Inhibition of Botrytis cinerea spore germination and mycelia growth by frequency-specific sound

The effect of sound waves on mycelial growth of Botrytis cinerea was investigated to explore whether frequency-specific sound could be used as a practical alternative to chemical fungicides to control plant diseases. The fungus was exposed to wave frequencies ranging from 1 to 5 kHz, and then observed using light and scanning electron microscopy to assess changes in several physiological and morphological aspects. Of the frequencies tested, 5 kHz sound wave significantly inhibited mycelial growth and spore germination. Furthermore, morphological changes, including low mycelial density, swollen mycelial tips, and irregular mycelial surfaces, were observed. Most internal hyphae were empty, and the ends of hyphae were significantly thinner or swollen. These observations suggest that 5 kHz sound waves create stressful growth conditions for the fungus, which leads to the inhibition of mycelia growth and spore germination. It is possible that sound wave treatment could represent an environmentally-friendly alternative to chemical fungicides. These results broaden our knowledge regarding the effective management of noxious nectrotrophic fungal pathogens by a nonchemical approach.