Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2007
Sammendrag
Several models for prediction of infection periods for lettuce downy mildew (Bremia lactucae) are based on the assumption that spores are produced at night and released in the early morning. The divergent light conditions at Nordic latitudes might affect both sporulation and spore release. Therefore, during the period 2001 to 2005 a total of 13 field trials were established in late season lettuce fields to evaluate efficacy of fungicide applications made according to the models PlantPlus (PP) and Modell-Analys (MA) in Norway. Disease severity varied from 0 to 89.4 % in unsprayed control plots at harvest. Fungicide treatments had a significant effect compared to untreated control in all but two of the field trials with disease incidence over 1 % at harvest. Fungicide applications at 10-day intervals and according to PP and MA resulted in an average of 3, 2.5 and 3.3 applications, respectively. There were no significant differences in disease severity at harvest between treatments according to 10-day interval, PP and MA for any of the field trials. Epidemics were created at two field locations that had no previous lettuce production, and a total of 59 days of spore trapping permitted the study of spore release under natural conditions. Spore production events predicted by MA were correct at 66 % of the days. However, when adjusting the criteria for spore production, 78 % of the days were correctly predicted.
Sammendrag
Virulence characteristics of Bremia lactucae populations from lettuce crops in the southeast and southwest of Norway from 2001 to 2005 were studied in relation to virulence factors (v-factors) and virulence phenotypes (v-phenotypes). The frequencies of 19 v-factors were analysed, and phenotypic diversity was calculated in relation to v-factors and v-phenotypes. A total of 39 different v-phenotypes were identified from the 58 samples analysed. Four of these were identical with the previously denominated races Bl:17, 18, 22 and 24. The most commonly occurring v-factors were v1, v2, v4, v5/8, v6, v7, v10, v11, v12, v13 and v18. V-factor v17 was not present in any of the tested isolates and v36 was found only once. V-factor v38 was first seen in 2004, coinciding with the observations of broken resistance in many cultivars. The population of B. lactucae in Norway was diverse, but not considerably different from other European populations of this pathogen.
Sammendrag
The prediction of infection periods for lettuce downy mildew (Bremia lactucae) is based on the assumption that spores are produced at night and released in the early morning. The divergent light conditions at Nordic latitudes might affect both sporulation and spore release. Therefore, we monitored release of B. lactucae spores in relation to the climatic conditions in lettuce fields to evaluate the performance of existing forecasting models in timing of fungicide applications for management of lettuce downy mildew in Norway. In 2005, epidemics were created at two field locations that had no previous lettuce production, and a total of 59 days of spore trapping permitted the study of spore release under natural conditions. Sporulation events were compared to predicted spore production events in Modell-Analys (MA). At the two locations, 76 % and 74 % of the spores were trapped between 08.00 and 16.00, respectively. Spore concentration icreased with decreasing relative humidity (RH), ofting coinciding with increasing solar radiation and temperature. Spore production events predicted by MA were correct at 66 % of the days. However, when the criteria for spore production were adjusted, 78 % of the days were correctly predicted.
Forfattere
Berit Nordskog Bodil Jönsson Richard Meadow Sverre Kobro Håvard Eikemo Klaus Paaske Irmeli Markkula Arne Hermansen Guro BrodalSammendrag
Models for prediction of diseases and pests in fruits and vegetables are important tools in the decision of crop management strategies. In the Nordic countries several models are currently available for the farmers and extension services on the Internet. The most widespread pests and diseases which are forecasted and/or monitored include apple scab (Venturia inaquealis) and apple fruit moth (Argyresthia conjugella) in apples, cabbage root fly (Delia brassicae) and turnip root fly (D. floralis) in Brassica vegetables, carrot root fly (Psila rosea) in carrots, and downy mildews in lettuce (Bremia lactucae) and onion (Peronospora destructor).
Sammendrag
We evaluated direct and interactive effects of light quality and intensity, temperature and light, diurnal rhythms, and timing of high relative humidity during long day lengths on sporulation of Bremia lactucae, the causal agent of lettuce downy mildew, using inoculated lettuce seedlings and detached cotyledons. Suppression of sporulation by light was strongly dependent upon temperature and there was little suppression at "10°C. The most suppressive waveband was in the range from 400 to 450 nm, although a lesser effect of wavebands from 450 to 500 and 500 to 550 nm could be detected. At 15°C, near the lower threshold for suppression of sporulation by light, a clear diurnal pattern of sporulation was observed independent of light and darkness. This diurnal rhythm potentially could interact with light and temperature to confound the results of controlled environment studies, and may be the controlling factor in timing of sporulation at low temperatures. Forecasting models that currently use sunrise and sunset to delimit periods conducive to sporulation can be adapted to short nights and extended twilight conditions by incorporating the effects reported herein. Additionally, models of sporulation could be adapted to better reflect a decrease or absence of the suppressive effect of light at
Sammendrag
Potettørråte vil også i 2007 kreve en aktiv bekjempelse. I likhet med de siste årene kommer vi med en omtale av varsling og middelvalg i forbindelse med bekjempelsen av denne viktige skadegjøreren. Artikkelen er en oppdatering av tilsvarende artikkel fra i fjor.
Forfattere
W.G Flier L.P.N.M Kroon Arne Hermansen H.M.G van Raaij B. Speiser L. Tamm J.G. Fuchs J. Lambion Jafar Razzaghian D. Andrivon S. Wilcockson C. LeifertSammendrag
Genetic variation and pathogenicity of Phytophthora infestans isolates collected from organic potato crops of the susceptible cv. Bintje and the moderately resistant cv. Santé were assesed in France, Norway, and the United Kingdom in 2001 and in Switzerland in 2001 and 2002. Population structures differed considerably between the four P. infestans populations. Those from France, Switzerland and the UK were mainly clonal populations showing restricted levels of genetic diversity, whilst those from Norway were mixed A1 and A2 mating type populations with high levels of genetic diversity, suggesting periodical sexual reproduction. Isolates collected from cv. Bintje were on average more aggressive than or comparable to isolates from cv. Santé. Race complexity varied considerably between the regional P. infestans populations with isolates from France and Switzerland showing the highest number of virulence factors. In all pathogen samples but the French, isolates collected from cv. Santé were more complex than isolates collected from cv. Bintje. No directional selection towards increased aggressiveness towards the more resistant cultivar Santé was observed. This suggests that there is no shift towards increased level of pathogenicity in P. infestans populations following the large-scale introduction of more resistant potato varieties in organic production systems in Europe.
Sammendrag
In Norway, Nordmann (Abies nordmanniana) and subalpine fir (A. lasiocarpa) are the dominant Christmas tree species and Noble fir (A. procera) the dominant species for bough production. In the spring of 2005 a survey was undertaken to determine the presence of fungi on seeds of these three plant species. Twelve seed samples were tested; five from Nordmann fir, four from subalpine fir and three from Noble fir. The test included seeds produced in Austria (Nordmann fir), Canada (subalpine fir), Georgia (Nordmann fir), Norway (Noble and subalpine fir) and Russia (Nordmann fir). The testing was done in a certified seed laboratory in Norway. One hundred seeds per sample were pre-treated in 1 % NaOCl and plated on potato dextrose agar (PDA), and 100 seeds per sample were pre-treated in H2O2 and plated on water agar (WA). The PDA Petri dishes were incubated for 5 to 7 days at 20 + 2 ºC and the WA Petri dishes for 15 to 19 days at 15 + 2 ºC, both under alternating 12 h NUV-light and 12 h darkness. To date not all of the fungi have been identified, but fungi from several genera have been found: Alternaria, Anthostomella, Aspergillus, Aureobasidium, Botrytis, Caloscypha, Cephalosporium, Chaetomium, Cladosporium, Dictyopolyschema, Epicoccum, Fusarium, Mucor, Penicillium, Phoma, Rhizopus, Trichoderma, and Trichothecium. Caloscypha was only found on one subalpine fir seedlot from Canada and Anthostomella on one subalpine fir seed from Norway. All the other fungi were more commonly found in all the samples. Fusarium species are well known to cause damping off in nurseries, but are not reported to cause problems in production fields. Species of Alternaria, Phoma, Botrytis and Trichothecium can damage seedlings. Anthostomella conorum is reported on cone scales of pine (Pinus spp.), but is not described as pathogenic. Aureobasidium is described as a saprophytic or weakly parasitic cosmopolitan fungal genus. Aureobasidium sp. is commonly found in Norway on buds of subalpine fir which fail to open in spring, and it will therefore be included in a pathogenicity test.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
I mai 2006 vart soppen Phoma hedericola (syn. Phyllosticta destructiva var. hederae) funnen på skadde eføyblad frå ei vegskjering ved ein ferjekai i Ryfylke. Soppen er velkjent elles i Europa der han også går på Hedera himalaica. I juni 2006 vart P. hedericola også funnen i ein planteskule i Rogaland, på importerte planter frå Nederland. På planteskuleplantene vart det i tillegg funne Colletotrichum trichellum, ein annan kjent skadegjerar på eføy i utlandet. I september same året vart det funne mykje C. trichellum på eføy i grøntanlegg i Bergen, men ikkje P. hedericola. Ingen av soppane har norsk namn. På engelsk vert "Ivy Leaf Spot" brukt om bladflekkar på eføy enten dei skuldast sopp (inkludert dei to artane vi har funne) eller bakteriar.