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.
2005
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.
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Det er ikke registrert sammendrag
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Biologisk bekjempelse av spinnmidd og trips i agurk med Phytoseiulus persimilis og Amblyseius cucumeris.
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Biologisk bekjempelse av veksthusspinnmidd og mellus i snittroser med Phytoseiulus persimilis og Encarsia formosa
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Artificial light effects on pests and beneficials: Overview
Sammendrag
Det er observert oppsvulmete skudd og kvister, som innholder larver, på rødpil. Skaden er forårsaket av en gallmygg i slekten pilegallmygg (Dasineura, syn. Rabdophaga). Larvene er lys rødgule (1,5 x 1,0 mm) og gallene dannes på 1-årige skudd. De bekjempes ved å fjerne og brenne (evt. grave ned) skudd og kvister med galler på våren og forsommeren.
Forfattere
Richard Meadow Linda Hjeljord Annette Folkedal SchjøllSammendrag
In order to infect target insects after application to soil or plant surfaces, Metarhizium anisopliae conidia must remain viable in the face of abiotic and biotic factors. As a part of an inveestigation to develop M. anisopliae as an agent against the black wine weevil, we investigated the fungus ability to compete with conidia of fungi commonly isolated from soil and aboveground surfaces of strawberry in Norway. In previous work, we determined the speed of germination of the isolates at various temperatures, and investigated the effects of inoculating various nutrient substances with conidia of the insect pathogens, before or together with conidia of Cladosporium sp., Trichoderma spp., Verticillium sp., Botrytis cinerea, and Gliocladium sp. Results showed that the insect pathogens, germinated as quickly as the other fungi only at temperatures >=25C. Although germination spees of the insect pathogens varied between isolates, none germinated nor grew as quickly at 15 or 20C as did the other fungi. When coinoculated with conidia of the environmental isolates on a range of agar media at 20C, growth of the insect pathogens was strongly inhibited. In contrast, when the insect pathogens were inoculated at a distance from the other fungi, their colonies inhibited mycelical growth of all the other fungi; M. anisopliae isolates produced clear antibiosis zones against Cladosporium sp. and B. cinerea. On nutrient-poor media, or when substrate nutrients were depleted, colonies of the insect pathogens were eventually overgrown by Gliocladium sp. and Trichoderma spp.In an experiment where weevil larvae were exposed to conidia of M. anisopliae and T. atroviride either separately or combined, and incubated in sterile soil at 22C, the Metarhizium appeared to be unhibited in killing the larvae and sporulating. Follow-up experiments are plannes to look at this interaction at different temperatures and when applying the fungi to the soil.
Sammendrag
Det er ikke registrert sammendrag