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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

Abstract

The European pine sawfly Neodiprion sertifer is a widely distributed defoliator of pines that can cause substantial growth losses over extensive areas. It attacks most species of twoneedle pines in its distribution area, and have occasional short-lived outbreaks that may cover up to 200.000 ha. In Norway we have had outbreak populations in the eastern part of the country since 2004, and in an ongoing research project we are evaluating aerial application of the Neodiprion sertifer nuclear polyhedrosis virus (NsNPV) to control Neodiprion sertifer....

Abstract

The difficulty in subculturing biotrophic fungi complicates etiological studies related to the associated plant diseases. By employing internal transcribed spacer rDNA-targeted quantitative real-time polymerase chain reaction, we now show that the heteroecious rust Thekopsora areolata, commonly associated in natural conditions to sapling shoots and cones of Norway spruce and leaves of wild bird cherry, frequently infects nurserygrown seedlings of the conifer. A spatial sampling scheme was used to investigate seedlings and saplings of Norway spruce showing phloem necrosis: the highest concentration of DNA of T. areolata was recorded in the area with necrotic phloem. The separate analysis of bark and wood tissues suggested that the initial spread of the rust to healthy tissues neighboring the infection site takes place in the bark. A Phomopsis species found to coexist with T. areolata in several seedlings showed very high DNA levels in the upper part of the lesion, and even in the visually healthy proximal tissues above the lesions, which indicates that the ascomycete, most probably a secondary invader following primary infection by T. areolata, has a latent stage during early host colonization. We hypothesize that this hemibiotrophic mode of infection contributes to the successful coexistence of Phomopsis with a biotrophic rust.