Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2008
Authors
Arvid Steen Turid Strøm Aksel BernhoftAbstract
No abstract has been registered
Abstract
To evaluate overwintering strategies of the fungus Neozygites floridana, an important natural enemy of Tetranychus urticae, hibernating T. urticae females were investigated for the presence of fungal structures throughout one winter (October 12, 2006 to February 19, 2007) in field-grown strawberries in a cold climate in Norway ( min. ambient temp -15.3 degrees C). Neozygites floridana was present as hyphal bodies inside live, hibernating females in T. urticae populations throughout the sampling period. The lowest percentages of hibernating females with hyphal bodies were found at the two first dates of sampling at 5.5 and 0% on October 12 and 19, respectively. The prevalence then increased and peaked at 54.4% on January 14. Resting spores (immature) were also found in live hibernating females at some dates, but at lower prevalence than for hyphal bodies and predominantly only until November 8. Prevalence of resting spores in live hibernating females ranged from 2.5 to 13.8%. Total number of T. urticae was also recorded, and most mites of all four categories (nymphs, males, non-hibernating and hibernating females) were found at the first sampling date. At this date non-hibernating females were the most abundant. A sharp decrease in non-hibernating females, nymphs and males was, however, seen from mid-October to mid-November; also numbers of hibernating females decreased, but not as fast. The relative abundance of hibernating females compared to non-hibernating females increased from 32.2% at the first collection (October 12) to 97.7% at the last collection (February 2). This study confirms that N.floridana survives the winter as a semi-latent hyphal body infection, protected inside live hibernating females. It is therefore ready to develop and sporulate as soon as climatic conditions permit, resulting in early season infection of T. urticae.
Abstract
No abstract has been registered
Authors
Sonja Klemsdal Maria Herrero L. A. Wanner Grete Lund Arne HermansenAbstract
No abstract has been registered
Authors
Leif Sundheim May Bente Brurberg Trond Hofsvang Christer Magnusson Trond Rafoss Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
No abstract has been registered
Authors
Leif Sundheim May Bente Brurberg Trond Hofsvang Christer Magnusson Trond Rafoss Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
In 2007, after many years of absence, Cucumber Green Mottle Mosaic Virus (CGMMV) reoccurred in Norwegian cucumber production. The Norwegian Food Safety Authority is considering to regulate CGMMV as a quarantine pest and commissioned a Pest Risk Analysis (PRA) of the virus. The Panel of Plant Health gives the following conclusions: Both recent and previous presence of CGMMV indicate that the pest is able to establish in the PRA area. The most probable pathway for long distance spread into the PRA area is seed transmission. Infected seedlings, people, water and soil are probable pathways for short distance spread. The probability of further spread is from location to location is high. Dry heat treatment has probably been the most effective measure to prevent the spread of CGMMV. There is a moderate level of uncertainty regarding the pathway for entry of CGMMV into the PRA area. There is a low degree of uncertainty regarding the pathogen survival and possibilty for transmission, establishment and spread in Norwegian greenhouse cucumber production.
Authors
Leif Sundheim May Bente Brurberg Trond Hofsvang Christer Magnusson Trond Rafoss Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
No abstract has been registered
Abstract
Pine Wood Nematode (PWN, Bursaphelenchus xylophilus) is the causal organism of Pine Wilt Disease (PWD), the worst forest pest of Japan. In Europe PWN is known to exist in Portugal. The Norwegian Food Safety Authority (Mattilsynet) is concerned about the plant health risks and the consequences to the society if PWN should establish in Norway. Mattilsynet needs a scientific assessment of the proposed measures in a contingency plan for PWN. Mattilsynet also needs the risks connected with recent spread of PWN in Portugal to be evaluated before possible changes can be made in the current phytosanitary policy of Norway. On this background Mattilsynet requested a pest risk assessment of PWN from the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM). To answer the request, VKM commissioned a draft pest risk assessment report from the Norwegian Institute for Agricultural Sciences and Environmental Research (Bioforsk). A working group appointed by VKM’s Panel on Plant Health (Panel 9) has been involved during Bioforsk’s work on the report. VKM’s Panel 9 has used the report as a basis for VKM’s opinion. The current document answers Part 1 of Mattilsynet’s request, and was adopted by Panel 9 on a meeting 3rd September 2008. VKM’s Panel 9 gives the following main conclusions of the risk assessment: The PRA area of this assessment is Norway. PWN is not known to occur in Norway. With present trade pattern the probability of entry of PWN into Norway is expected to be high. The most probable pathway for entry of PWN into Norway would be wood packaging material (WPM). The probability that PWN will establish and spread in Norway is considered as high. With regard to the so-called Pest Free Areas (PFAs) of Portugal, the criteria given in ISPM No. 4 (FAO 1995) for establishing and maintaining PFAs have not been met, and the data available is not sufficient to confirm the existence of PFAs. Acceptance of untreated conifer wood from all parts of Portugal will result in a very high probability of entry and a high probability of establishment and spread of PWN and its vector to Norway. Uncertainty factors: To the best of our knowledge PWN is absent from the PRA area. The beetle M. sutor is regarded as a potential vector or PWN, but this has so far not been demonstrated in nature. The currently low vector densities may retard establishment of the PWN and PWD, but it will probably not stop establishment in a longer perspective. Lack of information on the dynamics of PWN populations in cool climates complicates estimates of the spread of the nematode and PWD. Custom routines may fail in their detection of PWN. Import of a seemingly harmless material might therefore pose an unknown risk. WPM follows consignments of all kinds and is a good example of a hazardous material, which often escapes plant health inspections. Detailed assessments of economic consequences of a possible establishment and spread of PWN in Norway, the effects of global warming and other climate changes on the probability for PWD outbreaks, and the effect of possible phytosanitary measures, will be given in Part 2.
Authors
Leif Sundheim May Bente Brurberg Trond Hofsvang Christer Magnusson Trond Rafoss Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
No abstract has been registered
Authors
Leif Sundheim May Bente Brurberg Trond Hofsvang Christer Magnusson Trond Rafoss Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
Wild oats (A. fatua) is present in 155 out of 431 Norwegian municipalities. It is widely distributed in all municipalities in the main agricultural areas in south-east and central-east Norway, and in the municipalities close to the Trondheim fjord. Otherwise wild oats is present in only a few scattered municipalities not geographically connected to these main areas. Endangered area, not yet infested by A. fatua, is estimated to 228858 ha. This area is spread over the cereal growing part of Norway. The counties of North- and South -Trøndelag have a higher portion of endangered area not yet infested than south and central part of East Norway. The probability of entry of A. fatua from outside the PRA area (Norway) is very low. The probability of spread within Norway is high. In areas with low infestation, like in Trøndelag, the probability of spread is lower than in heavily infested areas. However, in areas with high level of infestation there are few new farms left to be infested. The official wild oats register is a valuable tool in regulations aiming to limit spread. The register also provides a tool to follow up infested farms. The register would be even more useful if inspection for infestation on new farms had been more systematic. Wild oats is no longer devastating even in cereal monocropping, due to cost efficient herbicides. However, in Norway an increasing area is infested with wild oats. The infestation may vary from only a few plants to total coverage of the field. In cereal monocropping chemical treatment with and without hand roguing is the only feasible control methods. Hand roguing alone is expensive and ineffective even on modest infestation. The structural changes in cereal farming result in more farms being managed by entrepreneurs. Field managed by entrepreneurs promotes use of herbicide even on small infestations since this is a cost effective measure to control the weed. Less official control of cereal fields can also be expected. The economical consequences are thus expected to be high. The economical consequences can be even higher in organic farming if the most profitable rotation has to be changed to a less profitable one because of wild oats infestation.