Neofusicoccum spp. Associated with Stem Canker and Dieback of Blueberry in Chile

Blueberry (Vaccinium spp.) plantings have significantly increased in Chile during the last decade and, currently, over 10,700 ha are cultivated throughout the country. Among other diseases, stem canker and dieback has been frequently observed in commercial plantations with incidences between 15 and 45%. The aim of this study was to identify and characterize Neofusicoccum spp. causing stem canker and dieback of blueberry in Chile. Three species, N. arbuti, N. australe, and N. parvum, were identified based on colony and conidia morphology, and nucleotide sequence analysis of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2). These Neofusicoccum spp. were found alone or coexisting with Pestalotiopsis spp., Truncatella spp., or Phomopsis spp. Koch's postulates showed all Neofusicoccum spp. isolated from infected plants to be pathogenic when inoculated on blueberry fruit and twigs using both mycelia and conidia suspension. All blueberry cultivars tested, including, Brigitta, Bluecrop, Brightwell, Duke, Elliott, Misty, and O'Neal, were susceptible to Neofusicoccum spp. infection. Pathogenicity tests showed N. parvum to be the most virulent species and Elliott to be the most susceptible cultivar. This report represents the first description of N. arbuti, N. australe, and N. parvum as canker-causing agents on blueberry in Chile.