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
Sammendrag
Potetene vil også i 2006 krever riktig tørråtebekjempelse for å unngå redusert avling og kvalitet. 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
Ricardo Holgado Janet Rowe Stig Andersson Christer MagnussonSammendrag
Cereal cyst nematodes, Heterodera spp., are recognised throughout the world as economically important parasites of cereals. The virulence status on cereal cultivars differs between and within different species of the H. avenae-complex, and several pathotypes occur among them. A survey during 1995-2005 in Norway revealed that Heterodera spp. is common throughout the country. Studies in Norway have recorded H. filipjevi and also additional and possibly new species. A number of cereal cyst nematode populations from various regions of Norway, Sweden and the British Isles have been analysed using molecular, morphological and host range studies during the last three years. Fifteen populations, of the initial group of forty, are being studied more closely. Studies using isoelectric focusing and silver staining have detected divergent populations of H. avenae. The Swedish populations Ringsåsen seemed to be identical to a population found in Australia and the Swedish population Halland shows a protein profile separate from H. avenae. DNA studies are being used to determine if these populations are new species. An assortment of cereal cultivars, based on an international collection used for resistance testing, differentiates three groups, H. avenae (pathotypes Ha 11 and Ha 12), H. filipjevi (pathotype "West"), and a population from central Norway close to H. pratensis. Knowledge of the diversity of cereal cyst nematodes and their multiplication rates on their cereal hosts is of fundamental importance for efficient control strategies involving resistant cultivars. In Norway, management based on these parameters are in operation and have increased yields and profits to cereal farmers.
Sammendrag
The aim of this three-year study (2001"2003) was to optimize fungicide application against anthracnose (Colletotrichum acutatum) in sweet and sour cherry orchards. The experimental sprays were applied to trees receiving normal fungicide programmes (grower schedule), although without the use of dithianon, except for the first year where only the experimental applications were applied to the sour cherry trees. Fungicide treatments were applied with either dithianon or copperoxychloride added prior to flowering or with dithianon added after flowering. Spraying with dithianon or copperoxychloride prior to flowering did not significantly reduce anthracnose compared to untreated. Two applications with dithianon during the green fruit stage (from petal fall and during the following 3"4 weeks) greatly reduced anthracnose at harvest. Three applications on green fruit did not reduce disease more than two applications. In sweet cherries, two sprays with dithianon at the green fruit stage in addition to the grower schedule reduced anthracnose at harvest from 14% to 3% in 2002 and from 15% to 1% the following year. In 2001, when very few fruit developed anthracnose, no treatment effects were evident. Treatments on green sour cherry fruit similar to those on sweet cherries reduced the attack of anthracnose from 85% to 42% in 2002 and from 51% to 12% the following year. In 2001, no treatment included only sprays on green fruit. However, one treatment, which included copperoxychloride at bud burst, one application of dithianon during flowering and two applications on green fruits, reduced anthracnose from 27% to 9%. Based on these results, cherry growers are recommended to spray twice with dithianon on green fruit if they have a history of anthracnose in their orchards.
Forfattere
Sverre Kobro Geir Kjølberg KnudsenSammendrag
Det hender at det er mark i eplene. Markene er larver av en liten sommerfugl. Den heter rognebærmøll fordi den normalt utvikler seg i bærene på rogn. I enkelte år er det for lite bær på rogna, bare da kan møllet angripe eple.
Sammendrag
Methods for measuring prevalence of Neozygites floridana in a Tetranychus urticae population collected from strawberries were developed and compared. T. urticae were extracted from leaves using a soapy water solution (0.5 ml washing detergent : 8 l water) and then placed into 80% alcohol for use in methods 1 and 2. Method 1: N. floridana-sporulating T. urticae cadavers were observed and quantified under a compound microscope (40-80X). Method 2: Adult females were mounted in lactophenol cotton blue and observed for the presence or absence of N. floridana hyphal bodies under a microscope (200-400X). Method 3: Live T. urticae females were incubated at 25ºC and 75% RH and observed for mortality and N. floridana infection under a compound microscope (6.4-40X). Method 1 was the most time-efficient method and it also allows processing of samples as time permits. Method 2 quantified significantly higher fungal prevalence than method 1 and 3, but method 2 is not considered to be reliable because hyphal bodies are difficult to detect. No significant differences were found between methods 1 and 3.
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
Sverre Kobro Trond RafossSammendrag
The presence of multiple phenological forms has previously made adults of Hoplothrips species difficult to identify. We present a set of diagnostic metric characters by which the 8 species recorded from Norway can be recognised.Some biological interpretations are also given.
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.
Sammendrag
Plantevernmiddelresistens hos skadedyr har vært et økende problem i veksthus her i landet de siste årene, og resistens er nå påvist eller mistenkes å forekomme hos flere av de viktigste skadedyrartene. Resistens har hittil vært mindre omfattende i frilandskulturer, men siden 2003 er det kommet inn rapporter fra dyrkere og veiledningstjeneste om feilslått bekjempelse av bl.a. gulrotsuger, jordbærsnutebille, potetsikade, rapsglansbille og ferskenbladlus. Bioforsk Plantehelse har i de siste årene gjort flere undersøkelser der vi har lett etter resistens mot plantevernmidler hos skadedyr i veksthus og på friland, siden 1998 har vi har undersøkt plantevernmiddelresistens hos ferskenbladlus (Myzus persicae), bomullsmellus (Bemisia tabaci), minerfluer (Liriomyza spp.), jordbærsnutebille (Anthonomus rubi), potetsikade (Empoasca vitis) og gulrotsuger (Trioza apicalis). Vi har brukt både biologiske tester (bioassays), hvor insektene eksponeres for en diagnostisk dose eller en fortynningsserie av plantevernmidlet.