Characterization and Biological Characteristics of Alternaria, Botryosphaeria, Pestalotiopsis, and Trichothecium Species Associated with Postharvest Loquat Fruit Rot in Yunnan, China

Postharvest diseases caused by various fungal pathogens pose a significant threat to fruit quality, storage, and market value, making their identification and biological characterization essential for effective management strategies. This study examines the morphological and phylogenetic characteristics of <i>Alternaria</i>, <i>Botryosphaeria</i>, <i>Pestalotiopsis</i>, and <i>Trichothecium</i> species associated with loquat fruit rot in Yunnan, China. In May 2023, fruit rot of loquat in Yunnan, China, was classified into four types: ring rot, brown spot, black spot, and soft rot, with incidence rates of 4%, 6%, 6%, and 12%, respectively. Based on morphological features and molecular approaches, two strains of <i>Botryosphaeria</i> were identified as <i>Botryosphaeria dothidea</i>, which causes ring rot. Three strains of <i>Trichothecium</i> were identified as <i>Trichothecium roseum</i>, which is responsible for the brown spots. Three strains of <i>Alternaria</i> were identified as <i>Alternaria alternata</i>, which led to the appearance of black spots on the leaves. Similarly, two strains of <i>Pestalotiopsis</i> were identified as <i>Pestalotiopsis kenyana</i>, which causes soft rot. All identified species were verified to induce harvest loquat fruit rot by validating Koch's postulates. This is the novel report of <i>B. dothidea</i>, <i>T. roseum</i>, and <i>P. kenyana</i> inducing postharvest fruit rot on loquat in Yunnan, China, and globally. It is also the first evidence that <i>A. alternata</i> causes postharvest fruit rot and gray leaf spot on loquat in Yunnan, China. The virulence differed among species, even within isolates of the same species. Additionally, the effect of temperature on the pathogenicity of <i>A. alternata</i> on loquat leaves was more than humidity. These findings enhance our understanding of the fungal pathogens affecting loquat fruit in the study area and highlight the importance of effective management strategies to minimize fruit rot. Further research is needed to investigate the ecological impacts of these species and potential control measures in agricultural practices.