Botryosphaeriaceae species associated with wood diseases of stone and pome fruits trees: symptoms and virulence across different hosts in Uruguay

Abstract

Apple, pear and peach orchards are usually planted in close proximity, and they might share pathogenic fungal species affecting different plant organs. In particular, species of Botryosphaeriaceae have been indicated as responsible for wood diseases in these fruit species. Symptoms frequently observed in Uruguay include papyraceous cankers in apple trunks, dead shoots in pears, and gummosis in peach shoots and branches. Symptomatic tissues of these species were sampled, and fungi resembling species within Botryosphaeriaceae were isolated and identified based on phylogenetic analysis of the internal transcribed spacer region (ITS), part of the translation elongation factor 1-α gene (EF1-α) and part of the RNA polymerase II subunit gen (RPB2). Pathogenicity of selected isolates was assessed under laboratory and field conditions. Botryosphaeria dothidea, Diplodia seriata and Neofusicoccum parvum were isolated from the three hosts from symptomatic tissues. However, only N. parvum proved to be pathogenic when inoculated on trees of all three species, while D. seriata showed pathogenicity towards apple and peach trees only. Diplodia mutila and N. australe were isolated less frequently and not from all the host species. However, they were the most virulent based on lesion length on all tested plant species. The fact that fungal isolates obtained from one host could cause disease symptoms also in some of the alternative hosts suggests that cross infections are possible between apple, pear and peach trees. Finally, Diplodia pseudoseriata in Prunus persica and Diplodia mutila in Pyrus communis, are new records for these hosts in Uruguay.