Molecular identification and disease management of false smut disease (Graphiola phoenicis) on date palms grown in Türkiye

The date palm (Phoenix dactylifera L.) is a significant ornamental tree in Turkey, commonly found in homes, hotels, and public gardens. This study aims to provide comprehensive new information on the fungal disease affecting date palms, the leaf spot pathogen Graphiola phoenicis, known as false smut or Graphiola leaf spot, and disease control for date palms. The symptoms characteristic of false smut disease were observed in some date palms in Adana, in 2020-2021. The symptoms included abundant cup-shaped, black fruiting structures (sori) sides of the auricles and rachis of fronds. Whitish filaments with attached powder yellow spores emerged from the black body. Furthermore, molecular analysis of Graphiola phoenix was performed based on internal transcribed spacer (ITS) and large subunit ribosomal DNA 28S (LSU-rDNA) gene region. The accession numbers given by NCBI for Graphiola phoenix ITS are PQ060144.1 and PQ060145.1, and the accession numbers for LSU-rDNA are PQ060146.1. Under field conditions, four fungicides were assessed for their capacity to manage Graphiola leaf spot. The 2-year trial data showed that 26.7 % boscalid + 6.7 % pyraclostrobin (90.40% - 88.48%) was the most effective in controlling false smuth. G. phoenicis was observed on date palms in Adana. The presence of this fungus in Türkiye has been reported for the first time, and this study is the first report of molecular characterization of Graphiola phoenix and its presence in Turkey has been reported for the first time.