Biografi

Jeg er forsker innen potet og grønnsaker. Jeg arbeider innenfor fagområdene lagring, postharvest, produktkvalitet, plantefysiologi og plantepatologi.

 

Utdanning:

2010-2016: PhD. Norwegian University of Life Science
2008-2010: Cand. Agro, Københavns Universitet
2004-2007: Bachelor i naturressourcer, Københavns Universitet

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Sammendrag

The maturity stage of carrot and the temperature strategy during storage are essential factors in maintaining storage quality during long-term storage. The aim of the study was to examine the effect of maturity and storage strategy on storage quality in different cultivars of carrot (Daucus carota subsp. sativus). Two cultivars, ‘Nominator’ and ‘Romance’, harvested at three different maturity levels were stored with different temperature strategies in small-scale experimental stores. The different maturity levels were obtained by different sowing dates. The study was conducted over 2 years and storage seasons in 2019-2020 and 2020-2021. The carrots were stored with three different temperature strategies with stable temperature at 0, 2 or 0°C interrupted with intervals of 2 weeks with 4°C in February and in March. After six-months storage we found that weight loss was higher (7.8%) after storage when the temperature was not stable during storage (fluctuations up to 4°C in February and March) than at stable temperatures at 0 or 2°C. The number of healthy roots after storage was highest in the most mature carrots (91%) while there were less healthy roots in the least mature roots (85%) (P<0.05). Diseases detected after storage were gray mold (Botrytis cinerea), liquorice rot (Mycocentrospora acerina), tip rot, crater rot (Fibularhizoctonia carotae), Fusarium rot (Fusarium spp.) and cavity spot (Pythium spp.). There was significantly more liquorice rot in Nominator (1.9%) than in Romance (0.6%). There was more tip rot in the least mature carrots (3.3%) compared to the other two maturity levels (1.3 and 1.5%).

Sammendrag

The resilience of global food security is a critical concern. Facing limited access to land and potential disruption of the food markets, alternative, scalable, and efficient production systems are needed as a complementary buffer for maintenance of food production integrity. The purpose of this study was to introduce an alternative hydroponic potato growing system where potatoes are grown in bare wood fiber as a growing medium. A system utilizing drip irrigation and plastic bags as containers was tested for three different types of wood fiber, two cultivars and two fertigation strategies. Implementation of the system resulted in ~300% higher tuber production when compared to the local conventional farming. Mineral composition of the tubers obtained from hydroponic system was similar to the composition of tubers grown in the field and revealed potential for biofortification. In addition, a fertigation strategy where the two application points were separated across the root zone resulted in tubers with dry matter content comparable to the potatoes grown in soil. The recyclability, reusability, and simplicity of this solution may encourage its application for improving security of food production in selected areas of the world as well as its utilization in urban agriculture.

Sammendrag

In the Nordic countries, ice encasement of golf greens and agricultural grass fields under sunlight heat often leads to grass death due to oxygen depletion and accumulation of carbon dioxide and metabolites from anaerobic respiration under the ice layer. The phenomenon is termed ‘isbrann’ in Norwegian and it is a severe type of winter damage that may also affect germination and growth after reseeding. We have employed soil water metabolome analyses to differentiate and identify small, water-soluble metabolites produced in ice-encased grass for a better understanding of how ice and anoxic soils might affect grass plants.

Sammendrag

Temperature and humidity were measured in 28 vegetable stores and corelated to quality of stored vegetable through two storage seasons. The vegetables swede, carrot and celeriac were grown at one site within each of the four regions in Norway ROG, MID, INN and OSL, respectively. After harvesting, the vegetables were weighed and visually assessed for any injuries or diseases and stored in different stores within the same region as grown. Four bags dug down in four storage bins in each store. Temperature and humidity were logged in each bag as well as on the top of each bin and on wall of the storage. In general, we found significant differences in the storage quality between the different storages as well as between regions. Correlating data on quality with temperature data shows for carrot a tendency to an increase in the proportion of fresh roots and reduction in incidence of tip-rot by an increased average temperature during the first two weeks of storage. This corresponds to results from tested various wound healing treatments. An increase in accumulated temperature during the storage period showed a tendency to increase the emergence of tip-rot and reduce the proportion of fresh roots. For celeriac, the effect of temperature varied between years, possibly due to a large difference in quality in the two test years, and it was difficult to draw any conclusion. In swede, the results suggest that a decrease in temperature in the first two weeks of storage increased the risk of the symptom shown as black veins in the phloem. Nutrient status was found to be a possibly predisposing factor for reduced storage quality in celeriac. Balance of boron (B) to calcium (Ca) and zinc (Zn) were studied in two sites. Highest incidence of brown spots and lowest proportion of fresh roots following storage was found in celeriac with the lowest Ca/B ratio in leaves, lowest content of Zn in the leaves and roots and lowest soil pH.

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Sammendrag

The objective of SCANGREEN 2019-22 was to find species, varieties and seed blends/mixtures of Agrostis, Festuca, Poa and Lolium that are suited for pesticide-free management of putting greens in the two major climatic zones of the Nordic countries and in the northern USA. The four test sites in the Nordic countries were Reykjavik GC, Iceland and NIBIO Apelsvoll in the the northern zone, and NIBIO Landvik, Norway and Smørum GC, Denmark in the southern zone. The two US test sites were located at Troll Turfgrass Research Facility in Massachusetts and at University of Minnesota. The trials included 30 candidate varieties representing eight different species and subspecies from 13 different seed companies/representatives, and three seed mixtures of red fescue and colonial and creeping bentgrass, a seed mixture of creeping bentgrass and perennial ryegrass and a seed blend of red fescue. Monthly evaluations of overall impression, tiller density, winter hardiness, disease and weed coverage etc., were done from three weeks after sowing in June-September 2019 until October 2022. The trial at Smørum GC was established in May 2021. The trials were established according to a split-plot design with three blocks (replicates), species on main plots and varieties on subplots. The experimental greens were mown three times per week – Monday, Wednesday, and Friday and deficit-irrigated to 80% of field capacity three to four times per week in periods without sufficient natural rainfall. Fertilizer (mean N–P–K ratio, 100–22–74) was given as completely balanced compound fertilizers every second week. Each experimental green was divided in different management levels: High and low fertilizer rate and high and low mowing. The two fertilizer rates were 10 and 17 g N m−2 yr−1 and the two mowing heights were 3 and 5 mm. Mixtures were managed at both regimes. There was no use of pesticides or plant growth regulators in any of the trials.

Sammendrag

Acrylamide has become an important measure when looking at profitability and sustainability in the potato processing industry. Acrylamide is a possible carcinogenic which is formed in starchy foods during high-temperature cooking processes. Crisps and French fries made from processing potatoes are consumed by people of all ages and therefore the pressure on the industry has been large to reduce the acrylamide levels. In the ongoing project POTETFRIT (2019-2022), the aim is to reduce acrylamide content and improve product quality, profitability and sustainability in the production of Norwegian crisps and French fries. The aim will be reached through new knowledge about the interaction between potato quality and storage conditions. The effect of different temperature strategies including cold storage (5 ⁰C) and reconditioning at 15 ⁰C was tested in eight different varieties (Lady Claire, Kiebitz, Pirol, Lady Britta, Peik, Innovator, Zorba and Gullflaks). The importance of elevated CO2 levels in the potato store on product quality and acrylamide content, was studied in the same potato varieties and in tubers with different maturity levels. Storage conditions in 29 commercial potato stores was also studied, with attention to temperature conditions and CO2 levels in different stages of the storage season. The effect of different ventilation strategies was also studied. So far results show that the varieties L. Claire, Kiebitz and Gullflaks can be stored at low temperature levels without developing high sugar and acrylamide levels and dark fry colour and at the same time keeping sprouting at a low level. In the CO2 trials, none of the varieties tested showed elevated sugar and acrylamide levels when exposed to high CO2 levels (15000 ppm) and also in the commercial stores there was no correlation between high CO2 and high sugar levels.

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Sammendrag

Dette prosjektet har hatt fokus på lagringsforholdene for potet til fritering, og på å redusere økningen i mengde akrylamid som naturlig skjer på lager. Innhold av akrylamid er en viktig faktor for lønnsomhet og bærekraft i produksjonen av friterte potetprodukter. Akrylamid dannes ved sterk oppvarming av stivelsesholdig mat og er knyttet til utvikling av kreft. Chips og pommes frites konsumeres av alle aldersgrupper, og det har derfor vært stort press på potetindustrien for å senke nivåene. Målet med prosjektet var å oppnå bedre produktkvalitet, lavere akrylamidinnhold og en mer lønnsom og bærekraftig produksjon av norsk chips og pommes frites. Målet skulle nås gjennom kunnskap om samspillet mellom råvarekvalitet og lagringsforhold. Acrylamide has become an important measure when looking at profitability and sustainability in the potato processing industry. Acrylamide is a possible carcinogenic which is formed in starchy foods during high-temperature cooking processes. Crisps and French fries are consumed by people of all ages and therefore the pressure on the industry has been large to reduce the levels. The aim of the project was to reduce acrylamide content and improve product quality profitability and sustainability in the production of crisps and French fries. Knowledge about the interaction between potato quality and storage conditions were important measures. The importance of elevated CO2 levels on product quality and acrylamide content, was studied.

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Sammendrag

Compact and healthy seedlings of Brassica increase the crop production and improve vegetable quality. Different climatic conditions and extensive light can cause young plants to become elongated and spindly. We investigated the effects of end-of-day (EOD) treatment on plant height (cm) of the seedlings of three cultivars of each of the following species: cauliflower (‘Delfino’, ‘Freedom’ and ‘Momentum’), broccoli (‘Achilles’, ‘Ironman’ and ‘Steel’), Brussels sprouts (‘Gladius’, ‘Brigitte’ and ‘Maximus’) and swede (‘Vigod’, ‘Vige’ and ‘Neve’) using red light (RL) with wavelength of 600 nm and intensity of 10 μmol m2 s‑1 as a supplement to natural light. All seedlings were planted in an experimental field. Yield of the mentioned species and vitamin C content were measured after harvest. Night EOD treatment resulted in 7% shorter and more compact plants in broccoli (p=0.04). There were yield differences (31-44%) among cultivars within the cauliflower (p=0.001), broccoli (p=0.01) and Brussels sprouts (p=0.001). There were significant differences in vitamin C content among cultivars in all four Brassica species (p<0.01). This study provides new information about the effect of night break treatment with red light on seedling length in broccoli, yield differences in cultivars of cauliflower, broccoli and Brussels sprouts and on vitamin C content in different cultivars of four studied Brassica species.

Sammendrag

Potato contributes highly to the global food security. It is predicted that the production of this crop will be negatively affected by future climatic changes. Application of hydroponics for table potato production can mitigate crop loss in highly vulnerable regions. A preliminary small-scale case-study was performed to test theoretical perspectives of hydroponic production of table potatoes in wood fiber by comparing different fiber types and fertigation strategies. Potatoes were also grown in the field to obtain a reference control. Hydroponic production of potato in a stand-alone wood fiber resulted in ca. 200% higher yield, when compared to standard soil cultivation. However, the quality of the tubers was slightly reduced (lower dry matter content). Productivity of table potatoes was affected by the growing medium and fertigation strategy. Production of potatoes in wood fiber is possible and, in the future, might complement the conventional production systems, or even become an important alternative in locations where in-field cultivation is not possible. Nevertheless, the effect of wood fiber properties and the applied fertigation strategy on yield potential and tuber quality should be further studied. Optimization of these factors will be a topic of a following full-scale research.

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Sammendrag

Seed mixtures with a nurse grass that germinates quickly at low soil temperatures can be an option for faster establishment of Agrostis stolonifera (AS) putting greens after winter damage. From 2015 to 2018 Poa trivialis (PT) ‘Dark Horse’ and Lolium perenne (LP) ‘Chardin’ were evaluated as nurse grasses in comparison with pure AS ‘Independence’ at two experimental sites in each of the two major climatic zones of the Nordic countries. Poa annua (PA) ‘Two‐Putt’ was also included as a nurse grass in the northern zone. As an overall trend, establishment was faster with AS+LP than with AS+PT and AS+PA, which in turn had faster establishment than pure AS. In the northern zone, AS+PT produced better turf quality than pure AS in the seeding year and year after and tended to be superior even on average for the entire trial period (mean value 6.0 vs. 5.8 for pure AS, 5.3 for AS+LP, and 4.6 for AS+PA; scale 1–9 where 9 is the highest quality). In the same zone, AS+PT also suffered less overall winter damage than the other combinations and was less infected with microdochium patch than pure AS. In the southern zone, PT and especially LP were far more persistent than in the northern zone and compromised turfgrass quality compared with pure AS. In conclusion, we recommend PT as a nurse grass for faster establishment of AS putting in the northern zone, but not in the southern zone where AS should rather be seeded in a pure stand.

Sammendrag

This research aimed to determine if creeping bentgrass (Agrostis stolonifera L.) can be used as an alternative to colonial bentgrass (Agrostis capillaris L.) in a mixture with red fescue [equal rates of Chewings fescue (Festuca rubra ssp. commutata Gaud.) and slender creeping red fescue (Festuca rubra ssp. littoralis [G. Mey.] Auquier)] on Nordic golf greens managed without pesticides. The two mixtures were compared in two experiments: Experiment 1 under the creeping bentgrass management regime (mowing height, 3 mm; fertilization, 15 g N m−2 yr−1) and Experiment 2 under the red fescue management regime (5 mm and 10 g N m−2 yr−1) at three sites during 2015–2018. A seed mixture of red fescue and velvet bentgrass (Agrostis canina L.) was included in Experiment 2 only. The results showed that red fescue plus creeping bentgrass produced greens of equal turfgrass quality and with less Microdochium patch than red fescue plus colonial bentgrass under both regimes. In Experiment 2, red fescue plus velvet bentgrass resulted in higher turfgrass quality than the other mixtures but was more susceptible to Microdochium patch than red fescue plus creeping bentgrass. Tiller counts in the mixed plots at Landvik showed that red fescue was not outcompeted by bentgrass in any of the mixtures and that it was easier to manipulate the balance between red fescue and bentgrass in the mixture with creeping bentgrass than that with colonial bentgrass. More research should be put into optimal management, especially irrigation and thatch control, of mixed red fescue–bentgrass greens.

Sammendrag

After harvest, vegetables go from storing assimilates to break down of assimilates and it is of crucial importance to slow down this process. Controlling the pre-storage period may contribute to maintain high quality in root vegetables during long-term storage. The aim of this 2-years study was to investigate the effect of seven different pre-storage strategies (direct to 0°C vs. down 1°C per day vs. 0.2°C temperature reduction per day and wound healing at 10°C with low/high humidity) on root storability in four cultivars of carrot (Daucus carota subsp. sativus) stored in 2016/2017/2018, swede (Brassica napus) in 2017/2018 and celeriac (Apium graveolens var. rapaceum) in 2017/2018. Mass loss and disease incidences were determined during and after long-term storage (6-7 month) in small-scale stores. Wound healing with low humidity resulted in larger mass loss than the other preharvest strategies in carrot and celeriac. In carrot, slow temperature reduction (0.2°C per day) also resulted in larger mass loss than the other strategies. Significantly higher numbers of infected roots, dominated by licorice rot (Mycocentrospora acerina), tip rot and gray mold (Botrytis cinerea), occurred in carrots stored at 0°C immediately compared to roots with a period of wound healing and slow temperature decline. In celeriac, the incidence of gray mold (Botrytis cinerea) and licorice rot (Mycocentrospora acerina) were significantly reduced with wound healing at low humidity. Storage quality of swede was not affected by pre-storage strategies. This study shows that prestorage strategies affect mass loss and disease incidence in celeriac and carrot during and after long-term storage.

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Sammendrag

I prosjekt OPTIROT samarbeider 26 produsenter, to kjøleteknologiselskaper, en sensorutvikler, en biopesticidutvikler, to emballasjeprodusenter, fire regioner under NLR, Gartnerhallen og fem forskningsinstitutter (Nofima, Sintef, NMBU, Århus universitet og NIBIO) i gjennomføring av undersøkelser for å redusere svinn under lagring av gulrot, kålrot og sellerirot. Sammendrag av arbeidspakkene: i) Optimal gjødsling med bor og kalsium for bedre lagringskvalitet. Det er testet ut 6 ulike metoder /tidspunkter for tildeling av bor. Vi så liten effekt av de ulike metodene og tidspunktene for tildeling av bor til knollselleri (felter LI & ST) og kålrot (felter APP & INN). Symptomene bormangel og brune flekker ses inne i røtten og bedømmes ved deling av roten. I begge kulturer var det stor variasjon mellom felt. For knollselleri var det størst forekomst av brune flekker og lavest andel friske røtter i ST, som hadde lavest Ca/B-forhold i blader, lavest innhold av Zn i blader og røtter og lavest pH. I kålrot var det symptomer på bormangel i begge felt i 2017, sterkest i INN. For begge felt var symptomene sterkest i behandlingr uten tilførsel av B. Andel friske røtter var lavest i INN. Vi anbefaler flere undersøkelser for å konkludere ytterligere....

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Sammendrag

After harvesting, the Norwegian root vegetables are normally stored at refrigerated temperatures for 5 to 7 months. During this period, up to 30% of the products are lost. The goal is to reduce the diseases, the product loss and energy consumption, in addition to increase shelf-life and storage period. Twenty-eight commercial root vegetable cold-stores were instrumented to measure air temperature, relative humidity and product temperature. The study was done over two years. The cold-stores were located in four different regions of Norway. The three focus-products carrot, swede and celeriac were harvested from one field in each region in open wire nets. The nets were placed in the various cold-stores in the respective regions and put in the wooden bins together with the producer's own products. The quality and yield of the products were determined and correlated to the storage condition. The various storage condition negatively affects the respiration and quality of the root vegetables, storage-life, and influence on the cooling capacity of the refrigeration systems.

Sammendrag

Det er stort fokus på akrylamid i mat, da dette stoffet er mistenkt å være kreftfremkallende. Akrylamid dannes ved sterk oppvarming av blant annet potetprodukter. Pommes frites og chips er produkter som konsumeres av alle aldersgrupper, og det er derfor viktig å senke akrylamid nivåene. For å redusere innholdet et det behov for økt kunnskap om lagringsforhold og råvarekvalitet, og samspillet mellom disse faktorene. Ut fra tidligere undersøkelser er det grunn til å tro at luftsammensetningen under lagring kan være en viktig faktor. Målsettingen med prosjektet var å redusere akrylamidinnholdet i potetchips gjennom ny kunnskap om optimale lagringsforhold for poteter. Det var særlig fokus på betydningen av forhøyede karbondioksidnivåer, og samspillet mellom luftsammensetning og råvarekvalitet.....

Sammendrag

Important factors for development of quality defects are the physical, physiological and chemical state of the tubers, which is also described as the maturity status of the crop. The use of maturity indicators as predictors of quality in potato tubers during and after storage was explored in cvs. Asterix and Saturna with three different maturity levels during three years (2010, 2012 and 2013). The maturity indicators measured 1–3 weeks before harvest and at harvest included haulm senescence (haulm maturity), skin set (physical maturity), dry matter content (physiological maturity) and contents of sucrose, glucose and fructose (chemical maturity). Potato quality parameters were measured three times during storage (December, February and April) and included dry matter content, sucrose, glucose and fructose contents, weight loss and fry colour. Cultivar and maturity level were included as categorical predictors in a linear regression model and contributed significantly (P < 0.001) to the models predicting reducing sugars during storage. Dry matter, sucrose, glucose and fructose were included as continuous predictors in the linear regression models and contributed significantly (P < 0.01) to the sucrose, glucose and fructose models and these models explained a high proportion of the variation (R2 ≥ 0.88). Skin set contributed significantly to the weight loss models (P < 0.01) but the models showed low R2 -values (R2 < 0.48). Sucrose contents contributed significantly (P = 0.05) to the fry colour model for Asterix and the fry colour models for both Asterix and Saturna had R2 -values of 0.50 and 0.51 respectively. This study provides new information about the influence of maturity on potato quality during storage and the potential of using field measurements of maturity as predictors of storage potential for processing potato cultivars Asterix and Saturna in Norway.

Sammendrag

Optimization of produce quality and storage conditions to reduce loss during long-term storage of root vegetables in Norway (OPTIROOT, 2016-2019) Authors: Thomsen, M.G., Indergaard, E., Asalf, B., Heltoft, P., Wold, A.B., Nordskog, B., Guren, G, Dyste, J. & Larsen, H. Author’s affiliation: Key words: carrot, swede, celeriac, storage technology, diseases, physiological disorder, packaging, nutrition Reducing yield loss along the supply chains is important for resource sustainability in vegetable production. Norwegian root vegetables are typically stored 6 to 8 months before consumption, often resulting in 20-30% loss post harvest. In OptiRoot 26 producers, refrigeration-technology companies, sensor developer, grower’s organisation, agricultural advisory service, and four research institutes are cooperating and conducting research to improve storage quality of carrot, swede and celeriac. The research focuses on: i) Fertilizer/Boron deficiency affects the storage quality of root vegetables and amount, methods of application, and timing of boron are studied in swede and celeriac. ii) Interaction between storage conditions/functions and produce quality of the root vegetables through mapping of technical features of 27 storages. The storage conditions recorded are relative humidity, air movement, temperature in boxes and storages, and physical features of storages. In addition, the physiological and health status of the produces are assessed one week before harvest, postharvest and post-storage. The prevalence of fungal diseases or disorders varied from region to region and between storages. iii) Effects of pre-storage wound healing are tested using seven different temperature strategies (direct to 0° C vs. down 0.2° C per day vs. 1° C per day) and low/high humidity in carrot (2016/17/18), celeriac and swede (2017/18/19). Preliminary results show that wound healing reduced loss due to fungal infections in carrot iv) CO2 concentration, temperature and relative humidity were recorded over time inside carrot storage bin liners with different numbers of perforations. An initial screening indicated a positive correlation between number of holes and number of fresh roots. As a post storage method, coating of swede with chitosan oligomers will be tested to inhibit growth of post-harvest pathogens. In conclusion, OptiRoot have gained good progress and promising preliminary results by connecting data on biology and technology for reduction of loss during long-term storage.

Sammendrag

Ventilation management and the tuber maturity at harvest are essential factors in maintaining potato quality during long-term storage. The aim of this study was to examine the effect of ventilation strategy on storage quality of potato tubers with three different maturity levels at harvest. Two potato cultivars, Saturna and Asterix, were stored in small-scale experimental stores and large-scale commercial stores. Both storage categories were ventilated by both low continuous air rates (natural ventilation) and intermittent high air rates (forced ventilation). The different maturity levels were obtained by a combination of pre-sprouting strategy, planting date and level of nitrogen fertilization of the seed tubers, where pre-sprouting, early planting date and low amount of nitrogen resulted in the most mature tubers. Storage quality parameters investigated during and after long-term storage (6 months in small-scale and 4 months in large-scale stores) included weight loss, respiration, dry matter, sucrose, glucose/fructose content and fry colour. In average over three years natural ventilation resulted in higher weight losses in small- and large-scale stores (1.36 and 3.93%), lower content of reducing sugars (glucose + fructose) in large-scale stores (2.35 mg g 1) and lighter fry colour than did forced ventilation. Immature potatoes had higher weight losses (4.16%), higher respiration rates (1.68 mg CO2 kg 1 h 1) and lower dry matter content (22.3–22.5%) than more mature potatoes. This study show that both maturity and ventilation strategy affects storage quality of potatoes as measured by weight loss, sugar content and fry colour.

Sammendrag

The prevalence of Fusarium dry rot in potatoes produced in Norway was investigated in a survey for three consecutive years in the period 2010 to 2012. A total of 238 samples (comprising 23,800 tubers) were collected, representing different cultivars and production regions in Norway. Fusarium spp. were detected in 47% of the samples, with one to three species per sample. In total, 718 isolates of Fusarium spp. were recovered and identified to seven species. The most commonly isolated species was Fusarium coeruleum, comprising 59.6% of the total Fusarium isolates and found in 17.2% of the collected samples, followed by Fusarium avenaceum (27.2% of the isolates and found in 27.7% of the samples). Fusarium sambucinum was the third most prevalent species (6.4% in 8.8% of the samples) and Fusarium culmorum the fourth (5.2% in 6.3% of the samples). Less prevalent species included Fusarium cerealis, Fusarium graminearum, and Fusarium equiseti (<1% in 0.4 to 1.3% of the samples). F. coeruleum was the most prevalent species in northern and southwestern Norway, whereas F. avenaceum was dominating in eastern Norway. The potato cultivars Berber and Rutt were susceptible to all Fusarium spp. A new TaqMan real-time PCR assay specific for F. coeruleum was developed, which successfully identified Norwegian isolates. This and other previously developed real-time PCR assays targeting different Fusarium species were evaluated for their ability to detect latent infections in potatoes at harvest. This study provides new information on the current occurrence of different Fusarium species causing Fusarium dry rot in potatoes in Europe including areas far into the arctic in the north of Norway.

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Sammendrag

A glasshouse experiment was carried out with the aim of quantifying the relative contribution of seed- and soil-borne inoculum of three Fusarium spp. (F. coeruleum, F. sambucinum and F. avenaceum) in causing dry rot in two potato cultivars, Asterix and Saturna. Different concentrations of inoculum; control (water only), low (102 conidia ml−1) and high (105 conidia ml−1) were used to inoculate seed and infest soil and disease severity on progeny tubers was subsequently assessed following an 8-week post-harvest storage period. Overall, F. sambucinum caused significantly (P < 0.05) larger rots than F. avenaceum, with the severity of rots caused by F. coeruleum being intermediate, and disease severity was greater in cv. Asterix than cv. Saturna (P < 0.01). None of the seed inoculation treatments resulted in dry rot development on progeny tubers. In contrast, soil infested with Fusarium species resulted in significantly more severe tuber rots on progeny tubers compared with controls (P < 0.01). Soil infested with F. sambucinum (low and high levels) resulted in significantly more severe rots than control treatments (P < 0.001), whilst only high levels of F. avenaceum soil inoculum increased the severity of tuber rots compared with control treatments (P < 0.05). Increased disease severity observed as a result of the addition of inoculum of F. coeruleum to soil was not significant.

Sammendrag

I dette forsøket undersøkes kvaliteten av poteter med ulik modningsgrad etter lagring på kommersielle lagre med forskjellige ventilasjonssystemer. I lagringssesongen 2010/2011 klarte potetene seg bedre på lager jo mer modne de var ved høsting. Det var også forskjell i potetenes kvalitet etter 4 måneders lagring mellom de to undersøkte ventilasjonssystemene.