Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2017
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No abstract has been registered
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Marcos Viejo Elena Carneros Hugh Cross Igor A. Yakovlev Carl Gunnar Fossdal Jorunn Elisabeth OlsenAbstract
No abstract has been registered
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K.A.G Nielsen Ingerd Skow Hofgaard Shiori Koga H.U. Aamot Ulrike Böcker Erik Lysøe Guro Brodal Ruth Dill-Macky Anne Kjersti UhlenAbstract
No abstract has been registered
2012
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Susanne Friis PedersenAbstract
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Arne StensvandAbstract
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2011
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Adam ParuchAbstract
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Espen GovasmarkAbstract
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Ragnar TveteråsAbstract
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John Morken Espen GovasmarkAbstract
No abstract has been registered
Abstract
Three primary causal agents are involved in the leaf blotch disease (LBD) complex of Norwegian winter and spring wheat: Phaesophaeria nodorum, Mycospaerella tritici, and Pyrenophora drechslera-tritici. The dynamics of symptom development, similarity of symptoms caused by each agent, and confounding of disease symptoms by leaf senescence interfere with accurate assessment of disease. Empirical and regression models for disease and yield loss forecasting are only as good as the data upon which they are based. Accurately describing the relationship between symptoms and yield loss is therefore critical to meaningful economic thresholds for management decisions and advisory systems. A general guideline for yield loss and disease severity has been described as 1% yield loss per 1% disease severity on the flag leaf at BBCH stage 70-75 (King et al., 1983). However, several years of field trials in Norway indicate that disease severity can increase exponentially during these developmental stages, making disease severity highly dependent upon time of assessment. LBD severity on flag leaves of the spring wheat variety ‘Bjarne’ at two different locations in 2010 varied during the above BBCH stages from 27% to 44% and from 4.45% to 23.2%. Different varieties may compensate differently for loss of photosynthetic area on the flag leaf due to leaf blotch pathogens, rendering the general guide line for yield loss inaccurate. Preliminary studies in Norway indicated that the relation between yield reduction (TKW) and disease severity of the flag leaf differed substantially for five different spring varieties and ranged from 0.03 to 1.4 at BBCH 70 and from 0.8 to 4.1 at BBCH 75, at one field site at Aas, Norway in 2010. The causes of the observed variation in the relationship between flag leaf severity and yield reduction are poorly understood. Effects of other diseases are not accounted for by leaf blotch assessments, nor are fungicides applied to reference plots necessarily eliminating all disease effects on yield. Timing of assessments may be as critical as the accuracy of the assessments; making it necessary to time the assessments properly, and distinguish clearly between leaf senescence and leaf blotch symptoms.