Antifungal Activity of Artemisia capillaris Essential Oil Against Alternaria Species Causing Black Spot on Yanbian Pingguoli Pear in China

Black spot is currently one of the most widespread diseases affecting Yanbian Pingguoli pears (<i>Pyrus pyrifolia</i> cv. 'Pingguoli'), resulting in significant economic losses for fruit farmers. It is mainly caused by infestation by the fungal group of <i>Alternaria</i> species. To date, no research has reported the presence of <i>Alternaria</i> species and the pathogen of black spot disease on Yanbian Pingguoli pears in China. This study isolated, identified, and performed molecular profiling of 124 <i>Alternaria</i> strains collected from 15 major growing areas of Yanbian Pingguoli pear (more than 5000 trees). Moreover, the study evaluated the ability of <i>Artemisia capillaris</i> essential oil (AcEO) to suppress the mycelial expansion of <i>Alternaria</i> pathogens and conducted comprehensive chemical profiling. Overall, 124 pathogenic fungi were identified as <i>Alternaria tenuissima</i> (67 isolates, 54.0%) and <i>A. alternate</i> (57 isolates, 46.0%). AcEO showed a strong inhibitory effect on the two <i>Alternaria</i> species, with a minimal inhibitory concentration (MIC) value equivalent to 5.0 μL/mL. Eucalyptol, 2,2-Dimethyl-3-methylenebicyclo [2.2.1] heptane, (-)-alcanfor, and β-copaene were identified as the predominant bioactive components of AcEO. AcEO demonstrated concentration-dependent inhibition of the mycelial growth of <i>A. tenuissima</i> and <i>A. alternata</i>. These findings position AcEO as a promising candidate for developing sustainable fungicides to combat <i>Alternaria</i>-induced crop losses.