1The Norwegian Crop Research Institute, Plant Protection Centre, Dept of Plant Pathology, Fellesbygget, 1432 Ås, Norway; 2Present address: Statens Gartner- og blomsterdekoratørskole Vea, 2390 Moelv, Norway

Background and objectives
Raspberry bushy dwarf virus (RBDV) is a seed and pollen transmitted virus causing damage to raspberry production on its own or in mixed infections with other viruses of raspberry [1]. RBDV can be latent or give varying symptoms depending on variety and growing conditions. Symptoms may be delayed flowering, crumbly fruits, yield reduction and chlorosis. In the county Sogn og Fjordane, the county where raspberry production is of greatest importance, virus diseases are important. The occurrence of nepoviruses and aphid transmitted viruses have been assessed earlier, but very little has been known about the occurrence of RBDV. In this work we report from a survey on RBDV in the county Sogn og Fjordane and other growing areas of raspberry in Norway.

Materials and methods
Leaf samples were collected from both commercial fields, variety trial fields, private gardens and wild raspberry. The samples were tested by enzyme-linked immunosorbent assay (ELISA). The antiserum and conjugate was delivered by Agdia, Inc. (Elkhart, IN, USA). In total 1345 samples collected from all over Norway were tested. Most samples were collected in the county of Sogn og Fjordane due to its importance in raspberry production in Norway.

RBDV was detected in several raspberry cultivars and also in several counties. The highest ELISA values were found in samples of the cultivars Glen Moy, 44-C-9,'Asker and Norna. Most infected samples were found in the cultivar Veten in Sogn og Fjordane, but these samples often gave low values, probably partly due to storing of the samples before processing in ELISA. Most infected Veten fields were more than 10 years old although positive samples were found also in as young as 2-year-old fields. RBDV was detected in both commercial fields, trial fields and private gardens. Only a few samples from locations of wild raspberry tested positive for RBDV. The cultivar Glen Moy is described to be susceptible only to the resistance breaking strains [2]. This means that resistance breaking strains also occur in Norway. Further research should be performed to assess the effect of RBDV on raspberry in the most important raspberry growing areas in Western Norway and to find how rapidly RBDV spreads in these districts.

1. Murant AF, 1987. pp. 229-234 in Converse RH (ed.), Virus Diseases of Small Fruits. United States Department of Agriculture, Agriculture Handbook No. 631.
2. Barbara DJ, Jones AT, Henderson SJ, Wilson SC, Knight VH, 1984. Annals of Applied Biology 105,49-54.