Identification of the Fungus Causing Strawberry Leaf Spot Disease and Screening of Fungicides

ABSTRACT

Strawberry ( Fragaria × ananassa Duch.) is an economically important fruit crop widely cultivated in China, yet its production is frequently constrained by fungal diseases. During field surveys in Xinjiang, symptoms of an unreported brown leaf spot were observed on strawberry plants. This study aimed to identify the causal agent, characterize its morphology and phylogeny, and evaluate its sensitivity to commonly used fungicides. Fungal isolates obtained from symptomatic leaf tissues were subjected to morphological observation and multilocus phylogenetic analysis based on the internal transcribed spacer (ITS) region, the large subunit ribosomal RNA gene (LSU), and the second‐largest subunit of RNA polymerase II ( rpb2 ). Pathogenicity was confirmed through inoculation of healthy strawberry leaves following Koch's postulates. Fungicide sensitivity was assessed by measuring mycelial growth inhibition on amended media. The pathogen was identified as Truncatella angustata , representing the first report of this species causing leaf spot on strawberry in China. Among the fungicides tested, 40% difenoconazole·pyraclostrobin SC, 25% difenoconazole·pyraclostrobin WG, 30% azoxystrobin·pentaconazole SC and 25% pyrimethanil SC exhibited the strongest inhibitory effects on mycelial growth. These findings provide a basis for accurate diagnosis and targeted management strategies for this emerging strawberry disease.