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.
2017
Authors
Leif Sundheim Daniel Flø Micael Wendell Guro Brodal Åshild Ergon Christer Magnusson Arild Sletten Halvor Solheim Anne Marte Tronsmo Bjørn Økland Trond RafossAbstract
No abstract has been registered
Abstract
Introduction and purpose: The ability of apple rootstocks to become infected by Neonectria ditissima, the cause of European canker, was studied over two years. Materials and methods: Rootstocks B9 and M9 with a size suitable for grafting (6-10 mm stem diameter, termed rootstocks), and smaller sized rootstocks (<5 mm stem diameter, termed transplants) of B9, M9, M26, MM106 and Antonovka were inoculated with N. ditissima at different times, either with contaminated map pins or with spore suspensions. In addition, the rootstocks were either defeathered (side shoots removed), topped (top shoot headed) or both, to create wounds that would normally occur during propagation, while wounds on transplants were made by removing leaves. Results and discussion: One month after inoculation, slightly sunken canker lesions had developed around the inoculation points of the map pins or wounds. No lesions developed on the non-inoculated controls. Map pin inoculation resulted in 30% to 89% infection and spore suspension sprayed on wounds from 5% to 45% infection. When the cankered areas were split open, brown lesions with necrotic tissue due to infection by N. ditissima appeared. The transplants of M9, M26 and MM106 inoculated with contaminated map pins in 2014 developed necrosis on 40% to 67% of the plants, but there were no differences in the incidence or severity among the different types. On the transplants of B9, Antonovka and M9 inoculated in 2015, there was more necrosis on B9 (42%) than on Antonovka (11%) and more sporulating lesions on B9 (29%) than on M9 (9%) or on Antonovka (4%). Conclusion: It can be concluded that rootstocks used for apple trees may become infected by N. ditissima, and wounds should thus be protected during propagation.
Abstract
Production of inoculum of Colletotrichum acutatum from both previously infected and overwintered tissue, as well as newly developed plant tissue of sour cherry (Prunus cerasus), was studied in southern Norway. Plant parts were sampled from commercial, private, or research orchards, and incubated for 2 to 14 days (time depended on tissue type) in saturated air at 20°C. In early spring, abundant sporulation was found on scales of overwintered buds and shoots. A mean of 35% infected buds in four cultivars was observed, with a maximum of 72% of the buds infected in one of the samples. Over 3 years, the seasonal production of overwintered fruit and peduncles of cv. Fanal infected the previous year was investigated. In all three years, the infected plant material was placed in the trees throughout the winter and the following growing season; in two of the years, fruit and peduncles were also placed on the ground in the autumn or the following spring. Old fruit and peduncles formed conidia throughout the season, with a peak in May and June. Spore numbers declined over the season, but the decline was more rapid for plant material on the ground than in the trees. On average over 2 years, 68.7, 24.0, or 7.3% of the inoculum came from fruit placed in the trees, placed on the ground in spring, or placed on the ground the preceding autumn, respectively. The number of fruit and peduncles attached to the trees in a planting of cv. Hardangerkirsebær was followed from February to July one year, and although there was a decline over time, fruit and/or their peduncles were still attached in substantial numbers in July, thus illustrating their potential as sources of inoculum. In observations over 2 years in a heavily infected orchard of cv. Stevnsbær, 75 and 47% of flowers and newly emerged fruit, respectively, were infected. Artificially inoculated flowers and fruit produced conidia until harvest, with a peak in mid-July. It may be concluded that previously infected and overwintered, as well as newly emerged tissue of sour cherry, may serve as sources of inoculum of C. acutatum throughout the growing season.
Abstract
No abstract has been registered
Authors
John P. Clarkson Rachel J. Warmington Peter G. Walley Matthew Denton-Giles Martin J. Barbetti Guro Brodal Berit NordskogAbstract
Sclerotinia species are important fungal pathogens of a wide range of crops and wild host plants. While the biology and population structure of Sclerotinia sclerotiorum has been well-studied, little information is available for the related species S. subarctica. In this study, Sclerotinia isolates were collected from different crop plants and the wild host Ranuculus ficaria (meadow buttercup) in England, Scotland, and Norway to determine the incidence of Sclerotinia subarctica and examine the population structure of this pathogen for the first time. Incidence was very low in England, comprising only 4.3% of isolates while moderate and high incidence of S. subarctica was identified in Scotland and Norway, comprising 18.3 and 48.0% of isolates respectively. Characterization with eight microsatellite markers identified 75 haplotypes within a total of 157 isolates over the three countries with a few haplotypes in Scotland and Norway sampled at a higher frequency than the rest across multiple locations and host plants. In total, eight microsatellite haplotypes were shared between Scotland and Norway while none were shared with England. Bayesian and principal component analyses revealed common ancestry and clustering of Scottish and Norwegian S. subarctica isolates while English isolates were assigned to a separate population cluster and exhibited low diversity indicative of isolation. Population structure was also examined for S. sclerotiorum isolates from England, Scotland, Norway, and Australia using microsatellite data, including some from a previous study in England. In total, 484 haplotypes were identified within 800 S. sclerotiorum isolates with just 15 shared between England and Scotland and none shared between any other countries. Bayesian and principal component analyses revealed a common ancestry and clustering of the English and Scottish isolates while Norwegian and Australian isolates were assigned to separate clusters. Furthermore, sequencing part of the intergenic spacer (IGS) region of the rRNA gene resulted in 26 IGS haplotypes within 870 S. sclerotiorum isolates, nine of which had not been previously identified and two of which were also widely distributed across different countries. S. subarctica therefore has a multiclonal population structure similar to S. sclerotiorum, but has a different ancestry and distribution across England, Scotland, and Norway.
Abstract
We present the complete genome sequence of Luteibacter rhizovicinus type strain LJ96T, a yellow-pigmented gammaproteobacterium isolated from the rhizosphere of barley (Hordeum vulgare) Johansen et al. (2005) , a species with numerous potential applications. The genome sequence was deposited to NCBI GenBank with the accession number CP017480.
Abstract
Ash dieback, caused by the ascomycete Hymenoscyphus fraxineus, was first observed in the eastern and southernmost Norway in 2008. Based on the age of stem bark lesions, it was concluded that the fungus had arrived to the region no later than 2006. Since 2008 the annual spread of the disease northwards along the west coast of Norway has been monitored. The registration was done each year during early summer around a disease frontier recorded in the previous year. The occurrence of necrotic bark lesions in the previous-year shoots and dieback of these shoots, and isolation of H. fraxineus from the discoloured wood associated with necrotic bark lesions were used as signs of ash dieback. These records indicate an annual spread of ash dieback in the range between 25 km and 78 km, and a mean annual spread of 51 km. The cause of the spread is discussed.
Authors
Leif Sundheim Inger Therese L. Lillegaard Christiane Kruse Fæste Anne Lise Brantsæter Guro Brodal Gunnar Sundstøl EriksenAbstract
Deoxynivalenol (DON) is the most common mycotoxin in Norwegian cereals, and DON is detected in most samples of crude cereal grain and cereal food commodities such as flour, bran, and oat flakes. The Norwegian Scientific Committee for Food Safety assessed the risk for adverse effects of deoxynivalenol (DON) in different age groups of the domestic population. This review presents the main results from the risk assessment, supplemented with some recently published data. Impairment of the immune system together with reduced feed intake and weight gain are the critical effects of DON in experimental animals on which the current tolerable daily intake was established. Based on food consumption and occurrence data, the mean exposure to DON in years with low and high levels of DON in the flour, respectively, were in the range of or up to two times the Tolerable Daily Intake (TDI) in 1-year-old infants and 2-year-old children. In years with high mean DON concentration, the high (95th-percentile) exposure exceeded the TDI by up to 3.5 times in 1-, 2- , 4-, and 9-year-old children. The assessment concluded that exceeding the TDI in infants and children is of concern. The estimated dietary DON intakes in adolescent and adult populations are in the range of the TDI or below, and are not a health concern. Acute human exposure to DON is not of concern in any age group.
Authors
Leif Sundheim Inger Therese L. Lillegaard Christiane Kruse Fæste Anne Lise Brantsæter Guro Brodal Gunnar Sundstøl EriksenAbstract
No abstract has been registered
Abstract
The impact of Delphinella shoot blight (Delphinella abietis) and Grovesiella canker (Grovesiella abieticola) on subalpine (Abies lasiocarpa) and corkbark fir (A. lasiocarpa var. arizonica) in a provenance trial in Idaho (ID) was evaluated in 2013. Both pathogens were previously reported from North America on fir species. D. abietis had been found on subalpine fir in USA, but not in ID, and G. abieticola on grand fir (Abies grandis) in ID, but not on subalpine or corkbark fir. D. abietis kills current-year needles and in severe cases buds and shoots, and G. abieticola results in dead shoots and branches and can eventually kill whole trees. Significant differences between provenances in susceptibility to D. abietis and G. abieticola were observed in the provenance trial in ID. In general, subalpine fir was more susceptible to both diseases than corkbark fir. In 2013, D. abietis was also found on subalpine fir in the Puget Sound area of Washington State and G. abieticola was seen on white fir (Abies concolor), but neither disease was detected in native stands of subalpine fir in Washington State. Morphological features of both fungi were described from samples collected in the provenance trial in ID in May 2016.