Branch cankers of loquat caused by Botryospaheriaceae spp. in Spain

Abstract

Samples of loquat (Eriobotrya japonica Lindl.) branches showing symptoms of branch cankers and dieback were collected in 2010 and 2011 from 30 orchards located in the main producing areas of Spain (Comunidad Valenciana and Andalucía regions). Several isolates with conidial morphologies corresponding to Botryosphaeriaceous species were obtained from these samples. A representative collection of 81 isolates was identified based on phenotypical characterization (dimensions of conidia and radial growth of mycelium) and phylogenetic analyses. Pycnidia were produced by plating mycelial plugs on 2% water agar plates containing sterilized pine needles, which were incubated at 25°C for 30-45 days with 12-h photoperiod and the conidia were measured. Maximum parsimony phylogenetic analyses, based on partial translation elongation factor 1-α (EF1-α) and internal transcribed spacers (ITS) sequences were performed to confirm the identity of the 81 isolates. The following species were identified: Diplodia seriata (n=55), Spencermartinsia viticola (n=11), Dothiorella sarmentorum (n=7), Neofusicoccum parvum (n=3), Diplodia olivarum (n=2), Neofusicoccum mediterraneum (n=1), Diplodia alatafructa (n=1) and Diplodia pinea (n=1). Radial growth rates of selected isolates of all species were determined after 7 days of incubation on PDA in the dark at 5-40°C with 5-degree intervals. Pathogenicity of representative isolates of all species was confirmed by inoculating the stem of 1-year-old loquat plants with mycelium plugs.