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.
2006
Forfattere
Jenny Fäldt Halvor Solheim Bo Långström Anna-Karin Borg-KarlsonSammendrag
To identify chemical resistant markers induced by fungal or mechanical injury, young trees of Scots pine (Pinus sylvestris) were subjected to inoculations of blue stain fungi associated with the pine shoot beetles Tomicus piniperda and T. minor. Among the 20 trees selected for chemical analyses, 16 were divided into four groups: one as control and three were pretreated by wounding only, or by inoculation with either the blue stain fungus Leptographium wingfieldii or Ophiostoma canum.Four wk after pretreatment, all 16 pretreated trees were mass-inoculated with L. wingfieldii. The absolute and relative amounts, as well as the enantiomeric compositions of monoterpene hydrocarbons in the phloem, were determined via a small sample of the phloem before and after the pretreatment and mass inoculation, by using two-dimensional gas chromatography (2D GC) and GC-mass spectrometry (MS).After mass inoculation, the absolute amounts of most of the monoterpenes decreased in the phloem sampled 20 cm from the fungal infection, and were higher in the phloem sampled within the infected reaction zone.The relative amounts of both ()--pinene and ()-limonene increased in phloem samples taken 20 cm above the fungal inoculation in the preinoculated trees compared with phloem sampled from the remaining four control trees. The enantiomeric compositions of -pinene and limonene changed, after fungal growth, at defined distances from the inoculation site: the proportion of the ()-enantiomers was highest in the phloem sampled 20 cm from the fungal inoculation.Four wk after pretreatment, monoterpene production in the phloem at the site of inoculation was more enhanced by L. wingfieldii than by O. canum. However, the different virulence levels of the fungi did not affect the enantiomeric composition of the monoterpenes. The biosynthesis of monoterpene enantiomers is discussed in relation to induced pathogen resistance.
Forfattere
Shala Werner Michael Albers Terry Cryderman Danko Dimenic Robert Heyd Boris Hrasovic Sverre Kobro Stig Larsson Roger Mech Pekka Niemela Matti Rousi Kenneth Raffa Kyoko Scanlon Shane WeberSammendrag
The introduced basswood thrips, Thrips calcaratus, undergoes outbreaks on and damages American basswood, Tilia americana, in North America, but is less common on and does not cause significant damage to little-leaf linden, Tilia cordata, in its native European range. A possible explanation is that altered host relationships in North America allow increased exploitation of T. americana. Three experiments were conducted to compare host associations of T. calcaratus between T. americana and T. cordata. In a laboratory choice bioassay, T. calcaratus occupied foliage of both tree species with equal frequency. A field assay conducted in North America revealed an identical trend on planted T. americana and T. cordata seedlings planted in a paired design. In a separate field experiment bud break phenology, peak T. calcaratus emergence, and foliar development showed similar temporal patterns in 10 T. cordata and T. americana sites distributed across the insect"s native range of Europe and introduced range of North America. These results suggest that physiological and phenological differences between native and newly acquired Tilia hosts are not likely responsible for the increased impact of T. calcaratus in its introduced range. Rather, temporal escape from natural enemies seems to be the more likely explanation. This is evidenced by the stronger synchrony of the North American predator, Leptothrips mali, with the native basswood thrips, Neohydatothrips tiliae, than with T. calcaratus. Understanding the basis for increased success of T. calcaratus in its introduced range may provide insight into managing this insect in basswood forests in the Great Lakes region.
Forfattere
Maria Herrero Brita Toppe Arild SlettenSammendrag
Det er ikke registrert sammendrag
Forfattere
Ricardo HolgadoSammendrag
Det er ikke registrert sammendrag
Sammendrag
I årene 1934-38 ble det laget 90 plansjer etter professor Emil Korsmos anvisninger. Etter mye dataarbeid, kan vi nå glede leserne med at de fleste ugrasplansjene etter Korsmo (1863-1953) nå blir tilgjengelig på digital form.
Sammendrag
Korsmos ugrasplansjer" har nå fått egne internettsider. Der finner du utvalgte plansjer, utfyllende tekter og flere bilder av hver art. På sidene finner du også oversikt over undervisningshagen med ulike ugressarter på Ås. Denne er oppdatert som besøkshage for publikum.
Forfattere
Richard MeadowSammendrag
Det er ikke registrert sammendrag
Forfattere
Richard Meadow Annette Folkedal SchjøllSammendrag
Bekjempelsesmidler som har vært brukt mot kålfluene i mange tiår vil nå forsvinne fra markedet. Dette har medført en kjempeutfordring i å finne nye metoder og midler for kålfluebekjempelsen. Et prosjekt ble startet opp i 2004 ved Planteforsk (nå Bioforsk) og Landbrukets forsøksringer (LFR) for å utforske flere metoder for bekjempelse, inkludert nye skadedyrmidler, i de viktigste kålvekstene som dyrkes i Norge. I tillegg er det i 2005 startet et prosjekt som er eid av Norges Gartnerforbund som tar opp samme problematikk, men som kun er rettet mot kålrotproduksjon. Resultatene så langt er presentert.
Forfattere
Ricardo Holgado Stig Andersson Christer MagnussonSammendrag
Cereal cyst nematodes, Heterodera spp. are known world-wide as parasites of cereals and grasses. Surveys of cereals in Norway have revealed that nematodes belonging to the H. avenae complex occur throughout the country, and that H. avenae (oat cyst nematode) is the most common species followed by H. filipjevi (rye cyst nematode). H. avenae and H. filipjevi are of economic importance in Scandinavia. H. avenae has two common pathotypes, Ha 11 and Ha 12. Work in Sweden, however, has detected the three additional pathotypes H. avenae- Knislinge, H. avenae- Ringsåsen and H. avenae- Våxtorp. These pathotypes were detected also in the Norwegian surveys. In Sweden H. filipjevi has two pathotypes, "East" and "West". In Norway, only the pathotype "West" has been detected so far. Nematode management practices must be based on the knowledge of the population dynamics, the population density required to cause economic damage, and the measures capable of reducing or keeping the population density below the threshold for economic damage. Crop rotation and the use of cultivars with resistance are important measures for controlling cereal cyst nematodes. For several years it has been known that resistance to cereal cyst nematodes may be found in some commercial cultivars, although no conscious breeding for resistance has been attempted. In 2004 and 2005 a majority of cereal cultivars on the Norwegian market were tested for susceptibility/resistance towards H. avenae pathotype Ha 11, H. avenae pathotype "Våxtorp" and H. filipjevi pathotype "West" The test program included 30 cultivars of barley, 23 cultivars of oats and 6 cultivars of summer wheat. The objective of this work was to increase our knowledge on cultivar selection for farmers. Resistance against Ha11 was found in 5 barley, 3 oat cultivars and in 1 wheat cultivar. Resistance against H. avenae pathotype "Våxtorp" was not present in barley, but 4 oat cultivars, and 1 wheat cultivar were resistant. For H. filipjevi "West" resistance was not detected in wheat, but in 6 barley and 13 oat cultivars. In Norway management systems based on careful nematode identification and good knowledge on appropriate resistant cultivars are in operation. Resistant barley is generally recommended when nematode populations are high due to its high tolerance compared to resistant oats. Farmers implementing this program have reported increased cereal yields on the average of 1000 kg /ha. It has been calculated that by implementing this program in full the county of Vestfold could make an economic gain of 800 000 " annually.
Forfattere
Ricardo HolgadoSammendrag
Det er ikke registrert sammendrag