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.
2009
Sammendrag
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Sammendrag
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Forfattere
Bjørn Molteberg Bernt Hoel Hans TandsætherSammendrag
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Forfattere
Per Jarle MøllerhagenSammendrag
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Sammendrag
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Forfattere
Kristian HaugSammendrag
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Sammendrag
The vine weevil, Othiorynchus sulcatus, is a serious pest in strawberries and biological control methods are needed to combat this pest. Formulations of the insect pathogenic fungus Metarhizium anisopliae is registered for use against Otiorhynchus spp. in several countries but no fungal control agents are avilable for control of O. sulcatus in Norway. All developmental stages of Otiorhynchus spp. are susceptible to virulent insect pathogenic fungal species, but best control has been achieved against the larvae (Moorhouse et al. 1992). A number of studies have shown that M. anisopliae and Beauveria bassiana have good potential against Otiorhynchus spp. (Cross et al. 2001). In field grown strawberries, good control with Metarhizium has been reported when environmental conditions for the fungus are favourable (Oakley 1994). Temperatures in excess of 15oC are required for good control by most fungal isolates. Low temperature is therefore a major restricting factor for use of fungi outdoors (Gillespie et al. 1989, Soares et al. 1983). Isolates with low temperature optimums could therefore be well suited for field conditions in Northern Europe, where soil temperatures at the time when most larvae are found in the soil in autumn are 10-12oC. Norwegian M. anisopliae and B. bassiana isolates have shown promising results against O. sulcatus larvae at low temperatures in laboratory bioassays (Hjeljord & Klingen 2005). One of the Norwegian M. anisopliae isolates has also shown good competition with other soil fungi in laboratory experiments (Hjeljord & Meadow 2005). In addition to being cold tolerant, rhizosphere competence is important for fungal control agents that are used to control root feeding pests. "Rhizosphere competence" has been defined when considering biological control agents as "the ability of a microorganism, applied by seed treatment, to colonize the rhizosphere of developing roots" (Baker 1991). In this study we therefore aimed at testing the survival and rhizosphere competence of two different cold active Norwegian isolates (M. anisopliae isolate NCRI 250/02 and B. bassiana NCRI 12/96) in a semi field experiment in Norway. These were compared with the commercially avilable M. anisopliae isolate Ma43 originating from Austria (the isolate is also known to have many other names (Eilenberg 2008)). The study was conducted by estimating fungal concentrations in the bulk and rhizosphere soil surrounding the strawberry plant roots by counting colony forming unists (CFUs). The highest numbers of B. bassiana NCRI 12/96 CFUs were seen in the rhizosphere at 1.87x109 per liter soil 3 months after application. The highest numbers of M. anisopliae NCRI 250/02 CFUs were seen in the rhizosphere at 2.41x109 per liter soil 1 year after application. Numbers of CFUs for the M. ansiopliae Ma43 CFUs were generally lower than for the Norwegian isolates, but also for this isolate a higher fungal concentration was found in the rihzosphere soil than in the bulk soil.
Sammendrag
Red stele in strawberry is caused by the oomycete Phytophthora fragariae. To prevent the introduction of the pathogen to Norway, it has been prohibited to import planting material of Fragaria spp. to the country since 1986. During 1995 to 1997 the Food Authority had a country-wide survey to reveal if P. fragariae was present. The pathogen was found in three separate regions: (i) Hedmark County, along the Mjøsa lake; (ii) Aust-Agder and Vest-Agder Counties, in coastal areas; (iii) Rogaland and Hordaland Counties, along the western border between the two counties. In the latter area there were clear indications of spread of infected plant material from a small certified nursery where P. fragariae was detected. All strawberry farms that had received plants from the nursery were thoroughly investigated and further sales of planting material was stopped. All other incidences in the 1995-97 survey were among strawberry fruit producers. In 2006 and 2007 there were two new detections of red stele in Vest-Agder, and one of the growers had produced and forwarded non-certified planting material to other strawberry growers. In 2008, a new country-wide survey was initiated, and the pathogen was found at a few new production sites for strawberry fruits in Hedmark and at one site in Vestfold County (in south eastern Norway). In 2009, red stele was also discovered at one site in Møre og Romsdal County (in western Norway). Totally, red stele has been found at 19 production sites in Norway. Since the mid 1990"s there have been no discoveries of red stele among certified plant producers. Sites where P. fragariae has been detected may continue to produce strawberry fruit for sale, but all production of strawberry plants or other planting material for further distribution is prohibited. For strawberry production on soil infested with P. fragariae, buffer zones to neighboring fields and creeks/rivers are required. No strawberry production can take place in the buffer zones, and normally the zones should be at least 100 m wide, but topographic and other conditions locally may increase or decrease the width of the zones. There are also restrictions on sharing machinery and equipment with other farms, and soil from infested farms may not be moved out of the farm. Testing of plant material is done by a root tip bait test and PCR.
Sammendrag
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Forfattere
Bernt Hoel Hans TandsætherSammendrag
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