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.
2011
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May Sæthre I. Godonou Trond Hofsvang Ghislain Tchoromi Tepa-Yotto B. JamesAbstract
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Venche Talgø Leif Sundheim Halvor B. Gjærum Maria Herrero Aruppillai Suthaparan Brita Toppe Arne StensvandAbstract
This paper presents powdery mildew species recorded on woody ornamentals, with special emphasis on the latest arrivals; Erysiphe flexuosa on horse chestnut (Aesculus hippocastanum), Erysiphe syringae-japonicae on lilac (Syringa vulgaris) and Podosphaera spireae on white spirea (Spiraea betulifolia). The two former were found in 2006, while the latter was first detected in 2008. Chasmothecia (formerly named cleistothecia) were not found on white spirea until 2010. Several locations seemed to have optimal conditions for development of powdery mildew diseases in 2006. That year the long established Sawadaea bicornis on sycamore maple (Acer pseudoplatanus), was found for the first time on tatarian maple (Acer tataricum ssp. ginnala) and one cultivar from hedge maple (Acer campestre "Red Shine"). Also several species and cultivars of Rhododendron had massive attacks of powdery mildew in 2006. In 2010, chasmothecia of E. azaleae were found on severely affected R. "Magnifica" in western Norway. Most powdery mildew species are host specific, but especially Phyllactinia guttata has a wider host range, e.g. hazel (Corylus spp.) and common ash (Fraxinus excelsior).
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The anticipated future changes in temperature, precipitation and snow cover caused by global warming may affect winter survival of autumn sown wheat. More variable weather conditions may cause an increased frequency of periods with alternating freezing and thawing and less stable snow covers. In the present study, the course of plant frost tolerance and growth potential was studied by exposing cold acclimated plants of winter wheat to conditions with alternating periods of freezing and thawing (either -1 °C or +5 °C), and differing durations of snow cover. Tests of frost tolerance and determination of growth potential were performed each time the temperature or snow cover conditions were changed. Periods without snow cover and + 5 °C caused dehardening, with loss of frost tolerance being more pronounced during the first dehardening period than in the second one. The ability to reharden after a dehardening period decreased towards the end of the experimental period. Mild periods during winter also seemed to exhaust plant growth potential, possibly by increasing respiration rate while photosynthesis was still restricted. The results indicate some of the challenges we may face regarding overwintering of winter wheat in a future climate.
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Aksel DøvingAbstract
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Tor J. JohansenAbstract
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Mekjell MelandAbstract
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