Etiology and Real-Time Polymerase Chain Reaction-Based Detection of Gremmeniella- and Phomopsis-Associated Disease in Norway Spruce Seedlings

St. Paul

The American Phytopathological Society

2006

S.1305-1314

5 Abb., 3 Tab., 34 Lit. Ang.

BandaufführungSonderdruck

141457

Phytopathology : An International Journal of The American Phytopathological Society, S.1305-1314

In spring 2002, an unusual disease outburst was recorded on Norway spruce seedlings in southeast Norway. Extensive damage was recorded on 1- and 2-year-old Norway spruce seedlings that had either wintered in nursery cold storage or had been planted out in autumn 2001. The damage was characterised by leader shoot dieback and stem necroses on the upper or lower part of the shoot from 2001. Gremmeniella abietina and Phomopsis sp. were frequently isolated from the diseased seedlings. ITS rDNA sequence analysis and random amplified microsatellites (RAMS) profiling indicated that the G. abietina strains associated with diseased nursery seedlings belonged to the large-tree type (LTT) ecotype of the European race of G. abietina var. abietina, and inoculation tests confirmed their pathogenicity on Norway spruce. Based on ITS rDNA sequence analysis , the Phomopsis strains associated with diseased seedlings did not represent any characterized Phomopsis species associated with conifers. Phomopsis sp. was not pathogenic in inoculation tests, indicating that it may be a secondary colonizer. ITS-based real-time PCR assays were developed in order to detect and quantify G. abietina and Phomopsis in the nursery stock. We describe here the Gremmeniella abietina- associated shoot dieback symptoms on Norway spruce seedlings and conclude that the unusual disease outburst was likely related to the G. abietina var. abietina epidemic caused by the LTT on large Scots pines in 2001.