Abstract:This study aimed to analyze the inhibitory effect of Ginkgo biloba exocarp extract（GBEE）on Alternaria alternata in apples.The active components of G.biloba exocarp were extracted by alcohol extraction and water extraction，and the inhibitory effect of GBEE on A.alternata in apples was determined by the method of mycelial growth rate to investigate the effect of ethanol extract of G.biloba exocarp on spore germination and germ tube elongation of A.alternata in apples.The inhibition behaviors were further studied by measuring the electrical conductivity，the amounts of protein and nucleic acid released，the degree of cell membrane damage，and the activity of resistance-related enzymes.The bacteriostatic effect of GBEE was concentration-dependent.The bacteriostatic rate of water-soluble extract at 1 200 mg/L reached 16.94%，and that of alcohol-soluble extract at 1 200 mg/L reached 61.39%，about 3.6 times that of water-soluble extract.The alcohol-soluble GBEE increased the permeability of the cell membrane of A.alternata in apples，intensified the degree of membrane lipid peroxidation，elevated the content of malondialdehyde and H2O2，promoted the leakage of intracellular nucleic acid and protein，and inhibited the activity of resistance-related enzymes.No cell wall compartment was observed in A.alternata in the ethanol extract group by the light microscope.The bacteriostatic effect of the ethanol extract was superior to that of the water extract，which was achieved by destroying the cell membrane integrity of A.alternata in apples and inhibiting the activity of resistance-related enzymes.