Hopp til hovedinnholdet

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.

2006

Sammendrag

To avoid problems with seed borne diseases in organic cereal production, seed health testing should be compulsory in certification of organic seed. In general, significantly lower infection frequencies of seed borne diseases are recorded on seedlings than on seed. Thresholds for the amount of seed borne inoculum that can be accepted for organic production are therefore needed. The aim of the work presented is to compare transmission rates of Drechslera on barley and oats under organic and conventional conditions, to be able to decide if existing thresholds used to assess the need of chemical seed treatment, can be applied for acceptance of organic seed lots, or for recommendation of alternative treatments. Field experiments were carried out in 2005 in conventional and organic fields situated close to each other at each of three locations (south/east-Norway, east-Norway and mid-Norway). 10 seed lots of barley and 10 lots of oats, with a range of seed infections (barley: 0-94 % Drechslera teres, average 23,7 %; oats: 0-66 % Drechslera avenae, average 22,0 %) were planted in rows of 100 seeds with 8 replicates in each location/`growing system". Percent emergence and seedlings with primary infections were recorded at BBCH 12-13. In average of the three locations 2,5 % and 2.1 % barley seedlings were infected when grown in conventional and organic fields, respectively. In oats, 2,0 % and 0,8 % infected seedlings were recorded in conventional and organic fields, respectively. Similar experiments will be carried out in 2006 and results from this will also be presented.

Sammendrag

On the southwest coast of Norway there are natural stands of holly (Ilex aquifolium), but a number of different varieties of I. aquifolium and I. meserveae are also grown in bough production fields, private gardens and public parks. Except for conifers, holly is the only tree we have with green foliage during the winter in Norway. The leathery, dark green leaves with prickly spines and the red berries have made holly a popular plant for Christmas decorations. Leaf-drop/defoliation has become an increasing problem during the last decades both before and after harvest, and thus destroys the marketability. We suspect that reduced grazing has resulted in more overgrown/dense stands and hence created ideal microclimate for fungal growth. Wet foliage due to shade and restricted air movement gives the spores good conditions for germination. On investigated diseased plant material collected from holly in the period 2001-2006, a number of possible pathogenic fungi were isolated; Fusarium avenaceum, Vialaea insculpta, Nectria sp., Colletotrichum acutatum, Trochila ilicina and Diaporthe ilicis (Talgø et al. 2006). The fungi were identified morphologically mainly based on information given by Ellis & Ellis (1997). Colletotrichum was identified to species level by PCR. In the literature we find very little about what kind of damage these organisms may cause on holly. Benson & Jones (2000) say that leaf-spotting fungi on holly can cause heavy defoliation before new growth starts in the spring, but they do not mention any specific pathogen. Therefore we will run pathogenesis tests with all the fungi mentioned above to fulfil Koch"s postulate.