Identification and distribution of species of <i>Neofusicoccum</i> that cause blueberry stem blight in Chile

Stem blight is a destructive woody disease of blueberry (<i>Vaccinium corymbosum</i>) caused by several species of the family Botryosphaeriaceae. A field survey was conducted in the mayor blueberry production area of Chile, comprising latitudes 32°49ʹS to 40°55ʹS, to determine the occurrence and distribution of Botryosphaeriaceae in the region. Together, a multilocus analysis, morphological characterization, and phytopathogenicity testing were used to identify 51 <i>Neofusicoccum</i> isolates belonging to <i>N. nonquaesitum</i> (28 strains), <i>N. parvum</i> (22 strains), and <i>N. australe</i> (1 strain). Of these, <i>N. parvum</i> and <i>N. nonquaesitum</i> were the most commonly found, with <i>N. parvum</i> most frequent from latitude 37°40ʹS to the north and <i>N. nonquaesitum</i> predominantly located from the same latitude toward the south. Morphological traits of the isolates were consistent with the species identified by molecular techniques, despite the overlapping of conidial size of some isolates among species. Pathogenicity trials showed that the three species were pathogenic to blueberry plants and revealed that <i>N. parvum</i> and <i>N. nonquaesitum</i> were the most aggressive species, although variability in virulence was observed among isolates of <i>N. parvum</i> and <i>N. nonquaesitum</i>.