Detection of Neofusicoccum nonquaesitum causing dieback and canker in highbush blueberry from Southern Chile

Abstract

Due to increased incidence of wood fungi from genus Neofusicoccum in highbush blueberry (Vaccinium corymbosum L.) established in various locations in Southern Chile. The objective of this study was the identification of Neofusicocum species in two highbush blueberry cultivars from commercial orchards in Southern Chile. During 2011-12 season, stems with basal cankers and twigs with dieback were collected from cultivars Brigitta and Elliott grown in Panguipulli (39º30’S; 72º 19’W) and Teodoro Schmidt (38°58’S; 73°02’W). Tissues were kept in humid conditions and from cirrus conidia were taken and incubated in PDA medium. The mycelia had a cottony consistency, with colour ranging from greyish-white to black; sub-epidermal pycnidia were eruptive, ostiolate, and brown to black in colour. The unicellular conidia were hyaline, smooth-bordered, coenocytic and septate (1-3), with dense granular content, fusiform and elipsoidal with truncated point, measuring 27.2 ─ 29.4 (±3.0) µm × 7.7 ─ 8.4 (±0.9) µm; length/width ratio (L/W) = 3.6 ±0.6 (n=100). The morphometric characteristics corresponded to those of Neofusicoccum nonquaesitum and corroborated genetically (100% homologation) by rDNA sequencing ITS and was recorded in CABI under number IMI-500168. Whereas, the sequencing was deposited into Genbank (accession number JX217819.1). The pathogenicity of the fungus was consistent in twigs and stems of highbush blueberry cultivars Brigitta and Elliott.