title: A revision of the history of the Colletotrichum acutatum species complex in the Nordic countries based on herbarium specimens.
abstract: Herbaria collections containing plants with disease symptoms are highly valuable, and they are often the only way to investigate outbreaks and epidemics from the past as the number of viable isolates in culture collections is often limited. Species belonging to the Colletotrichum acutatum complex infect a range of important crops. As members of the C. acutatum complex are easily confused with other Colletotrichum species, molecular methods are central for the correct identification. We performed molecular analyses on 21 herbaria specimens, displaying anthracnose symptoms, collected in Norway and Denmark before the first confirmed findings of C. acutatum complex members in this region. Sequencing parts of the fungal ITS regions showed that members of the species complex were present in 13 of the 21 specimens collected in different parts of Norway and Denmark between 1948 and 1991, representing seven plant hosts (three cherry species, apple, raspberry and rhododendron). This is the first time herbarium specimens have been used to study these pathogens under Nordic conditions. Differences in the ITS sequences suggest the presence of different genotypes within the complex, indicating a well-established population.
authors: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors: Thomas
authors: T
authors: Sundelin
authors: Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, 1430 Ås, Norway.
authors: Gunn Mari
authors: GM
authors: Strømeng
authors: Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, 1430 Ås, Norway.
authors: Halvor B
authors: HB
authors: Gjærum
authors: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors: Daniel Buchvaldt
authors: DB
authors: Amby
authors: Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, 1430 Ås, Norway.
authors: Kari
authors: K
authors: Ørstad
authors: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors: Birgit
authors: B
authors: Jensen
authors: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors: Ole Søgaard
authors: OS
authors: Lund
authors: Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Plant Health and Plant Protection Division, 1430 Ås, Norway arne.stensvand@bioforsk.no.
authors: Arne
authors: A
authors: Stensvand
mesh_terms: D020231:Colletotrichum / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004271:DNA, Fungal / Q000235:genetics; D003718:Denmark; D029964:Fagus / Q000382:microbiology; D005638:Fruit / Q000382:microbiology*; D016681:Genome, Fungal; D005838:Genotype; D027845:Malus / Q000382:microbiology; D009664:Norway; D010935:Plant Diseases / Q000382:microbiology*; D010944:Plants / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D027861:Prunus / Q000382:microbiology; D029793:Rhododendron / Q000382:microbiology; D065856:Rubus / Q000382:microbiology; D017422:Sequence Analysis, DNA; D031994:Sorbus / Q000382:microbiology
chemical_list: D004271:DNA, Fungal
keywords: Malus; PCR; Prunus; Rhododendron; herbarium