First Report of Penicillium olsonii Causing Leaf Blight Disease on Petunia in China

Petunia hybrida is an ornamental plant widely cultivated in China, boasting high ornamental and economic value. In June 2025, in Zhanjiang City, Guangdong Province, symptoms of blight disease were observed on Petunia hybrida plants in the plant growth chamber of the laboratory at Lingnan Normal University. To identify the pathogenic fungus, samples were collected from the diseased leaf tissues, and strains were isolated and purified using Potato Dextrose Agar (PDA) medium. For molecular identification, the genomic DNA of the strains was extracted, and PCR amplification and sequencing were performed using the primer pairs ITS1/ITS4, ITS4/ITS5, and LROR/LR5. Combining the morphological characteristics and sequence analysis results, the strain was confirmed to belong to the genus Penicillium and was identified as Penicillium olsonii.