A new species of Calonectria causing rot on ripe strawberry fruit in Brazil

Abstract

A major problem in the strawberry production chain is the occurrence of fruit rot caused by fungi, thus, accurate identification of the pathogens associated with these rots is important for suitable management of diseases. During an assessment of postharvest diseases of strawberry plants, a rot caused by Calonectria was found. The surface of the infected fruits showed a slight leakage of liquid and the presence of mycelium with clearly defined hyphae containing a mass of conidiophores and conidia. Morphological examination was performed on isolates derived from single germinated conidium cultures, and phylogenetic analyses of four DNA loci (β-tubulin, histone H3, elongation factor and calmodulin) was undertaken. In order to confirm the pathogenicity, strawberry fruits and plants were dipped or sprayed with a conidial suspension. Strawberry fruits showed rot symptoms similar to those initially observed, and the plants developed leaf spot symptoms. The fungus was successfully reisolated from the infected tissues. Based on morphological and phylogenetic analysis, the fungus was shown to be distinct, and is described here as Calonectria fragariae sp. nov. This finding provides additional information for the better understanding of strawberry diseases in Brazil, enabling the development of more effective strategies of management of these diseases.