Biografi

Jeg jobber hovedsakelig med prosjekter innen soppsjukdommer i gras og korn, med fokus på Fusarium og mykotoksiner i korn (epidemiologi, varsling og bekjempelse). Jeg har jobbet i NIBIO (tidligere Planteforsk, Bioforsk) siden 1997. I 1995 ble jeg Cand. scient. i plantefysiologi ved Universitetet i Oslo. I 2003, tok jeg doktorgrad innen plantepatologi ved NIBIO og Norges miljø- og biovitenskapelige universitet (NMBU). Jeg har jobbet på flere prosjekter med tema Fusarium og mykotoksiner, ofte med rollen som prosjektleder eller arbeidspakkeleder for NIBIOs aktiviteter. Siden 2012 har jeg koordinert alle aktiviteter innen forskning på Fusarium og mykotoksiner i NIBIO. Jeg er nestleder ved Avdeling soppsjukdommer i Divisjon for bioteknologi og plantehelse i NIBIO.
 

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High concentrations of the mycotoxin deoxynivalenol (DON), produced by Fusarium graminearum have occurred frequently in Norwegian oats recently. Early prediction of DON levels is important for farmers, authorities and the Cereal Industry. In this study, the main weather factors influencing mycotoxin accumulation were identified and two models to predict the risk of DON in oat grains in Norway were developed: (1) as a warning system for farmers to decide if and when to treat with fungicide, and (2) for authorities and industry to use at harvest to identify potential food safety problems. Oat grain samples from farmers’ fields were collected together with weather data (2004–2013). A mathematical model was developed and used to estimate phenology windows of growth stages in oats (tillering, flowering etc.). Weather summarisations were then calculated within these windows, and the Spearman rank correlation factor calculated between DON-contamination in oats at harvest and the weather summarisations for each phenological window. DON contamination was most clearly associated with the weather conditions around flowering and close to harvest. Warm, rainy and humid weather during and around flowering increased the risk of DON accumulation in oats, as did dry periods during germination/seedling growth and tillering. Prior to harvest, warm and humid weather conditions followed by cool and dry conditions were associated with a decreased risk of DON accumulation. A prediction model, including only pre-flowering weather conditions, adequately forecasted risk of DON contamination in oat, and can aid in decisions about fungicide treatments.

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During the last ten years, Norwegian cereal grain industry has experienced large challenges due to Fusarium spp. and Fusarium mycotoxin contamination of small-grained cereals. To prevent severely contaminated grain lots from entering the grain supply chain, it is important to establish surveys for the most prevalent Fusarium spp. and mycotoxins. The objective of our study was to quantify and calculate the associations between Fusarium spp. and mycotoxins prevalent in oats and spring wheat. In a 6-year period from 2004-2009, 178 grain samples of spring wheat and 289 samples of oats were collected from farmers’ fields in South East Norway. The grains were analysed for 18 different Fusarium-mycotoxins by liquid chromatography – mass spectrometry. Generally, the median mycotoxin levels were higher than reported in Norwegian studies covering previous years. The DNA content of Fusarium graminearum, Fusarium culmorum, Fusarium langsethiae, Fusarium poae and Fusarium avenaceum were determined by quantitative PCR. We identified F. graminearum as the main deoxynivalenol (DON) producer in oats and spring wheat, and F. langsethiae as the main HT-2 and T-2-toxins producer in oats. No association was observed between quantity of F. graminearum DNA and quantity of F. langsethiae DNA nor for their respective mycotoxins, in oats. F. avenaceum was one of the most prevalent Fusarium species in both oats and spring wheat. The following ranking of Fusarium species was made based on the DNA concentrations of the Fusarium spp. analysed in this survey (from high to low): F. graminearum = F. langsethiae = F. avenaceum > F. poae > F. culmorum (oats); F. graminearum = F. avenaceum > F. culmorum > F. poae = F. langsethiae (spring wheat). Our results are in agreement with recently published data indicating a shift in the relative prevalence of Fusarium species towards more F. graminearum versus F. culmorum in Norwegian oats and spring wheat.

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The proportion of Norwegian wheat used for food has varied significantly during the recent decade, mainly because of the instability of factors that are essential to baking quality (i.e. protein content and gluten functionality). During the same period, serious contamination of Fusarium spp. and mycotoxins was observed in some grain lots [1, 2]. A project was established to generate greater knowledge of the interface between gluten functionality and effects of Fusarium species and other microorganisms on Norwegian wheat quality. Instances of severe degradation of gluten proteins that resulted in an almost complete loss of gluten functionality were observed in some lots of Norwegian wheat. The degradation of the gluten appeared to be caused by exogenous proteases. Metabarcoding of fungi and bacteria in these grain lots identified fungi within the Fusarium Head Blight complex, as well as one bacterial species, as candidate species for influencing gluten functionality. Some of these candidates were inoculated on wheat during flowering [3]. Analysis of baking quality of the flour from this experiment revealed a reduced proportion of un-extractable polymeric proteins (%UPP) and severe reductions in the gluten’s resistance to stretching (RMAX) in wheat flour from plants inoculated with Fusarium graminearum. Flour from wheat inoculated with Fusarium avenaceum was generally less infested, and showed minimal or no reduction in gluten functionality and %UPP compared to flour from the F. graminearum infested samples. Flour from wheat inoculated with Michrodochium majus is yet to be analysed. References 1. Koga, S., et al., Investigating environmental factors that cause extreme gluten quality deficiency in winter wheat (Triticum aestivum L.). Acta Agriculturae Scandinavica, Section B—Soil & Plant Science, 2016. 66(3): p. 237-246. 2. Hofgaard, I., et al., Associations between Fusarium species and mycotoxins in oats and spring wheat from farmers’ fields in Norway over a six-year period. World Mycotoxin Journal, 2016. 9(3): p. 365-378. 3. Nielsen, K.A.G., Effect of microorganisms on gluten quality in wheat., in Faculty of Biosciences. 2017, Norwegian University of Life Sciences: Ås.

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High concentrations of the mycotoxins HT-2 and T-2 (HT2 + T2), primarily produced by Fusarium langsethiae, have occasionally been detected in Norwegian oat grains. In this study, we identified weather variables influencing accumulation of HT2 + T2 in Norwegian oat grains. Oat grain samples from farmers’ fields were collected together with weather data (2004–2013). Spearman rank correlation coefficients were calculated between the HT2 + T2 contamination in oats at harvest and a range of weather summarisations within estimated phenological windows of growth stages in oats (tillering, flowering etc.). Furthermore, we developed a mathematical model to predict the risk of HT2 + T2 in oat grains. Our data show that adequate predictions of the risk of HT2 + T2 in oat grains at harvest can be achieved, based upon weather data observed during the growing season. Humid and cool conditions, in addition to moderate temperatures during booting, were associated with increased HT2 + T2 accumulation in harvested oat grains, whereas warm and humid weather during stem elongation and inflorescence emergence, or cool weather and absence of rain during booting reduced the risk of HT2 + T2 accumulation. Warm and humid weather immediately after flowering increased the risk, while moderate to warm temperatures and absence of rain during dough development, reduced the risk of HT2 + T2 accumulation in oat grains. Our data indicated that HT2 + T2 contamination in oats is influenced by weather conditions both pre- and post-flowering. These findings are in contrast with a previous study examining the risk of deoxynivalenol contamination in oat reporting that toxin accumulation was mostly influenced by weather conditions from flowering onwards.

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The natural occurrence of fungi, mycotoxins and fungal metabolites was investigated in 100 samples of maize grains collected from south and southwestern Ethiopia in 2015. The maize samples were contaminated by Fusarium, Aspergillus and Penicillium species. Using liquid chromatography tandem mass spectrometry 127 secondary metabolites were analysed. Zearalenone was the most prevalent mycotoxin, occurring in about 96% of the samples. Zearalenone sulfate was the second most prevalent, present in 81% of the samples. Fumonisin B1 was detected in 70% of the samples with a mean level of 606 μg kg−1 in positive samples, while FB2, FB3 and FB4 were detected in 62%, 51% and 60% of the maize samples with mean levels of 202, 136 and 85 μg kg−1, respectively. Up to 8% of the samples were contaminated with aflatoxins, with a maximum level of aflatoxin B1 of 513 μg kg−1. Results were higher than earlier reports for maize from Ethiopia.

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The plant pathogenic fungus Fusarium langsethiae produces the highly potent mycotoxins HT-2 and T-2. Since these toxins are frequently detected at high levels in oat grain lots, they pose a considerable risk for food and feed safety in Norway, as well as in other north European countries. To reduce the risk of HT-2/T- 2-contaminated grain lots to enter the food and feed chain, it is important to identify factors that influence F. langsethiae infection and mycotoxin development in oats. However, the epidemiology of F. langsethiae is unclear. A three-year survey was performed to reveal more of the life cycle of F. langsethiae and its interactions with oats, other Fusarium species, as well as insects, mites and weeds. We searched for inoculum sources by quantifying the amount of F. langsethiae DNA in crop residues, weeds, and soil sampled from a selection of oat-fields. To be able to define the onset of infection, we analysed the amount of F. langsethiae DNA in oat plant material sampled at selected growth stages (between booting and maturation), as well as the amount of F. langsethiae DNA and HT-2 and T-2 toxins in the mature grain. We also studied the presence of possible insect- and mite vectors sampled at the selected growth stages using Berlese funnel traps. The different types of materials were also analysed for the presence F. graminearum DNA, the most important deoxynivalenol producer observed in Norwegian cereals, and which presence has shown a striking lack of correlation with the presence of F. langsethiae in oat. Results show that F. langsethiae DNA may occur in the oat plant already before heading and flowering. Some F. langsethiae DNA was observed in crop residues and weeds, though at relatively low levels. No Fusarium DNA was detected in soil samples. Of the arthropods that were associated with the collected oat plants, aphids and thrips species were dominating. Further details will be given at the meeting.

Sammendrag

High concentrations of the mycotoxin deoxynivalenol (DON), produced by Fusarium graminearum have occurred frequently in Norwegian oats recently. Early prediction of DON levels is important for farmers, authorities and the Cereal Industry. In this study, the main weather factors influencing mycotoxin accumulation were identified and two models to predict the risk of DON in oat grains in Norway were developed: (1) as a warning system for farmers to decide if and when to treat with fungicide, and (2) for authorities and industry to use at harvest to identify potential food safety problems. Oat grain samples from farmers’ fields were collected together with weather data (2004–2013). A mathematical model was developed and used to estimate phenology windows of growth stages in oats (tillering, flowering etc.). Weather summarisations were then calculated within these windows, and the Spearman rank correlation factor calculated between DON-contamination in oats at harvest and the weather summarisations for each phenological window. DON contamination was most clearly associated with the weather conditions around flowering and close to harvest. Warm, rainy and humid weather during and around flowering increased the risk of DON accumulation in oats, as did dry periods during germination/seedling growth and tillering. Prior to harvest, warm and humid weather conditions followed by cool and dry conditions were associated with a decreased risk of DON accumulation. A prediction model, including only pre-flowering weather conditions, adequately forecasted risk of DON contamination in oat, and can aid in decisions about fungicide treatments.

Sammendrag

Four field trials (spring wheat and oats) were conducted (one on clay soil, one on loam soil and two on silt soil) for three years in important cereal growing districts, to investigate the influence of tillage regimes (ploughing versus reduced tillage in either autumn or spring) and straw management (removed and retained) on plant residue amounts, weed populations, soil structural parameters and cereal yields. The effect of tillage on soil structure varied, mainly due to the short trial period. In general, the amount of small soil aggregates increased with tillage intensity. Reduced soil tillage, and in some cases spring ploughing, gave significantly higher aggregate stability than autumn ploughing, thus providing protection against erosion. However, decreasing tillage intensity increased the amounts of weeds, particularly of Poa annua on silt soil. Straw treatment only slightly affected yields, while effects of tillage varied between both year and location. Reduced tillage, compared to ploughing, gave only small yield differences on loam soil, while it was superior on clay soil and inferior on silt soil. Our results suggest that shallow spring ploughing is a good alternative to autumn ploughing, since it gave comparable yields, better protection against erosion and was nearly as effective against weeds.

Sammendrag

Over the recent decades, the Norwegian cereal industry has had major practical and financial challenges associated with the occurrence of Fusarium and mycotoxins in cereal grains. From 2011, payment reductions to farmers were implemented for oat grain lots with high levels of deoxynivalenol (DON). However, according to preliminary results by NIBIO, NMBU and Graminor, certain oat varieties with generally medium or low DON contamination, may contain high levels of HT-2 and T-2-toxins (HT2+T2). These mycotoxins, formed by Fusarium langsethiae, are considerably more toxic than DON. Resistance to F. langsethiae is not included in the variety screening in Norway. In 2016 a new project, SafeOats, was initiated. This project is led by NIBIO and is a collaboration between NIBIO, NMBU, Kimen, and the main Norwegian and Swedish breeding companies, Graminor and Lantmännen. Harper Adam University (UK) and Julius Kühn-Institut (Germany) are international collaborators. SafeOats will develop resistance screening methods in order to facilitate the phase-out of susceptible oat germplasm. Furthermore, SafeOats will give new insight into the biology of F. langsethiae and HT2+T2 accumulation in oats, and thus facilitate the choice of relevant control measures. The results from SafeOats will benefit consumers nationally and internationally by providing tools to increase the share of high quality grain into the food and feed industry. SafeOats is financed by The Foundation for Research Levy on Agricultural Products/Agricultural Agreement Research Fund/Research Council of Norway with support from the industry partners Graminor, Lantmännen, Kimen, Felleskjøpet Agri, Felleskjøpet Rogaland Agder, Fiskå Mølle Moss, Norgesmøllene and Strand Unikorn/Norgesfor.

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During the last ten years, Norwegian cereal grain industry has experienced large challenges due to Fusarium spp. and Fusarium mycotoxin contamination of small-grained cereals. To prevent severely contaminated grain lots from entering the grain supply chain, it is important to establish surveys for the most prevalent Fusarium spp. and mycotoxins. The objective of our study was to quantify and calculate the associations between Fusarium spp. and mycotoxins prevalent in oats and spring wheat. In a 6-year period from 2004-2009, 178 grain samples of spring wheat and 289 samples of oats were collected from farmers’ fields in South East Norway. The grains were analysed for 18 different Fusarium-mycotoxins by liquid chromatography – mass spectrometry. Generally, the median mycotoxin levels were higher than reported in Norwegian studies covering previous years. The DNA content of Fusarium graminearum, Fusarium culmorum, Fusarium langsethiae, Fusarium poae and Fusarium avenaceum were determined by quantitative PCR. We identified F. graminearum as the main deoxynivalenol (DON) producer in oats and spring wheat, and F. langsethiae as the main HT-2 and T-2-toxins producer in oats. No association was observed between quantity of F. graminearum DNA and quantity of F. langsethiae DNA nor for their respective mycotoxins, in oats. F. avenaceum was one of the most prevalent Fusarium species in both oats and spring wheat. The following ranking of Fusarium species was made based on the DNA concentrations of the Fusarium spp. analysed in this survey (from high to low): F. graminearum = F. langsethiae = F. avenaceum > F. poae > F. culmorum (oats); F. graminearum = F. avenaceum > F. culmorum > F. poae = F. langsethiae (spring wheat). Our results are in agreement with recently published data indicating a shift in the relative prevalence of Fusarium species towards more F. graminearum versus F. culmorum in Norwegian oats and spring wheat.

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Lack of resistance to pink snow mould (Microdochium nivale) is a major constraint for adaptation of perennial ryegrass (Lolium perenne L.) to continental regions with long-lasting snow cover at higher latitudes. Almost all investigations of genetic variation in resistance have been performed using cold acclimated plants. However, there may be variation in resistance mechanisms that are functioning independently of cold acclimation. In this study our aim was to identify candidate genes involved in such resistance mechanisms. We first characterized variation in resistance to M. nivale among non-acclimated genotypes from the Norwegian cultivar ‘Fagerlin’ based on relative regrowth and fungal quantification by real-time qPCR. One resistant and one susceptible genotype were selected for transcriptome analysis using paired-end sequencing by Illumina Hiseq 2000. Transcriptome profiles, GO enrichment and KEGG pathway analysis indicate that defense response related genes are differentially expressed between the resistant and the susceptible genotype. A significant up-regulation of defense related genes, as well as genes involved in cell wall cellulose metabolic processes and aryl-alcohol dehydrogenase (NADP+) activity, was observed in the resistant genotype. The candidate genes identified in this study might be potential molecular marker resources for breeding perennial ryegrass cultivars with improved resistance to pink snow mould.

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A glutathione (GSH) adduct of the mycotoxin 4-deoxynivalenol (DON), together with a range of related conjugates, has recently been tentatively identified by LC-MS of DON-treated wheat spikelets. In this study, we prepared samples of DON conjugated at the 10- and 13-positions with GSH, Cys, CysGly, -GluCys and N-acetylcysteine (NAC). The mixtures of conjugates were used as standards for LC-HRMS analysis of one of the DON-treated wheat spikelet samples, as well as 19 Norwegian grain samples of spring wheat and 16 grain samples of oats that were naturally-contaminated with DON at concentrations higher than 1 mg/kg. The artificially-contaminated wheat spikelets contained conjugates of GSH, CysGly and Cys coupled at the olefinic 10-position of DON, whereas the naturally-contaminated harvest-ripe grain samples contained GSH, CysGly, Cys, and NAC coupled mainly at the 13-position on the epoxy group. The identities of the conjugates were confirmed by LC-HRMS comparison with authentic standards, oxidation to the sulfoxides with hydrogen peroxide, and examination of product-ion spectra from LC-HRMS/MS analysis. No -GluCys adducts of DON were detected in any of the samples. The presence of 15-O-acetyl-DON was demonstrated for the first time in Norwegian grain. The results indicate that a small but significant proportion of DON is metabolized via the GSH-conjugation pathway in plants. To our knowledge, this is the first report of in vivo conjugation of trichothecenes via their epoxy group, which has generally been viewed as unreactive. Because conjugation at the 13-position of DON and other trichothecenes has been shown to be irreversible, this type of conjugate may prove useful as a biomarker of exposure to DON and other 12,13-epoxytrichothecenes.

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The proportion of Norwegian wheat used for food has recently been dramatically lower due to both reduced production and poor quality. Furthermore, the Norwegian milling and baking industries have experienced major challenges in utilizing Norwegian wheat due to the instability of factors, such as protein content and gluten functionality, that are of major importance for baking quality. The variation in the wheat quality can itself cause economic losses for the milling and baking industry due to uncertainty in the marketplace. In the same period as a large variation in baking quality was reported in Norwegian wheat, serious contamination of Fusarium spp. and mycotoxins were observed in some grain lots. We have revealed the severe degradation of gluten proteins in some Norwegian wheat samples leading to an almost complete loss in the gluten functionality. The degradation of the gluten appears to be caused by exogenous proteases, and was associated with the presence of Fusarium spp., and their metabolites, and other microorganisms in the wheat. Increased knowledge is needed to establish the cause of the poor gluten functionality and to develop control measures to reduce the amount of poor quality wheat entering the food value chain. In 2014, a new project was established to generate deeper knowledge in the interface between gluten functionality and effects of Fusarium spp. and other microorganism on wheat quality, and to better utilize Norwegian wheat grown in this challenging environment. A metagenomic analysis, designed to identify microorganisms associated with reduced baking quality, has been undertaken. To study the influence of the identified microorganisms and their metabolites on gluten functionality, wheat plants were inoculated with microorganisms, selected based upon the results of the metagenomics study. Fusarium species are among those microorganisms being tested.

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This paper presents peer-reviewed studies comparing the content of deoxynivalenol (DON), HT-2+T-2 toxins, zearalenone (ZEA), nivalenol (NIV), ochratoxin A (OTA) and fumonisins in cereal grains, and patulin (PAT) in apple and apple-based products, produced in organically and conventionally grown crops in temperate regions. Some of the studies are based on data from controlled field trials, however, most are farm surveys and some are food basket surveys. Almost half of the studies focused on DON in cereals. The majority of these studies found no significant difference in DON content in grain from the two farming systems, but several studies showed lower DON content in organically than in conventionally produced cereals. A number of the investigations reported low DON levels in grain, far below the EU limits for food. Many authors suggested that weather conditions, years, locations, tillage practice and crop rotation are more important for the development of DON than the type of farming. Organically produced oats contained mainly lower levels of HT-2+T-2 toxins than conventionally produced oats. Most studies on ZEA reported no differences between farming systems, or lower concentrations in organically produced grain. For the other mycotoxins in cereals, mainly low levels and no differences between the two farming systems were reported. Some studies showed higher PAT contamination in organically than in conventionally produced apple and apple products. The difference may be due to more efficient disease control in conventional orchards. It cannot be concluded that any of the two farming systems increases the risk of mycotoxin contamination. Despite no use of fungicides, an organic system appears generally able to maintain mycotoxin contamination at low levels. More systematic comparisons from scientifically controlled field trials and surveys are needed to clarify if there are differences in the risk of mycotoxin contamination between organically and conventionally produced crops.

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The plant pathogenic fungus Fusarium langsethiae produces the highly potent mycotoxins HT-2 and T-2. Since these toxins are frequently detected at high levels in oat grain lots, they pose a considerable risk for food and feed safety in Norway, as well as in other north European countries. To reduce the risk of HT-2/T- 2-contaminated grain lots to enter the food and feed chain, it is important to identify factors that influence F. langsethiae infection and mycotoxin development in oats. However, the epidemiology of F. langsethiae is unclear. A three-year survey was performed to reveal more of the life cycle of F. langsethiae and its interactions with oats, other Fusarium species, as well as insects, mites and weeds. We searched for inoculum sources by quantifying the amount of F. langsethiae DNA in weeds, crop residues, and soil, sampled from a predetermined selection of oat-fields. To be able to define the onset of infection, we analysed the amount of F. langsethiae DNA in oat plant material sampled at selected growth stages (between booting and maturation), as well as the amount of F. langsethiae DNA and HT-2 and T-2 toxins in the mature grain. We also studied the presence of possible insect- and mite vectors sampled at the selected growth stages using Berlese funnel traps. All the different types of materials were also analysed for the presence F. graminearum DNA, the most important deoxynivalenol producer observed in Norwegian cereals, and which presence has shown a striking lack of correlation with the presence F. langsethiae in oat. Preliminary results show that F. langsethiae DNA may occur in the oat plant before heading and flowering. Some F. langsethiae DNA was observed in crop residues and weeds, though at relatively low levels. More results from this work will be presented at the meeting.

Sammendrag

The plant pathogenic fungus Fusarium langsethiae produces the highly potent mycotoxins HT-2 and T-2. Since these toxins are frequently detected at high levels in oat grain lots, they pose a considerable risk for food and feed safety in Norway, as well as in other north European countries. To reduce the risk of HT-2/T- 2-contaminated grain lots to enter the food and feed chain, it is important to identify factors that influence F. langsethiae infection and mycotoxin development in oats. However, the epidemiology of F. langsethiae is unclear. A three-year survey was performed to reveal more of the life cycle of F. langsethiae and its interactions with oats, other Fusarium species, as well as insects, mites and weeds. We searched for inoculum sources by quantifying the amount of F. langsethiae DNA in weeds, crop residues, and soil, sampled from a predetermined selection of oat-fields. To be able to define the onset of infection, we analysed the amount of F. langsethiae DNA in oat plant material sampled at selected growth stages (between booting and maturation), as well as the amount of F. langsethiae DNA and HT-2 and T-2 toxins in the mature grain. We also studied the presence of possible insect- and mite vectors sampled at the selected growth stages using Berlese funnel traps. All the different types of materials were also analysed for the presence F. graminearum DNA, the most important deoxynivalenol producer observed in Norwegian cereals, and which presence has shown a striking lack of correlation with the presence F. langsethiae in oat. Preliminary results show that F. langsethiae DNA may occur in the oat plant before heading and flowering. Some F. langsethiae DNA was observed in crop residues and weeds, though at relatively low levels. More results from this work will be presented at the meeting.

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Hvilken jordarbeiding som benyttes i den enkelte kornåker påvirker blant annet avlingsmengde, kvaliteten på kornet og miljøet. I denne publikasjonen er det samlet informasjon om effekter av ulik jordarbeiding, som hjelp til korndyrkere ved vurdering av jordarbeidingsmetoder, og for myndigheter ved beslutninger om jordarbeiding i regionale miljøprogram (RMP).

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Aksfusariose er en utbredt og destruktiv sjukdom i korn som kan forårsakes av en rekke ulike sopparter innen slekta Fusarium. I tillegg til å redusere avlingsmengde, kvalitet og frøspiring, kan ulike Fusarium-arter produsere en rekke ulike soppgifter (mykotoksiner) som kan være giftige for mennesker og dyr. Fuktige værforhold i perioden rundt blomstring av kornet ser ut til å øke risikoen for angrep av Fusarium. I tillegg kan dyrkningspraksis påvirke forekomsten av aksfusariose og utvikling av mykotoksiner i kornet.

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Plogen har tradisjonelt vært viktig for å få et godt såbed, for innblanding av halmrester og gjødsel i jorda, og for god bekjemping av ugras og sjukdommer. Redusert jordarbeiding uten bruk av plogen, gir imidlertid store miljøfordeler i form av mindre erosjon og utvasking av næringsstoffer. Denne rapporten fokuserer på konsekvenser av ulik jordarbeiding på plantevernsituasjonen i korn. Basert på dagens kunnskap fra norske og internasjonale studier konkluderes det med at redusert jordarbeiding gir økt risiko for utvikling av ugras og plantesjukdommer, samt mykotoksiner. I tillegg kan redusert jordarbeiding føre til økt bruk av kjemiske plantevernmidler som glyfosat, fenoksysyrer og soppmidler. Ugraset og de fleste plantesjukdommer kan som regel bekjempes med plantevernmidler, mens Fusarium spp. og mykotoksiner bare delvis kan bekjempes av kjemiske midler. Miljørisikoen av kjemiske plantevernmidler påvirkes av egenskaper til plantevernmidlene. Redusert jordarbeiding fører til økt risiko for transport til grunnvann av fenoksysyrer og lavdosemidler (sulfonylurea-preparater). Risiko for transport til overflatevann av ugrasmidler og soppmidler er minst når åkeren ligger i stubb. Været og klimaet har stor betydning for utvikling av skadegjørerne, risiko for utvikling av mykotoksiner og utvasking av plantevernmidler. Vårpløying kan være gunstig miljømessig sett fordi det kan redusere erosjon og næringsstofftap. Samtidig gir det mindre behov for, og derfor redusert miljørisiko av, plantevernmidler enn andre typer jordarbeiding. Vårpløying egner seg derimot dårlig på stiv leirjord, det fører til større tidspress på våren og risiko for forsinka våronn og derved lavere avling.

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Gårdsvarsling gjør det mulig å beregne lokalt tilpassede plantevernvarsler ved bruk av værvarsel og radarmåling av nedbør. Vanligvis beregnes plantevernvarsler på grunnlag av data fra værstasjoner, men mange gårdsbruk ligger langt unna nærmeste målepunkt. For disse brukene vil varsler basert på værvarsler og radarmålt nedbør være et godt alternativ. Gårdsvarsler tilpasset det enkelte gårdsbruk vil derfor øke nytteverdien av varslingstjenesten innen planteskadegjørere (VIPS) for mange dyrkere.

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Aksfusariose er en kornsjukdom som kan angripe alle kornarter. Sjukdommen forårsakes av sopparter innen slekta Fusarium. Ulike Fusarium-arter kan produsere en rekke forskjellige mykotoksiner (soppgifter). Grenseverdier for innhold av enkelte mykotoksiner i korn og kornprodukter til mat og fôr er fastsatt av Mattilsynet (i henhold til EU’s regelverk). Denne dyrkningsveiledningen gir, på bakgrunn av dagens kunnskap, råd om hvordan en kan redusere risikoen for utvikling av mykotoksiner i korn.

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The effect of potential resistance inducing chemicals on disease development of Fusarium head blight was studied in winter wheat (Triticum aestivum L.). As a pre-screening test, the effect of different treatments on development of Microdochium majus (syn. Microdochium nivale var. majus) was studied in detached leaves. Based on these tests, DL-3-aminobutyric acid, Bion (benzo-(1,2,3) thiadiazole-7-carbothioic acid S-methyl ester), and a foliar fertilizer containing potassium phosphite were selected for further studies. Greenhouse-grown winter wheat was sprayed with aqueous solutions of the potential resistance inducers 7 days prior to Fusarium culmorum point inoculation of the heads. Disease development was registered as number of bleached spikelets per inoculated spike. Spraying plants with the foliar fertilizer reduced the disease severity of F. culmorum by up to 40%. A reduced disease development of M. majus was also observed in detached leaves pre-treated with the foliar fertilizer. When the foliar fertilizer was added to the growth medium, a reduced in vitro growth of M. majus and F. culmorum was observed, indicating that the effect on disease development is at least partly due to a fungistatic effect. No significant reduction in disease development was observed in wheat pre-treated with DL-3-aminobutyric acid or Bion, although these compounds tended to reduce disease development, especially when applied in combination with other potential resistance inducers. We conclude that spraying winter wheat with a solution containing potassium phosphite can reduce development of M. majus and F. culmorum.

Sammendrag

De senere årene er det registrert økt forekomst av sopparten Fusarium graminearum i norskprodusert korn. F. graminearum produserer blant annet soppgiften deoksynivalenol (DON). Korn høstet fra angrepne planter kan derfor være uegnet til mat og fôr.

Sammendrag

Aksfusariose er en utbredt og destruktiv sjukdom i korn. Korn høsta fra angrepne planter kan inneholde soppgifter (mykotoksiner) og derfor være uegnet til mat og fôr. I Fusariumprosjektet ved Bioforsk Plantehelse ønsker vi å kartlegge faktorer som kan ha betydning for angrep av aksfusariose og utvikling av mykotoksiner i kornet.

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For å kunne imøtekomma EU sine krav (som er handheva av Mattilsynet) om å redusera innhaldet av mykotoksin i korn som går til mat og for, jobbar vi på ’Fusariumprosjektet’ på Bioforsk med å etablere ein strategi for identifisering av kontaminerte kornprøver. Denne strategien går blant anna ut på å etablere ei metode for hurtigtesting av eit større antal prøver.

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Welcome Dear participants, Welcome to Norway and to the campus of the Norwegian University of Life Sciences. The organizing committee is very pleased and honoured that the meeting will be attended by close to 80 participants from 18 countries, specialized in areas ranging from molecular biology to modelling. We expect PMAC2009 to be a unique forum for an integrated perspective on plant and microbe adaptation to cold. Climate change presents a main challenge for agriculture and forestry. Scientists are asked to predict the fate of plants and microbes under new conditions. Our aim at understand the impact of climate change on plants and microbes in ?cold? environment can be approached by modelling, but no model can be better than the knowledge it is based upon. Knowledge gaps need to be filled. In this meeting, scientists in agronomy, forestry, genetics, plant physiology, plant pathology and microbiology, as well as specialists in modelling, will share new knowledge and new approaches in their respective fields, and thereby hopefully fill some of the gaps. We extend our sincere thanks to the speakers and poster holders for their positive response to our invitation to contribute at PMAC2009. And the good advices and contributions from the international committee are much appreciated. PMAC2009 could hardly have been arranged without a grant from the Norwegian Research Council. We therefore wish to express our great appreciation for this. We also wish to thank the plant breeding company Graminor for their contribution. We are looking forward to a productive and enlightening meeting during the darkest time of the year! On behalf of the local organizing committee, Anne Marte Tronsmo

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I felt finnes en rekke ulike Fusarium-arter som kan forårsake aksfusariose. Disse artene påvirker hverandre i et komplisert samspill. Dette samspillet har betydning for sykdomsutviklingen hos den enkelte kornart, og vil influere på veksten av den enkelte Fusarium-art og på mengden av de ulike mykotoksinene som blir produsert.

Sammendrag

The most important and widespread disease on golf courses is Microdochium nivale. It is a psycrotrophic fungal plant pathogen that is the main cause of biotic winter injury in grasses in the temperate and sub-arctic climates, both with and without snow cover. It is an opportunistic pathogen, with the ability to attack plants under a wide range of environmental conditions. A large variation in both host preference and aggressiveness among isolates has been documented. It is speculated that these traits as well as competition between isolates may be dependent on temperature. The fungus is spread by infected seeds and from infected plants or debris. Besides seed transmitted inoculum, it is not clear whether the primary inoculum source is wind dispersed ascospores or soilborne/plant debris borne inoculum. Wind borne ascospores has been claimed to be the main inoculum source, but perithecia are hardly observed on grasses on Norway. The aim of the present project was obtain better understanding of what is the source of primary inoculum for snow mould caused by M. nivale; to understand how inoculum of M. nivale survives from spring to fall, and from year to year, to understand how climatic conditions affects the potential inoculum by monitoring symptoms on plants, occurrence of the fungus and growth characteristics in vitro of strains sampled from snow melt and through summer and autumn. To obtain such knowledge, surveys and sampling on selected golf courses was conducted. Snow mould symptoms and the occurrence of M. nivale in leaves and stems of grasses sampled from golf greens and foregreens was reduced during the growth season. We also found that M. nivale could be isolated from locations without visible symptoms. Despite a lower isolation rate in autumn, M. nivale was again isolated in some of the originally locations, the following spring. The M. nivale isolation rate was similar from sites located on greens compared to foregreens, and from greens located at more sunny sites compared to more shadowy located greens. We conclude that this fungus seem to survive from year to year within the same locations on greens and foregreens.

Sammendrag

Microdochium nivale (syn. Microdochium nivale var. nivale) and Microdochium majus (syn. Microdochium nivale var. majus) are important pathogens which cause snow mould on grasses and winter cereals. These fungi are also able to cause leaf blotch of oat and seedling blight, foot rot and ear blight in cereals. Although no distinct differences in the host range of M. nivale and M. majus are found, indications for differences in host preferences between these fungal species have previously been discussed. The culture collection at Bioforsk contains about 250 Microdochium sp. isolated from grasses and cereals over the last 20 years. Most of the isolates collected from leaves of cereals displaying snow mould symptoms in spring, were identified as M. nivale (71 %), whereas most of the isolates collected from cereal seeds (mostly wheat) belong to the species M. majus (92 %). All, except one out of the sixty nine Microdochium sp. isolated from grass leaves were identified as M. nivale (99 %). The relatively higher incidence of M. majus vs. M. nivale on cereal seeds (mostly wheat) harvested in Norway, is in agreement with studies in UK (Parry et al. 1995). Parry et al. suggested that higher natural occurrence of M. majus (vs. M. nivale) on seeds of cereals could be partly due to the higher proportion of M. majus isolates producing perithecia and thus, a relatively higher amount of M. majus spores spreading to the ear (Parry et al. 1995). The high frequency of M. nivale (99 %) vs. M. majus on grasses collected in Norway could indicate that M. nivale is more aggressive on certain grass species. Studies in our lab indeed point towards a higher aggressiveness of M. nivale vs. M. majus on perennial ryegrass at low temperature (2?C) (Hofgaard et al 2006). However, the high incidence of M. nivale on grass leaves could also be caused by differences in temperature preferences, saprophytic ability or ability to infect certain plant parts. Isolates of M. nivale display a higher in vitro growth rate compared to isolates of M. majus at 2?C (Hofgaard et al. 2006). In conclusion, the higher natural occurrence of M. nivale vs. M. majus on turf grasses and the relatively higher aggressiveness of M. nivale on perennial ryegrass could indicate that M. nivale somehow is better adapted to infect certain grass species.

Sammendrag

The most important and widespread disease on golf courses is Microdochium nivale. Attempt to control the disease is mainly by prophylactic spraying with fungicides in fall. The aim of this project has been to understand how inoculum of M. nivale survives from spring to fall and to clarify the efficiency of selected fungicides. Snow mould symptoms and the occurrence of M. nivale in leaves and stems of grasses sampled from golf greens and foregreens was reduced during the growth season. We also found that M. nivale could be isolated from locations without visible symptoms. Despite a lower isolation rate in autumn, M. nivale was again isolated in some of the originally locations, the following spring. The M. nivale isolation rate was similar from sites located on greens compared to foregreens, and from greens located at more sunny sites compared to more shadowy located greens. We conclude that this fungus seem to survive from year to year within the same locations on greens and foregreens. A significant correlation was found between mycelial growth rate of M. nivale isolates at 2?C compared to growth at 20?C. At 20?C, a greater variation in growth rate was registered between strains isolated right after snow melt, compared to strains isolated in spring, summer, autumn or prior to snowfall. No clear picture emerged in growth rate differences between groups of M. nivale strains isolated at different time points throughout the year. Significant reduction in mycelial growth rate of M. nivale was registered on agar added low concentrations of all the fungicides tested.The products were: Acanto Prima (cyprodinil, pikoksystrobin), Amistar (azoksystrobin), Amistar duo (azoksystrobin, propikonazol), Baycor (bitertanol), Bumper (propikonazol), Comet (pyraklostrobin), Proline (protiokonazol), Rovral 75WG/Chipco Green 75WG (iprodion), Sportak EW (prokloraz), Stratego 250 EC (propikonazol, trifloksystrobin), Topsin WG (tiofanatmetyl). It was large variation among the fungicides in the effect on fungal growth rate. Sportak, Stratego and Topsin were the most efficient products; 90-100% reduction in mycelial growth rate was registered on agar added 0.1% of the fungicide concentration recommended for disease control on golf greens. Acanto Prima, Bumper, Comet and Stratego were also tested for their effect to reduce snow mould damage on golf greens. Due to severe water damage on the greens the second season, only results from one season of the fungicide field trial could be used. Acanto prima was ranked as the best product, significantly reducing winter injury on average from 21% (in control plots) to 6% in the treated plots.

Sammendrag

Målet med dette prosjektet er å utvikle metoder som kan bidra til å redusere risikoen for Fusarium-toksiner i norsk korn. I samarbeid med næringa pågår aktiviteter på to hovedområder: 1 Kartlegging av klimatiske og agronomiske forhold som påvirker angrep av Fusarium og utvikling av mykotoksiner (grunnlag for varsling), samt fokus på dyrkingsteknikk, inkludert sprøyting, som kan redusere risikoen for Fusarium-angrep/toksin-utvikling. 2 Komme fram til analysemetodikk som raskt og rimelig kan måle innhold av mykotoksiner i kornprøver (hurtigmetode) for å identifisere kornpartier med uakseptabelt høyt toksinnivå og dermed avverge at slike partier brukes til mat og fôr.

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Hovedmålsetningen til prosjektet er å redusere mengden av mykotoksiner i norsk korn. Vi ønsker blant annet å klargjøre hvordan klima og dyrkningsmessige forhold påvirker utvikling av Fusarium og mykotoksiner i havre og vårhvete. De resultatene som fremkommer i løpet av prosjektperioden vil videre brukes til å utvikle systemer for varsling ved særlig fare for Fusarium-angrep (på regionnivå, evt. gårdsnivå).

Sammendrag

The effect of plant age and cold hardening on resistance to pink snow mould caused by Microdochium nivale was studied in perennial ryegrass. Resistance to M. nivale was estimated as relative regrowth after inoculation and incubation under artificial snow cover at 2 degrees C. Resistance increased with increasing plant age. Cold hardened and unhardened plants of the same age displayed identical resistance. Preliminary studies indicate that expression of genes coding for the PR proteins chitinase and PR-1a increased during incubation of inoculated perennial ryegrass, but no clear difference in expression of these genes was found between plants of different ages, or in hardened versus unhardened plants.

Sammendrag

Fusarium-toksiner i korn utgjør en helserisiko for mennesker og dyr, og fra 2006 har Mattilsynet fastsatt grenseverdier for innhold av noen slike toksiner i korn. Denne utgivelsen av Bioforsk TEMA omtaler dyrkingsforhold som har betydning for angrep av Fusarium og utvikling av toksiner i korn. På side 3 er det vist en tabell for vurdering av risiko for utvikling av Fusarium-toksiner i vekstsesongen.

Sammendrag

Development of Fusarium head blight (FHB) was studied in winter wheat pre-treated with potential defence activators. Several chemicals were pre-screened for their capacity to reduce development of Microdochium nivale in a detached leaf assay. Selected compounds were further tested for their capacity to reduce Fusarium culmorum development in heads of winter wheat in greenhouse and field experiments. In the detached leaf assay, leaves from plants pre-treated with a foliar fertilizer displayed reduced disease development compared to untreated control. A significantly reduced disease development of FHB in plants pre-treated with the foliar fertilizer was also registered in the greenhouse and field experiments. In the field experiment, harvested grainsfrom plants treated with the foliar fertilizer had up to 75% reduction in Fusarium infected seeds compared to grains from non-treated plants.

Sammendrag

Wintering ability in the field and resistance to different winter-stress factors under controlled environmental conditions were studied in a full-sib family of perennial ryegrass (Lolium perenne L.). Significant variation in tolerance to freezing and ice encasement, resistance to pink snow mould (Microdochium nivale) and also in winter survival and spring growth were found between the different genotypes. No strong correlations were found between the resistances to the different stress factors. These results indicate that resistance to different winter-stress factors is controlled by separate genes in perennial ryegrass. A low but significant positive correlation was found between spring growth of plants in the field after the first winter and both freezing tolerance and M. nivale resistance measured in controlled environments. Cold hardening seemed to influence freezing tolerance and M. nivale resistance differently in the different genotypes, since no distinct correlation in tolerance to freezing or resistance to M. nivale was found between unhardened and hardened plants. Tolerance or resistance to most of the winter stress factors measured was positively correlated with plant size.

Sammendrag

The effect of cold acclimation and defence activators on snow mould resistance and expression of pathogenesis-related (PR-) genes were investigated in winter cereals and perennial ryegrass. Cold acclimation, known to induce snow mould resistance, had apotentiating effect on snow mould-induced PR-gene expression in winter wheat. Chitosan treatment induced chitinase expression and in some cases also snow mould resistance in winter wheat. Bion treatment reduced snow mould resistance in perennial ryegrass.