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.
2023
Abstract
No abstract has been registered
Authors
Arne Stensvand Nan-Yi Wang Vinh Hong Le Claudio Dias Da Silva Jr Belachew Asalf Tadesse Chloé Grieu William W. Turechek Natalia A. PeresAbstract
Powdery mildew, caused by the ascomycete Podosphaera aphanis, is an important disease of strawberry. A slightly modified version of a method using steam thermotherapy to rid diseases and pests from strawberry transplants was tested against strawberry powdery mildew. Experiments took place in Norway and Florida, with potted strawberry plants heavily infected with the fungus. Aerated steam treatments of the plants were carried out as follows: a pre-treatment with steaming at 37 °C for 1 h was followed by 1 h at ambient temperature before plants were exposed to steaming at 40, 42, or 44 °C for 2 or 4 h in Norway and 44 °C for 4 h in Florida. Following steaming, plants from the different treatments and the untreated control were kept apart and protected from outside contamination of powdery mildew by growing them in closed containers with over-pressure. On steamed plants, hyphae of P. aphanis were dead and without any new spore formation after treatments, independent of temperature or exposure time; however, up to 99% of the area infected with powdery mildew prior to treatments contained actively sporulating lesions on non-steamed plants. None of the new leaves formed after steaming had powdery mildew, whereas more than half of the new leaves on non-treated plants were infected by P. aphanis. This investigation clearly indicates that steam thermotherapy can eradicate powdery mildew from strawberry transplants, and this can be achieved at lower temperatures and exposure times than previously reported for other pathogens.
Abstract
No abstract has been registered
Authors
Ingerd Skow Hofgaard Guro Brodal Heidi Udnes Aamot Marit Almvik Aina Lundon Russenes Morten Lillemo Simon Graham EdwardsAbstract
Oat harvested from plants infested with plant pathogenic fungi within the Fusarium head blight (FHB) complex may sometimes contain high levels of mycotoxins, which makes the grain unsuitable for food and feed. Fusarium graminearum, a deoxynivalenol (DON) producer, and Fusarium langsethiae, a T-2 toxin (T2) and HT-2 toxin (HT2) producer, are commonly occurring in Norwegian oats. We have analysed grains of Nordic oat varieties and breeding lines for the content of mycotoxins and DNA of Fusarium species belonging to the FHB disease complex (Hofgaard et al. 2022). The grains were harvested from field trials located in South-East Norway in the years 2011-2020. The ranking of oat varieties according to HT2+T2 levels corresponded with the ranking according to the DNA levels of F. langsethiae. However, this ranking did not resemble the ranking for DON and F. graminearum DNA. Our results implies that a moderate resistance to DON producers does not guarantee a moderate resistance to HT2+T2 producers. Separate tests are therefore necessary to determine the resistance towards DON and HT2+T2 producers in oats. This creates practical challenges for the screening of FHB resistance in oats as todays’ screening focuses on resistance to F. graminearum and DON. We identified oat varieties with generally low levels of both mycotoxins and FHB pathogens which should be promoted to mitigate mycotoxin risk in Norwegian oats.
Authors
Ingerd Skow Hofgaard Heidi Udnes Aamot Till Seehusen Marit Almvik Guro Brodal Ruth Dill-Macky Simon Graham EdwardsAbstract
In Norway, Fusarium diseases and associated mycotoxin contamination in spring oats occasionally cause problems for growers, livestock producers and the food and feed industries. Besides weather factors, such as rainfall and temperature in the critical periods around flowering and before harvest, inoculum production and disease development are influenced by agricultural practices. The occurrence of Fusarium graminearum and DON in oat grain lots do not generally correlate with that of Fusarium langsethiae and HT-2/T-2-toxins. Therefore, to develop a robust disease management strategy, there is a need to reveal the influence of weather and agricultural practice on disease development in oats for both these fungal species. Through various research projects NIBIO researchers have performed field trials to study the effects of straw management, tillage practice, cultivar, and chemical and biological control treatments on the development of Fusarium spp. and mycotoxins in oats. In particular we have investigated whether the amount of straw residues and tillage practice influences the survival of Fusarium spp. in residues, and the subsequent Fusarium spp. infection of the harvested grains. In addition, Fusarium spp. DNA and mycotoxin content (DON and HT-2/T-2) have been analysed in oats from current official cultivar trials. This work has been a collaboration between NIBIO and the Norwegian Agricultural Extension Service. Results will be presented on the Fusarium spp. and mycotoxin contamination of grains harvested from oats grown under various agricultural practices. High incidence of Fusarium avenaceum are often observed in harvested grains as well as straw residues. Fusarium graminearum is also commonly detected. Despite the high concentrations of F. langsethiae DNA and HT-2/T-2 toxins sometimes recorded in oat grain, only low levels of F. langsethiae have been detected in crop residues and air samples. We speculate that the life cycle of F. langsethiae differs from those of F. graminearum and F. avenaceum with regards to survival, inoculum production and dispersal.
Authors
Britt Puidet Romain Mabon Michele Guibert Riinu Kiiker Kaire Loit Vinh Hong Le Håvard Eikemo Pauline Dewaegeneire Guillaume Saubeau Catherine Chatot Frédérique Aurousseau David E. L. Cooke Alison K. Lees Isaac K. Abuley Jens G. Hansen Roselyne Corbière Melen Leclerc Neda Najdabbasi Didier AndrivonAbstract
Since the mid-2010s, Phytophthora infestans clones that have been dominant in Western Europe from the beginning of the 21st century, for example, EU_13_A2, EU_6_A1 and EU_1_A1, are being replaced by several other emerging clones, including EU_37_A2. The objective of this study was to determine whether the main drivers for the success of EU_37_A2 in Western Europe are associated with decreased fungicide sensitivity, increased virulence and/or aggressiveness. Axenic P. infestans cultures were sampled in the 2016 and 2017 growing seasons from potato crops in France and the United Kingdom. Amongst these, four genotypes were identified: EU_37_A2, EU_13_A2, EU_1_A1 and EU_6_A1. Although a wide range of fluazinam sensitivity was found amongst individual isolates, clonal lines EU_13_A2 and EU_37_A2 showed decreased sensitivity to fluazinam. EU_37_A2 overcame the R5 differential cultivar more often than isolates of EU_1_A1 or EU_6_A1. However, this does not explain the competitive advantage of EU_37_A2 over the virulent EU_13_A2. The fittest genotype, as measured by aggressiveness under controlled conditions, was EU_6_A1, followed by EU_37_A2, EU_13_A2 and then EU_1_A1. EU_37_A2 isolates also showed a shorter latent period than either EU_6_A1 or EU_13_A2, which could favour its long-term persistence. Overall, the data suggest that the emergence of EU_37_A2 in Western Europe was driven by its resistance to a then-major fungicide and shorter generation time. This conclusion is further supported by the fact that EU_37_A2 emergence was slowed by the progressive reduction in the use of fluazinam as a single active ingredient in the years following its initial detection.
Abstract
Carrot is the main field vegetable in Norway and is stored at 0-1°C for up to 8 months. In long-stored carrots, postharvest diseases are problematic. Better knowledge of the causal agents of postharvest diseases can help producers apply appropriate control measures to reduce carrot loss and waste. The objectives of this study were to determine the extent of the tip rot problem and the prevalence of other storage diseases of carrots in different regions in Norway. The study was conducted from 2019 to 2021 by collecting carrots from 16 commercial cold storages, representing four regions. From each storage, representative carrots were randomly sampled, washed, and sorted into different disease categories and healthy carrots. Representative samples from each category were further analyzed in the NIBIO laboratory to identify the causal agent(s) and confirm the disease. Causal agent(s) were identified by symptom and sign description, microscopy and when necessary, DNA sequencing. One or more pathogens were identified from each symptomatic carrot. The incidence of postharvest diseases significantly varied among regions. Taking all years and regions together, only 42% of the carrots were healthy. In other words, 58% of the carrots were with one or more diseases, representing a waste due to diseases alone. Tip rot alone contributed to about 30% of the postharvest loss. Our results indicate that the burden of postharvest diseases of carrots is increasing. This includes diseases like tip rot disease complex, Cylindrocarpon root rot and cavity spot. The results are useful to direct research investigation of the most problematic diseases. Most of the post-harvest diseases of carrots are the result of latent infections that occur in the field, and stress during handling, storage, and processing operations. Hence, postharvest disease control measures should consider the pre-and postharvest predisposing factors of carrots for storage rot.
Authors
Theresa Weigl Ingunn Øvsthus Jorunn Børve Hanne Larsen Carl Gunnar Fossdal Siv Fagertun RembergAbstract
No abstract has been registered
Authors
Theresa Weigl Ingunn Øvsthus Hanne Larsen Carl Gunnar Fossdal Jorunn Børve Siv Fagertun RembergAbstract
No abstract has been registered
Abstract
No abstract has been registered