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.
2016
Abstract
Researchers in plant pathology and entomology often study the interaction between a host plant and its pathogen or an insect pest separately. Although studying single pathogen or insect interactions with a host plant is critical to understand the basic infection processes and to model each disease or pest attack separately, this is an extreme simplification of nature’s complexity, where multiple pests and pathogens often appear in parallel and interact with each other and their host plant. Effective management of pests and diseases require understanding of the complex interaction beteween diseases and pests on the host. Under natural conditions, wheat plants are subjected to attack by several insects and pathogens simultaneously or sequentially. The Bird cherry-oat aphid (Rhopalosiphum padi) and the necrotrophic pathogen Parastagonospora nodorum (syn. Stagonospora nodorum) the causal agent of Stagonospora nodorum blotch (SNB) are economically important pests of wheat in Norway. Since they colonize a common host, they may interact directly through competition for resources or indirectly by affecting the host response either positively (induced resistance) or negatively (induced susceptibility or biopredisposition). The effect of aphid infestation on P. nodorum infection and development of the disease could be an important factor in predicting SNB epidemics. However, studies on this multitrophic interactions are scarce. We conducted controlled greenhouse experiments to study the effect of aphid infestation on subsequent SNB development. The wheat cultivar ‘Bjarne’ was treated as follows:1) Aphid infested + insecticide sprayed + P. nodorum inoculated; 2) Insecticide sprayed + P. nodorum inoculated; 3) Water sprayed + P. nodorum inoculated; 4) Control plants (without aphid, insecticide or P. nodorum). When plants were at ca. BBCH 37, 18 adult female aphids (R. padi) were released per pot (treatment 1). Aphid inoculated plants were kept in an insect proof cage in a greenhouse compartment at 20°C, 70% RH, and 16 h photoperiod. Plants for the other treatments were kept in separate insect proof cages in the same greenhouse. Ten days after aphid release, plants infested with aphids (treatment 1) were sprayed with the insecticide BISCAYA (a.i. thiacloprid) at recommended concentration to remove aphids. Plants in treatment 2 and 3 were sprayed with the insecticide and water, respectively. Twenty-four hours after application of the insecticide or water, plants in treatment 1, 2, and 3 were inoculated with P. nodorum spore suspension (106 spores ml-1). The experiment included three replicates and was repeated two times. SNB incidence and severity were recorded. SNB incidence and severity were significantly higher on aphid infested plants than on non-infested plants (P < 0.05). Ten days after P. nodorum inoculation, disease severity were about 3-fold higher on aphid infested plants (treatment 1) than on non-infested plants (treatment 2 and 3). Plants in the blank control (treatment 4) were free of aphids and showed no symptoms of SNB . Infestation of wheat plants by the bird cherry-oat aphid prior to fungal inoculation enhanced the severity of SNB. P. nodorum is a necrotrophic pathogen that lives on nutrients from disintegrated plant cells. The increase in severity of SNB on aphid infested plants could be due to the increased number of dead or dying cells around the aphids feeding sites. However, whether aphids activity induced local or systemic susceptbility to plants is not yet known and needs to be studied further.
Abstract
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.
Authors
Guro Brodal Jan Netland Elin Thingnæs Lid Åshild Ergon Christer Magnusson Arild Sletten Leif Sundheim May Sæthre Anne Marte Tronsmo Bjørn Økland Trond RafossAbstract
No abstract has been registered
Authors
Heidi Udnes Aamot Ingeborg Klingen SG Edwards May Bente Brurberg Guro Brodal Toril Eklo Hege Særvold Steen Jafar Razzaghian Elisa B. Gauslå Ingerd Skow HofgaardAbstract
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.
Authors
Heidi Udnes Aamot Ingeborg Klingen S.G. Edwards May Bente Brurberg Guro Brodal Toril Eklo Hege Særvold Steen Jafar Razzaghian Elisa B. Gauslå Ingerd Skow HofgaardAbstract
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.
Authors
Leif Sundheim Åshild Ergon Christer Magnusson Jan Netland Egil Prestløkken Arild Sletten May Sæthre Elin Thingnæs Lid Tron Øystein Gifstad Micael Wendell Guro Brodal Halvor Solheim Anne Marte Tronsmo Bjørn Økland Trond RafossAbstract
No abstract has been registered
2015
Abstract
No abstract has been registered
Authors
Raphael C. Castilho Vanessa S. Duarte Gilberto J. de Moraes Karin Westrum Nina Trandem Luiz Carlos D. Rocha Italo Jr Delalibera Ingeborg KlingenAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered