Four new fungal pathogens causing avocado dieback in Brazil

Abstract

Dieback is a disease with a complex etiology that results in the death of branches or entire plants in avocado producing regions. Losses associated with this disease have already been reported in the main producing regions of Brazil. The etiological agents of this disease are different and an association between fungi is often observed. This study aimed to identify fungi associated with avocado dieback in Brazil. Fungal isolates were collected from symptomatic avocado stems from orchards in São Paulo state. Identification was based on phenotypic characteristics and multilocus phylogenetic analysis of the translation elongation factor 1-alpha, RNA polymerase II, β-tubulin, actin, the internal transcribed spacer (ITS) region of rDNA, and the large subunit ribosomal RNA regions, according to the previously identified genus. The pathogenicity test confirmed that all species were pathogenic to avocado seedlings and fruits. This is the first report of Neopestalotiopsis arecacearum, Neocosmospora bostrycoides, Nectria pseudotrichia and Cytospora viridistroma causing avocado dieback in Brazil and worldwide. Identifying emerging pathogens that cause losses is crucial for avocado-producing countries with different climatic conditions, as it helps understand the geographic distribution of these phytopathogens and the conditions that favor their development.