First report of Biscogniauxia mediterranea causing cankers on almond trees (Prunus dulcis)

Abstract

Biscogniauxia mediterranea is the causal agent of charcoal disease in Quercus suber, the main species of the dynamic ecosystem, known as “Montado”, in the Alentejo region, Portugal. In the last years, almond orchards have been introduced in this region due to water availability through the Alqueva dam and the possibility of mechanical harvest. The high-density planting associated with mechanized harvesting and irrigation systems observed in these new orchards can potentiate the appearance of new diseases. In a survey conducted in March 2022, symptomatic diseased trees from Soleta and Vairo cultivars were detected in Beja, Portugal. From this material, we have isolated numerous cultures and could identify B. mediterranea from all individuals analyzed by molecular and morphological techniques. Pathogenicity tests were performed in almond plant material and successfully reisolated from lesions, confirming Koch’s postulates. Phylogenetics analyses demonstrated the similarity between our sequences and sequences from Quercus suber worldwide. To our knowledge, this is the first report of B. mediterranea causing diseases on almond trees (Prunus dulcis) in Portugal and worldwide.