 h, and then at 0-6°C were optimal methods for the identification of tip rot pathogens of carrot. Based on the combination of molecular and morphological identification methods, we found that tip rot of carrots is a disease complex caused by several fungi but principally Mycocentrospora acerina and Cylindrocarpon destructans. Diagnosis of postharvest diseases is often a complex problem, and this research demonstrates that a combination of methods is a useful approach. Furthermore, the study indicated that the common approach of trying to associate a disease with a single causal agent does not work for all postharvest diseases. The possibility of multiple causal agents and predisposing factors must be considered, and we should be cautious not to jump to a hasty decision.