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
Forfattere
Gunnhild Wærsted Takle Lisbeth J. Hyman Ron Wheatley Paul Birch May Bente Brurberg Ian K. TothSammendrag
Bakterien Pectobacterium atrosepticum forårsaker stengelråte og bløtråte på potet. Til tross for stor utbredelse vet man lite om bakteriens liv utenfor potet. Vi presenterer her forsøk som peker mot en alternativ livsstil for P. atrosepticum som en mulig symbiont på brassica-røtter i tillegg til den velkjente rolle som potetpatogen. Dette kan få konsekvenser for bekjempelsesstrategier mot denne bakterien.
Sammendrag
Ved å utnytte det mobile soppmiddelets kirale egenskaper har man oppnådd en lavere risiko for negativ innvirklning på helse og miljø. Men i enkelte jordtyper kan en miljørisiko likevel ikke utelukkes. Nedbrytingsstudier i ulike jordtyper fra SØ-Norge viser at nedbrytingen av metalaksyl er svært langsom i siltig planert mellomleire og at nedbrytingen er moderat i siltig sandjord. Metalaksyl-M benyttes i dag i ulike grønnsakskulturer, særskilt gulrot. Gulrot dyrkes gjerne på sandjord. Våre feltforsøk viste at metalaksyl kan lekke raskt ut av sandjord og konsentrasjonene som lekker ut vil være avhengig av nedbrytingshastigheten av soppmiddelet i jorda. Moderat til langsomme nedbrytingstider gjør oppholdstiden for soppmiddelet lenger og risikoen for utlekking større. Metalaksyl-M er så mobilt at selv bruk i lave doser kan gi en risiko for utlekking.
Forfattere
Arnstein StaverløkkSammendrag
Presentasjon av undersøkelse på importerte planter. Ved undersøkelse av nylig importerte planter fra Nederland, Tyskland og Danmark ble det funnet 16 nye arter for Norge. Undersøkelsen viser at det kommer inn mange nye organismer som det ikke blir kontrollert for.
Sammendrag
Foredrag om varsling av sjukdommer i korn og oljevekster
Forfattere
Oleif ElenSammendrag
Det er gitt en oversikt over varslingsmodeller for sjukdommer i korn
Sammendrag
Det ble funnet til dels gode korrelasjoner mellom mengde Fusarium og mykotoksiner.
Sammendrag
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).
2006
Forfattere
Venche TalgøSammendrag
On the southwest coast of Norway there are natural stands of holly (Ilex aquifolium), but a number of different varieties of I. aquifolium and I. meserveae are also grown in bough production fields, private gardens and public parks. Except for conifers, holly is the only tree we have with green foliage during the winter in Norway. The leathery, dark green leaves with prickly spines and the red berries have made holly a popular plant for Christmas decorations. Leaf-drop/defoliation has become an increasing problem during the last decades both before and after harvest, and thus destroys the marketability. We suspect that reduced grazing has resulted in more overgrown/dense stands and hence created ideal microclimate for fungal growth. Wet foliage due to shade and restricted air movement gives the spores good conditions for germination. On investigated diseased plant material collected from holly in the period 2001-2006, a number of possible pathogenic fungi were isolated; Fusarium avenaceum, Vialaea insculpta, Nectria sp., Colletotrichum acutatum, Trochila ilicina and Diaporthe ilicis (Talgø et al. 2006). The fungi were identified morphologically mainly based on information given by Ellis & Ellis (1997). Colletotrichum was identified to species level by PCR. In the literature we find very little about what kind of damage these organisms may cause on holly. Benson & Jones (2000) say that leaf-spotting fungi on holly can cause heavy defoliation before new growth starts in the spring, but they do not mention any specific pathogen. Therefore we will run pathogenesis tests with all the fungi mentioned above to fulfil Koch"s postulate.
2005
Sammendrag
Various needle discolorations, often due to lack of uptake of certain nutrients are frequently observed in nordmann fir (Abies nordmanniana) in Norwegian Christmas tree plantations. Most common are the yellow to necrotic needle tips on older needles caused by magnesium (Mg) deficiency (confirmed by chemical analysis of foliage). Even though chemical analysis of soil samples show that Mg is present in sufficient amount, various soil factors may cause Mg-deficiency; too high or too low pH, excess potassium (K) or too wet or too dry conditions. Antagonism, causing imbalance in nutrient uptake, can lead to negative effects. High pH may give Ca2+/Mg2+ antagonism, too low pH NH4+/Mg2+ antagonism, and abundant K K+/Mg2+ antagonism. During wet conditions K+ and other monovalent cations may leave the colloids to regain equilibrium between liquid and solid material. Then Mg2+ may easily bind to the free spaces on the colloids, and thereby becomes unavailable for the plants. If the soil is very dry there may not be enough liquid for the nutrients to be dissolved, and thus uptake inhibited. Nordmann fir is mainly grown in the southwestern coastal region of Norway since the climate there is fairly mild and suitable for this plant species. The yearly rainfall is high in that region, so a main cause for Mg deficiency on nordmann fir is probably related to wet soil conditions. Uptake of Mg after foliage application has proved to be ineffective due to the wax layer on the fir needles. However application on young needles and shoots has been reported by the Norwegian extension service to be successful. K deficiency also results in discoloration of older needles, but symptoms can easily be distinguished from Mg deficiency. Both deficiencies results in yellowing of the needles, but different from K deficiency, the base remains green on needles suffering from Mg deficiency. Both Mg and K are very mobile nutrients in plants, and they are therefore easily translocated from older to younger needles. Samples with yellow discoloration of the youngest needles have been observed to be low in iron (Fe) and manganese (Mn), especially when the trees have grown in soil with high pH. Both nutrients are nearly immobile in plants after they have been transported to the cells, and they are therefore not available for the young shoots. Nitrogen (N) deficiency is seen as a uniform, pale green discolouration of both young and old needles.
Sammendrag
In 2004, damages resembling those caused by Phytophthora spp. were observed on three different fir species in Norway. Isolations were carried out from all the host plants on the Phytophthora selective medium PARP (with and without hymexazol added). In a nordmann fir (Abies nordmanniana) Christmas tree field at the southwestern coast of Norway, approximately 70 % of the plants died within a few months after planting. The massive infestation in a field previously used for grass production over decades, left no doubt that the disease had followed the imported transplants. Symptoms included poorly developed roots and discoloration under the bark from the stem basis downwards. The foliage had different stages of drought symptoms; pale green, yellow or brown. Isolations were carried out from the area between healthy and diseased tissue, both from roots and stem base, and a Phytophthora sp. was isolated. The culture produced nonpapillate sporangia with internal proliferation. The sexual stage was observed in water, but not on agar. The oogonia were large. The oospores were aplerotic and the anteridia predominantly amphigynous. ITS rDNA sequences of the isolate were obtained and found to be most similar to P. inundata. Samples were examined from diseased 15-year-old noble fir (A. procera) grown in a bough plantation at the southwestern coast of Norway. Approximately 25 % of the trees were dead or dying. The foliage had turned chlorotic to brown. On one tree a typical stem canker extending approximately 1.5 meters above ground on one side of the tree resulted in dead basal branches (flagging). Isolations were carried out from both roots and the cankered stem. Based on morphological characters (nonpapillate sporangia, internal proliferation, characteristic hyphal swellings, heterothallic culture) and ITS rDNA sequencing, the isolate was identified as P. cambivora. In a Christmas trees planting in southeastern Norway, several seven-year-old trees of subalpine fir (A. lasiocarpa) were dying. The tree loss was estimated to 25 %. Typical Phytophthora canker was found at the base of several trees. Isolations resulted in a culture that readily produced oogonia. The average diameter of the oogonia was 48 "m. The oospores were aplerotic with an average diamerter of 40 "m. The antheridia were paragynous, but a few amphigynous antheridia were also observed. The culture produced nonpapillate sporangia with internal proliferation ITS rDNA sequences matched P. megasperma. A pathogenesis test to fulfil Koch"s postulate was carried out on all three species of fir, each of them inoculated with the respective isolate. After seven weeks, root growth was poor on all the inoculated plants, and canker symptoms had developed in the lower part of the stem. Reisolated culture from noble fir was ITS rDNA sequenced and found identical to the original culture used for inoculation. Results from the ITS rDNA sequencing of the other two reisolated cultures are not yet available.