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In May 2008, symptoms of blueberry blight were observed on half-high blueberry (Vaccinium corymbosum L.) in a plant nursery in Anning, Yunnan Province. Symptoms included dieback and bud and branch blight. Symptomatic plant samples were washed with running tap water, disinfected with 2% sodium hypochlorite and then 70% alcohol, rinsed in sterile distilled water, plated on potato dextrose agar (PDA), and incubated at 26°C. Conidia forming on PDA were hyaline, granular, fusoid to ellipsoid, widest in the upper third with an obtuse apex and flattened, subtruncate base, and 18 to 21 × 4.5 to 8 μm. The pathogen was also identified to the species level by sequencing the ribosomal internal transcribed spacer regions 1 and 2 (ITSI-5.8S-ITS2) and the translation elongation factor 1-alpha (EF1-α). BLAST searches at GenBank showed the highest nucleotide sequence identity with Neofusicoccum vitifusiforme reference sequence (ITS: >98%, EF638785; EF1-α: 100%, EF638744 and AY343343). Representative sequences of isolates from both regions were deposited in GenBank (ITS: Accession No. HM131604; EF1-α: Accession No. HM454277). Pathogenicity tests were conducted on 2-year-old blueberry seedlings (half-high blueberry). Mycelial plugs (3 mm in diameter) of N. vitifusiforme from actively growing colonies (PDA) were applied to same-size bark wounds in the center of the stems. Inoculation wounds were wrapped with Parafilm. Control seedlings received sterile PDA plugs. Inoculated and control seedlings (five each) were kept in a greenhouse and watered as needed. After 2 weeks, all of the inoculated but none of the control blueberry seedlings showed dark vascular stem tissue. N. vitifusiforme was reisolated from symptomatic tissues, thus fulfilling Koch's postulates. N. vitifusiforme has been reported as a pathogen of olive (2), plum, peach (1), and grapevine (3). To our knowledge, this is the first report of N. vitifusiforme on blueberry in China as well as worldwide. References: (1) U. Damm et al. Mycologia 99:664, 2007. (2) C. Lazzizera et al. Plant Pathol. 57:948, 2008. (3) J. M. van Niekerk et al. Mycologia 96:781, 2004. |
