First report of stem gray blight on Hylocereus megalanthus and Hylocereus polyrhizus caused by Diaporthe arecae in Brazil

February 26, 2024 | Plant Disease |

Conducted by Universidade Federal do Ceará, Brazil, this study investigates stem gray blight symptoms observed on two dragon fruit species, Hylocereus megalanthus and H. polyrhizus, in Fortaleza, Ceará, Brazil. The disease incidence reached 100% in the orchard. Symptoms began as yellowish to dark-brown lesions, progressing to grayish lesions with small black pycnidia. Isolation and identification of the causal agent were performed, resulting in two monosporic isolates identified as Diaporthe arecae based on morphological and molecular analysis.

Morphologically, the isolates exhibited characteristics similar to Diaporthe sp., with alpha and beta conidia conforming to the description. Molecular analysis confirmed their identity as D. arecae through sequencing of beta-tubulin (TUB2) and translation elongation factor 1-alpha (TEF1) genes. Koch’s postulates were fulfilled, demonstrating the pathogenicity of D. arecae on both dragon fruit species. This marks the first report of D. arecae causing stem gray blight on H. megalanthus and H. polyrhizus in Brazil, expanding the knowledge of this pathogen's distribution and host range.

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